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Dnnglison's American Medical Library.
RESEARCHES.
/  PHYSIOLOGICAL AND ANATOMICAL.
BY
       V
JOHN DAVY, M.D. F.R.S.
  ASSISTANT IXSPECTOR OF ARMY HOSPITALS.
■ "       ■ >

         PHILADELPHIA:
PUBLISHED BY A. WALDIE, 46 CARPENTER STREET.
             1840. 
J)JLLSr 
PHYSIOLOGICAL  AND  ANATOMICAL
RESEARCHES.
                              i,


AN ACCOUNT OF SOME EXPERIMENTS AND OBSERVATIONS ON THE
                           BLOOD.

   Many of .the following observations and experiments were con-
tained in  my inaugural dissertation on the blood,  under the  title
of Tentamen. experimentale quondam de Sanguine conplectens,
written on the occasion of graduating, in 1814.
   The views taken rtf the composition of the blood which I then
adopted, and have not yet seen any reason, founded on facts, for
relinquishing, were at that  time, I believe I may say, commonly
taught in  the schools,  at least in Edinburgh, and received as well-
substantiated  doctrines, resting chiefly on  the researches of the
great physiologists of our own country, and especially of Hewson.
   In making this  remark,  of course 1 allude  to the general  and
broad views of the subject; not to details  and special views de-
ducible from  particular experiments, to which,  considering the
nature of  the blood,  and the accumulated experience of ages rela-
tive to the investigation of its properties,  there seems to be hardly
any limit: at least, we cannot at present discern the limit.
   One  of the  distinguished  physiologists  of the 17th  century,
Lower, in  the dedication of his very original work,  De corde,  item
de Motu et Colore Sanguinis, appears to have thought it necessary
to offer some apology to his friend for writing on such a topic: —
"Mirabuntur alii,  forte et  ipse  miraris, vir ornatissime, de corde et
sanguine  post viros celebres, qui materiam  hanc non tantum trac-
tasse sed et exhausisse videantur, a  mequicquam amplius proferri."
How different is the feeling now; instead of exhausted, the inquiry
seems, fiiiimanly speaking, rather inexhaustible.
       9—d                                     1 dav 
4
davy's researches.
1.— Observations to endeavour to determine whether any heat is
             evolved by the blood in  coagulating.

  Although the remarkable property of coagulation which the blood
possesses  has  been laboriously and carefully  investigated, yet, it
must  be confessed, we know but  little  respecting it; it is still one
of the many mysteries of nature.   The little we know on the sub-
ject, appears to be chiefly this,—that the phenomenon depends on a
portion of the  blood, its fibrin, from being liquid, becoming solid,
and from being generally diffused  in uniform mixture, approximat-
ing and collecting in a mass, entangling the red particles and in-
cluding a portion of the serum.
  Now, as generally, during the conversion of liquids into solids,
the mere  change of form  is connected with a disengagement of
heat, it might,  perhaps, a priori, be expected, that a disengagement
of heat  would  be witnessed during the  occurrence of the phenome-
non in question.
  Fourcroy has  stated, that the effect of the blood's coagulation is
attended with an elevation of several degrees of the  thermometer.1
Mr. Hunter, on  the  contrary, from his own experiments, inferred
that no heat is evolved on the occasion.  The experiments,  from
which he deduced his conclusion,  "that in the coagulation of blood
no heat  is formed," were  made  on the bl^od  of a comparatively
cold-blooded animal, the turtle.2   Notwithstanding the high autho-
rity of the inquirer,  and  the very favourable circumstances under
which his observations were made, his experiments have not  been
considered entirely conclusive.   Dr. Thomson  and the late Dr.
Gordon, from their own observations, were averse from his opinion,
and rather favoured  that of Fourcroy—induced to do so,  as stated
by Dr. Gordon, in his Lectures on Physiology, from witnessing th&
process of cooling of the  blood either retarded or quite interrupted^
at the time of coagulation.
  The consideration of these discrepancies induced me to enter on
the inquiry;  and I  shall now describe some of the experiments
made in carrying it on.
  The subject of the first trials was the mixed venous and arterial
blood of lambs.   It  was  received from the- divided  vessels into a
thin glass bottle of the capacity of eight and a half ounces of water.
The bottle was  quickly  filled,  and when full, closed with a per-
forated cork holding the projecting stem of a delicate  thermometer,
the bulb of which reached the middle of the vial.

                        Experiment  1.

The temperature of the blood the instant it was drawn   -  104°
After 1 minute }      , ,.   ,              -       -      103 5
      o       > coagulation beginning                    ino r
1 Ann. de Chimie, vii. p. 147.       2 Treatise on the Blood, &c. p. 28. 
EXPERIMENTS ON the blood.
5
Afte	r 3	minutes
>;	4	)>
»	5	J3
!)	6	))
)3	7	••I
J)	8	>>
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	15 20	51
                                                      102-5
                       .....102-5
                                                      102°
                       .....101-75
                    .....1015
                                                    -  101°
                    .....100-5
                                                    -  100°
                    .....97-5
                       .....950

  This  experiment was made  in  the open  air in fine weather in
summer, in the neighbourhood  of Edinburgh, when the thermome-
ter in the shade was 67°.   The following experiment was made at
the same  time:  it differed principally from the preceding in two
circumstances, viz. in the vial  being left open,  and in the bulb of
the thermometer being near the surface of the fluid.

                        Experiment 2.
Temperature of  blood when drawn      ...  103°
After 1  minute       ....      -     103°

     o  [ coagulation commencing       -       -      -  103°
     4  minutes      -----     103°
     5    „-----      -  102-75
     6    „  -      -      -      -       -       -     102-5
     7    „-----      -  102°
     12    ,.----       -              99°
     17    „-----      -    965
   At first view, the temporary  pause in the cooling of the blood in
these two experiments, just after the commencement of coagulation,
would  seem  to indicate an  evolution of heat, commensurate with
the arrested cooling effect: but, as the result may be owing to other
causes,  this conclusion, however specious,  may be erroneous.  It
appeared to me, therefore, advisable to repeat the above experiments
on  cooling, as accurately as  possible, substituting  water for the
blood.   I thus reasoned:  if the results in regard to the rate of cool-
ing of the blood and water should be similar, the thermometer being
stationary for a time, must depend on some other cause than coagu-
lation ;  on the contrary, if the fall of the thermometer in the cooling
water should be regular and uninterrupted, the pause in the instance
of the  blood  might fairly be attributed to and accounted for by a
certain  degree of heat evolved.

                        Experiment 1.

Temperature of water on admission     -        -      -   102°
After 1 minute       -       -      -      -      -     102° 
6
davy's researches.
After 2 minutes  -
  u  &   »
 - »  ^   M
     Q
  »  v   jj
Temperature of water
After 1 minute
  »   2   „
  »>   3   „   -

  »   5   „   -

                        Experiment 3.

  The bulb of the thermometer immersed in the warm water in
the middle of the bottle being at 100°, was suddenly thrust  to the
bottom; it immediately rose to 102°.

  These comparative results  are manifestly not  in favour of any
heat being evolved during the coagulation of the blood; from them,
it appears most probable, that  the pause in the descent of the ther-
mometer is  rather owing to a disengagement of heat,  from the
warmer bottom  of the vessel and the deeper fluid.
  With  the hope of removing all doubt on the point at issue, the
following experiment was instituted.  To guard against rapid cool-
ing,  chiefly the  effect of exposure to the air, the bottle for receiving
the blood was enveloped  in a large quantity of fine wool, which is
one of the worst conductors of heat; a thermometer, as before, was
introduced into  the middle, through a cork, and the vessel was filled
with warm water  of the  temperature  10S°.   Thus prepared, the
carotid artery of a lamb  was  divided;  the bottle was emptied of
water, and as soon as possible filled with arterial blood.  The ther-
mometer immediately stood at 104-5; it was thus stationary during
five minutes; and even after twelve minutes it had fallen only half
a degree.
  From these results generally, it appears to me,  the conclusion is
unavoidable, that  little or no boat is evolved from the blood, as the
effect of coagulation.   If it be asked, is this an exception  to the
general rule, before announced,  I would  answer that it is not. It
was before observed, that what is commonly called the coagulation
of the blood, is merely the coagulation of one of  the ingredients of
this fluid, viz. the fibrin,  which constitutes only a very small  part
of the whole mass;  for instance, in the blood  of  the lamb, it does
not exceed 2 per cent, as  I have ascertained by experiment.  More-
over, it is worthy of remark, that though the coagulation commences
suddenly, and is apparently rapid, yet the contraction or condensa-
tion depending  on the coalescing of the sohd particles,  is slow;
Experiment 2.
102°
10L-5
101°
 99°
106-5
106-5
106-25
105-75
105-25
104-75 
experiments on the blood.
7
requiring many hours for its completion.  All these circumstances
considered,  even admitting the law referred to,  how small should
be the degree of heat evolved in accordance with it, during the act
of coagulation !   So small,  indeed,  that it  can hardly be admitted
to be cognisable by our senses;  its detection, 1 must confess, would
appear to me almost miraculous.
   In confirmation of this conclusion,  I  shall give some  additional
facts  on the subject, which I had  an opportunity of collecting in
1816, on my voyage to Ceylon, in  experimenting on the blood of
the turtle and shark.
   On the 15th of March, when our ship was  in  latitude 4°  9'  N.
and longitude 19° 15' W. by chronometer, at sunset, a large shark
was taken by means of a harpoon.   As soon as it was  brought  on
board, while it was yet alive, it was cut in two.  The blood flowing
from the greek dorsal vein was 82°;  the  surrounding thick muscles
were  82-5, the water of the sea was 805, and the air  79°.   Some
of the blood was collected in a glass vessel.  In about two minute's
it had  firmly coagulated.  During the whole time I watched  the
thermometer immersed  in it.  The mercury sunk from  815 to 8L°;
it did not rise at the instant that the coagulation commenced,  nor
did it remain stationary whilst the  coagulation was  going on,  but
continued gradually sinking.
   The  day following another shark  was taken.  The same experi-
ment  was made with the blood, and a similar result was obtained.
   On the 23d of March, when in latitude 2° 29' S. and in longitude
24° 30' W.  a large turtle was killed, which had been caught about
three weeks before at the island of Ascension.   The air at the time
was 79°; the blood of the turtle, flowing from the carotids, was 91°.
When collected in  a tumbler it was 885. The thermometer placed
in the midst of it immediately began to  fall, and  continued  falling
gradually, without any sensible interruption, whilst the  blood was
coagulating.1

  1 On this subject I made,  in Ceylon and Malta, some additional experi-
ments.  Bearing date of Colombo, May 4th, 1817, is  the following note,
which I shall transcribe verbatim. " Testudo Mydas—about 50 lbs. weight—
caught yesterday; thermometer in recto 84-5; stream of arterial  biood flow-
ing;;tro.m the divided carotids 85°; temperature of air 66°.
  "Made three experiments with the blood to ascertain, under such favour-
able circumstances, whether any heat is  evolved during the coagulation of
the blood.  The general results proved decidedly that there was  no sensible
heat evolved.
  " The blood, as it flowed, was 85°; collected in a glass vessel it was the
same; it coagulated in about a minute,—still no change; in about two mi-
nutes  the coaguluni was firm,—temperature  still  the same.   In about  half
an hour  the blood had acquired the temperature of the air, which was then
87°."
  And another, bearing date of the 23d October, 1819.—"A large green turtle
was brought to me this morning.  The great vessels of the neck were imme-
diately divided. A wjne glass was, quickly filled with arterial blood : a ther-
mometer in it rose  to. 82° (air at  the time  79°);  in. two minutes  it  was 
8
davy's researches.
  These results were inserted  in a paper published  in the second
volume of the Journal of (he Royal Institution, with some others,
in reply to Dr. Gordon.   This gentleman, about eighteen months
previously, had endeavoured  to support his original opinion by  fur-
ther experiments, an account  of which appeared in Dr. Thompson s
Annals of Philosophy.   I shall  add  my remarks on them, believing
that they  may help to explain the effect, in accordance with what
I witnessed.
  The difference between the results of Dr. Gordon's experiments
and my own arose, perhaps, from the different modes in which our
experiments were  made.  Dr. Gordon, I believe, kept the bulb of
his  thermometer near the bottom of the vessel containing the blood —
and when this fluid began to coagulate towards the surface, he drew
the instrument up.   On  the contrary, in all my latter experiments,
viz. those on the  blood of the shark  and turtle,  and many which
were  made on  the blood of sheep at the Cape of Good Hope, the
thermometer was  not allowed to  remain stationary—it was gently
moved from one part to another,  so that the whole  might be kept
of  the same temperature, till  the  coagulation  commenced;—for
when  the  blood is viscid and  the  vessel deep, the  surface  or the
portion last drawn  is warmer than  that below—and  when shallow,
the bottom is warmest, as I have frequently observed in my experi-
ments.
  Further,  in confirmation of  the  conclusion that  no appreciable
degree of heat is  noticed during the coagulation of blood—I may
mention, analogically, the fact, that when the serum of the blood is
coagulated by  means of dilute  nitric acid,  there is not the slightest
elevation  or change of  temperature.  The following are  the  par-
ticulars of an experiment in proof of this.  An ounce of serum was
added to an ounce of dilute nitric acid, each  of the  temperature of
the air of the  room, viz. 75°; coagulation  was  immediately  pro-
duced, but not the slightest change of temperature was occasioned;
the mixture was exactly 75°.  The  dilute nitric acid  used contained
five parts of water to  one  of  strong acid.   The  serum employed
was of specific gravity 1030;  and  when slowly evaporated to dry-
ness,  an ounce of  it afforded a  brittle translucent  residue,  weighing
367 grains.   It was procured from the blood of a patient labouring
under a tedious chronic disease;  which blood was only of specific
gravity 1-047; and an ounce of it afforded  2 4 grains of dry fibrin.
coagulated slightly—thermometer still 82°; in five  minutes it had coagulated
firmly—thermometer 81°.   A very delicate thermometer was used."
  At  Malta, a similar trial was  made on the 21st December, 1838, on the
 blood of a  turtle, which had been kept  about two  months  in water, without
 eating, and yet was active.  The temperature of the  water was 58°, and
 that of the air of the room 60°, two hours earlier it was 5S°; the blood of
 the turtle, flowing from the great vessels'of the neck (the jugular veins ;ind
 carotid arteries) was 58°.   It was  collected in cups, and, in about half an
 hour, was firmly coagulated.  During this  lime, whilst the coagulation was
 taking place,  I tried, repeatedly,  the temperature of the  different portions
 with a delicate thermometer, but could  perceive no change. 
experiments on the blood.                9
  The inference  from this fact, reasoning analogically, seems to
me unavoidable, viz. that it  is highly improbable  any heat can be
given off, during the coagulation of the blood, in which so small a
quantity of matter becomes solid, and that slowly—since  not the
smallest degree is evolved during the coagulation of serum, when
so large a quantity of matter, so similar to fibrin in its nature,  is
solidified, and  that suddenly.
  I would  remark, in conclusion, that as regards the general rule
before referred to, of change of temperature with change of form—
it has so  many exceptions,  that no  reliance can be  placed on it.
Every instance requires to be specially considered and determined
experimentally.   Thus, contrary to  rule, theoretically considered,
all the detonating compounds, whether they contain oxygen or not,
emit  heat in the act of explosion, and of conversion entirely, or in
part,  into  the state of an  elastic fluid;  thus, carbonic acid, when
expelled from  lime  by dilute  muriatic acid, is converted from the
solid  to the gaseous state, without any change of temperature; and
thus, further, when ammoniacal gas and muriatic acid gas combine,
they form a solid salt, without the slightest disengagement of heat.

2.— Observations to determine whether there  is any well  marked
  difference, in point of  time, in the coagulation of venous and
  arterial  blood, and in the degree of contraction accompanying it.

  To endeavour to determine the first question, the following ex-
periments were  made in Edinburgh, during  the summer of 1811,
on  the*blood  of  lambs.   The  two  kinds of blood compared were
taken from the same animal—one from the jugular vein, the other
from the carotid artery; and each  was received  in a glass vessel,
either the  same or  similar, of about three ounce capacity.   The
thermometer in the open  air, where the experiments were made,
stood at 70°.
  1.  Venom? blood;—in four minutes  there was a commencement
of coagulation; in six it was firmly  coagulated.
  Arterial  blood;—in half a minute it had begun to coagulate;  in
two minutes it was firmly coagulated;  and in three, there was a
distinct separation of serum.
  2.  Venous  blood;—in two  minutes  there was a commencement
of coagulation, and in two and a half, it was firmly coagulated.
  Arterial  blood;—its coagulation commenced as it flowed from
the vessel; in a minute it was firmly coagulated.
  3.  Venous blood ;—in two minutes it was slightly coagulated.
  Arterial  blood;—in one minute it was firmly coagulated.
  From these experiments  and others, the results of which were
similar, and which, therefore, it is unnecessary to describe,  it ap-
pears that  arterial  blood  coagulates  with  greater  rapidity than
venous. 
10
davy's researches.
  Relative to the  degree of contraction attending the coagulation
of each kind*of blood—it was unquestionably greatest  in  the in-
stance of arterial; the difference  of appearance was so distinct,
measured merely by the eye,  that  there could  be no mistake.   In
every comparative tria^ after many hours,  the venous  blood was
found softer and less contracted.

3.— Observations  on the degree of coagulability of the first and
        last portion of blood from a slaughtered animal.

  Mr. Hewson observed that blood which flows last from a slaugh-
tered  animal coagulates more readily than that which flows first.1
Mr. Hay,  in his  work on the blood, inferred  the  contrary from his
own experiments.2  The  trials  which I  have instituted  on this
point, using the blood of the lamb and sheep, perfectly accord with
those  of Hewson.   I shall  give  a  few  of  the  results.  The same
glass vessels were employed to collect the blood in  as before.  The
temperature of the air was 68°.   In one  vessel, the blood which
first gushed out, on the division of the great cervical vessels, was
caught—and,  in another similar, that which flowed just before the
animal expired.

  1. On  the  sheep.—The blood  which  flowed  first was firmly
coagulated in  two  minutes; but that which flowed last, in half a
minute.

  2, 3,  and 4.—In three experiments on  lambs, the results were
perfectly similar; the first  portion  coagulated  in one minute;  the
last in half a minute.

  It is not easy to reconcile  these results, and those of Hewson,
with Mr. Hay's.  His, perhaps, may be held as  exceptions.  The
two former  at least show  that  in certain cases,  the blood which
flows from an  exhausted animal possesses an unusual proclivity to
coagulate: and if  consequences  are attended  to, it is  difficult  to
avoid  considering  it,  whatever may be  its caus<>,  as a happy pro-
vision of nature to aid in arresting  hemorrhage.


4.— Observations on the specific  gravity of the different parts of
 the blood—viz. the serum,, coagulable lymph, and red particles.

  Mr. Hunter, from a few very simple experiments, arrived at  the
conclusion, that of the different constituent  parts of the blood,  or
those  in  which it  is  resolvable when  abstracted from  the vessels,
the  red  particles are  of the greatest specific gravity, the serum of
least,  and the coagulable lymph  intermediate.  That the red par-
ticles  are  as he  considers  them, is now universally admitted :  but
it has been more than doubted by one inquirer, that  the serum  is

  ' Hewson on the Blood, p. 62.            2 Hay on the Blood, p. 26. 
EXPERIMENTS OS THE BLOOD.
11
lighter than the lymph;1 and by another,  that there Js any differ-
ence of specific gravity between them.2
  I have repeated the experiments,  on the results of which  Mr.
Hunter founded his conclusion, and  I have no hesitation in adopt-
ing it entirely.  In every  instance in  Which,  according  to his
method,  I  have immersed coagulable lymph in serum, I have in-
variably seen it sink, unless buoyed up by adhering particles of air.
  The specific gravity of the different parts of the blood is probably
variable within certain limits, as is the specific gravity of the blood
itself, even within  the limits of health,  according to a variety of
circumstances, which it  may be difficult to enumerate, and much
more to appreciate, connected with age,  sex, climate, diet, &c.
  I shall not in this  place endeavour to determine what  may be
considered the standard specific  gravity, either of  the blood itself,
or of its serous or fibrinous parts.  To accomplish this, a very wide
comparison of accurate observations would be required,  beyond
my reach ; and which, I fear,  in  the present state of our know-
ledge, is hardly practicable.
  FYom the results of  the experiments which I have had  an oppor-
tunity of making on healthy serum, and which will be individually
given hereafter, I may state that I have  found it  to vary between
1020, and  1031.
  The trials which I have  made of the specific gravity of coagu-
lable lymph or fibrin have been comparatively few in number.  I
can  find mention of three only in my note-books.  In the 1st, it
was found of specific gravity 1046 ;  in the 2d of 1057 ; and in the
3d, 1060.  The  first  was procured from blood  not  buffed ;  was
separated  by  washing with water, and the fibrin or lymph  thus
obtained, was weighed after having been gently pressed between
folds of blotting  paper.   The second  was a fibrinous concretion
from the heart, free from colouring matter; it was weighed  without
having  been  subjected to the action of water, after  having  been
gently pressed in blotting paper.  The third was a portion  of buffy
coat; it was weighed  after  having  been  well washed with water,
and  the  excess  of moisture  removed, as  in the two preceding
instances, by  paper.
•   M.y,experiments on  the specific gravity of the red particles have
also  been  few in number.  From those on the results of which I
think most reliance can be placed, it would appear, that the specific
gravity of a red particle is about 1132, which very nearly agrees
with the estimate of Jurin,  indirectly obtained, made more than a
century ago.3  The method by which  I arrived at this result, was
by putting a minute portion of blood, less than a drop, in solutions
of  different  degrees  of strength of sulphate of soda.   In one  of
specific gravity 1090, the red particles slowly subsided:  in that  of

  1 Sir C. Scudamore.  Essay on the Blood, p. 35.
  2 Dr. Benjamin Babbage, Med. Ch. Trans, of London, vol. xvi. Part II.
p. 304.
  3 He estimated it at 1126.  Phil. Trans, for 1719. 
12
davy's researches.
the specific gravity  above mentioned, when agitated  in  it,  tneV
remained for sometime suspended, but rather inclining downwards
than upwards.   This was nearly a saturated solution at a temper-
ature of about 120°:  it ultimately deposited a considerable quantity
of crystals; but it remained without change sufficiently  long to
allow of the  trial described  being made.  This result is  perhaps
more deserving of confidence in as much as  the red particles did
not appear to be materially changed by the strong saline solution ;
under the microscope they exhibited their usual disc-like form.  .
  Relative to  the cruor,"or admixture of the red  particles  and
serum, 1 may mention one or two trials which I have made on its
specific gravity, weighing it  in the usual manner.  A mass of cras-
samentum from blood, the specific gravity of the whole of which
was  1055, and  the serum of which was 1029, was broken up and
subjected to moderate pressure in a linen bag without any addition
of water.  The liquid which  passed through, consisting  of red
particles  and a little serum, was found  to  be  of specific gravity
1074.  This cruor was next poured on a filter of cotton cloth, to
drain off as much as possible of the serum.   It was left for twenty-
four  hours covered over with  a glass receiver  to prevent loss by
evaporation.  Now weighed again, it  was found of  the increased
specific gravity 1087.  It was of the consistence of molasses;  and
was not further concentrated by being kept in a filter of very bibu-
lous  paper: the paper became saturated with it; but not a single
drop separated.                                    >
  Probably the phenomena of the buffy coat have given rise to the
idea, before alluded to, in opposition to Hunter, of the comparative
lightness of fibrin.   The  buffy coat appears on the surface of the
blood, and therefore seems naturally to suggest the idea. But when
the circumstances are inquired into, under which it forms, there is
no difficulty in  relinquishing it.
  In sizy blood, or that blood which affords a buffy coat, the serum
and coagulable lymph appear to be of greater tenuity  or less viscid
than in  blood that is  not sizy; and sizy blood is generally slower in
coagulating than blood that is not sizy, although not universally so.
When  the former quality alone  prevails,  the  buffy coat which
forms is  thin ;  when both qualities coexist, the  buffy coat is thick,
from the greater depth of the subsidence of the heavier red parti-
cles.  Now, though the fibrin of the buffy coat is of greater specific
gravity than the  serum,—the liquid mixture of coagulable lymph
and of serum,—the liquor sanguinis, as it has recently been called,
—is of less specific gravity than the liquid mixture of red particles,
serum, and coagulable  lymph, and  in consequence  the  former
becomes supernatant.   Before  coagulation takes place, it is this
comparatively  dense  fluid which supports the  liquid  fibrin,  and
when coagulation has  occurred the  substratum of  red particles
enveloped in fibrin still gives support; and, the longer the coagu-
lation is  in taking place, so much the less fibrin is mixed with the
red particles, so much the more rises  or is pressed up, and, cceteris 
EXPERIMENTS ON THE BLOOD.
1 •>
paribus, so  much the thicker the buffy coat becomes..  In healiliy
blood, on the contrary, in which the serum  and confutable lymph
are more viscid, the  red  particles  are supported till coagulation
takes place,  and then are retained, like water in a sponge, and, like
water,  may  be  expressed  from the  sponge-like  texture; or,  if in
excess, a part of them  will separate and fall down as the  fibrin con-
tracts.   This view  is  in accordance with Hunter's well authenti-
cated facts,  confirmed as above.  And,  as  another experimental
confirmation of them,  I may mention, that  when fibrin, or a portion
of buffy coat which sinks in serum, is plunged into the cruor of
blood, it rises  to the surface and floats, in  accordance with  their
respective specific gravities.
  Relative to the second  opinion, already referred to, that there is
no  difference  of specific gravity  between  serum  and  lymph, it
appears  to me inadmissible,  simply because  it is not in accordance
with facts.  The ingenious author of it seems  to found the idea
chiefly on the  circumstance of the  uniformity  of composition of
the crassamentum in  relation  to fibrin.   Granted that the crassa-
mentum is uniform in this respect, that there is no accumulation of
fibrin  towards  its  bottom,  and no deficiency of it towards the
surface, it does  not therefore follow that the fibrinous part, not even
when liquid, as coagulable lymph, is of the same specific gravity aa
the serum with which it  is  equally mixed,  and much  less  when
solid.   It might, it  appears  to  me, as well be said, that the serum
of the blood and water is each of the same specific gravity, because
they are miscible, and that  equally.  The  mere circumstance of
the  coagulable lymph and serum being  in  intimate  mixture,
appears  to me  to be quite sufficient to account  for  the fact of the
uniform composition of the crassamentum, admitting it to re so.
  Dr. Benjamin Babington has  connected the above idea with some
views  peculiar to  himself, relative to the liquid  part of  the blood,
which  I must confess do not appear to me to Le well borne out  by
the facts.  The opinion of Hewson and of Hunter  appears to me
more in harmony with them.   They considered the fluid part of
the blood an equable mixture of liquid lymph, and of serum;  both
capable  of being separated  from the  mass  of the  blood, apart, or
together, Tinder  peculiar circumstances in health and disease; the
one  spontaneously  coagulable,  the other  not.   Dr.  Benjamin Ba-
bington, on the contrary, is of opinion, that no such  fluid as serum
exists in the blood, and no such fluid as coagulable lymph;  but a
liquor  sanguinis, not capable, compatibly with health, of affording
either serum alone,  or lymph alone, and capable of being separated
ir.to serum  and lymph or  fibrin,  only when removed from the
circulation, and not under the influence of the laws of life.   And
in accordance  with this view  he  considers the denomination of
serous  membrane improper.
  If serum  was never found  in closed  cavities, without its due
proportion of lymph, (taking as a measure the albuminous part of
each.) then Phis view would  be plausible; but as this is not the case
       9—e                                     • 2 dav 
14
DAVY'S RESEARCHES.
—as serum, differing very little in specific gravity from the serum
of the blood, is not [infrequently to be found in such cavities, espe-
cially in the pericardium, unaccompanied by any lymph, (as I have
often satisfied myself,) or by the deposition of lymph in the form ot
a false membrane, the  hypothesis appears to me  untenable.   Dr.
Babington  admits the  facts I have  alluded to in the latter  part
of his^paper, where, contrary to what he  advances in the first part
of it, he has recourse, to explain them, to the ordinary doctrine of
secretion.

5._ Observations on  the  specific gravity of blood,  venous and
  arterial, of  different animals, and of different ages,  not inclu-
  ding man.

  As  a preliminary, it may be right to  mention the method  em-
ployed in the trials, the results of which are about to be given.  It
was the  same  as that now commonly used for ascertaining the
specific gravity of other fluids.  On  entering upon  the  inquiry, I
provided myself  with  a certain number of thin globular  bottles,
varying in capacity from 200 to 400  grains of water.  Each bottle
had a narrow neck, to which  was adapted by grinding a  perforated
glass-stopper, so as to admit of accuracy in filling.   The weight of
the fluid  examined was always  compared with  that of distilled
water; and trial of the latter was made as often as any  material
change of temperature  occurred to render it advisable.   In  each
instance, before making trial of the blood, it was allowed  to acquire
the temperature of the atmosphere, and then the small vacant space
in the bottle, the effect of cooling, was filled with serum.   In the
earliest experiments a balance was  used of no great  delicacy: it
was affected, however, readily by the one tenth of a  grain.  In the
latter, one was substituted which was affected by the one fiftieth of
a grain :  and in the latest of all, one still more delicate, constructed
by  Robinson, which when loaded with 600 grains,  was  turned by
an  hundredth  of a grain.
   For the sake of brevity, I shall give the results of my experiments
in a tabular form. 
EXPERIMENTS ON THE BLOOD.
15
Table I.
Showing the specific gravity of blood, venous  and arterial, of dif-
     ferent animals, and of different ages, not including man.
			Specific Gravity.						
			T3	*o	S	s	T3 C C3		
			O	o	3	3	3 -a		
Animal.		Age.	J2 3	o 3	Oj	s-O)	o o a o J2	Place.	Season.
			!s	in a	Is	in 3	> -o "3		
				o		O	a, •£		
			Ol	c	Ol	c	xs a>		
			s_	Ol		11			
	1		< 1050	> 1056	< 1025	> 1027	^ a		
Sheep		_						Edinburgh.	Summer.
<(	2	6 years.	1057	1058 1030		1030	—	u	a
ti	3	16 mths.	1049|1051		—	—	—	i(	u
u	4	u	1017!l050		—	*	—	u	<(
ti	5	3 years.	1047	1051	1019	1029	—	Malta.	(C
Lamb	1	11 wks.	1052 1055 1027 1028				—	Edinburgh.	t(
	2 3		1046 1057,1024 1054'1054 1024			1024 1024	_		
<(	4	((	1050 10531024			1024	—	it	u
(<	5	If	1047	1050	—	—	—	k	((
Horse	-	12 years.	—	1053	—	1027	—	Chatham.	Spring.
Zebra	.	—	—	1053	—	— i —		Edinburgh.	Autumn.
Ox	-	—	1058	1061	1027	1029 —		it	Summer.
Calf -	-	—	1040,1046		1022	1023 —		u	u
Dog - -	-	—	1048 1053		1022	1023 —		u	a
Pig - -	.	—	—	1060	—	—		u	u
Cat	-	—	—	1050	—	—		Chatham.	Winter.
Turkey	-	—	1061	—	1021	—		u	;t
Salmon	-					— 1051		Edinburgh.	Summer.
Holybut	-					— .1028		Chatham.	Spring.
Cod -						— 1034		u	u
Plaice	-						1032	u	it
Skate (R. batis)	-						1035	((	it
Dogfish (M.laevis)							1022	a	tf
Eel (M. l%tirostris)							1042	u	it
Frogs, males	-						1040	Edinburgh. Summer.	
   In  all the instances of the mammalia the blood taken was from
the jugular vein and carotid artery.
   All  the  animals were in apparent good  health  at the time the
trials  on the blood were made,  with  the exception of  the zebra,
which had a tumour in the nostril, and of which it died after a few
weeks.
   From the results stated in the table, it clearly appears that arte-
rial blood is of somewhat less specific  gravity than venous, and
arterial serum  than venous serum.   Taking the mean  of all the
  * In this trial, the venous blood was first received ; the arterial when the
vessels were nearly emptied.                         ••• 
16
davy's researches.
 experiments, the specific gravity of each kind of blood and serum,
 appears to be as follows :

       Arterial blood      -                         1050
           "    serum         -      -       -       1022
       Venous blood      ...       -   1053
           "    serum         -      -       -       1026

  Relative to the cause of the greater  specific  gravity of venous
 blood, it  probably  does not solely depend  on the  arterial blood's
 containing a larger proportion of water ; it probably depends partly
 on this cause and partly on the venous blood containing, besides a
 smaller  proportion of  water, a larger proportion  of animal matter.
 But what the kind of  matter is, whether the coloured particles, or
 fibrin, or some other substance, as free carbon, remains to be deter-
 mined.   Independent  of this point, there seems to be little.difficulty
 in accounting for the difference, considering the many fluids which
 are secreted from the arterial  blood, and those comparatively dilute,
 and  thereby  manifestly tending to augment  the  density of the
 venous  blood.   It  was  long  ago observed by Dr. Crawford, that
 arterial blood is apparently more liquid than venous ; if so, in reality,
 which is probable,  it may be partly owing to its being more dilute,
 as indicated by its specific gravity.
  The number of experiments on the specific  gravity of the blood
 and serum of animals  of different ages is hardly sufficiently  large
to allow of any satisfactory conclusion;  they seem  to indicate that
 the blood of adult animals is of greater specific gravity than that of
 young—an inference in accordance with analogy, and which Bryan
 Robinson, one of the  ablest of the iatro-mathematical  sect,  many
 years ago deduced  from his own experiments.1
  That  the specific gravity of the blood of different animals varies,
 is manifest from the preceding table.   The difficulty is to  reply to
 the question, in what manner  the variation accords with the nature
 or species of animals.
  As the degree of density of the blood appears  to depend chiefly
 on the proportion of red particles; and as the use of  the red  parti-
cles  seems to be connected less with nutrition  than with action,
 according to the views of  Hunter,2 and more, I may add, with the'
 production of animal  heat,  than perhaps with  any other function
 it is very probable, that the  blood of birds is of greatest specific'
 gravity, (varying in degree according to the temperature  of  each
 individual, and perhaps its strength and energies,)—that the specific
gravity of the blood of the mammalia is  next,—next that of rep-
tiles,—then that of fishes,—and lastly, that of  the different classes
of animals having colourless blood, amongst which it is probable
grounded on the preceding  considerations, that the blood of insects'
will hold the highest  place.  Many things  already known favour

  1 Vide Animal Economy, p. 245.       2 Hunter on the Blood,  p. 431. 
                 experiments on the blood.               17

this view of the subject: but  still it must be considered hypotheti-
cal, until it has been fairly investigated experimentally.

6.— Observations  on the specific gravity of the blood of animals
                       blooded to death.
  To endeavour to determine whether, in the instance  of animals
blooded to death, any difference exists in the specific gravity of the
blood which  flows first, and that which flows last,—I made  a few
experiments in Edinburgh in  the  summer of 1812, the results of
which are contained in the following table:

                           Table II.
Animal.	Specific Gravity.			
	1st. Arterial blood.	2d. Arterial blood.	1st. Serum.	2d. Serum-
Sheep 1 " 2 Lamb 1 " 2 Ox I	1049 1050 1049 1051 1058	1048 1044 1046 1045 1051	1024 1027 1024 1024 1027	1023 1022 1020 1018 1021
  All these results seem clearly to show, that the blood which flows
last, when the vessels of the animal are nearly exhausted of their
fluid contents, contains a diminished quantity of animal matter, or
an  increased quantity of the aqueous part.  And that the difference
of specific gravity is mainly owing to the latter, rather than the
former cause, may be inferred  from the circumstance, that there is
not a greater difference in  the  specific  gravity of the blood before
the separation of the serum, than in the serum  itself.  Whence it
may be asked, is this dilution of the blood, this augmentation of its
watery part? Does it depend on increased activity of the absorbent
vessels, in connection with an undue langour of the terminal secern-
ing arteries? or solely on the debility of the latter, the action of the
former remaining neither diminished nor altered? It appears to me,
that the latter supposition  is most probable, and is most accordant
witb^he general doctrines of pathology and therapeutics.1  I know
not whether  the results obtained  by Mr. Hay, will bear the  same
interpretation.   He,  from  his  experiments,  inferred that  the last
portions of blood  which flowed  contain less serum than the first, in
the  ratio of 28.8 to 55.8.2   But  his results  are defective, inasmuch

  1 It may be owing to an unusual  flow of the contents of  lymphatics into
the  circulation, as the blood Hows out: the  lymph certainly  is of much less
specific gravity than the blood,—whether spontaneously coagulable as Hew-
son  found it, in different instances  in  which he examined it, or only coagu-
lable by heat, as 1 have occasionally found it in the lymphatic vessels of the
spermatic cord of the bull.
  * Op. cit. p. 28. 
18
davy's researches.
as he did not determine the specific  gravity of the serum, merely
the quantity of it which separated in  the act of coagulation.   The
crassamentum of the blood, as already observed, and as is now gene-
rally  admitted, consists of red particles, serum and  fibrin,—the
serum contained or held  in  the interstices of the fibrin as in  a
sponge;  and consequently, the softer the fibrinous mass is, or the
less contracted,  so  much  the  more serum  it must hold.   These
remarks apply to the deductions of  Mr. Hay :  the argamentum ad
absurdum is also applicable to them;  for by adding water to the
blood before coagulation, the volume of the  coagulum is increased,
and the separation of fluid  from it is diminished : therefore the infer-
ence from the quantity of serum, independent of its specific gravity,
is of no weight in this question.

7.— Observations on  the  specific  gravity of human blood and
               serum in instances of disease.

  The following observations were made at three different periods,
viz. in the years 1811-12,  in Edinburgh ;  in 1818-19,  at Candy in
the island of Ceylon,  and  in 1826-27, in  Corfu.   As both the cli-
mate and the circumstances affecting the condition of the individuals
were very different, 1  shall give the results obtained at each period,
in a table apart.
  In these instances the same precautions were taken in ascertain-
ing the specific  gravity of the blood as in the former: and, I may
add, that the blood  from which the serum  was collected  for  trial,
was kept so as to prevent evaporation, either in a bottle and corked,
or defended by a cover if  in a bleeding-cup.  The necessity of this
to insure  accuracy  is obvious: if the air have free access to the
surface of the blood, a portion of the  aqueous part will necessarily
be carried off by evaporation, and the specific  gravity of the serum
will be augmented. 
EXPERIMENTS ON THE BLOOD.
19
1.— Table showing the specific gravity of blood and serum in
               instances of disease in Edinburgh.

                          Table III.
Age
and
Sex.
Women.
30 years
25 "
24 "
22 "
26 "
40 "
27 "
Ditto
17 "
60 "
Men.
20 years
33 "
23 "
23 " )
Negro \
19 years
42 "
19 "
Disease.
Phthisis pulmonalis: the blood not burled: little
  pyrexia     -
Mild pneumonia   -
Severe catarrh, with much pyrexia  -
Pleuntus: the blood puffed
Severe headach: slight pain of side:  slight py
  rexia       -
Hemiplegia      -
Emansio raensium       ...
Convalescent  -      -     -     -     -
Chlorosis.—Serum green -
Slight cough, and pain of side, without pyrexia

Severe  headach, the effect of high temperature;
  without pyrexia    -
Severe headach during convalescence from fever
Pneumonia: blood slightly buffed
Slight pneumonia -     -      -      -
Phthisis pulmonalis; a short time before death
Diabetes mellitus -     -      -      -
Diabetes mellitus    -
Blood drawn at evening  -
Blood drawn in the morning -
Blood drawn at evening with milky serum
Blood drawn in the morning not milky
Sp. Gr.	Sp. Gr.
of	of
Blood.	Seturn.
1054	1027
	1023
1061	1023
1058	1026
1056	1031
	1026
10518	1028
	1029
1055	1027
1059	1026
1062	1026
1061	1027
1060	1025
1061	1033
1045	
- 1061	1030
1060	1025
1062	1026
1058	1026
1050	1023
  The blood in each instance was venous, and was taken from the
arm.   The individuals from whom it was abstracted, were patients
in the  Royal Infirmary, and belonged chiefly to the working class,
and were, with few exceptions, inhabitants of the town.
  The results are too limited in  number to admit of any general
conclusions being deduced from  them in a clear and satisfactory
manner. The following inferences, however, they seem to warrant,
as probable:—viz. that in inflammatory complaints the  proportion
of animal matter is increased, the proportion of water diminished ;
and also that the density of the  female blood  is less than  that  of
man.   The  former  inference accords with the experiments   of
Robinson, Tabor, and Langrish, which, although imperfect in them-
selves, may at least perhaps be depended on for comparison.  In the
majority of the examples adduced, nothing  unusual  was manifest
in the appearance of the blood.  Whenever the  blood exhibited a 
20
davy's researches,
buffy coat,  the inferior surface  of the mass of crassamentum
appeared softer than usual, as if from a deficiency of fibrin ; which
is  not surprising, considering  that the specific gravity of the red
particles is greater than that of the fibrin.   The green colour of the
serum of the chlorotic woman is worthy of remark ;—its  cause, I
was not able to ascertain ;  it did not appear to depend on  the pre-
sence of bile.  The blood of the  man labouring under  diabetes
was, in  each  instance, less firmly coagulated  than healthy blood.
In two  instances, the serum of this blood, last drawn,  hod a milky
hue : a common occurrence in this disease, and which I first learned
from  the lectures of Dr. Home.   The serum of this  blood I fre-
quently examined according to Dr. Wollaston's method, but unsuc-
cessfully ; I could never detect in it a particle of saccharine matter:
nevertheless, I  believe it contained an undue proportion of animal
matter:  this  was indicated  by its  comparatively high  specific
gravity. In the last case of diabetes, the depleting plan  of treatment
was  fairly tried : blood  was abstracted for some time every other
day, and the effect in diminishing the specific gravity of the blood
and  the serum was  well marked.   In this case, further, it may be
mentioned that some relation  appeared between the blood  and the
urine.   The  specific gravity of the  urine was always greatest in
the morning; when it uniformly exceeded 1040, and  was once as
high  as 1051; and yet in other respects, it then appeared  most
analogous to  healthy urine;  it abounded  in urea, and contained
hardly a trace of saccharine matter.  In the evening, on the  con-
trary, when  its specific gravity was least, viz.  between 1030 and
1040, the urea gave place  to saccharine matter: the former could
not be  detect^ in  it; the latter abounded.  And, like the urine,
the blood in this case was of greater specific gravity in  the morning
than in  the evening.

2.— Table showing the specific gravity of blood  mid serum, and
  also of bile  in certain instances  of disease, in the interior of
  Ceylon.
                          Table IV.
Age.	Disease.	Blood 1 Sernm.		Bile.
25 27 23 35	Fatal remittent fever; no organic disease could be detected by dissection; the liver appeared healthy; it weighed 41b. 10oz.; about an ounce of glairy yellow bile in gall-bladder Convalescent from a severe attack of remittent fever; seized with pain of side Fatal remittent fever; about 2oz. of brownish bile in the gall-bladder; no well-marked lesion dis-covered ........ Remittent fever (2d day); blood not buffy; serum of the colour of ale ...... 24 hours after, after having been well purged, was blooded again on account of severe headach	1054 10511	10238 10240	1011 10133
 
EXPERIMENTS ON  THE BLOOD.                  21
Table continued.
Disease-
Blood.	Serum.	Bile
 Slight remittent fever (3d day); blood not buffy;
   serum tinged slightly red     ....
 Intermittent fever; 8oz. of blood abstracted in hot
   stage, which it cut short; blood of natural ap-
   pearance; serum of reddish hue
 Fatal remittent fever, with yellowness of skin, and
   bloody urine; the inner coat of bladder of urine,
   of stomach, and duodenum, red, as if inflamed ;
   liver soft; gall-bladder turgid with dark, thick,
   ropy bile; mouth of common ducts apparently
   inflamed, but not obstructed  ....
 Continued fever (3d day); second V. S. not buffed;
   very dark and soft......
 Remittent fever (2d day); it began as intermittent,
   on a severe march; pain in hypochondria; buffy
   coat of blood near half an inch thick; serum
   light yellow.......
 Remittent fever with pain of chest (7th day); very
   slight buffy coat.....
 Ephemeral fever, after confinement in hospital for
   a peculiar debility of legs;  no buffy coat; eras
   samentum soft; serum limpid and red
 Fatal remittent fever; liver weighed 5lb 4oz.; bile
   dark and ropy      .....
 Continued fever (6th day);  blood  not buffed; se
   rum very yellow   .....
 Slight pneumonia;  blood not buffed; serum of
   reddish tinge .......
 Severe catarrh ; some pain of chest; no buffy coat
   on blood; serum of reddish hue
 Negro:—Slight pneumonia; blood not buffed; se
   rum of ale colour   .....
 2d day; aggravation of complaint; V. S. repeated
   collected  in two portions; first portion not
   buffed; of natural appearance .
   2d portion, a good deal buffed and cupped
 Sepoy:—Pneumonia; a week ill; blood of natural
   appearance, collected in  two portions; serum
   of the colour of porter; first  .
   Second .......
 Epilepsy, with severe headach .
 Hepatitis, with occasional dysenteric symptoms
   2d V. S.   Blood collected in two portions; first
   portion slightly buffed; second,  of natural ap
  pearance; both of.....
 Chronic hepatitis; blood not buffed; serum green
  ish yellow......
Hepatitis; blood not buffed; serum of the colour
   of ale, after a severe and harassing march
Acute dysentery (10th day);  2d V. S.  Blood very
   slightly buffed and cupped   ....
   3d V.  S. after halt an hour; blood  even less
   altered.......
10585
10588
10551
1055
10281
10281
10281



10290

10250


10279



1022

1027

10295

10296
10296
10275
10286
10281
10295
10274

10281

10316

10288

10278 
22
davy's researches.
Table continued.
Age
Disease.
Blood	Perum.	Bile.
—	10303	—
10565	10281	—
—	—	10371
—	—	10491
—	—	10113
10590	10330	
—	10316	—
—	—	10165
		10430
—-	10215	—
		10238
—	—	10107
27

30
27
Acute dysentery; blood not buffed; serum slightly
  tinged red; after a severe and harassing march*
Acute dysentery; blood not buffed; serum light
  greenish yellow   .
Died on 6th day. Rectum and colon gangrenous.
  Bile of natural colour, ropy   ....
Acute dysentery, fatal on the 10th day; inflamma-
  tion,  thickening and ulceration of large  intes-
  tines ; inflammation of peritoneum and of small
  intestines;  gall-bladder  distended with dark
  ropy bile      .......
A notorious drunkard;  died of dysentery and ab-
  scess of liver; large intestines inflamed, thick-
  ened and ulcerated; five small abscesses in the
  liver, containing a puriform fluid ; the gall-blad-
  der distended with viscid bile, not distinctly
  morbid ;  the liver weighed 4lb. 13oz., and was
  softer than natural .....
Dysentery, after ague; for  some time they alter
  nated; blood not buffed; serum of colour of Ma
  deira wine; it was  collected in two portions
  first portion   ......
  Second portion    .....
Fatal dysentery; colon and rectum thickened and
  ulcerated;  ileum inflamed; bile of natural  ap-
  pearance  ........
Fatal dysentery; ccecum ulcerated: colon ulce-
  rated and gangrenous; ileum slightly inflamed;
  in right lobe of liver two abscesses, one holding
  about 8oz. of matter, the other about 2oz.; dark
  brownish  bile in gall-bladder destitute of mu-
  cus     ........
Dysentery, after intermittent fever; blood of  na-
  tural appearance   ......
Fatal dysentery, complicated  with abscess and
  gangrene  of liver, not suspected during life;
  large intestines thickened and ulcerated; about
  three inches of lower portion of ileum severely
  ulcerated; a large cavity in the liver, its walls
  gangrenous, full of a foetid  bloody fluid; gall
  bladder distended with  brown bile  .
Fatal dysenter}'; liver of natural appearance; gall-
  bladder distended with  thin,  limpid, green bile
  * This man was one of a chosen party of about sixty, who in twenty-one hours
made a most severe march  from Atgale to Nalandi, and after sleeping on the
ground two or three hours, returned in about the same time.  They were sent to
relieve a post which they found evacuated.   Creat part of the way, both in com-
ing and going, they were opposed by the  enemy, and  found the road variously
obstructed.   Their exertions were extreme; every man of the party, with the
exception of the commanding officer, was in the sick-list within the last fortnio-ht,
labouring under remittent fever, dysentery, and hepatitis, and a considerable pro-
portion of them died. 
experiments on the blood.              23
Table continued.
Age.	Disease.	Blood.	Serum.	Bill!.
27	Gun-shot wound in lumbar region; V. S. on 3d day; blood received in two portions; first, slight-			
	ly buffed.......	—	10279	—
	Second, free from buff.....	—	10278	—
23	Gun-shot wound of lung. V. S. 4 hours after;			
	blood of natural appearance ....	—	10295	—
	After about 10 hours V. S. repeated, when labour-			
	ing under much dyspnoea, with pyrexia; blood			
	not buffed .......	—	10275	—
20	Malay:—Gun-shot wound of lung. V. S. on 3d			
	day; blood not buffed.....	—	10325	—
30	Singalese:—Gun-shot wound of neck, implicating trachea and oesophagus. V. S. on 3d day; blood			
	not buffed; serum of the colour of porter .	—	10303	—
22	Singalese:—Gun-shot wound of back. V. S. 6			
	hours after; blood of natural appearance .	10508	—	—
30	Fatal gun-shot wound of pelvis and spine; the he-patic duct in this instance exhibited an unusual peculiarity; just within the substance of the. liver it was distended into a cyst, into which several branches opened, and from which a duct passed to the gall-bladder; it contained a good deal of thick, viscid, greenish mucus; there was			
	healthy bile in the gall-bladder	—	—	10165
20	Negro :—Contusion of side from a fall; blood not			
	buffed; serum reddish .....	—	10281	—
20	Singalese:—Contusion from a fall; blood not			
		1058	10316	—
28	Fatal tetanus, after gun-shot wound fracturing both bones of fore-arm; tetanus began on 2d day; amputation was performed on the 3d, with-out benefit; death on the 5th; blood coagulated,			
	not buffed; bile dark brown .	—	—	1043
  The observations contained in  this second table were all made
in the military hospital in Candy, during the rebellion in 1818-19,
when our troops were most  actively employed  in  the  field, were
exposed to excessive fatigue and severe privations, often in most
unhealthy parts of the country, and suffered dreadfully from dis-
ease, especially from those scourges of camps, remittent fever and
dysentery.  Some idea of the severity of the diseases  may be formed
from the fact, that  the  mortality from  disease alone, whilst the re-
bellion  lasted, was about twenty-five  per cent, of the strength.
Besides the  specific  gravity of the  blood  or serum, in many in-
stances I ascertained that of the bile; which I have thought it right
to give, although not strictly belonging to the present subject.
  All the cases  referred  to, with  the  exception of the Singalese,
who were camp  followers employed as coolies or porters, were men
belonging to our regiments,  serving in Ceylon, the Negroes and
Malays to the 1st Ceylon regiment, the others to the 19th, 73d, and 
24
davy's researches.
83d foot.   The Negroes were Africans, of Mozambique;  the Ma-
lays were natives of Java, or the adjoining islands; the men belong-
ing to the other regiments were either English, Scots, or Irish.
   As regards  the  general scope of the results, some  plausible  in-
ferences perhaps might be  drawn from them, in relation not only
to the effects of disease on  the circulating fluids,  but also on the
influence  of climate, variety of race, &c.  But  I think  it best  to
abstain from the attempt, considering the basis of facts as too slender
for a foundation for theoretical views.   As facts, however, bearing
on an important part of pathology, few and imperfect as they  are,
I have thought it  right  to bring them forward, even after the lapse
of twenty years, with the hope that they may not be altogether  use-
less in themselves, and  that they  may lead to further inquiry.

3.— Table showing the specific gravity of blood and serum in in-
   stances of disease in Corfu, and also the proportion of fibrin.

                              Table V.
No.	Age.
1	20
2	22
3	25
4	23
5	26
6	25
7	20
8	20
9	25
10	30
11	38
Disease.
Remittent fever; blood of natural appearance
Remittent fever; blood slightly buffed
Chronic visceral  disease  of many months'
  duration.  V. S. repeatedly performed
Slight  erysipelatous  inflammation of  arm;
  blood slightly buffed, and the first portion
  more than the second    .
Epileptic fit  preceded by rigour.  V.  S. to
  24oz. First portion  had a pretty strong
  buffy coat; the last in a less degree
The following day V. S. repeated; 2lbs. ab-
  stracted, not buffed ; the last portion
Slight  pain of chest without pyrexia  after
  intoxication.  V. S. to 31b.; blood slightly
  sizy; no distinct difference between first
  and last portion    .....
Obscure abdominal disease (tumour)  after
  fever. V. S. to 24oz.; first portion slightly
  buffy; second portion in a less degree
Sudden pain in region of liver with pyrexia
  when convalescent from fever.  V. S. to 8
  ounces, syncope. Blood buffed in sp. grav.
  bottle, not in bleeding- cup
Acute dysentery.  V. S. to 2lb.; first portion
  not buffed, last portion, which flowed  most
  freely, much buffed      ....
Acute dysentery.  V. S. to 26oz.;  blood not
  buffed in the bleeding-cup, but distinctly
  so in sp. gr. bottle       ....
Intermittent fever, hot stage, with distressing
  retching and pain at scrobiculus cordis. V.
  S. to lib.; blood slightly buffed in bleed-
1060
1052

1047

1054
1053

1041
1042

1032
1055
1054
1051
1052
1038
1058
ios:
1056
1030

1025
1023

1021
1029
1027

1027
1024
 Fibrin
per 1000
 parts.
1.7
5.25
3.76
3.4

4.78
3.7

4.1
1.3
1.3
1.7
1.6
3.4
3.6

4.0
4.0
*# >
Sf?" 
experiments on the blood.               25
Table continued.
					Fibrin j
No.	Age.	Disease.	Blood.	Serum.	per 1000 parts.
		ing-cup, and distinctly in sp. grav. bottle;			
		an appearance of air in the blood; it oc-			
		curred in that which flowed last; a few			
		small bubbles appeared to be disengaged,			
		as it flowed into the cup, which was then			
		close to the vein .....	1052	1025	3.9
12	26	Pain of side; little or no pyrexia. V. S. to			
		lib.; blood slightly buffed	1051	_	4.1
13	49	Rheumatic pains of three weeks' duration;			
		blood slightly buffed ....	1047	_	3.6
14	25	Dislocation of hip-joint, from jumping out of window when drunk. V. S. to 4lbs.; blood not buffed; serum subjected to distillation,			
		yielded no perceptible traces of alcohol .	1054	—	—
15	40	Catarrhal symptoms, with stupor after exces-sive drinking for five days.' V. S. to 2oz.; blood slightly buffed ; urine collected during the night, was of sp. grav. 1007; it was subject to distillation; no traces of spirit could be detected in what passed ovei; it was of the specific gravity of dis-tilled water.			
16	35	In perfect health, (for comparison)	1052	—	4.5
       The observations  in  this table were chiefly made in the mili-
     tary hospital in Corfu, and principally in  the autumn.   With one
     or two exceptions, the patients  from whom the blood was  taken,
     were soldiers of our regiments serving in  the Ionian  Islands.   As
     regards salubrity,  these islands  may be considered as intermediate
     in degree between England and  Ceylon ; the average mortality in
     them amongst  the troops being about 2.3 per cent, of  the strength.
     Both the  fevers and  dysentery are less severe and  fatal than  the
     same diseases within  the tropics, and especially the latter.
       The experiments were  principally instituted with a view to  en-
     deavour to determine two doubtful points:—1st, whether there is
     any constant relation, between the specific gravity of the blood  and
     its capability of yielding a buffy coat;  and, 2dly, whether the pro-
     portion of fibrin is augmented in  blood  possessing this  quality.
       Relative to the first point, by one inquirer, it has been maintained
     that "blood which gives the fibrinous coat in a great degree, has a
im .-Jipwer specific gravity than  healthy blood ;"2—ait the same time re-
^   marking, "that moderately sizy blood  drawn from a person  before

      1 According to  the man's  statement, he  drank about two bottles of spirits
     daily, besides beer and porter. This case occurred in England, in an old soldier
     after just landing  from India.
      8 Sir Charles Scudamore, Essay on the Blood, p. 35. 
26
davy's researches.
 he becomes weakened,  has  not commonly a very  low specific
 gravity."
   The results of the trials contained not only in this table, but also
 in the two  preceding  tables, are not in  accordance with the first
 conclusion.   The only fair inference, it appears to me, that can be
 drawn from them, is, that there  is no necessary,  that is to say, no
 constant connection  between the specific  gravity of the blood and
 the presence or absence of the buffy coat.   Confining the attention
 to the last table, it appears that in five instances in which the buffy
 coat was slight, the  specific gravities were  1047, 105i, 1055, and
 1054; in other five  instances, in which the buffy coat was mode-
 rately thick, the specific gravities were 1041, 103<, 1052, and 1056;
 in one instance in which  it was thick, the specific gravity was 1057;
 and in one,  in which it was absent, (the blood of  a person in per-
 fect health) it was  1052.
   It may be laid down,  I believe, as a general  rule, that the blood
 of persons labouring under acute diseases,  differs in specific gravity
 very little from healthy blood; and is of comparatively high specific
 gravity, whether  buffed  or not—or at least not below the mean:
 whilst on the contrary, the blood of persons labouring under chro-
 nic diseases, attended with debility and wasting, is comparatively
 dilute, and of low specific gravity; and this, though most frequently
 associated with the  property of  having a  buffy coat, is not  neces-
 sarily so.
   Moreover, in connection with the  present subject, I would further
 remark, that I do not believe, that the time required for coagulation
 is in  any wise constantly connected with specific gravity, as the
 same author asserts; his words  are, "blood possessing the highest
 specific gravity coagulates the  most quickly," and "that which
 gives the fibrinous coat  in a great degree is slowest in coagulat-
 ing."1   The last portion of blood which flows  from  the vessels of
 a slaughtered animal, is of less  specific gravity than the first; yet
 it coagulates more rapidly.   The blood of the patient No. 8, in the
 last table, which was of  the low specific gravity 1038, coagulated
 rapidly: on  the contrary, I have known blood which differed very
 little  from the healthy blood,  and which  did not  exhibit a buffy
 coat, remain liquid eight  minutes after having been drawn, and not
 till the tenth minute was its incipient coagulation distinct.
   When the serum  and  coagulable lymph  are not viscid, and in
 consequence not capable  of supporting the red particles, these par-
 ticles fall down  rapidly; if the fluidity of the blood is great,  two
 minutes  are  sufficient  for their  subsidence an eighth  or even  a
quarter of an inch, as I have many times  witnessed, and instances
of which I  shall hereafter bring forward.  No doubt, very buffy
 blood is very slow in coagulating, for the red particles cannot sink
far in a very short time; and it  is well known  that healthy blood,
 which is of comparatively high specific gravity, coagulates rapidly.
1 Op. cit. p. 35. 
EXPERIMENTS on the blood.
27
It is my wish to be understood to maintain merely, that the quali-
ties in question—high specific, gravity and rapidity of coagulation ;
low  specific  gravity and slowness of coagulation—are not neces-
sarily connected, but rather accidentally, and consequently, that
neither can be considered as a general fact, and be announced as a
rule or principle.
  Relative to the second point—whether the proportion of fibrin is
augmented in sizy blood, as is the opinion  of the same author,' the
results of the trials, detailed in ihe last table, favour rather the con-
clusion, that  there is no constant relation  between the appearance
of the buffy coat of the blood and the proportion of fibrin which the
blood contains.
  Sir Charles Scudamore, in the experiments from which he draws
the conclusion,  that sizy blood  contains a much larger proportion
of fibrin  than healthy blood, estimated the proportion of fibrin not
for  the blood as a whole, but for the crassamentum.  Now, as sizy
blood commonly affords a  contracted crassamentum in which the
fibrin is comparatively condensed, and in  which the  residual pro-
portion of serum is comparatively small—it follows that a definite
quantity  of sizy crassamentum must contain more fibrin than the
same quantity of healthy crassamentum, and yet the  healthy blood
may contain more fibrin than the sizy blood.
  In the fifth example  in  the last table, the serum  was decanted
from the  crassamentum in the two successive instances of V. S.
and the red  partictes were  expressed from it: the following were
the results—estimated per cent.2
			Expressed	
	Decanted Serum.		colouring matter and Serum.	Dried Fi-brin.
1st V. S.	—1st Portion .	. 39.65	53.68	.478
	2d Portion .	. 44.6	42.8	.37
2d V. S.	—2d Portion .	. 30.3	30.8	.41
  Now, doubtless, although  the  last portion of blood did not con-
tain more fibrin than the first, yet, had the estimate been made not

  1 Op. cit. p. 119, et passim.
  2 The colouring matter mixed with the serum of the clot was obtained by
breaking up the clot  in a moist  linen bag, and subjecting it to a moderate
pressure by means of the fingers, till little but fibrin remained.  The fibrin
was then well washed  in the same  bag until all the colouring matter was
removed, when it was collected, and, previous to being weighed, dried on a
plalina capsule thoroughly at a temperature of 212°.  And the same method
in relation  to  the fibrin  was used in  every instance in which the proportion
of it obtained is given in the table. 
28
davy's researches.
for the entire blood,  but for  the  crassamentum, the proportion of
fibrin in this last would have  appeared  to have been very much
greater than  in the first, in accordance with the preceding remark.
  Regarding the results generally, the same remarks are applicable
to them, as to those contained  in the second table ; and, independent
of the particular  application, they are  brought forward with  the
same view.  The only  ones  which appear to  me  to require any
special  notice are  those connected with  the  patients Nos. 14 atid
15. from whom  blood was taken after excessive drinking of spirits.
  In  these two instances I have mentioned, I could not detect alco-
hol;  in one case in the serum of  the blood, and in  the other in the
urine.  It  is an  interesting  and important question, what becomes
of the spirit taken into the stomach.   Should other experiments
confirm the above, the unavoidable inference seems to be, that it is
decomposed.1


  8.— Observations  on  the formation  of the  buffy coat of the
                             blood.

  In  the preceding pages, I have  endeavoured  to  show, first, that
thero is no necessary connection between the buff on the blood, and
the specific gravity of that fluid; and,  secondly,  that  there  is no
necessary connection  between  the quantity of fibrin in  the blood,
and  its tendency to exhibit the  buffy coat.
  The circumstances, or qualities, on which  the  formation of the
buffy coat  depends are,  I believe,  chiefly  those  so  sagaciously and
ingeniously pointed out  by Hewson, and principally confined to the
coagulable lymph, little  dependent on  the serum and red particles
which may  be  considered  as  passive,  in a  manner,  rather than
active.2  The circumstances  or qualities alluded to, belonging to
the lymph, are its coagulating more slowly than in healthy blood,
and  its possessing greater tenuity or liquidity, not only than lymph

  1 Recently, I am informed, in instances of death from alcohol, either taken
by men in excessive quantity, or introduced  into the stomach of animals, it
has been detected in the blood, but  in a larger proportion in the brain.  The
author of these interesting results  is Dr. Percy, who, greatly to his credit,
obtained them whilst-a student at Edinburgh, during (if I have been rightly
informed) the past year, 1833.
  2 As the serum of the blood and its red particles  appear to be subject to
some variations, they may occasionally in a minor degree influence the pro-
duction or prevention of a  buffy coat.  The serum is naturally in  a certain
degree viscid; an increase of this quality, cater is paribus, would  retard or
prevent the  appearance of the buffy coat, and vice versa.   The red particles
are naturally of comparatively high specific gravity, owing  to which they
rapidly subside, in a fluid of no or of little viscidity; any  diminution of this
quality, whether from expansion  of the corpuscles, as from a kind of dropsi-
cal state, or from greater buoyancy from adhering particles of  air, also
cceteris paribus, would have a similar retarding or  preventing effect on the
formation of a buffy coat;  but, let  me remark, these are hypothetical consi-
derations. 
experiments on the blood.
29
in its healthy state, but even than serum; in consequence of which
the red particles more readily subside, and the lymph coagulating,
free from the presence of colouring matter, appears colourless, con-
stituting the buffy coat.
  Of late years, this  view of Hewson's relative to the formation of
the buffy coat, has commonly been only partially adopted, and the
circumstance, viz. the slowness of coagulation, which he held to be
least important, has been  most insisted on, and has been considered
most essential.   Even Professor Muller is not an exception in this
respect; in his Elements of Physiology,1 he enumerates as the prin-
cipal causes of the subsidence of the red particles and the formation
of the buffy coat in inflammatory blood, not an increased tenuity of
the coagulable  lymph, but the slow coagulation of the blood  or
lymph, and an increased  quantity of fibrin.
  In a paper on this subject which was published in the Philoso-
phical Transactions  for  1822, I endeavoured to call  attention  to
Hewson's original views,  and to show, that in the production of the
phenomenon in question, diminished viscidity is more concerned
than diminished coagulability, using the expression in relation to
time.   And in support of this theory, I adduced some instances, in
which the buffy coat appeared on blood which was not  marked for
slowness of coagulation.   I stated, that in certain cases "in which
the inflammatory diathesis is  best marked,  the  separation of the
red particles from  the blood drawn is  most rapid, often occurring
in one or two minutes; and, that in some diseases, particularly ery-
sipelas, the blood taken from a vein coagulates as rapidly as healthy
blood, and yet  exhibits the buffy coat.   In  instances of this kind
(it  was remarked) when  I have  watched the coagulation of  the
blood, the  red  particles  have  subsided in the short space of two
minutes, leaving a supernatant stratum of coagulable lymph, trans-
parent and liquid.   The buffy  coat, in  these instances,  did  not
appear on the blood  collected in the common bleeding cups—only
when small vessels,  as wine-glasses  or small  gallipots, were used,
and quickly filled and set aside to rest."  And, I added, as a general
inference from the observations also  in conformity with Mr. Hew-
son's views, "May it not be inferred generally, that the buffy coat
is principally owing, not to the slow coagulation of the blood on
which it appears, but to its increased tenuity, or, in other words, to
the diminished  viscidity of coagulabie lymph, the effect of morbid
vascular action, connected with the inflammatory diathesis?"
   Mr. Hay, in  his " Observations on the Blood,"  had  objected to
Mr. Hewson, that the coagulable lymph is not itself attenuated in
inflammatory diseases,  and that when it appears to be so, it is from
dilution with serum.  Were this opinion correct, I  remarked in the
same paper, such blood should be of a specific gravity unusually-
low, which it is not,  as I  had satisfied myself by numerous experi-
1 Elements of Physiology, part i. p. 117, translated by Dr. Baly.
  9__f                                     3 dav 
30
davy's researches.
nients, made  both at home  and  in  Ceylon, and of which experi-
mental proof has already been afforded.


9.—Historical  Notices respecting  the  Blood,  particularly  its
                           coagulation.

   A carefully drawn-up history of the speculations which  have
been  formed, and of ihe observations which  have  been made  by
ingenious  men,  relative to the coagulation of the  blood, and the
formation  of the buffy coat, would  be curious  and  interesting in
many respects ;  and it  may be noticed as a desideratum in medical
literature.
   Aristotle appears  to have  attributed  the  effect of coagulation  to
the presence  of  a fibrinous maiter  in the blood, either in the state
of minute solid  fibres, or liquid with the power of  forming  fibres.
From an incidental expression,' it  is not improbable that the latter
was his opinion; and  that he considered  the matter liquid  whilst
the blood was in motion  in the  living animal, like the matter  of
curd in uncoagulatcd milk; and, solid only and fibrous, after extrac-
tion, the coagulation being the effect of the  change.2

   1 Meteorol. lib. iv. c.  7. D.
   2 Harvey thus gives the opinions entertained by Aristotle respecting  the
blood :  " Aristoteles (a) quoque ut sanguinem alendi gratia institutum puta-
vit, ita eundem etiam  veluti e partibus  compositum  censuit.  Nempe ex
crassiore et atra, quae in fundum pelvis inter concrescendum subsidit, eaque
pars illi deterior habetur (o) : sanguis enim, inquit, si integer est, rubet et
dulcis saporis est; sed, si vel natura  vel morbo sit vitiatus, airior cernitur.
Ex parte  etiam fibrosa sive fibris constare voluil: iisque demptis, ait (c),
sanguis neque  concresit nequespissatur.  In sanguine prseterea saniem agno-
vit: Sanies, inquit, sanguis incoctus  est;  aui, quia nondum percoctus,  aut
quod in seri modum dilutus fuerit. Atque hunc  frigidiorem esse ait: fibras
autem partem sanguinis terrenam esse statuit." (rf)
   There  are other particulars mentioned by Aristotle respecting the blood,
not uninteresting  in the history of  this fluid, and clearly  showing what
great attention he  had paid to it:—the following are some of the  more re-
markable.
   " Sanguis in primis necessarius communisque sanguineis  omnibus ani-
malibus est, nee  adventitius suppetit, sed vernaculus, atque  intimus  in
omnibus  integris,  atque imputidus habetur.  Venas (he  included the aorta
and its branches)  hie vasa sibi, et conceptacula babet; nee in ullo alio  nisi
in corde, praeter venas continetur. Tactum nullo  in genere  sentit; sicut
excrementa quoque in alvo contenta, sensu carere certum est.  Q,uinetiam
cerebrum et medulla tactum non  sentiunt.  Copia sanguinis in primis ani-
malibus, iis, quae animal et intra  se formant, et in lucem edunt: mox  iis
sanguineis, quae pariunt ova.  Palpitat intra venas sanguis omnium  anima-
lium pulsuque simul undique movetur,  solusque  omnium humorum sparsus
per totum corpus animalium est.  Et semfer quandiu  vita servatur, sanguis
unus animatur et  fervet.  Oritur primura in corde, ante, quam totus corpus

   (a) De Part. Anim.  lib. ii. c. 3.
   (6) De Hist. Animal, lib. iii. c. 19.
   (c) De Hist. Animal, lib. iii. c. 19.
   (d) De General. Animal, 402- (Op. Ora. a Col. Med. Lond. edit.) 
EXPERIMENTS ON THE BLOOD.
31
   H.nvey appears to have adopted an opinion on the subject very-
similar to that of Aristotle;1 as did Sydenham also some years later;
but with this difference and refinement,—an anticipation of a recent
doctrine already abandoned, that the buffy coat is  formed of the
substance of the colouring matter, deprived of its pellicle.2
   Amongst the distinguished physiologists, the immediate succes-
sors of Harvey, Lower holds a  high place;  and he appears to have
been  one of the earliest,  who had a more precise and a more accu-
rate  knowledge of the  blood,  than  was  then  current, or had
descended from antiquity.   He seems to have considered the serum
of the  blood in  the light of a  vehicle: "Propter seri defectum,

formatur. Si multum sanguinis effluat, anima deficit: si nimium, vita inte-
nt.  Si sanguis  immodice humescit, morbus infestat: sic enim in speciem
saniei diluitur, et adeo serescit, ut jam nonnulli  sudore cruento exundarint.
Idem  etiam   inlerdum  causae est, ut qui effluxerit, aut omnino concrescere
nequeat, aut  incompte, particulatimque spissatur.  Dormientibus pono san-
guinis copia partes  exteriores deserit, subitque interiores,  ita  ut  adacto
cultello  non  eeque effluere possit.    Minus sanguinis  per  summa corporis
fseminarum  est:  plus enim  parte  interiore  continetur,  et quae  menstrua
appellamus,  plurima  fieri in  mulieribus solent:  quod genus sanguinis vitia-
turn, cegrotansque, fluit immodice, atque profluvium ob earn  rem dictum est.
Cseteris  morbis  sanguinis minus mulieres infestantur, quam viri.  Paucis
item  mulieribus  fiunt mariscae, aut varices, aut e  naribus  profusio  sangui-
nis.   Et si  quid eorum acciderit,  detrimentum in  menstrua  decumbit.
iEtatum etiam ratione sanguis discrimen,  turn in  modo,  turn in genere reci-
pit.   Etenim in  aetate admodum juvenili saniem trahit, et largior est: in
senectute auiem  crassus,  niger et paucus.  Medium tenei in media, firmaque
aetate. Concrescit etiam facile senum vel in corpore sanguis, qui per summa
est: quod idem nunquam  juvenibus evenit.  De Hist. Animal, lib. iii. c. xix.
   1 In the following passage, Harvey appears to give  his opinion on the
nature of the blood, founded on that of Aristotle;  but  modified, and approach-
ing a  little nearer to the present  state  of our  knowledge on the subject.
u Hie enim  (sanguis)  ut est naturale quid, heterogeneum sive dissimilare
exsistens, in succis  aut partibus  illis  componitur.  Prout  autem vivit,
parsque animalis praeciqua est, ex succis iis simul mistis constans; est pars
similaris animata ex anima et corpore composita.  Evanescente autem, ob
exstinctum calorem nativum, ilia sanguinis anima, substantia hujus  nativa
illico  corrumpitur et dissolvitur in ea, ex quibus olim constituebatur : primo
scilicet in cruorem, postea in  partes rubras et albas ; partesque rubra? supe-
riors  sunt  floridiores, inferius  autem  sitae  nigricant.   Partes  poiro alias
fibrosa?  sunt  et densiores (reliquarum vesiculum) : alia? ichorosae el serosae,
quibus coagulatus thrombus  innatare solet.  Atque  in  hoc serum sanguis
tandem fere  lotus degenerat.  Partes autem istae  non insunt vivo sanguine,
sed a  morte solum corrupto et jam dissoluto."—Op. Cit. p. 404.
  2 Sydenham thus  expresses  himself on the  subject of the buffy coat:
"Sanguis in pleuritide saltum ilie,  qui post primam vicera  extrahitur ubi
refrixerit, sevi liquati prse se fert speciem ad crassitiem satis conspicuam,
ac superficiem habet veri puri semulam, el tamen  ab eo  longe diversam
utpote quae  fibris, instar reliqui sanguinis, arete contexitur, nee non  ad
modum puris diffluit,  quin a reliquo divulsa discolor  ilia pars, formam cuti-
culae tenacis et fibris  refertse exhibit;  et, fortasse  nihil aliud est, quam fibrae
sanguinae, quae rubicundo ac naturali suo  integumento per  praecipitationem
exutae, ambientis aeris frigore  in membranam hujusmodi  subalbidam concre-
vere."—Op. Univers.  Lug. Bat. 1741, p. 264. 
32
davy's researches.
sanguis, vehiculo suo spoliatus, circulatione ineptus redditur."1  He
was not only acquainted with the  coagulability by heat of serum;
but also of the liquor  pericardii, and of lymph,—" lympha e glan-
dulis secreta."2  He appears to have been well acquainted with the
existence  in the blood, of a glutinous fluid, its nutritive and  its
coagulable  part,—to which the coagulation of the blood is owing,
and many morbid  phenomena are referable; thus, at page 130 of
his work on  the heart, he  speaks of it, as  "succus  nutritius in
sanguine ad mod urn glntinosus;" and which " sensim concrescit, et
pro cordis et vasorum continentium figura, varie configuratur, unde
pro cordis polypo, verme et serpente interdum habitus est."
   Borelli  about the same  time, or shortly after,  entertained  the
same view of the  blood, and announced  it with even  more preci-
sion, and  illustrated  it by  experiment.3   He had  come  to  that
conclusion  also, which 1 have inferred Aristotle had  formed,—that
the glutinous part of  the blood, in the living animal, is liquid ;  he
was led to  it by considerations connected  with microscopical obser-
vations: " ideo fatendum est, gluten  album  sanguineum lubricam
et fluidam consistentiam retinere  dum in  animale vivente move-
tur."
   These just  views may have been  adopted by a small number of
individuals, but they seem to have made  no general  impression at
the time, or to have been objected  to, or  rejected, as if erroneous.4
For a  considerable   period  after Harvey's  great discovery,—for
nearly a century, whilst many branches of physical science were
most successfully cultivated, comparatively little advance was made
in the knowledge of the true  nature of the blood.   The attention
of the philosophical chemists was then chiefly directed to the effects
of heat  on  it, and to the products obtainable by distillation ;5 whilst

  1 Tractus de  Corde, p. 131.—London, 1669.
  1 Op. cit. p. 6.
  3 " Primaria pars rubicunda constat ex  glutinossisima quadam substantia
lubrica, et ex succo quadam purpureo, qui simul implicati sponte conscrescunt
in grumos; et post concretionem crebris aquae ablutionibus apparel pars glu-
tinosa, constipata in fibras Candidas, vel in membranas recticulares similes
tendinosis, ut in sanguine  columbino patet; pars vero rubra grumefacta, et
abstersa ab aqua, abit in pulverem  rubicundissimara, in fundo aquae subsis-
tentem."—Borelli de Motu Animalium, p. 192, (1685.)
  * Haller, in his Comment, on Boerhaave, vol. ii. p. 310, published in 1742,
referring to the opinion that the clot contains  fibrous matter,—the opinion,
he  says, of Malpighi, Michelotti,  Guglielmini,  Hacquet, and of Adams;
observes, "Nerum, ne errori nascatur locus, fibrosa ea substantia non alia
est ab ipsis globulis dictis (i. e. of Leeuwenhoeck) et evanescit solo calore."
  5 Macquer, one of most philosophical chemists of his lime, in his Elements
of Chemistry, published towards  the middle of the last  century, speaks of
the analysis of the blood, as " a sort of general, though imperfect, analysis
of the animal."  Speaking of the  blood  out of the body,  he notices  only
" its yellowish serum or lymph." and the red curdled part which swims in
the midst thereof.  He adds, " these two  substances, when analysed, yield
nearly the same principles; and, in that respect, seem to differ but little from
each other."—Elements of the Theory and Practice of Chemistry, En"-.
Trans. 1764. 
experiments on the blood.
33
that of the natural  philosopher and physician  was  directed, prin-
cipally, almost exclusively, to  its red  particles, to which they at-
tached  vast importance, making their microscopial observations
the foundation of  various speculations  and  wide-reaching hypo-
theses.1
   At what time exactly the more precise ideas on the subject began
to prevail,—ihose which are  inculcated in the writings of Hewson
and the Hunters, and some  of their able contemporaries, it is not
easy to determine.   The term "coagulable  lymph" was  then  in
common use, according  to Hewson's definition of it;  thus, Sir John
Pringle, in the description of a fatal case, in which  the heart was
found to adhere to the pericardium,  says, it was u in such a manner
as parts adhere from recent inflammation, that is, by an exudation
of coagulable lymph."2    The  probability, however, it  appears  to
me, is, judging from the writings of Jurin,3 Haller,4  and Marherr,5


  1 Boerhaave, opposing the hypothesis of Galen, that the blood is composed
of four peculiar humours, remarks, " it appears clearly from the experiments
of Leeuwenhoeck, that the red clot (the first of Galen's Elements) is com-
posed merely of red particles united so as to form one  mass; that the yellow
bile (his second Element) is merely serum,  and  that its  more dilute and
pellucid parts (his  third Element, in which the yellow bile was supposed to
be dissolved) is to be considered  as phlegm  ; and that  the black parts of the
crassamentum, its inferior portion (his black bile, and fourth Element) does
not differ from the  red, excepting it not  being exposed to the air"—Praelect.
Acad.  1. 328.  The elaborate medical  doctrines which this distinguished
man built up, on the incorrect microscopical observations of Leeuwenhoeck,
afford the most remarkable instance of what has been stated in the text; and
should ever  be a warning in refined and  obscure inquiries, in  which the
microscope is brought into use.
  2 Hewson,  in his Treatise on  the Lymphatic System, published  in 1764,
gives the case at page 114, transcribed from Sir John Pringle's notes.
   3 Dr. Jurin, in his able paper,  in the Philosophical Transactions for 1719,
on the specific gravity of the blood and its different  parts, distinguishes only
the red particles and the serum.   He  was of opinion that the crassamen-
tum is composed " of the globular particles united together by their attractive
power."
  4 Haller. in the second volume of his Elementa Physiologiae, published in
1760, at page 42, remarks,—" Solent Medici  Galli nuperiores (Petit Mem.
de  l'Acad/des Scien.  1732, p.  393; Senac,  t. ii.  p. 92,)  monere,  duriora
coagula esse, quae ex sero nascuntur, et serum vi densabili cruorem superare,
cum in frigida coeat, dum sanguinis pars rubra conservat."  "Verum cerium
est,"  he  continues, "etiam ex  rubro cruore,  dura  nasci coagula, et quidni
nascantur, cum in  ea sanguinis  parte, et terrae et ferri, plurima sit portio."
So vague is this great physiologist on the subject.
  5 Marherr,  in his admirable " Prselectiones Medicae," published in  1772,
probably expressed  the doctrines  then current, and considered most orthodox,
in the continental schools,  at least in the North of Europe;  he attributes the
buffy coat of  th? blood to a change  in the serum.  " Augetur vero visciditas
ilia  seri  saepe tantum  ut etiam more cruoris protinus coagulatur et ipsum
dum sanguis  de vena missus coit.  Atque turn cruor concretus pellicula alba
densa, tenace tegitur, quae ex sero viscidore  nascitur, et crusla? pleuriticae
nomine insignitur, quoniam," &c. torn.  ii. p.  251.  The crassamentum,  he
considered, composed of red particles adhering together; "thus," he says,
"coagulum hoc rubrum minui sensim mole et mora temporis in vase sero- 
34
davy's researches.
that the views on the subject of the blood entertained by our great
English physiologists last  mentioned, (passing, by ihe earlier and
similar opinions, which  never took root, and seem  to have  been
lost,) belonged to their time, and chiefly to our country; and that
to them, and perhaps to one  or two French  inquirers, belong the
merit of reviving, or rather of originating, them de novo, and of
proving them true.
  One or two remarks of Hewson's seem to point to this, and  in  a
manner claim the honour of discovery; thus, in a foot-note, at page
51, of his " Experimental Enquiry into the Properties of the Blood,"
after having detailed some of the most remarkable of his results, he
observes, ""that most of the  facts which occur in the preceding
pages have been mentioned in my Anatomical Lectures, ever since
the year  1767;  and some of them  were mentioned  publicly even
before  that time."   And he  adds, " This I thought it necessary to
observe, because many of them have since appeared in other publi-
cations."  Thus, in another place, also in a foot-note, after describing
the crassamentum,  which, he says,  "it is well known  consists of
two parts, of which  one  gives it solidity, and is by some called the
fibrous part of the  blood,  or  the gluten, but  by others with more
propriety termed  the coagulable lymph? remarks, "It  may  be
proper to mention here, that  till of late, the coagulable lymph has
been confounded with the serum of the blood, which  contains  a
substance  that is  likewise  coagulable.  But in these sheets, by the
lymph is  always meant that part of  the blood  which jellies, or be-
comes  solid spontaneously,  when blood  is received into  a basin,
which the coagulable matter  that is  dissolved  in the serum  does
not, but agrees  more with the white of an egg, in remaining fluid,
when exposed to  heat, or when mixed with ardent spirits, or some
other chemical substances."1
  The views of Hewson, on the subject of coagulable lymph, on
the coagulation of  the blood, the formation  of the  buffy coat, the
contents of the lymphatics, on the analogy between the coagulable
lymph which they contain, and the coagulable lymph of the blood,
are so clear and precise, and deduced from such admirable  experi-
ments, that it appears not a little difficult to comprehend, how they
could be either overlooked  or not  perfectly  understood or appre-
ciated. And  yet, that they have been, is the unavoidable impression
received in reading  some of the works of the  able physiologists of
the present day.   Justice has not yet been done to the high merits
of Hewson, either as a most  acute and  accurate observer, or as  a
very original inquirer.  Dr.  Baly,  in his translation of Professor
Muller's work  on Physiology, in a  note to that part of  the text in
which  it is said, that Berzelius suggested the idea  that the clot is
composed  of fibrin  enclosing the red particles,  supports the just

sum liquidum augeri,  quod antea in interstitiis  eoaguli  interclusum, per
moram et quietera magis sese  attrahentibus moleculis rubris, ex hisce inter-
stiis exprimitur, dum illoe ad se proprius accedunt."
  •  Op. cit. p. 6. 
experiments on the blood.
35
claims of his countrymen, and in part those of Hewson, but not, I
think,  to the  full  extent of his  merits.   Hewson's ideas on  the
nature of coagulable  lymph, founded on the results of his experi-
ments and observations, appear to me as clear as possible—even  as
clear as those of Professor Midler himself, and that he would have
made the same ingenious experiment in confirmation  of them (I
allude to the separation of the fibrin of the blood of the frog from
its red particles, by filtration in its liquid state) had he been aware
that these particles, on account of their large size, could be detained
on a filter.
  As Dr. William Hunter was senior to Hewson, and as the latter
was  associated with him, it may be a question, whether the merit
of the discovery of coagulable lymph is not due to him.
  In  his controversy  with the late Dr. Monro, published in  1777,
under the  title of " Medical  Commentaries," he gives a quotation
from his lectures, delivered in 1759-60, from which it appears, that
then he had a clear apprehension of the part performed in the blood
by coagulable lymph.  I shall  transcribe the passage, as it is on
many  accounts  interesting.  Accounting for  the  red  blood  not
transuding through the vessels, he refers it principally to the gluti-
nous quality of the blood, when "equally mixed up with its coagu-
lating part."   " That part," he adds, " coagulates as certainly as the
blood  stagnates, even in living  bodies; and when the universal
stagnation  happens in death, this  part  of the blood  collects itself
into irregular polypi and  coagulations all over the body, and the
rest of the blood  is no  longer the thick viscid fluid  it was before.
but  rather a  bloody serum that will ooze through all the  vessels
and membranes."
   Now as Hewson, at  this time, was only about 20 years  of age,
(according  to Mrs. Hewson, he was  born in November, 1739, and
was in partnership with Dr. Hunter in  1768,') Dr. Hunter's  know-
ledge  of the nature of coagulable lymph could  hardly have been
derived from Hewson, and it must be considered either as the result
of his own observations, or of observations common to him and his
contemporaries, and not claimed by any one in  particular, which,
on the whole, perhaps, is most probable.  Still, however, to Hew-
son, I believe, belongs the  merit of elaborating the doctrine,  and of
making precise what  was before vague.
   In mentioning the revival of correct ideas on the subject  of  the
coagulation of the blood, I have alluded  to one  or two French
inquirers, who perhaps may be considered entitled to share  in  the
merit I have attributed to our English  physiologists, if not to have
anterior  and superior claims, particularly those very able and dis-
tinguished men, Petit and Senac. They certainly preceded Hewson,
in adopting Borelli's view, or the analogous view alluded to, of  the
nature of coagulation of the blood, as  solely depending on a white
coagulable part, which they called lymph; but I am not aware that
1 Biograph. Med. 1, 428. 
36
davy's researches.
either of them brought forward in support of it any facts, or experi-
mental results more decisive than those of  the Italian physiologist;
nor do their statements appear to have had any influence  on  the
doctrines of the  day, judging from the opinion of Haller,  already
alluded to.  Below, I shall  give  some extracts from their writings,
expressing their ideas on the subject.1

  1 Petit, in his second " Memoire sur la maniere d'arrester les Hemorragies,"
published  in Mem. de l'Acad. des Sciences for 1732, makes the following
remarks:
  " Attendu que la lymphe est plus legere, la moitie superieure de ce caillot
est blanche, et I'inferieure est d'un rouge-brun."
  " Si 1'on examine le bassin  dans lequel on vient  de  saigner du  pied, on
trouvera toutes les parties du sang noyees dans l'eau chaude, tH si l'on veut
voir a l'instant quelle est la partie du sang susceptible de coagulation, on n'a
qu'a jetter  un pot d'eau froide  dans le bassin, et sur le  champ, on  verra la
partie blanche se separarer de la partie rouge, et s'elever sur  la surface de
l'eau  ou. elle forme  des  caillots tres-durs, pendant que la partie  rouge
demure universellement  et exactement melee  avec l'eau, et sans former
ancuns caillots.
  De ces experiences connues de tout le monde, on peut conclure que la
partie blanche est non-seulement plus disposee a la coagulation que  la partie
rouge, mais qu'elle est la seule qui se  coagule, et que la partie rouge ne feroit
point partie du caillot, sans la partie  blanche qui la retient.  Les differents
degres de consistence qu'on  trouve  dans les caillots en sont une seconde
preuve.  En effet, le caillot de toute  la masse exactement melee a quelque
consistence, mais lorsque la partie rouge et la partie blanche  se sont coagu-
lees, pour ainsi dire, separement;  le caillot blanc est tres dur, parce qu'il ne
contient point de partie globuleuse, et le rouge  est d'autant  plus mol qu'il
contient peu de lymphe; du maniere que quand la partie  globuleuse et la
serosite restent fluides, et que la lymphe se coagule, le caillot est encore plus
dur et plus blanc: ainsi les differents degres de  blancheur et de solidite des
caillots dependent du plus ou du moins de parties gobuleuses que la lymphe
retient, en se coagulant."—p. 393.
  Senac, in the first edition of his Treatise on the Heart, published in 1749,
(vol. ii. p. 660,) speaks of lymph, incidentally, in connection with the colour-
ing particles, when refuting some errors of Leeuwenhoeck relative  to the
latter.  He mentions it as "cette matiere  blanche, qui se coagule d'elle-
meme et qui forme  la coene du sang des pleuretiques."  He continues,
"J'ai d'abord  voulou l'examiner quand la sang s'en separe et  se refroidit;
mais  on ne peut  pas la saisir exactement ou elle est encore fluide.  J'ai done
pres cette matiere figee et fort blanche; mais je n'y ai vu aucune trace des
globules."   He does not claim to himself the discovery  of the  coagulability
of lymph ;  more than he does the globularity of pus, the globules of which,
as seen under the microscope,  he correctly describes as larger than the blood
particles.
  The next passage I shall transcribe is  from the second edition, which
appeared in  1783, after the death of the  author;  he  thus opens  the 13th
chapter of  the 5th book, on the causes which keep the  blood  liquid, " Cet
assemblage de matieres inegalement pesantes, n'est qu'un fluide artificiel, ou
pour mieux dire  ce n'est pas un corps fluide; il n'est qu'une matiere fondue
par diverses causes; sa liquidite  ne subsiste qu'autant que ces causes agis-
sent; abandonne a luimeme il se coagule dans ses propres vaisseaux;  si on lie
une carotide en deux endroits, dans un animal vivant, le sang se condense
entre les deux ligatures;  si les issues du cceur ne sont pas libres, il peut se
former des concretions dans les ventricules; elles ne  sont pas rares dans
l'aorte, lorsxu'elle se dilate. 
observations on the blood.
37
  Should the historical desideratum  to which I have alluded, in
introducing these brief notices, be supplied, written  with the scien-
tific accuracy and "philosophical spirit suitable to the subject, it  will
prove, I apprehend, no less curious than instructive: the history of
this our vital  fluid, will be any thing but a triumph of human intel-
lect;  it will show how difficult is  the attainment of  physiological
knowledge, (considering merely the coagulation of the blood,—as
it were, a single quality;) how insecure is the tenure of this know-
ledge ; how unstable  and fleeting  is  opinion; and  how prone  the
philosopher has been  to adopt wild and  fantastic notions; and to
fall into almost absurd errors, when deviating from the rigid induc-
tive method.
                               II.

    MISCELLANEOUS OBSERVATIONS  ON  THE BLOOD.

  Most of the following observations were made between the years
1824 and 1833, in the Mediterranean,  chiefly in Corfu  and Malta ;
and were published at intervals in the Edinburgh Medical and Sur-
gical  Journal.   They are now given  in many instances  more  in
detail, on the persuasion, that to be  useful, detail is necessary, even
at the risk of tediousness.

        1.— On the effect of violent agitation on the Blood.

  Dr. Bostock, in the  first  volume of his  Elementary System  of
Physiology, remarks, "It  is well known that if blood, as it is dis-
charged from the  vessels, be briskly stirred about for some time, the
process of coagulation  is entirely  prevented from  taking  place,
either in consequence of  a more complete  union  of its parts with
each  other, which prevents their future separation,—or from the

  Toutes les parties du sang ne forment pas par elles-memes le foods  de
ces concretions ; c'est la lymphe seule qui se coagule, el qui en se coagulant,
es le lieu des autres matieres qui y sont melees;  elle  lie, par example, avec
elle les molecules rouges et leur donne de la consistance;  si elles etoient
seules elles ne s'attacheroient point les unes aux autres; des quelles sont
separees du reste, elles flottent dans l'eau ; ou si elles se rapprochent, leur
cohesion est legere ; elles retienment meme qulque portion de matiere lym-
phatique  qui les unit; aussi leurs concretions  sont elles tendres, et sem-
blables a une gelee presque liquide."
  Hewson's Experimental  Inquiry into the Properties  of the Blood, was
published  three  years before the last edition of Senac's work, viz. in 1780,
with  the very characteristic motto, both  as regards the inquiry  itself and the
author's own mind,  " Vere  scire, est per causas scire," words  of the author
of the Novum Organum. 
38
davy's researches.
fibrin after  it has been  for some time discharged from the blood,
losing this peculiar  property  by which its particles are attracted
together "l                                                     f
  To ascertain  if a  brisk motion really prevents ihe coagulation ol
the blood, as is asserted  by Dr. Bostock, I made the following ex-
periment, preferring it to be the means mentioned by him ias we
Low thai  by moderately  stirring  the blood  its fibrin merely•*
separated, and not its property of coagulating des royed.  About wo
ounces of blood were received into a  large vial  and immediately
shaken violently, and the agitation was continued without inter-
mission for ten minutes,  which was  two minutes after the blood at
rest coagulated.   The result was,  that the blood thus shaken ac-
quired a scarlet  hue from being mixed  with, and from the action ot
air,  and appeared to  be liquid.   But  this was  merely in  appear-
ance ; for when poured on a filter, it separated into two parts-one,
the  serum,  containing,  suspended  in  it, the red  particles  which
passed through the filter:—the other, the  fibrin  in a finely divided
state, coloured by adhering red particles which remained  on the
filter   This effect of agitation may  be  imitated by breaking up the
crassamentum of the blood with the fingers, when an apparent solid
is rendered an apparent liquid.  Nor  is this at  all surprising, con-
sidering the small quantity of solid  matter contained in the crassa-
mentum, to which it performs the part, as it were, of a cement, or
of calcareous matter to sand, combined with which the sand consti-
tutes a solid rock, and deprived of which it is as a yielding quicksand,
almost as fluid as the red particles of the blood deprived of fibrin.
   In confirmation of this explanation, I may add, that blood ren-
dered apparently liquid, as above described, when examined by the
 microscope is found to  contain, besides the blood-discs, which are
 little altered2 floating in the serum, masses  of fibrin, of irregular
 form and  structure—(neither distinctly globular  nor fibrous) and
 particles also of irregular form,  very much smaller than the blood-
 discs.  On rest, after a few hours a  separation takes place,—the red
 particles, in consequence of their  greater specific gravity, subside
 towards the bottom, and the particles of fibrin, owing to entangled
 air, collect  at the surface.

        2.—On the effect of moderate agitation on the blood.

    Sir Charles Scudamore, in his Essay on the Blood, endeavours
 to show that moderate agitation of the  blood  favours  its  coagula-

   1 Lower supposed that agitation had  this effect on  blood, and in  his time,
 (now at least  170 years ago)  the opinion appears  to have been current:
 thus, when  on the subject of transfusion, and considering the  best state
 of blood for the purpose, he  gives the preference to that flowing  from a
 living animal, because, he remarks,—the blood which has been collected in
 a vessel, (utcunque satis prsecaveri posset, crebra\ agitatione, ne congeletur)
 is  necessarily in some respects changed.—De Corde, p. 173.
   2 The discs after agitation are not quite so regular  in form as before. 
OBSERVATIONS ON THE BLOOD.
39
tion,1 and, conceiving that his experiments prove the fact, he accounts
for it on  the idea, that agitation  accelerates the escape of the car-
bonic acid gas, which, as he believes,  the blood contains,  and on
the escape of which, he is of opinion the phenomena of coagulation
depend.
   It  may appear a most easy matter to  determine whether moderate
agitation does or does not accelerate the coagulation of the blood,
the experiment is so simple, and so easily made ; and  yet, I must
confess I have experienced considerable difficulty in arriving at a
conclusion from the contradictory nature, not of one or two, but of
many results.   The great difficulty in  this inquiry, and in most in-
quiries relative to the blood, is,  the impossibility of knowing that
any  two  portions of the same fluid are  exactly similar.  My opinion
is, that no two portions are, and even that no two drops ol this fluid
are exactly similarly constituted, or  possessed of exactly the same
properties; and  that  the portions of a continuous stream flowing
from the arm, were it divided into a hundred, may all  be different.
The results of experiments first led me to  adopt this notion,  in
which I was  confirmed by further experiments, and by reflecting
on the subject.  Not to be tedious, I shall mention only one experi-
ment.  Six gallipots of the same size, and  a platina crucible  of
nearly the same size, were filled in succession with venous blood as
it flowed from the arm of a soldier labouring under a slight ailment,
and  on whom no well-marked  effect connected with loss  of blood
was  perceptible during the operation.   They were placed  close to
each other, and  carefully observed.  The blood in each did not co-
agulate,  as might have been expected,  in the order in which it was
received, but irregularly.  Thus the first received was the last but
one  to coagulate, and  that which was received  in  the  crucible,
which was the fourth in succession, coagulated first.  When one
reflects on the subject, the inference appears to me to be obviously
what I have  suggested  above, viz. that no  two drops of blood are
precisely similar in their composition and properties.  It is evident
on reflection that the fluid of a continuous stream of blood  must be
derived from different parts of the body.  In one portion there may
be an unusual or less than usual quantity derived  from the vessels
of the  muscles, or brain, or liver, or spleen, &c.; and we cannot but
suppose, that the blood  from the kidney, after urine has  been se-
creted  from it, is different from  the blood from the liver or pancreas,
after supplying bile and the pancreatic fluid.  The preceding exper-
iments and this  reasoning  are  confirmed by another fact which I
have observed ; viz. that if the crassamentum, the instant it is formed,
is removed, it will be succeeded  by another coagulum ; and if this is
removed, by another—and so on repeatedly till  all the fibrin has
coagulated,—clearly demonstrating, that in  any given quantity of
bloxl, then? are p.irticles of fibriti of various degrees of rapidity of
coigulatioii.   And is it not also  confirmed by microscopical obser-
'Op. cit. p. 40. 
40
davy's researches.
vation ?  If we examine, with a powerful microscope, a minute por-
tion even of a drop of blood, as indeed is necessary ;  is there not a
variety observable  in the  particles, either as regards the outlines  01
the discs, their thickness, or their other dimensions?   Ihe resem-
blance  of one to the other is general and considerable ; but not wun-
out, as it has appeared to me, slight differences.
  To return now to the effect of moderate agitation on the coagula-
tion of the blood.—it may be easily understood how seemingly con-
tradictory results  mav be  obtained, if the  effect is  not very  well
marked.   It certainly'is not well marked.  In some instances it has
appeared rather to  retard ; in  others, neither  to  retard nor accele-
rate, and in others, and these  the  majority, to accelerate  coagula-
tion.
  As the majority of the experiments which I have made indicate
this, 1 infer that agitation does promote the coagulation of the blood
out of the body.  "But admitting it to be a fact, I cannot adopt  fcir
Charles Scudamore's explanation of it, as it  does not appear to  me
proved that  any carbonic acid gas is disengaged from blood in  the
act of coagulation ; or if it were, that iis removal would have  the
effect imagined.   I believe it  is owing to a very  different cause.   1
find that when a small portion of crassamentum is put  into blood,
the coagulation is distinctly accelerated, having, as it would appear,
an effect similar  to that of*a crystal  in a saturated saline solution
ready to crystallise; and it has occurred to  me that agitation may
promote coagulation by producing a more intimate mixture of  the
particles, of those which are first coagulated, with those which  are
still liquid;  I say "first coagulated,1'because it maybe inferred from
what has been already stated, that some  particles of lymph  are co-
agulated almost  immediately after the blood  is drawn, and these
may act on  the  mass like a  portion  of  crassamentum  introduced
into it.

           3.— On the effect  of lightning on the blood.

   It is commonly believed that the  blood of those killed by light-
ning does not coagulate.  The opinion has been adopted  by Hunter,1
but on what evidence  is not stated.   Now,  as it appears that  the
blood of animals killed by the discharge of an electrical battery is not
deprived of its power of coagulating, and as electricity, applied  as a
chemical agent, seems rather to promote than  retard the coagula-
tion of  the albuminous contents of the blood,  a  priori,  it does not
seem probable that the  popular  belief is correct.   The  question,
however, cannot be determined  excepting  by an appeal to facts.
The following case, with this view, may be  deserving of being  re-
corded ; I shall give it in detail, from my notes taken at the time, on
account of the interesting nature of the subject.
   Durino- a  violent thunder storm at Malta, on the loth of Novern-
1 Treatise on the Blood, &c. p. 34. 
OBSERVATIONS ON THE BLOOD.
41
ber,  1832, a Maltese labourer, aged 65, previously in good health.
was struck dead by lightning. The body was conveyed to the civil
hospital, where I had an opportunity of examining it twenty-four
hours after the event.
  The hair on the left side of the chest was slightly singed.  The
cutaneous vessels generally were much distended with blood ; the
face  and neck were purplish red ;  the inferior surfaces  purplish.
The fingers were contracted  and rigid.   The abdomen  was  very
much distended, tense  and tympanitic.   There was froth at the
mouth,  mixed apparently  with some of the discharged contents of
the stomach.
  On inspecting the abdomen,  the stomach and intestines  were
found enormously distended with air.   There was much air in the
cellular structure from putrefaction; the cellular  structure even in
which the gall-bladder is embedded in the liver, was distended with
air.   There was a general staining of  the different structures by
the blood, atid the blood-vessels,  and the lining  membrane of the
heart and bronchia was dyed dark red.   There was frothy blood in
the veins, and in the right cavities of the heart with a little soft co-
agulum.  The lungs were very  red and distended with air, and its
vessels were strongly stained.
  The atmospheric temperature during the time that elapsed  be-
tween the event and the examination, and the temperature of the
room where the body was deposited, varied between  55°  and  60°.
Such advanced  putrefaction as was witnessed, is  uncommon in the
time specified, in the hottest weather.   At  the moment,—reflecting
on the degree of putrefaction, and the state of the blood, I had little
doubt, that the latter was  owing to the  former, however that might
be produced.  This idea,  1 am still disposed to entertain,  and  even
to extend to all similar cases.  And the conclusion is the more pro-
bable, in relation to the like events  in this country, in as  much as
thunder storms are of rare occurrence, and seldom severe, excepting
in summer and autumn, and in the most sultry weather, when the
tendency to rapid putrefaction is greatest.
  It is mentioned in the account of the post mortem appearances,
that  the fingers were contracted and rigid.   Hunter was of opinion,
that  the muscles of those  struck by lightning  are relaxed and en-
tirely deprived of their tone.  I am equally ignorant how he arrived
at this conclusion, which I am disposed to think was peculiar to him,
and, perhaps,  founded on hypothetical views.  Some of the older
writers  particularly insist  on the rigidity of the  muscles in those
struck by lightning;  and Mayow, in  his  Tractatns  Quartus de
Motu Musculari, endeavours to  explain, by means of his very ori-
ginal speculations  connected  with  the nitro-aerial  principle, " cur
fulmine percussi obrigescunt,v treating of the effect as if it  was then
generally acknowledged.1
1 Op. cit. cap. vi. ad finem. 
42
davy's  researches.
4.- Effect of hydrocyanic odd, and of violent and long-continued
                muscular exertion on the blood.

  It  has been asserted that the blood of animals, hunted to death,
and  killed by  the  prussic or hydrocyanic  acid, continues  in  the
liquid state;  and even the high authority of Hunter may be adduced
in support of the opinion, that in animals run down in the chase,
the blood  is deprived  of its power of coagulating.   From all the in-
formation, however, which I have been able to collect, I am com-
pelled to conclude that the opinion  in  both cases has been  hastily
taken up, and is not correct.
  In  relation to the  hydrocyanic acid, in no instance  have I wit-
nessed the blood liquid or deprived of its power of coagulating,
in animals poisoned by it,—and I have paid attention to the state of
the blood in  many animals thus killed,—the cat, the dog,  the rabbit,
—and the appearance which it has exhibited  has been  in  no wise
peculiar;  its coagulation, as  well as I  could judge, was neither re-
tarded nor accelerated. And this might be fully expected, a priori,
considering that the hydrocyanic acid  has no visible effect, even in
large quantity, when  mixed with the blood, out of the body.
  Relative to animals hunted to death, the results  of my inquiries
has been very similar.  From what I  have been able to learn from
sportsmen, and especially from some of my professional friends, fami-
liar with field sports, coagulated blood is commonly to be found in the
hearts of animals thus killed ; and I am authorised by  an observer.
on whose accuracy I  have perfect reliance, viz. Dr. Andrew Smith.
to state that  this is  the result of his experience  in Southern Africa,
where the larger antelopes are frequently run down by dogs.  Per-
haps, in  this instance, as  well as in that of death from lightning,
when a loose or liquid state of the blood has been observed, putre-
faction has been more concerned in producing it, than the  mode of
death.

5.— On the effect of  change of temperature on the coagulation of
                            the blood.

   It is agreed by all  those who have made experiments on the sub-
ject, that  cold, instead of being the cause of the  coagulation of the
blood, as  was for a long time believed after Aristotle,1 actually re-
  ' Aristotle, speaking of the coagulation of the blood in connection with its
cause, says, " Si fibras  detraxeris, sanguis  non cogetur.  Ut enim si ex luto
terrenam portionem semoveris, aqua non concrescit; ita  sanguis, fibris de-
tracts, incongelabilis manet; fibrarum  enim terrena est.  Quod si non exi-
mantur, cogitur, ut  terra humida, frigore.  Cum  enim calor exprimitur,
humor circa  trahitir, atque evaporatur: atque ita concrescit, non  a calore
siccescens, sed a frigore."—De Part. Animal, lib. ii. ch. 4.
  Harvey, as  appears from the  passage already quoted,  refers  the coagula-
tion  of the blood to an escape of the native animal heat; and Sydenham  to
the cold of the atmosphere. 
OBSERVATIONS on the blood.
43
tards coagulation.  My own results are in conformity with this, and
with the results of the accurate Hewson, that the viscidity of the
blood is, at the same time, increased.   At the temperature of  32°, I
have seen blood remain  liquid more than an hour;  a reduction  of
tempeiature, some degrees lower,  was required to freeze it,— when
it appeared as a homogeneous mass.
  Hewson, from his experiments on the freezing of the blood, in-
ferred, that its qualities were not thus altered ; that when thawed, it
returned to its liquid state, and that it was then subject to coagulate.
He speaks very decidedly on  this  point: he says,—"the blood was
always evidently fluid ou  being thawed,—and as evidently jellied
when exposed to  the air."1
   Mr.  Thackrah,  from his experiments, infers  the contrary,  viz.—
that by freezing, the blood permanently loses its  power of coagu-
lating.2
   The few experiments which I  have  made on  this subject, insti-
tuted long before I had  seen  Mr.  Thackrah's book, perfectly agree
in their results with those of Mr.  Hewson.   I  shall describe them
from notes taken  at the time, in  the  month of  January, 1828, at
Corfu.
   Received into a thin  glass tube, the temperature of which had
been reduced by ice and dilute sulphuric acid, some blood of a fowl,
and immediately  placed it in the freezing mixture.   The blood was
frozen in a few seconds.  After three or four minutes it was taken
out of the mixture;  it  presently became liquid.   It was again  re-
 placed and refrozen.  It was once more taken out, and it  melted
 again ; and it was again speedily replaced.  At the end of four or
 five hours, left in ice  thawing, and which was then thawed, I found
 it coagulated.  Some of the same blood not cooled artificially,  co-
 agulated in less  than a minute;  and  in less  than three minutes,
 when  received into a platina crucible, and suddenly cooled  by ice,
 to 40°.
   The subject of the next experiment was venous blood, from  a
 soldier labouring under a slight  ailment.  About an ounce  of this
 blood, received into a glass tube,  was instantly put  into a freezing
 mixture.  After about ten minutes, a thermometer introduced into
 the blood fell  to  26°.  It remained at this temperature about an
 hour,  and all the time liquid : the red particles had subsided, and the
 supernatant fluid was colourless.   It was then put into  a freezing
 mixture of greater strength, and placed under  the receiver of an
 air-pump; the air was  exhausted, and the pump was worked till
 the blood was apparently frozen.   After  it  had been some minutes
 frozen, I took it out, and applying a thermometer, found the freezing
 mixture at 10°.  On pressing the  frozen white part, a little fluid rose
 from the cruor,—the temperature of which was found to  be 32°.

   ' Experimental Inquiry, p. 28.
   2 An Inquiry into the  Nature and Properties of the Blood, by L . L.  L haclt-
 rah, 2nd edit. London, 1834, pp. 67, and 37. 
davy's researches.
The experiment was repeated till the whole was frozen.  The lymph
was kept in a frozen state about twenty minutes,—the cruor about
three or four.  The blood was  now placed in a room, the tempera-
ture  of which was about 55°.  It gradually thawed, and, when
thawed, was liquid,—perhaps a little thicker than when first drawn.
From the time it was completely melted,  it  began to coagulate  in
about eight minutes,—and,  in about ten minutes,  a  soft crassa-
mentum^ was  formed-   On examination, the  following day,  the
crassamentum was found soft and not much  contracted; serum had
separated from it distinctly.
  These results sufficiently accord with the  more numerous experi-
ments of Hewson, and in consequence, I am more disposed to con-
sider his inference just,  than  the contrary  one of Mr.  Thackrah.
And if we examine the detail of the experiments of this ingenious
inquirer, this conclusion, I think, will be strengthened.   In one ex-
periment, after having been thawed, he states that a small quantity
of serum separated from the blood;  in  another, when  the  thawed
blood was mixed with water and  passed through a filter,  some very
small portions of coagulum were retained;  and describing his  re-
sults  generally,  he says,  that the blood  "on being  afterwards
thawed becomes a  grumous mass, and does not separate into serum
and crassamentum."   Now, the grumous mass, and the  other par-
ticulars mentioned, indicate at  least a certain degree of coagulation.
As in one experiment, he appears to have placed the blood to thaw
in a warm room at  65°, and  to have observed it eighteen  hours
after, it is not  improbable, that the fibrin might have been in part
reduced to the liquid state from  putrefaction.  Be this as it may,
negative results must almost always be considered of inferior value
and force than positive ; and if exceptions are to be made,  commonly
there is more  propriety in selecting, for  this purpose,  the  former
than the latter.
  Admitting the  accuracy of  the above, it  is probable,  that blood
may be frozen for any length of  time, without  losing its power of
coagulating,  and without losing its power  of becoming liquid ; a
happy circumstance, in  relation to the animal economy in these
regions in which the cold of winter is severe, and exposed parts of
the body are liable to be frost-bitten ; and perhaps equally so, 1 may
remark farther, is the circumstance of the fluidity of the blood being
diminished by cold in relation  to animals which  hibernate  during
several months of the year in  a state of torpor, in which  life is
barely maintained.
  From the experiments which I have made on the effect of a high
degree of temperature,  as 120°; of a moderate degree, as 100°; and
of degrees between this and the freezing point, I am disposed to
infer that the first  immediately renders  the  blood more liquid, and
accelerates its coagulation; that the second rather retards  than
accelerates coagulation ;  and  that  at 80° or 90°, its coagulation is
less rapid than at 120°, and more rapid  than at 100°.   It may ap-
pear a paradox,  that heat above 100° should increase the liquidity 
observations on the blood.
45
of the blood and accelerate its coagulation ; but is it more so  than
that cold should render it more thick and viscid, and  yet retard or
prevent coagulation?  I infer that the effect of heat is  such  as I
have represented it, from observing blood heated to the degree  men-
tioned, and which coagulated more rapidly than blood not so heated,
covered with a buffy coat, when the cool blood,  slower in coagulat-
ing, was free from  it.  The blood is a mysterious fluid ; nothing can
with  propriety be  taken  for  granted  respecting it.   Its properties
can be ascertained only by exact experiment  and unbiassed obser-
vation.   Every property which  it possesses seems to be  adapted to
admirable ends ; and even these peculiarities in relation to the  effect
of the higher as well  as  the lower degrees of temperature  in its
coagulation may be considered as such  adaptations.  The effect of
high temperature on coagulation may tend to limit the  destructive
effect of heat to the surface; the effect of a temperature of 80° or
90°, which is about the temperature of the skin, may tend to sup
press hemorrhage, the consequence of superficial wounds.

6.— Of the effect of different kinds of vessels on the coagulation
                          of the blood.

   It is generally supposed, that the kind  of vessel in which the  blood
is received, its size, form, and quality, have a considerable influence
in  promoting or retarding its coagulation and the formation of  a
buffy coat.   I have made many experiments to  endeavour to  ascer-
tain the truth of this opinion ; but I have not yet been able to arrive
at a satisfactory conclusion.  I am rather  disposed to think that  wood
and polished  metals retard coagulation,  and that glass and earthen-
ware accelerate it.  The form and size of the vessel will, of course,
have some influence,  were it merely in connection with tempera-
ture.   The remarks which I have made relative to the difficulty of
ascertaining the effect  of moderate motion on  the blood, are particu-
larly applicable here ;  and, a fortiori, as the effect of the quality of
the vessels I have  tried, is even  more  ambiguous than that of mo-
tion.  In illustration I shall give the results of one trial on the same
blood, with different vessels, extracted from my  note-book.
   On the 12th December, in the military hospital  at  Corfu,  blood
from the arm of a patient slightly indisposed, was received, first,
into a wooden cup; second, into a circular  pewter  one,  divided
equally into two compartments;  third, into a silver dish, placed on
lint moistened with ether; fourth, into a small cupping-glass.  The
coagulation of the blood first took place in the wooden dish, and
not at the circumference, but in the middle; next,  in the  semi-
circular compartment  of the  pewter  vessel, in that  in  which  the
quantity received was greatest, and in it also in the  middle; next
in the silver dish at the surface: and, last, in  the other compart-
ment of the  pewter vessel, in which  only a very small quantity,
about four  or five drops,  had been spilt.
   Perhaps it may be  safely laid down  as a general rule, that  the
       9—g                                      4  dav 
46
davy's researches.
 form and quality of vessel best adapted for preventing sudden cool-
 ing, and therefore an  increase  of the  viscidity of  the  blood or
 coagulable lymph, favour most the rapid subsidence of the red  par-
 ticles, and  consequently the formation of the buffy coat.   This is in
 accordance with  Dr.  Benjamin Babington's  experience with  thin
 pear-shaped glass vessels, such as he used for the purpose of ascer-
 taining the specific gravity of the blood ;* and also with mine, on
 thin globular glass vessels.   Very often I have  found a bufiy  coat
 in these globes, when none appeared on the blood  collected  in the
 usual way.

 7.— On the influence of the blood-vessels or of vital action on the
                    coagulation of the blood.

   This is  allowed to be, and necessarily is, a point  of inquiry of
great obscurity;  both as  regards the fluid  itself and the causes re-
ferred to.  I shall enter on it very partially.
   Hewson, from his  experiments and  observations,  inferred  that
 "the properties of the blood depend on the state of the blood-vessels;
or that they have a plastic power over it, so as to be able to change
its properties in a very short time;" that what increases or strength-
ens vascular action, or the heart's action, tends to retard coagula-
tion, and that which has a contrary  agency, promotes and accele-
rates it.2
   He arrived at  this, which he calls his "most remarkable conclu-
sion," from witnessing the sudden change in the coagulating power
of the blood, during the same blood-letting, as exemplified in differ-
ent portions, received separately; confirmed by what  he witnessed
in instances of animals blooded to death.
   In these  last mentioned instances, it has been shown, that  the
specific  gravity of the blood which flows from the slaughtered ani-
mal, when  nearly exhausted, is less than of that  which flows  when
the vessels  are first divided.
   The  circumstance  necessarily gives rise  to reflection.   As it
seems to show that the composition of the blood is altered at least
as regards the relative proportions of its constituent  parts,  as ob-
tained in the process of draining the  vital fluid, it is matter for con-
sideration,  whether something similar may not take place in the
other instances  referred to by Hewson; and whether the changes
in the  circulating mass which he attributed to the vessels,  acting
on the blood, may not be  owing to a vascular action more analogous
to that of secretion.
   It is easy to conceive that, under different degrees of vital action,
the nature  of the current  of blood, either in the  minute vessels,
arterial  and venous, or in the capillary vessels connecting them, or
in both,  may be  modified;  that in one condition more red particles
may pass,  in another a  larger proportion of serum,  in another of
1 Medico-Chirurg. Trans, vol. xvi. 297.
2 Op. cit. p. 125. 
observations on the blood.
47
lymph.  Is it  not  probable,  that, were  blood  extracted from  the
cheek, under  the influence of the peculiar feeling connecled with
blushing, it would be found to contain an undue portion of red par-
ticles?—that the  reverse would happen in blood  abstracted from the
same surface  under the  influence of fear; when probably it would
be found to abound  more in serum.   And, in a third instance,  as
in erysipelas of the face, it would  probably be found to contain  an
excess of fibrin.
  In the embryo, a colourless fluid  is  the first which  circulates.'
Whether, independent of the lymphatics, there is an order of vessels
in the  adult conveying only a similar fluid, is a  subject for inquiry.
In the brain, in an  instance of jaundice, I have  witnessed, on mak-
ing sections of the organ, points distinct from  the ordinary blood-
specks, tinged  by bile, otherwise colourless, and which,  were it not
for the adventitious hue, would have been imperceptible.   I regret
I had  not an  opportunity of examining the fluid of these puncta
with the microscope.2  The most probable inference seems to me to
be, that they were either divided  lymphatics, or  vessels of the order
just alluded to.  But, even supposing that no such vessels exist, the
lymphatics, under  different  influences,  may pour  more or less of
their contents into the general circulation, and  so affect the quality
of the  blood.
   The quantity of  blood abstracted by the leech perhaps  may be
adduced in support of the argument,   It is commonly believed that
the blood  so  abstracted does not differ from that procured by the
use of the lancet.   According to  my observations, it abounds much
more  in  red  particles,  and very much  less in  serum and  lymph;
and, in  consequsnee,  its character is different—coagulating much
less firmly, or often not  at all, exhibiting merely a grumous appear-
ance,  of unusually high specific gravity, and when evaporated to
dryness, affording a larger proportion than common of solid matter.
One leech, which I tried in Malta, in May, 1830, gorged with blood,
was of specific gravity 1087;  cut in two and deprived of blood, one
moiety was of specific gravity 1062; the other of specific gravity
1054; the latter was  the caudal portion.  This leech, distended
with   blood,  weighed  161-4  grs.   Another, smaller,  which dis-
tended with blood weighed only 18-4  grs. was, with the blood, of

  1 This fact appears to have been discovered, if I may say so, at least  three
different times; by Glisson, nearly  two centuries  ago,—more recently by
John Hunter,—and very lately again  by MM. Delpech and Coste.  Glisson,
in his Treatise  on the Anatomy of the Liver, published in 1564, says, "Ma-
teria prima, e qua partes fiunt, non est sanguis, sed succus quidam  liquidus,
albumini  ovorum non absimilis, unde pullus efformatur."—Anatomia Hepa-
tis, p.  495.  Amstel.  1659.  Needham, a disciple of  Glisson, is even  more
explicit on the subject: in his treatise " De Formato  Fcetu," he speaks of a
nutritive fluid, which "per venarum  oscula nondum rubentia facile recipia-
tur," p. 83.
  2 Since the above was  written, another similar opportunity has occurred ;
the yellow fluid of the puncta, under  the microscope, was found to contain a
very few blood  particles: it was probably, therefore, extremely  dilute blood. 
48
davy's researches.
specific gravity 1076, and empty, or very nearly so, of specific gra-
vity  1051.   Blood abstracted from the arm, from a patient labour-
ing under an inflammatory complaint, of specific gravity 1061, and
which after coagulation was  slightly buffed, yielded on evaporation
to perfect dryness 207 per  cent, solid  matter.  Blood abstracted
from the same patient from the scrobiculns cordis by a large leech,
similarly evaporated,  yielded  223 per cent.  Now is it not probable,
that these peculiarities of the  blood abstracted by leeches is connect-
ed with the  size of the aperture, and the effects  of  the pumping
force  exercised by the animal?  That  the latter influence is con-
cerned, at least  in part, may, I think, be inferred from the circum-
stance, that the blood which flows from the wound after the removal
of the leech, commonly coagulates more readily and firmly than the
blood procured from the  leech itself.  The blood extracted  by the
mosquito is again different in character  from that by the leech.  It
coagulates readily, and is not deficient in fibrin.

8.—On the effect of oxygen and of carbonic acid gas on the
                            blood.

  My brother, the late Sir Humphry Davy, in his Researches on
Nitrous Oxide, states that he did not find the coagulation of venous
blood affected by either of these gases.1   According to Sir Charles
Scudamore,  blood coagulates sooner in  oxygen gas than in atmo-
spheric air,  and cools slower; and, in carbonic acid gas it coagu-
lates slower, and cools  sooner.2  The experiments which I have
made have afforded results similar to those first mentioned. I have
not found the coagulation of the  blood distinctly accelerated by
oxygen or retarded by carbonic acid; nor have I  found any well-
marked difference in either, in relation to the time of cooling.  And
I did not simply expose the surface of the blood to the influence of
the gases, in the manner in which Sir  Charles Scudamore  made
his experiments, but  I agitated the blood in each gas.  Of the oxy-
gen, there did not appear to  be any absorption; if there were any,
it must have been slight,  which the form of the experiment was not
fitted to detect.  Of the carbonic acid gas there was a very consider-
able absorption, equal in  volume to that of the blood used, or very
nearly so. I have also tried the effect of water strongly impregnated
with carbonic acid gas on the blood, and of oxygen gas on the cras-
samentum of the blood, and the results have been similar. The tem-
perature of the cold crassamentum  was  not raised, and the coagu-
lation of the fluid blood was  not prevented.
   Merely hypothetically considered, I  do not comprehend  how
either  oxygen,  hydrogen, or azote, or any other gas which is not
absorbed rapidly by the blood, can materially affect the coagulation
of this fluid, or can be the means of producing a sensible evolution
of caloric, at least by the simple contact of surfaces.  I would re-
1 Op. cit. p. 381.
Essay on the Blood, pp. 59, 61. 
OBSERVATIONS ON THE BLOOD.
49
mark,  however, that  I do not consider the negative results of my
experiments with oxygen in the slightest degree hostile to that
view of the generation of animal heat, in which the chief source of
it  is referred  to  the  lungs.   I  need  not say, that there is an im-
measurable difference between the  natural  process of respiration
and the  rude experiments just now alluded to, whether  we consi-
der the apparatus, the material, or the situation, and more particu-
larly when we consider that in one instance vitality is present, and
in the  other that life is extinct, and the agents are merely chemical
and dead.
   I must confess, too, that, viewed hypothetically, I am equally at
a loss to conceive how carbonic acid gas should retard the coagu-
lation  of the blood.   If it were true that blood abounds in carbonic
acid gas, and the coagulation of the blood depends on the evolution
of carbonic acid gas, then, in the act of coagulating, it ought not to
absorb an additional quantity of this acid gas; or if it did not absorb
it, it ought not to coagulate;  and indeed it ought  not  to coagulate,
though it did not absorb it,  so long as it was  in  an atmosphere of
carbonic acid gas, and so long as it retained the proportion of gas
supposed  to belong to it.   Were there  not a consistency in nature,
there could be no science.  It is not a contradiction that the blood,
a fluid not saturated  with carbonic acid, capable of combining with
a fresh portion, should contain free carbonic acid, and be capable
of giving it off.  I speak of the blood out of the body, as of a bone
or muscle, detached from the animal, deprived  of life, and subject
to the  same laws as ordinary dead  matter.  Farther on, I  shall
recur to the important points^—the carbonic acid  in the blood, and
the absorption of oxygen by the blood, with which are involved so
much  of physiological doctrine.

9.— On  the effect  of removing atmospheric pressure from the
           blood, and of excluding atmospheric  air.

   According to Sir Charles Scudamore, blood coagulates in vacuo
more  rapidly than in the open air,  and becomes of a considerably
darker colour.1  I have  tried this experiment  repeatedly, and the
result  apparently has been negative.   The blood which coagulated
under  the exhausted receiver  was of  the same colour as some
which, for the sake  of comparison, was left exposed to  the atmo-
sphere, and  its rate of coagulating was much the same—certainly
not quicker—rather slower.  On account of the interest of the sub-
ject, I  shall describe two or three  experiments,  from which, and
from others, I  made these deductions in January, 1828, at Corfu.
   Put  under the receiver of an air pump about an ounce of venous
blood,  collected as it  flowed from  the arm in a cylindrical  glass
vessel,  and immediately exhausted the  receiver.  Until the ex-
haustion was  nearly complete, the  blood was perfectly  tranquil;
8 Op. cit. p. 22. 
50
davy's researches.
suddenly it boiled up, almost in the manner of an explosion, and
continued bubbling during half a minute at least.  On the admis-
sion of air into the  receiver,  all the bubbles  instantly subsided.
The blood was not coagulated;  it coagulated slower than a portion
set  by in the.open air for comparison.
  A few days after I repeated this experiment, with this difference—
the air of the  receiver was slowly exhausted  to allow the blood to
cool below the boiling point of water in vacuo.  Now,  there was
no ebullition, no effervescence, no disengagement of air,  excepting
of two  or three  adhering globules.  When taken out, this portion
of blood had just begun to coagulate;  another portion, left exposed
to the atmosphere, was coagulated firmly.  The colour of each was
similar.
  Repeated the experiment; taking precautions to prevent, as much
as possible, the adhesion of air to the sides of the  glass,  by  careful
cleaning, and wiping, and rinsing it out, previous to the admission
of the blood, with distilled water, which had been purged  of air.  In
this instance,  no bubbles of gas appeared in the blood on exhaustion,
and the coagulation took place a little later than in another portion
of blood exposed to the air.   There was no difference of colour be-
tween them.
  In the paper in which the general results of these  experiments
were  given, and which was published in the  Edinburgh Medical
and Surgical Journal, vol.  xxx, for 1828—I  further stated  that I
found  no material effect produced on the coagulation of the blood
by receiving it as it flowed from the arm into oil, which had been
previously deprived of air  by  the air-pump, whether under the in-
fluence of atmospheric pressure in the open air, or excluded from
it under an exhausted receiver.
  Turning back to the notes  of these experiments, I find  it re-
marked, that  the blood coagulated slower under the oil (whether
under pressure or not) than when exposed to  the air;—and that,
in the former, a much thicker buffy coat formed than on the latter.
This result accords with others which I  had obtained several years
previously in Ceylon; and also with the results of the later experi-
ments of Dr.  Benjamin Babington, on the effects of oil.1  Probably
it is,  in  part,  connected with the cooling effects of the oil  on the
blood  in passing through  it;  and, in part,  to the exclusion of
air.


10.— On the effect of water, milk, urine, and bile, on the coagula-
                       tion of the blood.

  It has been remarked by  Dr. Crawford, in his treatise on Animal
Heat.2 that,  by the dilution of blood with water, in the  proportion
of twelve parts of the latter to one of the former, its coagulation is

  1 Med.-Chirurg.  Trans, xvi. 298.
  * Experiments and Observations on Animal Heat, p. 278, 2d edition. 
OBSERVATIONS ON THE BLOOD.
51
 retarded for several hours.   In one instance, in which 1 made this
 experiment,  at the end of two hours the diluted blood appeared to
 be liquid;  but, when thrown upon a filter, this appearance  proved
 to be deceptive; the fibrin had coagulated, and it  was collected on
 the filter in the form of a very tender gelatinous mass.  From this,
 and from  other experiments,  I  am inclined to infer, as might be
 expected, a priori,  that dilution, by removing the particles of fibrin
 to a greater distance from each other, and  by suddenly cooling the
 blood, does retard its coagulation—but not so long as Dr. Crawford
 conceived, who formed his opinion on the subject  merely from the
 appearance of the blood.
   Milk, urine, and  bile,  I find, also retard the coagulation of the
 blood, and more so even than water.  The urine and bile used  were
 human—the milk,  cow's.
   The results of the experiment with the urine are, perhaps, not
 undeserving of more particular notice.  About two ounces of blood
 were mixed, as it  flowed from the arm, with  four ounces of urine,
 containing,  perhaps, rather a larger proportion than usual of urea.
 After about an hour and half the  blood  had gelatinised.   After
 twenty-four  hours,  it had coagulated pretty firmly; the  coagulum
 was much contracted and slightly cupped, and covered with a thick
 buffy coat.   After  forty-eight hours,  the coagulum was  still more
 contracted, and it  had acquired a globular form, with a  little  con-
 cavity on  its upper surface.   The urine was only just perceptibly
 coloured  by the  colouring matter  of  the blood.  I may  here  inci-
 dentally remark, that this fluid is particularly well  adapted  as  a
 medium for displaying the  phenomena  of the coagulation  of the
 blood, from its retarding the effect, and yet not diminishing it—and
 from its not dissolving the colouring matter of the red particles.  It
 enables one to determine, in  a satisfactory manner, especially  with
 the aid  of sections, that the phenomena of the buffy coat, and the
 cupping of the blood, are owing to an unequal distribution of the
 fibrin;  and that, when they occur, there is an  excess of fibrin at
 and  towards the surface of the crassamentum,  which, it may be in-
 ferred,  was  pressed up by the red particles in descending; and  a
 deficiency  of it at the bottom, and  towards it, in regular gradation;
 and  that the buffy coat is cupped in consequence of the unusual
 contraction of the fibrin, and  its accumulation at the circumference.

               11.— On the coagulation of serum.

  It has been supposed by Mr. Brande, and alter him, it has been
asserted by several authors, that the  liquidity of the serum of the
blood is owing to the presence of an alkali—and  its coagulation,
under certain circumstances,  to the abstraclion or neutralisation of
this alkali.1   Dr. Bostock  has objected to this view, on the ground

  ' Whether the property of serum was known to the ancients, oi,  indeed,
whether they were acquainted with the fluid itself,  is,  by some, thought 
52
DAVY'S RESEARCHES.
of the minute portion  of alkali existing in the blood—and that this
alkali may be neutralised—and yet the serum remain  liquid.  He
is of opinion that the effect of coagulation, in the instance of serum,
is one sui generis.1

  The experiments which I  have  made on  serum, have afforded
results in favour of this latter view.  I shall briefly describe them—
preliminary to others on the coagulation of the blood.

  The following acids, I find, do not coagulate serum, when  cold,
namely—distilled vinegar, strong  acetic acid, citric acid, boracic
acid;  the  tartaric and  oxalic acids, and the aqueous solution of sul-
phurous acid.  I shall notice, in detail, a few of the experiments.

  In two instances of  the trial of citric acid, it was added in mode-
rate excess  to the serum, its crystals  having been previously re-
duced to the state of fine powder.   On agitation, the acid was dis-
solved, and some carbonic aeid gas was disengaged.   The serum
acquired a slightly opalescent hue, and its fluidity,  perhaps,  was in
a slight degree diminished.   The serum used was that  of the blood
of the sheep, which does not  coagulate at 160°.2  It was  immersed


doubtful, so imperfect is the history of physical  science;  moreover, it is
even doubtful at what time, and  by whom, the  coagulability  of serum, by
heat, was  first ascertained.  Some writers, as Haller, refer, if not  the dis-
covery, at least  the first mention of this quality,  to Harvey;—others, as Dr.
Bostock, consider Harvey's notice of it obscure—and seem to be of opinion
that Lower was the first who clearly  described  it. Lower,  in  his account
of the liquor pericardii,  remarks,—*'Porro humorem istum non mere excre-
mentilium aut instar roris stillatitii aqueum,  sed seri potius nutritii e san-
guine promanantis, partem esse, exinde constat, quod ignis ealori vel paulu-
lum admotus, non aliter quam serum sanguini post vena? sectionem innatan=,
aut lympha e glandulis secreta in gelatinam albam incrassatur: qualum qui-
dem consistentiam nee sudor neque urina qualicunque coctione acquiiit,  sed
vel omnino in auras exhalat, aut  in sabulum induratur."—(Tract, de Corde,
1669, p. 6.)  The author here speaks  of  the property as  if well known to
belong to the serum of the blood;  and, I apprehend, the same inference may
be  made from  certain remarks of Harvey, in connection with coagulable
lymph,—his mucago "si saniem illam a  grumo separatam et effusam leni
foco decoxeris,  eandem brevi in  mucaginem hanc mutatum iri conspicies.
Indicio manifesto, aquam illam sive saniem, a sanguine in pelvi  separatam,
urince forsan materiam aliquam,  non autem urinam ipsam esse;  licet colore
et consistentia talis videatur.  Q.uippe urina coctione non densatur  in fibro-
sam mucaginem,  sed  potius  in  lixivium: aquosa autem sive sanio»a haec
pars, aliquandiu leviler cocta, in mucaginem innatantem abit:  quemadmo-
dum, vice versa, mucago istbogc, corruptione recrudescens, in saiem colli-
qualione revertitur."—Op. Omn.  p. 406.  How slow was the progress of ani-
mal chemistry, before it was methodically cultivated !  Between the time
of Aristotle and Harvey, no  positive advance appears to have been made;
and the former, probably, was acquainted with the property of serum in
question ! il may be inferred from some expressions which he uses.
  1 Elements of Physiol, vol. i. p. 476.
  2 The point of coagulation of the serum of ihe blood of different animals
is not the same; even amongst the mammalia I have observed a variation of
temperature of  10° in this respect. The serum, the subject of the  experiment
coagulated at 16S°. 
OBSERVATIONS ON THE BLOOD.
53
in a glass tube in water of this  temperature;  it remained transpa-
rent, and acquired the consistence of thin jelly.
   The same acid was next tried in great excess—more was added
to the serum than it was capable of dissolving.  The results were
similar, with this  difference—that the jellying of the serum was
prevented by heat—even at the boiling temperature of water. The
effects of the oxalic  and  tartaric acids  were analogous.
   Strong acetic acid, in great  excess, added to  the same serum,
did not coagulate it—some  gas was disengoged,  and, perhaps, the
fluidity of the serum was slightly impaired, but of this  I was  not
quite certain.  The mixture, placed in water of 160°. firmly coagu-
lated, and the coagulum was opaque.1
   A solution, in water, of the sulphurous acid, of moderate strength,
appeared  to have no effect  mixed with  serum.  When, however,
the acid gas was  condensed  in serum, there was a  decided  effect,
a coagulation was occasioned—a transparent jelly formed—which
appeared  to be quite insoluble in water, and not liable to  putrefy.
   The effects of the mineral acids—the  muriatic, nitric, and  sul-
phuric, vary with  their degree of solution.  Equal parts of muriatic
acid and  water, coagulate serum as readily as the strong acid;  but,
when diluted with six parts of water, the effect was scarcely visible.
Nitric acid, largely diluted,  has a distinct effect; thus, one part of
this acid to thirty  parts of water, had rather more  visible effect than
the muriatic with six of water;  with  twenty of water, the serum
 was rendered very  turbid.
   The alkaline earths,  lime and magnesia, have,  apparently, no
 effect on  serum.  Baryta, mixed with serum, formed with it  a  firm
 semi-transparent jelly.   A few hours  were required for  the combi-
 nation  to take place.  In the instance of lime and  magnesia, no
 change was perceived either immediately or after many hours.
   Ofthe salts, some, as the sulphate of copper, the sulphate of zinc,
 coagulated  serum, or occasioned a precipitation of its albumen, and
 even when extremely diluted.   The super-tartrate of  potash, in
 solution, rendered it turbid.   Others, as nitrate of barytes, oxalate
 of ammonia, borax, triple prussiate of potash, chlorate of potash—
 the neutral salts—did not disturb its transparency.
    Nitrate of silver unites with the albumen of the serum, which it
 precipitates in the  form of an  insoluble  compound ; but, though
 insoluble in  water, it is readily  soluble in acetic  acid; and,  it is
 not a little remarkable, that iis solution  in this acid  is not precipi-
 tated by  common salt.
    A strong aqueous solution of chlorine  did not coagulate serum.
    Calf's rennet was tried on it, both cold and warm, without effect.

   1 Vinegar, as it is well known, coagulates milk.  The effect of a few drops
 of stron<? acetic acid  is immediate, even  unassisted by  heat,  presenting a
 remarkable  contrast with the effect of the other vegetable acids mentioned
 above,  which, even when  in large excess, and boiled, did not coagulate
  milk. 
54
davy's researches.
12.— On the effect of substances on the blood, which do not coagu-
                          late serum.

  According to their effects, as I have ascertained by experiment,
these substances may  be divided into three classes; viz.  1st, those
which do not retard distinctly, or distinctly accelerate  the coagula-
tion of  the  blood;  2d, those which  retard or prevent its coagula-
tion ;  and 3d, those which  accelerate its coagulation, or  otherwise
alter it.

(I.)— Of those substances which do not distinctly retard  or accele-
                       rate coagulation.

  The following substances, which I have tried, may be enume-
rated  as belonging to this class, viz. chloride of silver,  protoxide
and peroxide of antimony, red precipitate, sulphur, iodine, hydro-
cyanic acid, carbonate of lime, starch, sugar, camphor,  sulphuric
aether, oil of  peppermint, cantharides, oil of turpentine, hydrobora-
cic acid, white oxide of arsenic, and gum-arabic.
  In each instance, there was some slight peculiarity  in the result,
as in  relation to the colour which the crassamentum  exhibited, or
its degree of contraction or consistency.   I  shall notice a few of
them, those which were best marked.
  Sugar, refined in powder, added to the  blood the instant it was
drawn, did  not  appear to  retard  coagulation; the coagulum was
very soft, and bright red. After twenty-four hours very little serum
had separated, and there was  scarcely any perceptible contraction
of the clot; the  fibrin  collected by means of a linen  filter, gentle
pressure being used,  was very soft.  The fluid  part, obtained by
filtration, did not jelly  when diluted  with water.   The experiment
was made in  Corfu, in  November, when the temperature of the air
of the room  was between 50° and 60°.   After a  week, there were
no signs of putrefaction, either in the diluted or undiluted mixture ;
both had a very slight smell of vinegar.
  The effect of the white oxide of arsenic on the blood differed but
little from that of sugar; it did not appear either to  retard or ac-
celerate its  coagulation.  The coagulum, however, after twenty-
four hours,  was comparatively soft,  having scarcely perceptibly
contracted, and no separation of serum had taken  place.  The sur-
face was unusually fluid, and also the bottom of  the  coagulum in
contact  with the principal  part of the oxide.   This experiment
was made in England, in January, on the blood  of a young man,
which was healthy in  appearance.  It appeared  to prevent putre-
faction.
  Gum arabic, added in the state of fine powder,  did not appear to
retard the coagulation  of blood, excepting, perhaps, in a very slight
degree.   The coagulum formed  was  very soft, and it contracted 
OBSERVATIONS ON THE BLOOD.
55
very little.  Mucilage of gum arabic, retarded it about twenty-four
hours.
  Oil of turpentine, also, perhaps retarded the coagulation of the
blood in a very slight degree.  The effect on the colour of the blood
was more distinct;  the oil changed it to a brownish hue.
  Cantharides in powder did not appear to retard coagulation ; the
crassamentum remained soft, and not contracted.
  Red precipitate neither retarded coagulation, or the contraction
of tha crassamentum when formed, nor consequently the separa-
tion of the serum.
  Iodine did not appear to retard or accelerate coagulation.  Eight
grains of it were added to an ounce and a half of blood.  It ren-
dered the blood brownish.

  (2.)—Of those substances which retard or prevent coagulation.

  The following  substances, which  I have tried, belong to this
class;  viz.  rhubarb,  ipecacuanha,   cinchona, columba,  myrrh,
catechu, jalap, the  extracts prepared  in vacuo of belladonna, digi-
talis, aconite, conium and  sarsaparilla, the common extract of cin-
chona, magnesia,  carbonate of  magnesia, sulphate of zinc, tartar-
ized  antimony, supertartrate  of potash, triple  prussiate of potash,
muriate of barytes, nitrate of barytes, borax,  common salt,  nitre,
sal-ammoniac,  the  sesquicarbonate of ammonia, the  carbonate of
soda, sulphate of ammonia, aqua ammonias, aqua potassse, distilled
 vinegar.
   The effects of the substances arranged under this second class,
 individually considered, are still  more  various than those of the
 first.  Most of them produced a thickening, and increased the vis-
cidity of the blood.  The former was especially the effect of the
vegetable substances, and the latter of some of the salts, particularly
 borax and carbonate of soda.  Very few of the  substances  tried
 had a contrary  effect;  it was well marked only in a  few instances,
 as  in those of the triple prussiate of potash, cream of tartar, tartar-
 ized antimony,  magnesia, and carbonate of magnesia, with each of
 which the red  particles rapidly subsided ; no coagulation took place,
 and  the  fibrin  remained  completely dissolved in  the serum.  In
 some instances, and that the majority, owing to the thickening of
 the blood,  or  the increased  viscidity imparted, the red  particles
 were  kept suspended.  In a very few, as in  those of  distilled vine-
 gar, aqua ammonia, and  aqua potasse?, they were dissolved.  The
 difference of effect, as to  change of colour, was  very  various in-
 deed •  most commonly the  colour  was darkened—in  a very few
 instances it was rendered of a brighter and lighter  red.  This latter
 effect was most distinct in the instances of nitre, common salt, and
 borax-  it was  never permanent.  On dilution with  water, almost
 in  every  instance, the influence of the  foreign substance ceased,
 and the blood coagulated; and, I believe, it would have done so in
 every instance, with the exception of vinegar, and aqua ammonia?, 
56
davy's researches.
and potassae, and apparently of magnesia,  were the due proportion
of water known  which should have been added.   Mr. Hewson, I
believe, was  the  first who noticed this suspension of the power of
coagulation and the restoration of it by the addition of water.  His
observations were confined to the neutral salts.1 The notices which
he gives of his experiments are very  brief; he does  not allude to
the length of time the  effect  of suspension of coagulation may be
continued, nor does he appear to have been  aware, that conjointly
with this the tendency to putrefaction is arrested.  From what I
have  witnessed, I  believe that blood  may be  kept liquid or viscid
for days, or even weeks, without  losing the  power of coagulating,
and the  fibrin of contracting, when properly  diluted  with  water.
In the one state, I find  it resists putrefaction ; in the other it readily
yields  to  it.   I  have said, that vinegar, and ammonia, and aqua
potassae, are exceptions in this class of substances, differing from
them  in  preventing the coagulation of the blood, however carefully
diluted with  water, and that  magnesia is  apparently an exception
also.   The vinegar  and the aqua ammoniae, and  potassa? clearly
keep liquid, and  that  permanently, the  fibrin of the blood, as well
as dissolve the colouring matter of its red particles.2  The appear-
ance of magnesia being an exception also, I have found is a decep-
tion, and chiefly in consequence of the circumstance, that on dilu-
tion the  coagulable lymph does not form a glutinous mass, but is
precipitated in flocculi.
   From these general remarks, I shall  proceed  now to particular
instances, noticing only those in which the effects were best wit-
nessed.
   Extract of digitalis  prepared in vacuo.   Previous to  mixing it
with  blood,  it was softened with  water and  made of thin consis-
tence ; a dram of water having been added to half that quantity of
extract.   The blood (about two ounces) as it flowed from the arm,

  1 The following note appears to contain the results of Hewson's experi-
ments on this subject—(i The salts which keep the blood fluid by itself, and
yet allow it afterwards to jelly on being mixed with water, are sal glauberi
verus (sulphate of soda), sal digestivus sylvii  (chloride of potassium), sal
communis, nitrum  commune, nitrura cubicum  (nitrate of soda), sal diure-
ticus (acetate of potassa), borax, the salt made of vinegar and the fossile
alkali, and the salt made  with vinegar and chalk."  He adds, "the follow-
ing salts, likewise, keep the blood fluid, but do not  allow it to jelly when
mixed  with water: tartarus vitriolatus (sulphate of potash), sal epsomensis,
sal ammoniacus communis, sal ammoniacus nitiosus, sal rupillensis (tar-
trate of potassa and soda).1'—Experimental Enquiry, foofr-note, p. 13.
  2 Strong acetic acid  renders blood dark and viscid ; in one instance in
which a dram of acid was added to three drams of calf's blood, the mixture,
though viscid, admitted of being poured from one vessel into another.  The
red particles did not subside;  under the microscope, their appearance was
disti rt, perhaps a little  wrinkled at their edges, and  perhaps a liltle ex-
panded. When a drop of this viscid blood was mixed with a dram of strong
acid, from almost black it became of a reddish hue; and the red particles,
it may be  inferred,  were  dissolved, as under the  microscope they were no
longer perceptible. 
OBSERVATIONS ON THE BLOOD.
57
was received into the vessel containing the extract and immediately
stirred.  The first effect was a thickening of the blood ; it acquired
the consistence of paste.   After twenty-four hours, the appearance
was much  the same, as it was also afier thirty-eight.  The follow-
ing day, the lower part of the mixture was found to be more vis-
cid, as from the subsidence of the coagulable lymph.  Water was
now  mixed with it, and the result was that it jellied.
   Extract  of opium;  similarly and in  like quantity mixed  with
water, and  afterwards with blood.  After two hours ihe blood was
liquid : the red particles  had subsided, leaving a stratum of viscid
fluid which admitted of being drawn out into threads ; after  three
hours, slight coagulation had taken place ; after twenty-four hours,
the coagulation was firm, cupped, and exhibited a buffy coat.
   Sulphate of zinc.   A  drain of  this salt  in powder, was mixed
with about an ounce of blood.  It thickened immediately but did
not coagulate.  After  twenty-four hours there was no further ap-
parent change.  On  dilution with  water, a white pellicle  formed
suddenly, resembling a false membrane, from the sudden coagula-
tion of the  fibrin.
   Sulphate of ammonia, in aqueous  solution.  After three hours
the blood  with which  it  was mixed was liquid and  its colour un-
changed.   After twenty-four hours, the colouring matter had sub-
sided, the supernatant fluid was like serum, it did not jelly.
   Magnesia and carbonate of magnesia—15 grains of each in im-
palpable powder were mixed with  half an ounce of blood.  The
blood in each instance acquired a more florid hue, remained liquid,
and  the  red  particles subsided.  On the  following day,  viz. the
19th January at Corfu, the  supernatant fluid  had the appearance
of serum.  Now diluted  with water, after twenty-four hours, in the
instance  of the carbonate it was found to have jellied ; and in that
of the  magnesia, to have afforded  a precipitate of lymph in a  flaky
form.
   Cream of tartar:  a dram of this salt  was added  to an ounce of
blood.  The blood  thickened a little  and effervesced slightly, and
became of a brighter red.  After three hours it had not coagulated.
After twenty-four hours  the red particles had subsided ; the super-
natant fluid was like serum.  On  dilution with water it jellied; the
coagulum was of a very soft consistence.
   Chloride of barium  : 12 grains of this salt were  mixed with an
ounce of blood.  After five minutes, it remained liquid; the colour
of the blood was perhaps a little brighter.  After twenty-four hours,
there  was  a slight subsidence of red particles  and separation of
fluid.  It was a little thicker, but still liquid.  With water it jellied.
   Nitrate of barytes,  mixed with blood in the same quantity, had
an effect very cimilar.
   Muriate  of ammonia:  20 grains  of this salt  in  powder  were
mixed with an ounce of blood.  The  blood was immediately  dark-
ened.  After twenty-four hours, it was of a very dark red, and vis-
cid like thick bile. No fibrin could be obtained separate, by passing 
58
davy's researches.
 it through a  linen filter.  It  had a strong ammoniacal odour.   A
 portion of it diluted with water  coagulated  pretty firmly.   After
 six days, in  November, at Corfu,  the diluted  blood  became putrid.
 Tiie portion not diluted was  free  from putridity, and  after this in-
 terval coagulated with water  as in the first instance.
   Sesquicarbonate of ammonia :  50 grains of this salt  in powder
 were mixed with three ounces and a  half of blood.  There was a
 change of colour as  in the  preceding, in which the muriate was
 added.  After twenty-four hours, it had  separated  into two parts,
 a supernatant orange-yellow  fluid, and a  viscid dark red sediment.
 A portion of each diluted with water coagulated ; the former firm-
 est.  After three days, in the same place and season, the diluted
 portion  was  slightly  putrid;  whilst that  not  diluted  was  un-
 changed, and retained its  power of coagulating when  mixed with
 water.
   Sesquicarbonate of soda: 50 grains of this salt in powder were
 mixed with three ounces and  a half of blood.  The blood  immedi-
 ately became of a brighter red.   After twenty-four hours it dark-
ened, became very dark  and  viscid, in consistence like thick bile.
 There  was only a very slight subsidence of the red particles.  On
dilution with water, it did not coagulate.  The portion diluted af-
ter three  days,  in November, was  putrid : the undiluted portion
 was free from taint.
   Common salt: two drams of this salt in powder were mixed with
two ounces of blood.  Examined  a few hours after, the blood was
found thickened, but not  distinctly coagulated.   After forty-eight
hours, it was much, in the same state.   Passed through  a linen
filter, no fibrin  remained.   Diluted with  about four times its bulk
of water, it coagulated and formed a gelatinous mass.
   In another experiment,  20  grains of common salt  were mixed
with an ounce of blood.   It prevented coagulation :  and the colour
of the blood  was immediately  brightened.   After twenty-four hours
the blood was found viscid and dark.   Filtered through linen, no
fibrin was collected.  It jellied with water.  After six days, in No-
 vember, the  diluted portion had become putrid;  the other  not, and
retained its power of coagulating on admixture with water.
   Saltpetre:  mixed two drams of this  salt  with  two ounces of
blood;  after a few hours  the  blood was found thickened.  Passed
through a linen  filter, a minute portion of very soft fibrin  was col-
lected ;  after forty-eight  hours, the  filtered  portion  jellied  with
 water.
   In another experiment, 20 grains of this salt were mixed with an
ounce  of  blood ; partial  coagulation  presently took place:  after
twenty-four  hours, a soft  crassamentum  formed, and  pretty  much
fluid separated.  Subjected to  filtration, gentle pressure being used,
some fibrin of soft consistence was collected.  The filtered  fluid
coagulated weakly on dilution  with water. After  twenty-four
hours, this portion was putrid: the undiluted had  no unpleasant
smell;  but it did not now coagulate with  water. 
OBSERVATIONS OX THE BLOOD-               59
  In a  third  experiment, twenty  grains  of nitre in powder  were
mixed with an ounce of blood, previously deprived of its fibrin, by
agitation  with pieces of lead in a bottle, quite full of blood, and
from which in consequence  atmospheric air was  excluded.   The
colour of the blood became a little lighter, but rather of a brick-red
hue than  vermilion.   Now on exposure to the air, at the surface it
acquired a very florid scarlet hue, very similar to that imparted by
oxygen.  This thin coloured stratum subsided,  and it was succeed-
ed by another and another;  till the whole mass exhibited a strati-
fied appearance—a succession of  bright  and darker lines; analo-
gous to what takes  place in the cruor,  similarly exposed without
the addition of nitre, but less strongly marked.1
  Borax: fifty grains  of this salt were  mixed with  three  ounces
and a half of blood; it immediately assumed a  brighter  red ; after
twenty-four  hours, the blood  was liquid ;  the red  particles had
completely subsided ; the supernatant fluid was of  a bright yellow
colour, like   serum.  Both the inferior  and the superior  portion
coagulated pretty firmy on dilution  with  water.   After  three days
the diluted portion was slightly putrid ; the other was free from
any unpleasant smell,  and retained its power of coagulating; and
even  after sixteen days it  possessed  this power.   The experiment
was made in  Corfu,  in November.
   Triple prussiate of potash :  a dram of this salt,  in fine  powder,
was mixed with three ounces and a half of blood ; coagulation was
prevented; the colour  of the blood was  a little  brightened: the
red  particles rapidly subsided, and the supernatant fluid  was like
serum.   Ou  dilution with water, the fibrin coagulated very slowly,
and the coagulum which formed  was of very soft consistence.

 • ' These results accord  with those of Haller, as described by him in his
Elementa Physiolog. ii. p. 74.   After  noticing the difference of opinion pre-
viously existing on  the subject, whether nitre  dissolves or coagulates the
blood, he says, " A nitro sanguis neque solvitur, neque cogitur, in meis qui-
dera experimentis.   Admisto enim nitro laminae equidem cruoris floridis-
sime rubenles  nascuntur, verum eae, etiam absque nitri ope, pariier ex eodem
sanguine coeunt.  Color autem  vividissime coccineus utique nitro debetur,
quo sale non alius  laetore purpure  sanguinem ditat."  Relative to the dif-
ference of opinion previously entertained, he observes, "Ceterum, si d? lite
ilia omnino definire oporteret, crederem nitrum sanguinem potius  resolvere,
siquidem leviorem  reddit, neque mea experimenta penitus repugnant."  He
adds, "Alii sales medii utcunque similia faciunt.  Sal marinus  cum san-
guine  commistus  floridum colorem facit,  caeterum  coagulalionem  neque
valde promovet, neque impedit, nisi molus accesserit, qui etiam solus coag-
ulationem impedivissit."  This may be considered as a tolerable summary
of what was then known on the subject, coupled  with a remark which pre-
cedes his  observations on nitre.  " Ea communis salium mediorem et lixi-
viosorum natura est, ut fluidum  plerumque sanguinem reddant, aut liquidem
conservent, colorem vero rubrum aut firment, aut omnino augeant." 
GO
davy's researches.
(3.) — Qf those substances which accelerate coagulation, or other-
                     wise alter the blood.

  The following  substances, I find, belong to this class, namely—
the oxalic, tartaric, and citric acids, chlorate of potash, lime, and
calomel.   No  doubt, the number will augment on farther inquiry.
I shall notice, briefly, the apparent effects of each.
  Oxalic acid : fifty grains of this acid, in powder, mixed with two
ounces of blood, immediately coagulated it; the coagulum was of
a pitch  colour, and of  firm  consistence, and  no serum separated
from it.   A smaller proportion of the acid rendered the blood thick.
  Tartaric acid:  thirty  grains of this acid,  dissolved in two drams
of water, mixed with two ounces of blood, prevented immediate
coagulation: after two hours, the mixture  became frothy from the
disengagement of air, thick  like  tar, dark brown and viscid ; after
twenty-four hours it  had lost its viscidity, was firmly coagulated,
but without contraction  and separation of serum, and was easily
friable.
  Citric acid :  thirty grains  of this acid, with the same quantity of
saturated  aqueous solution, mixed  with  two ounces of sheep's
blood, slightly retarded  its coagulation ; in half an  hour the blood
coagulated.  The coagulum  was firm and  tough, and of a brown-
ish hue;  after  twenty-four hours it  had  not contracted or yielded
serum.  A small  portion of it, agitated with serum, reddened it. A
portion of a drop of this  reddened serum, under the microscope,
was found to contain red particles, little, if at all altered ;—they had
their usual disc-like form.
  Lime,  mixed with  blood, immediately darkens  its  colour, and
speedily forms with it a  tough mass,  which, on exposure to the air,
shortly becomes firm and hard.
  Chlorate of potash :  fifty  grains of  this salt, in  powder, mixed
with an ounce of blood, retarded its coagulation, and brightened
its colour; after twenty-four hours, it was found firmly coagulated
and of the colour of pitch.  No serum  had separated  from the
coagulum ; it contained some air-bubbles and had a peculiar smell.
  Calomel : thirty grains of this chloride  were added to  half an
ounce of  blood;  its coagulation was rather accelerated,  and  the
coagulum was  firm.

13.— On the effect of substances on  the blood which coagulate sc-
                 rum, or precipitate its albumen.

  The following  substances come  under the above denomination:
the sulphuric, nitric, and muriatic acids ; sulphurous acid, barvtes,
alum, nitrate of silver, sulphate of copper, alcohol.
  All of these apparently coagulate,  both the fibrin and the serum
of the blood.   The effect is produced almost instantaneously, ex-
cepting in the instances  of sulphurous acid  and barytes—and is 
OBSERVATIONS ON THE BLOOD.
61
generally  attended  with  a change of colour of the  red  particles.
Neither the  sulphurous acid gas, nor its aqueous solution, nor ba-
rytes, has any perceptible  immediate effect, except that of darkening
the blood ; but, in a few  hours, both the acid and barytes, as might
be expected from their operation on serum, render it of firm consis-
tence like strong jelly..
  The blood used in all the experiments, the results of which have
been given,  when not specially mentioned., was venous blood, taken
chiefly from men  in the prime of life, or but little beyond it, labour-
ing under various diseases.   I have  not considered it necessary to
specify the nature of these diseases, or the peculiarities of the blood
in each instance—the object of my inquiry being, on the present
occasion, totally different from the investigation of the properties
of this fluid in a morbid state.  It may be proper, at the same time,
to notice,  that disease was not lost sight of—and that in such ex-
periments, in which it was desirable to use healthy blood, the blood
employed was from men labouring under slight complaints, or just
attacked with severe ones, and a portion of it was always set aside,
undisturbed, for comparison.
  Hewson states that  he  did  not give a detailed account of his ex-
periments on the action  of the neutral salts on  the blood, because
he was of opinion that they were not applicable to medicine. Hal-
ler, after passing in review the operation of a considerable number
and variety of re-agents,  arrived at the same conclusion.   The par-
agraph in which he expresses this opinion, is deserving of attention
in the present times ;  1 shall  give it entire.
   "Arsenicum, dubium  corporis genus, sanguinem cogit1 rubrum-
que reddit.  Caeteruni infinita alia eum variis succis instituta ex-
perimentis,  apud  cl.  viros legere  oportet,  quos  excitavi.   Obiter
autem in  iis, quae repetii, discas, quam  par urn  ad medicamentorum
virtutes dignoscendas utilitatis ab his experimenlis possis arguere.
Arsenicum enim, suramum venenum, sanguinem fere ut beneficnm
illud nitrum mutat.  Acetum inter omnia pharmaca tristissimum
colorem  sanguini  inducit,  non  ideo  minus  innocuum.  Acidi
liquores et lixiviosi pariter cogunt."2
   Reflecting on the results which I have described, and proceeding
on  the principle of induction, the conclusion of Hewson and Hal-
ler, in  the present state  of our knowledge, appears  to be the only
ligitimate one.   Haller contrasted the  effects  of white oxide of ar-
senic and vinegar.  Other substances might be brought forward in
the same manner—as the hydrocyanic and hydro-boracic acids ;
the salts of  barytes and  strontites, and of lime and magnesia ; the
oxalic and the citric acids ; and a large number of the  vegetable
extracts.
   If no relation can be discovered between the operation of a sub-
stance  on the blood, out of  the body, and of the same  substance

             ' This effect  I have not witnessed, vide p. 54.
            2 Element. Phys. torn. ii. p. 83.
       10—a                                     5 dav 
62
davy's researches.
taken internally,  the conclusion above referred to  is necessarily
strengthened;  and  it seems  unwise to have confidence  in any
hypothesis, founded on partial relations  of the kind.  As the subject
of the blood, in all its bearings, is one of great obscurity, all specu-
lations concerning it require to be received with much caution and
examined with all possible  rigour.    Adopted,  without due ^and
searching scrutiny, hypothesis can  hardly fail to exercise a very
injurions'influence; and to have the contrary tendency, if it stimu-
late research, and that careful inquiry, by which alone disputed
points cati be determined.

14.—Some remarks chiefly of a speculative  kind relative  to the
             question, Is the blood a living fluid?

   By one train of reasoning, the conclusion, that the blood is a liv-
ing fluid, seems  almost demonstrated; whilst by another  train of
reasoning, the same appears almost doubtful.
   Can it be supposed probable, or even possible, that  a fluid, itself
void of life, can circulate through the body imparting  vital energy;
deprived of which  fluid, every function is interrupted, every organ
soon ceases to act.  and the part, or  parts, or whole, almost imme-
diately die?
   Again, is it possible to conceive, that a fluid which  belongs only
to animals, which is generated  in them from its elements, which
can exist in them only under ordinary  circumstances, changing its
character the instant it is abstracted, without absorbing, or evolving
any thing sensible or cognisable "in  quo (as Harvey forcibly and
eloquently states) vegetativae et sensitives operationes primo elucent:
cui calor, primarium et  immediatum  animas instrnmentum, inna-
scitur:  qui corporis animae que commune vinculum est: et quo ve-
hiculo anima omnibus totius  corporis partibus influit."*  Is it possi-
ble to conceive that this is a dead fluid?
   In opposition to this view, it may be replied; it is only a little
more difficult to conceive  the blood  dead, than the chyle, and the
chyle than the chyme.  The  food is admitted to be dead; yet it is
grateful to the  palate, and certainly  not injurious to the gullet and
stomach, and whole primal via.  From it chyme is formed.  May
not chyme, in relation to  the duodenum, act the part of the food  in
relation to the stomach, and  like the food be dead?   Chyle is sup-
posed to be derived, or formed from chyme; and, may not it act on
the parts with  which it comes in contact, like the food on the sto-
 mach, and the chyme on the duodenum,  and be considered also
dead?   And may not  the same be  said of the  blood which is de-
rived from it?   In many of their properties, chyme and chyle have
 a certain resemblance,  and  chyle and blood a  close  resemblance.
 They (chyle and blood) both contain suspended in  them solid par-
 ticles of a definite  form;  both  contain a spontaneously coagulable
* Op. omnia, p. 398. 
OBSERVATIONS ON THE BLOOD.
63
 fluid, and, another fluid ingredient coagulable by heat:  they differ
 chiefly as regards the solid  particles—in  the  one, spherical  and
 colourless, or nearly so; in the other, coloured,  and in the instance
 of the mammalia, of a disc-like form.
   Descending in  the scale of organisation, the reasoning just em-
 ployed appears even  more conclusive.  In  certain  animals, there
 appears to be but  little difference between the chyme or alimentary
 fluid and the blood—the former passing into the  blood-vessels direct.
 And in certain  other  animals, there appears to be no difference—
 their chyme  or alimentary food, being what is commonly  called
 their vital fluid, and distributed by ramifications of the alimentary
 canal, they  having no regular  vascular system.
   In further prosecution'of the latter train of argument, it might be
 maintained, that many of the reasons which  are  commonly assigned
 in favour of the blood not being dead, are applicable only to arterial
 blood;  and  so far  they may be" retorted to prove, that if one kind of
 blood is alive, the other is dead; and,  consequently, that the circu-
 lation of the blood may be viewed as a perpetual miracle, in  which
 material particles are without cessation dying and reviving.
   Farther, in prosecution of the argument,  it may be said, that the
 blood considered chemically, however extraordinary,  is  not with-
 out analogy, and that some vegetable juices make a near approach
 to it in  their proneness to change, and in the tendency  of their ele-
 ments to enter  into new combinations.  Witness the juice of the
 grape and most of the  other saccharine vegetable juices, which at a
 certain  temperature, like the blood, can only exist, in their proper ves-
 sels and receptacles.  The instant they are abstracted the process of
 fermentation  begins, and that even in close vessels, and though
 oxygen be excluded, as it appears  to me, I have proved by experf-
 ment.   Here  then, we have an instance of change as great as that
 which the blood undergoes, when drawn from the body, spontane-
 ously taking place amongst the elements of dead matter. If it  be
 said, that  the  vegetable juices possess vegetable life, by which they
 are preserved in their vessels, and that they are to be considered
 only as dead when expressed,  and  when in  consequence they are
 liable to fermentation, another instance free from such objection
 may be substituted, viz. a  solution  of crystallised sugar,  which  is
 subject  to the  same change on  admixture with a little leaven—the
 leaven itself, it would  appear, undergoing no change in the  act of
 exciting fermentation.
  The subject maybe considered under many other points of view,
 and arguments for and against the vitality  of the blood easily ad-
 duced.  Perhaps it may not be amiss to prosecute it a little farther,
 nor  uninteresting   to  those who  are fond  of  such  speculative
questions.
  In support of the vitality of  the blood, it may  be urged, that one
of its ingredients—fibrin,  or lymph—when  effused, often becomes
solid in a very short  time, and vascular.   When vascular and
organised, it may be admitted as  alive, even by the casuist; and. 
64
davy's researches.
  also, when the vessels are forming in it, and the moment before that
  event; and so on to the period when it was effused, or prior to that
  when it formed a part of the circulating fluid: and, if one part of
  that fluid be allowed  to possess life, it\vould be extraordinary in-
  deed, if the  other  parts of it were destitute of life.  By a similar
  mode of  reasoning, from the changes which take  place in the egg,
  from the  formation of the foetus, and the influence of the  spermatic
  fluid—(a fluid derived immediately from the blood)—the same con-
  clusion may be drawn.   How difficult  to suppose a living fluid a
  particle derived from a dead fluid—that that which animates should
,  be itself destitute of life, or be furnished by one without life.
    In opposition, it  may be replied, organisation is an effect of life;
  but the effect or product is not necessarily living, and a part may
  belong to the living body,  and yet  be without life.  Tartar, a mix-
  ture of phosphate of lime and a little carbonate with mucus,  desti-
  tute of life,  occasionally firmly encrusts the teeth.  Dead bone, it
  has recently been  found, may be  united to living  bone; a union
  may take place by a deposit of new  bony matter, connecting the
  two, so that, were  it not known that the added bone was dead, it
  might be inferred  to  be alive.1  Moreover, we know,  that foreign
  bodies have  often continued enveloped in living parts, as a ball in a
  limb, as  if they were not  foreign  bodies,  occasioning  no pain, no
  irritation, no morbid action.  Very recently, a patient was admitted
  into the general  hospital at Fort Pitt, after amputation of his fore-
  arm on account of a malignant tumour.   The  stump  was  cica-
  trised, but the ligatures  employed  in  securing  the vessels had not
  come away.  About four  months  after the operation  he died, ex-
  hausted from the effects of the malignant disease which had broken
  out in the arm and shoulder.  I examined the ligatures; they had
  been  perfectly preserved,  enclosed in  the  cicatrix, as if they had
  been  living  parts, indicating  demonstratively that lymph had been
  thrown out  around, and that it had adhered to them.
     The hair, nail, cuticle, and enamel of the teeth are products from
  living parts, and all of them may  be  considered as  organised ; but
  they are not generally considered as alive, and  yet how little do
  they differ in want of indication of vitality from the  lens of the eye,
  from bone, cartilage, tendon, and even the blood-vessels themselves.
  It is not  necessary to insinuate, if the former are dead, why not the
  latter?   But, it might be urged rather, if the latter possess life, why
  not the former?  Is it not as reasonable to suppose hair, or the cuti-
  cle alive, as the substance of an adhesion formed  of effused coagu-
  lable lymph ?
     Or, taking a wider range of argument, the mystery of the subject
  may  be dwelt on.   It may be asked, is it more mysterious or inex-
  plicable  that a dead fluid  should  circulate  in living vessels,  than

     1 Vide Transactions of  Medico-Chirurgical Society of London, vol. xix.,
  Jbr a notice of this curious fact by Mr.  Gulliver; and also the 3d Fasciculus
  of  Drawings, selected from the Museum of Morbid Anatomy, at Fort Pitt. 
OBSERVATIONS on the blood.
65
that dead parts should be attached to living parts?  Is it more mys-
terious, that one kind of fluid, the spermatic, should excite an ovum
to change, developement, and growth, than another kind of fluid,
milk or broth (both having been previously subjected to the boiling
temperature) should nourish an animal, supplying new living par-
ticles to the body; in excess occasioning growth in infancy; in de-
ficiency, decay in old age?  The serum of the  blood, after coagu-
lation,  apart from the  clot, may be injected  into the vessels of a
living  animal, and  will circulate without deleterious effects.  The
cruor,  after the separation and coagulation of the  fibrin, after having
been out of the body several hours, may also be injected into the
blood-vessels, and resume its place in the circulation, without inju-
rious effects;1 if dead, acting as if alive, and consequently in a man-
ner confounding the difference.
   I am tempted  to give another form of argument, because con-
nected with a  curious fact.
   Against the vitality of the blood, it may be said, its characteristic
properties may be preserved out of the body, under some circum-
stances most unfavourable to life.   Thus by  the addition of a neu-
tral salt, it may  be kept  liquid, and on dilution with water, after
many  days it will coagulate.  It may be kept liquid  too by a tem-
perature of 32°, I know not how long; and on raising the tempera-
ture, it will coagulate.   Even  freezing the blood, by reducing its
temperature below 32° does  not destroy  its peculiar properties.
When  exposed  frozen  to  a gradually increasing temperature, it
liquefies,  and  the  liquid presently coagulates.   How, it  may be
asked, are these phenomena  compatible with its being  a living
fluid?   Can it retain  life  when frozen?   If not, and yet become
liquid  and  after  that coagulate, its liquidity  and coagulation are
independent of life.
   To  these arguments, again,  it may be replied, it does not neces-
sarily  follow  that  a neutral salt, or  a  temperature of 32°, or the
freezing of blood-deprives it of vitality.  Certain seeds will bear a
very low temperature,  much below  the freezing point of water, and
germinate afterwards.   Some  parts of warm-blooded  animals may
be frost bitten, and yet not destroyed.  The common medicinal leech
may be frozen and kept  frozen for a length of time, and yet not
killed.  In the winter of 1827, I had proof of this, when going, in
company  with my brother, the  late Sir  Humphrey  Davy, from
England,  through France, into Italy, by Mount Cenis.  It may be
proper to give some details respecting a fact, which  to the best  of
my knowledge is new.   For  about  a  month, the  cold was  very
severe, so much  so, that  some leeches which were kept inside the
carriage in a bottle of  water, were  included in a solid mass of ice,


   1 Provided it is not from a different class, or even species, of animals; it
the former, a fatal effect is rapid •, if the latter, the effect is injurious, often
mortal.  Vide Annates de Chemie et Physique, torn, xviii. p. 295, for the
results  of the researches of M. M. Prevost and Dumas on this subject. 
66
davy's researches.
from London nearly to  Modena: and, it must be  inferred, were
frozen, as the temperature was often below the freezing point, and
in passing the Alps,  only a few degrees above zero, of Fahrenheit s
scale; notwithstanding, when the ice  was  gradually  thawed, the
leeches all, with the exception one, revived, and after this lived a
considerable time.1
  It may indeed be said, however improbably, all the circumstances
considered, that the leeches were  merely included in the ice in this
instance, and not actually frozen.  To ascertain the truth of such
a notion, I have tried the effect of artificial cold, by means of freez-
ing mixtures, on these animals, by which they have been  rendered
rigid and  hard, so that they were doubtlessly frozen; an 1 yet, when
thawed they revived; but with the  exception  of one,  the death of
all of them speedily followed.   This result is the more remarkable,
as the experiment was made during the height of summer  in Malta,
and  with  leeches  suddenly taken  from water almost tepid, and
plunged into  a freezing mixture, and when  rigid were as  suddenly
plunged into  the tepid water.  Now, to return to the  argument, if
an animal, or even a part  of an  animal, can be frozen and not de-
prived of  life—why  may not the same  h.ippen to a fluid?  Why
may not its animation, in the same way, be suspended and  restored?
  The blood, after death, I have often found liquid, and that many
hours after death, when cold, but still retaining its power of coagu-
lating.  What  is to  be hence inferred?  Does it not follow either
that the liquid blood, though coagulable, is dead, and consequently,
that coagulability is not a vital property? or  that  this blood pos-
sesses life .after  the death of the body—after the muscular fibre has
lost its irritability, and the limbs have become rigid, and even par-
tial decomposition  has commenced?
  It would require little ingenuity to extend and vary  these specu-
lations; but I apprehend,  the farther they are extended,  the more
difficult it would be  to decide  and  come to a positive  and satisfac-
tory conclusion. The question is almost metaphysical.   Whichever
conclusion is adopted—whether the blood be a living  fluid—or
merely the product of life and pabulum, without vitality—not much
stress need be laid on it, or value attached to it.  Our great object
should be to investigate its properties by careful  observation and
accurate experiments,  by which method alone our knowledge of it
can be extended, and, if possible, our doubts removed.   Anticipatio
mentis, as emphatically called by Bacon, is admirably adapted  to

  1 The fact is thus described by my brother, in bis Journal:  "On the 14th
(March, 1837), 1 made  use of two leeches, which bit immediately, and per-
formed their office well; yet they had been frozen from January 23d to Feb.
22d, and had been sometimes exposed (as on Mount Cenis)  for  more than
fifteen hours to a temperature below 10° Fahrenheit.  They were thawed
very gradually, and appeared dead when first thawed, but recovered in some
hours in a warm room.   They had all (they were tweke) adhered together
in a sort of ball, and were precisely in the centre of the bottle, at the Neatest
distance from the cooling causes." 
observations on the blood.
67
create doubt, but not to remove  it.  It is chiefly useful, when  it
leads to honest and zealous inquiry, by which alone truth, the inter-
pretatio natural of the same author, can be attained.

15.—Observations relative to  the question—Is the appearance  of
  the blood abstracted, as a remedial  means, a just criterion  in
  considering the propriety of repeating the operation of blood-
  letting ?
  It is of importance, in so momentous a subject as the abstraction
of blood, that we should come  to  some  decisive conclusion relative
to the above question—and,  whether negative or affirmative, that it
should be well  founded on facts, and not matter of opinion.
  Let us first consider the appearances and qualities of the blood,
which are commonly supposed to  be  indicative of inflammation,
and to warrant rather than forbid  further blood-letting.  They are
chiefly the following:—an unusual  degree of fluidity of the blood,
the instant it is  drawn; unusual slowness in coagulating; and, when
coagulated, being covered with a  buffy coat and cupped.
  Relative to these appearances and qualities of blood, experience
seems to show, that they are  met with in the  majority of cases of
local  inflammation, but  with  shades,  differences, and exceptions,
involving much difficulty and perplexity.
   1.  When the inflammation is violent, rapidly running on to sup-
 puration, and very extensive,  as  attacking at the same  time more
 than one texture—or only the same texture, but in  different organs
 —the blood  drawn, 1 have observed, is neither buffed nor cupped.
 This I have witnessed most strikingly, in  cases of peritoneal inflam-
 mation,  either pure or complicated, with inflammation of the mucous
 coat of  the intestines, or with  diffuse cellular inflammation.
    2.  In diffuse cellular inflammation, I have often noticed that  the
 blood coagulated rapidly, as  rapidly  as in health, and yet being
 unusually liquid,  exhibited a slight buffy coat—provided, as has
 been already mentioned, the  vessel used for  holding it was filled
 in a few seconds,  and  instantly  put aside and allowed to remain
 undisturbed.
    3. In ordinary cases of inflammation, as of the pleura and lungs,
 the blood drawn at the  commencement  of the disease is, occasion-
 ally, not buffed nor eupped; but,  on repeating the operation the  fol-
 lowing  day, the blood exhibits both these qualities.
    4. In cases of inflammation of the mucous coat, whether of  the
 air-passages, or of the alimentary canal, the blood drawn sometimes
 shows  the appearances and qualities  enumerated, and sometimes

    5. Experience does not seem to have established, even generally,
 any relation in point of degree, between these appearances and quali-
 ties  and the intensity of the  inflammation.  Sometimes the buffy
 coat on the blood is very thick, and the crassamentum is  much
 contracted, and the symptoms of inflammation are not violent—and 
68
davy's researches.
 the recovery is not long protracted; and sometimes the reverse of
 this occurs.
   6. In a large proportion of fatal cases, fibrinous concretions, or
 polypi,  as  they were formerly  called, corresponding to the  buffy
 coat on the blood drawn, are found in the heart and great vessels,
 and, as  well as I can judge from  my experience, as often when the
 lancet has been freely used, or only moderately, or not at all.
   The consideration of such facts, I  most confess, deprives  me of
 confidence in these appearances, as indications for practice and the
 repetition of blood-letting,  and  induces me to conclude,  that as a
 criterion in this way, they cannot be pronounced just or safe.
   Let us next consider  the appearances  and qualities of the blood,
 commonly supposed to be connected with a state of the system, as
 it were, the opposite of the inflammatory,  and not to warrant further
 blood-letting.  They are chiefly, as it is supposed, a very soft cras-
 samentum, very little, if at all,  contracted—or the  blood remaining
 liquid—or the proportion of crassamentum to the serum being un-
 usually small.
   So far as 1 am  able to judge, these  appearances and qualities of
 the blood are not proved, by  experience,  to be connected with the
 state of the system supposed.
   1. In the remittent fever of hot climates, and in cholera  morbus,
 both the common  kind  and the epidemic, the crassamentum of the
 blood drawn is generally softer than  natural, and little,  if at all,
 contracted; and yet, blood-letting, in these diseases, is not generally
 injurious—it is often beneficial—and  occasionally beneficial even
 when repeated.
   2. Blood, without fibrin, in  any disease, is very uncommon.  I
 have witnessed it  in extreme degree,  only in  cases of  pulmonary
 ecchymosis or pulmonary apoplexy, as that lesion has recently been
 called —and that after death, in  the cavities of the heart and vessels
 —but so soon after death, that  it may be taken for granted, that it
 was not a post mortem change—that it existed  previously, and
 was probably connected  with, and  may have  been  partly  the
 cause of the  fatal  effusion.  In such cases, no practitioner, I sup-
 pose, would  have  hesitated, if called in in time, in abstracting
 blood, especially taking into consideration the  plethoric habits of
the individuals to  whose cases  I  allude,  and their  previous appa-
 rent robust health.
   In a less degree, I have witnessed the same state of blood  in  cases
 ofcynanche—and in one  in particular,  after death, which made a
strong impression on my mind.  This I shall briefly notice, as  it ap-
 pears to me instructive, bearing on the points in question. A young
 healthy man, previously liable to cynanche tonsillaris, was attacked
 with sore throat.  On admission the same day into hospital, he com-
 plained  of little excepting some  difficulty  in opening his mouth and
swallowing.  An emetic was administered and a purgative. At the
 evening  visit, he appeared to  be easier; the  pulse 70, soft, and
rather feeble; no pyrexia.  The  medical officer left him without the 
OBSERVATIONS ON THE BLOOD.
69
slightest apprehension.   At three o'clock, the  following morning,
lie was called to see  his patient  and found him dead.  According
to report he fell early asleep;  awoke a little before three in a state
of confused alarm and of breathlessness. and expired before  aid
could be afforded.  I  was present at the  post  mortem inspection :
osdema of the glottis, and epiglottis, and of one of the sacculi laryn-
gis, accompanied with the same  state of the uvula, and some eflu-
sin in the course of the  great vessels, sufiiciently accounted for the
fatal event.  The  probability is,  that had he been  blooded, and
largely, his life might have been saved; yet, the blood, after death,
was  almost destitute of fibrin;  no fibrin had  been poured out—
merely serum;  nor did the state of the pulse or of the skin seem to
indicate the propriety of blood-letting.
   Of the efficacy of blood-letting, in cases of this description, I may
mention an instance,  analogous to the  preceding, excepting in its
termination.   A patient, with cynanche, in the general hospital at
Fort Pitt,  suddenly experienced  a feeling of suffocation.   I was,
fortunately, in  the ward at  the  time with an assistant.  A vein in
each arm  was  opened as speedily as possible, and a considerable
quantity of blood abstracted.   As the blood flowed, the dreadful
sensation of suffocation  subsided; perfect relief was affordtd; and
he soon recovered completely; but it is worthy of remark that the
large  blood-letting was  followed  by  violent  delirium  of short
duration.
   3. The proportion of the crassamentum to the serum being small,
may often  be witnessed in acute diseases in their advanced stage,
or in acute diseases supervening on chronic of long duration—or
occurring  in persons of great delicacy of constitution, of feeble
health, or of valetudinary habits.   In such cases, no judicious prac-
titioner would  think  of using the lancet, unless  he  considered it
urgently necessary; and then surely he would not be hindered from
using it, even if certain  of the blood being below par, in respect to
the proportion of the crassamentum it might yield.
   Lastly, there is another, and extensive and most important class
of diseases  (were a classification  formed  according to the appear-
ances and qualities of the blood) in which the blood,  as far as we
have learned from  experience,  is  not apparently altered, as in  the
continued fever of summer,  especially in  the south of Europe,  dif-
fering  but  little  from  the ephemera—as in the early stage of syno-
chus—as in apoplexy, and tetanus, and many of the diseases strictly
belonging to the neuroses, in the treatment of which blood-letting is
often  useful  and  sometimes indispensable—and  as  in aneurism.
These considerations tend to  support the former conclusion.   It
appears to  me, that the more experience medical practitioners have,
the less confidence they place  in the appearances of the  blood, in
forming their opinion on the nature of a disease and en the  mode of
treating it.   What were the sentiments of the late learned and  ex-
perienced Dr. Heberden on  this  matter?  He says, "the  more we
know of the human body, the more reason we find to believe, that 
70                   DAVY'S RESEARCHES.

the seat of diseases is not to be sought for in the blood, to the sensi-
ble qualities of which  they seem to  have very little  relation;  and
though it be supposed  to hold in all maladies, yet  in  reality, it is
but in very few, that  the blood  affords the practitioner any useful
information."   This is called  by Sir Charles Scudamore, in  his
Essay on the Blood, a remarkable passage.  In the  state of know-
ledge of the blood, at the time it was written, there can be no doubt,
thai the practical conclusion with which  it ends was perfectly cor-
rect; and I fear it is still so, and believe that it is, though our know-
ledge of this fluid, since then, has been increased; and  that it is so,
even more strictly than expressed, even in all diseases, and  without
the exception of '" very few."  Is there, I would ask, any one dis-
ease, in  the considering and  management of which, the  skilful prac-
titioner  considers himself under the necessity of examining  the
blood?  I am  not aware  that there is one such.   In  cases of pneu-
monia and pleurisy, it was,  and is perhaps still usual for the prac-
titioner  to look at the blood.   Suppose the blood is not buffed, and
in a few hours the symptoms generally indicate the  propriety of
abstracting more blood, will the practitioner hesitate to abstract it,
merely from the absence of the buffy coat on the blood just drawn?
Suppose the blood abstracted in a case of pulmonary inflammation,
supervening on tubercular phthisis, is strongly buffed, and the symp-
toms continue but little if at all mitigated, will the practitioner, on
account of the state of the blood, repeat  the operation  of blood-let-
ting?   Most  probably he will  not.   He  will  consider rather  the
peculiar state of his patient, and endeavour to subdue the inflamma-
tion  by other means.
   Though I believe the time is not  yet arrived, that in relation to
practice, we can derive advantage from  inspecting the  appearances
of the blood, yet it is to be hoped that it will arrive ; and that it will
come, seems probable, if the subject is carefully investigated  in  a
strict scientific manner  by  those who are unprejudiced,  and are
competent to  engage in the investigation.  Dr. Heberden, in the
passage quoted, no  doubt, gave the result of his experience, which
was unfavourable to examining the  blood, but as he has expressed
it, it does  not so appear.  His conclusion appears to  be founded on
a hypothetical basis, the soundness of which may be  called in ques-
tion.
   It is an important question for inquiry, whether the blood is, or is
not,  the seat of some diseases; whether unhealthy blood has not an
injurious  effect in every instance; and if so, what are  its modifica-
tions and  their effects.
   These are legitimate subjects for  experimental  inquiry.   They
can  be  determined only by experiments  carefully and  laboriously
made by the scientific physician, whose taste leads  him to engage
in such a pursuit, with zeal to support him through it, and opportuni-
ties such as a public hospital affords. Such pursuits belong  to the
higher departments of the profession, and must be conducted in the
quiet walks of science.  They are, in relation to the ordinary mode 
OBSERVATIONS ON THE BLOOD.
71
of inspecting and examining the blood by practitioners, like ihe in-
vestigations of the philosophical navigator, in comparison with the
observations of the trading mariner; the one intent on the natural
history and physical laws of the terraqueous globe, the other  limit-
ing his attention to the circumstances which obviously, or are sup-
posed to expedite or impede his voyage,  and  render secure,  or
occasion risk  to  his  vessel.  As it  is advantageous  that the two
characters should be  kept distinct in ordinary navigation, so it seems
equally proper in  medicine, that the practical part should not  be
blended with the scientific, and that the  practitioner should keep on
his course guided by certain experience, and so far as  science gives
a steady light, enlightened by its rays, leaving the scientific  physi-
cian to explain at his leisure, aided by the best methods and instru-
ments of research, the  doubtful  regions  of the profession, and
investigate the mysteries of the system  in  health and  disease.  Sir
Charles Scudamore,  in the essay referred to, is of a different opinion,
and strongly  recommends the  attention  of the  practitioner to the
appearances of the blood, persuaded that.they will give "important
information of the power and action  of the heart and arteries, and
of the condition  of  the system itself."  And he  points out a num-
ber  of circumstances,  to  which, he says, the attention must  be
directed in blood-letting;  as 1st,  "the  kind  of orifice ;"  2dly, the
stream in which the blood flows; 3dly, the  state of the  pulse during
the bleeding; 4thly, "the  apparent  density, the  colour,  and other
appearances of the blood on it  first  being  received in the basin;"
 5th, "the time in which  it coagulates;" 6thly, "the internal appear-
 ance of the coagulated blood ;" 7thly, " the texture of the coagulum;"
 Sthly, "the comparative conditions of the several portions of blood
 in different cups ;" Othly, " the appearance and quality of the serum."
   These, 1 admit, and other circumstances, deserve the attention of
the scientific inquirer.   I should hope,  however, that  the mind of
the practitioner and  his eye would be more intent on the state of the
patient, than on that of  the blood ;  and having made the  orifice,
 thought proper in the vein, the blood  flowing  as he could wish,
 that he would concentrate his attention  on  the effect taking place in
 the living system, if the case be an urgent one. and that  he  would
 observe whether there is abatement of pain, or of the  sense  of op-
 pression ;  whether the pulse rises or falls as the blood flows : and
 reflect, judging  from the  supposed nature of the  disease, and the
 immediate impression produced, on the  extent to which the abstrac-
 tion of blood  should  be carried. For my own part, I must candidly
 confess, I  have never been able to combine in myself the two cha-
 racters of the practitioner and inquirer  at the same time; and that I
 have  always found  it beyond  my power  to watch the pulse and
 countenance, and feelings of the patient, and study the fleeting ap-
 pearances of the biood in a satisfactory manner; and  consequently,
 when I have attempted  the one, even the  investigation of a single
 property of the blood, I have always been a mere spectator, and have
 o-enerally  requested  the practitioner to judge for himself of the quan- 
72
DAVY'S RESEARCHES.
tity of blood which should be drawn.  And,  I would recommend
the same plan of proceeding to most others; lest, in the ardour and
interest of the scientific inquiry, the patient have not that attention
paid him which  is his due, and humanity suffer in a cause, which
should have humanity for its chief object and end ; and  the name
of science in its turn suffer and fall into disgrace amongst those who
do not distinguish between the genuine and the false.
                             III.

AN ACCOUNT  OF SOME  EXPERIMENTS  ON THE  BLOOD,
  CHIEFLY IN  CONNECTION WITH THE THEORY OF RES-
  PIRATION.

  Connected  with the theory of  respiration and of animal heat,
there are  many  questions of interest  respecting the blood,  about
which physiologists differ in  opinion, and which, consequently, are
fit subjects for further iuquiry.
  Some of the more important and fundamental of these questions,
I investigated, experimentally, in the winter of 1837-8; the results
were communicated to the Royal Society ; they were published in
the Philosophical Transactions for the latter year ; and were, essen-
tially, as follow,  exclusive of the  ninth  and tenth sections, which
have since been  added.

I.—Is blood capable of absorbing oxygen independent of putre-
                           faction.

  To endeavour to satisfy myself on this point, on which, in a former
inquiry,1 I had arrived at a negative conclusion, in opposition to the
commonly received opinion,  I have  employed two methods of ex-
perimenting:  one, of agitating blood,  recently drawn and rapidly
cooled, in  common air and in oxygen,  in  a tube of the capacity of
two cubic  inches, divided into a hundred parts;  the other,  of agi-
tating it in larger quantities  with the same airs, in the very conve-
nient  apparatus  employed by Dr. Christison when  engaged in a
similar inquiry, consisting of a double  tubulated bottle of the capa-
city of thirty-two cubic inches, provided with stop-cocks adapted by
grinding,  to one of which a movable  bent glass tube was fitted to
connect it with a pneumatic trough, and to the other a perpendicu-
lar tube surmounted by  a funnel.
   The blood subjected to experiment in every instance was prepared
by the displacement of  its fibrin.   This was done by agitating  it

     ' Edinburgh Medical and  Surgical Journal, vol. xxxiv. for 1830. 
EXPERIMENTS ON THE BLOOD.
73
with small pieces of sheet lead in a bottle filled to overflowing and
closed with a cork, enveloped in moist bladder and  covered" over
with  the same, tied  round  the neck of the  bottle, so as to exclude
atmospheric air, whilst in the act of coagulating aud of cooling, and
to allow,  when  cooled, of the withdrawal of ihe cork.
   Prepared thus, and rapidly cooled, 1 have tried different specimens
of blood,  venous and arterial,  of man, of the sheep, of the ox, and
dog;  and  the results, when the blood  has been taken from a healthy
animal, have been decisive and  consistent. In every instance, whether
atmospheric air  or oxygen was used, after  agitation, there was a
marked diminution of the volume of air.
   In  the examples which it may be advisable to bring forward, I
shall  confine myself to a few  of the experiments 1 have  made on
the blood  of the sheep.
   Using the graduated tube over mercury,  sixty-two measures  of
arterial blood from the  carotid artery agitated with thirty-three
measures  of common air, produced a diminution of two measures ;
and  sixty-three  of the same  arterial blood, agitated  with thirteen
of pure oxygen,  a diminution of three ; whilst sixty-three of venous
blood from the jugular vein of the same animal, agitated with thirty-
three of common air, produced a diminution of six ; and seventy of
this blood, with  thirteen of oxygen,  a diminution  of eight.*
   In  experiments on  a  larger  scale, using the double-mouthed
bottle, in which  about ten cubic inches of blood were  agitated with
about twenty-two cubic inches of air, the results were in accordance
with the preceding.  Thus, when the arterial blood  of the sheep
was agitated with common  air  and with  oxygen, on turning the
stop-cock  of the  bent tube there was an absorption in one instance
of about .3 cubic inch ; and in the other of about .4 cubic inch ; and,
with  venous blood, in the instance of common air, of  about  1.
cubic inch, and  in that of oxygen, of about 1.35 cubic inch.
   These experiments were all made on the blood of the same ani-
mal.  In experiments on the blood of different  individuals  of the
same species of  animal, and on the blood  of animals of different
species, the results have varied in regard  to the  degree of absorp-
tion, and remarkably so in the  instance of the blood of man
   In every instance the absorption or disappearance of a portion  of
the air has been attended with some  change in  the  colour  of the
blood ; the venous has  invariably acquired the florid vermilion hue
of arterial blood, and the arterial has had its florid hue heightened.
  The air that has been  absorbed,  or which disappears, when  at-
mospheric air has  been  used, in accordance with the commonly

  ' Notwithstanding  the frothiDg atlending the agitation of blood in air, the
absorption or diminution of volume was ascertained with tolerable accuracy
by observing the rise of the mercury in the tube. The experiments were
made as nearly as  possible under ordinary atmospheric pressure, which was
easily  effected, as  the mercurial pneumatic trough used exceeded in depth
the length of the tube. 
74
DAVY'S RESEARCHES.
received opinion and the results of Dr.  Christison's experiments,
has been found to be oxygen.
   Relative to  the  residual air, when  pure oxygen has been used,
whether on the smaller or larger scale of experiment, no carbonic
acid gas has been  detected in  it in the  most  carefully conducted
trials."   When  common air has been employed,  then a trace  of this
acid gas has been found in the  residual air after agitation with the
blood, but not  exceeding one per cent, at a temperature between
40° and 50D.   I shall notice in detail an experiment with each,  as
the results are of consequence.
   Ten cubic inches of venous blood (its  fibrin  displaced) from the
jugular vein of a sheep, rapidly cooled, were agitated in twenty-two
cubic inches of oxygen gas, which had been well washed with lime-
water.  After an absorption equal to about one cubic inch, some of
the gas was expelled and passed into  lime-water, the transparency
of which it did  not in the slightest degree impair.
   The  same quantity of similar blood was similarly treated with
common air, which also had been washed with lime-water.  After
an absorption equal to about  one cubic  inch, some of the air was
passed into lime-water ;  it occasioned  a just perceptible  cloudi-
ness: and eighty measures of it agitated  with  lime-water were re-
duced hardly to 79.5.
   Taking it for granted that this very minute quantity of carbonic
acid derived from the blood existed in  the state of gas, and not con-
tained in the aqueous vapour, as is possible, it is matter for consider-
ation from whence it was derived,—whether it was formed at  the
moment by the action of the air on the  blood, or, previously exist-
ing in the blood, was now merely expelled.  Further on  I propose
to return  to this important question.
   When I reflect on the results stated above relative to the  absorp-
tion or disappearance of oxygen, and compare  them with those al-
luded to formerly obtained, I am not a  little surprised at their discre-
pancy; and I can only account  for it by supposing that it may have
been owing in part to the difference of season when the two sets of
experiments were conducted.  The first were made in Malta, in 1829,
in the hot months of July and August, when the thermometer in the
open air was generally above 80° and occasionally above 90°.  The
last have  been  made in England, and principally in January of the
year 1838, when the temperature of atmosphere was occasionally
low, the greater part of the time below the freezing point, and often
so low as  20°.  From what I have witnessed, 1 am induced to infer,
that the higher the atmospheric  temperature is, and the less necessity
there is for the production of animal heat, the  less difference there
is between venous and arterial blood, and the less power the former
has of combining with oxygen,  and of forming or evolving carbonic
acid.  In  Malta I carefully compared the blood of the jugular vein
and carotid artery of a sheep during the season mentioned  ; when
'Edinburgh Medical and Surgical Journal, vol. xxxv. p. 94. 
EXPERIMENTS ON THE BLOOD.
75
coagulated and still hot, there was no perceptible difference in their
colour; in each it was less florid than the arterial blood of the same
animal in England in winter, and  less dark  than  the venous; its
hue was as it were a  mixture of the two.  And in  this observation
1 could not. be mistaken  ; the circumstances under which  it was
made precluded mistake ;  vessels of the same size were used ; sim-
ilar quantities of blood were  introduced, and they were seen in the
same  light side by side.   Referring to  Dr. Crawford's Treatise on
Animal Heat, I find in confirmation that he had arrived at the same
conclusion more than fifty years ago, from his own experiments on
the influence of heat and cold on the  colour of the blood, and the
quantity of oxygen consumed in respiration.  In the most decisive
experiments detailed by him, he states, that "the venous blood (of a
dog that had been immersed in warm water for  half an  hour) as-
sumed  very nearly the  hue  of the arterial, and  resembled it so
much  in appearance that it  was difficult to distinguish  between
them."1  And, in another experiment,  the reverse of this, in  which
a dog was immersed in cold water at 45°, for about a quarter of an
hour, he says, that the blood now taken from the jugular vein ap-
peared to him, as well as  to several other gentlemen who  assisted,
"to be the darkest venous blood we had  ever seen."2  In my com-
munication to the Royal Society, in corroboration of the view taken,
I laid too much stress on  an  inferred higher temperature in  winter
compared with summer of the deeply-seated parts of animals, speci-
fying that of the heart and rectum of sheep, and which has not been
fully  borne out by my later observations; those  indicating that the
average heat in summer is not less, but is very little higher than in
winter. But, as regards the theoretical conclusion, so small a differ-
ence  of animal temperature, contrasted with  the very great differ-
ence of atmospheric temperature—the  former not exceeding  1°, the
latter often 50°—can be considered very little less cogent, than if, as I
erroneously supposed, the winter temperature of the heart were ac-
tually the highest.


2. — Does the blood, especially venous  blood, contain carbonic acid
   capable  of being  expelled by agitation with another gas, as
   hydrogen or oxygen.

   In a paper published in the Philosophical Transactions for 1835,

  1 Experiments and observations or. Animal Heat, p. 309.  Second  edition.
  2Perhaps the influence of atmospheric temperature may in some measure
help to reconcile the apparently discordant results of numerous observations on
the colour of arterial and venous blood ; thus on one side Haller says, " Scepe
comparavi arteriae pulmonalis cavaeque venae sanguinem, cum arterioso san-
guine  venas de pulmone reducis,  nunquam  in multis experimentis, aliquam
in colore utriusque sanguinis diversitatem vidi, neque Harveius vidit, neque
Guilielmus Cheselden, neque cl. Knight, neque cl. noster auditor Evertsen,
neque ipse contrariae opinionis auctor Hambergerus."—Element. Physiol, ii.
p. 11. 
76
davy's researches.
Dr. Stevens has answered this question in the affirmative; he main-
tains that carbonic acid gas exists in venous blood; that it may be
expelled by oxygen or by hydrogen, although not by the air-pump;
and he supposes that the difference of effect is owing to a peculiar
attraction for carbonic acid exercised by these gases.
  To endeavour to resolve my doubts on this  important  point,  I
have  had recourse  to  the apparatus  already mentioned,  viz.  the
graduated tube "with the mercurial  pheumatic trough, and  the
double-mouthed bottle furnished with stop-cocks, <fcc.  as being well
adapted for simple and decisive experiments.
  By means  of the graduated tube, I have agitated  venous blood
in hydrogen over mercury, as about a cubic inch of each, and other
proportions, and have left the blood exposed to the influence of the
gas for several hours; and 1 have made similar trials  with it, using
larger quantities  in  the  double-mouthed  bottle, as sixteen  cubic
inches of each, and also other proportions.  The results have been
either  of the same negative character, or, if different, indicating
only the disengagement of carbonic acid gas in an extremely
minute quantity.   In all the experiments with the graduated tube
in which fresh blood was used, whether of man or  of the sheep,
the fibrin displaced out of the contact of the air, on agitation with
hydrogen, there was  no sensible increase of the  volume of the gas,
and  no diminution of it when it was transferred to, and shaken
with, lime-water,   And in the best experiments, on a larger  scale,
with the double-mouthed bottle, when  most attention was paid to
all  the  circumstances  likely to  insure accuracy, (as in the first
instance the exclusion of air from the blood, and in the second the
having it of  the temperature of the bottle  and  of the room,)  the
results have  been similar, and negative.   I shall describe  a  small
number of experiments, those, the results of which appeared least
ambiguous.
  Seven cubic inches of sheep's blood from the jugular  vein, its
fibrin broken  up by  agitation with lead whilst coagulating, out of
contact with  air, and cooled under water, were agitated with hydro-
gen, (twenty-five cubic inches,) previously well-washed with lime-
water, and which, tested by lime-water, after this precaution were
found perfectly free from carbonic acid.  On turning  the stop-cock
of the bent tube connected  with distilled water, no change of
volume was indicated, and  the blood was agitated again with  the
same result.   By means of the perpendicular tube distilled  water
was admitted, and some of the gas expelled ; first a cubic inch into
a graduated tube filled with lime-water, and next about four  cubic
inches into a vial filled with distilled water, and in  which  after-
wards a little lime-water was added to the gas; in neither  could
any traces of carbonic acid  be detected ;  the lime-water remained
transparent.
  Ten cubic inches of venous blood, taken by a large orifice from
the arm of a young man threatened  with haemoptysis, the  fibriti
broken up in the same manner as the last, and rapidly cooled under 
experiments on the blood.
77
water in a running stream to the  temperature  of the room, 51°,
were similarly treated with hydrogen, and with precisely the same
result; after having been twice well shaken, on turning the stop-
cock, there was  no change of volume.  The blood was  kept in
contact with the hydrogen over night, the stop-cocks closed.   The
night, that of the 23d of January, was severely cold ;  at 11 o'clock
the following morning the temperature  of the room was only 45° ;
now on  turning the stop-cock of the bent tube, the water rose  in it
to the extent of about one eighth of a cubic inch.
   Twenty-four cubic inches of the mixed arterial and  venous blood
of the sheep, collected and prepared  with similar precautions, were
divided  into two portions of about  twelve cubic inches; one was
agitated in the double mouthed bottle with hydrogen after the intro-
duction of a little  milk  of lime, the other without this addition.
The result in each instance was the same; on  opening the stop-
cock, after the  agitation, the water  rose a very little in the  bent
tube,—about one-twentieth of a cubic inch.
   The results of some of the trials already described on the action
of oxygen on venous blood, both pure and mixed with azote, in the
form of common air, are very consistent with those just detailed on
hydrogen.  Previously to stating some other results in quest  of
fresh  evidence  on the same subject, it  may be advisable to notice
particularly the power which blood possesses of absorbing carbonic
acid.
   From experiments which  I  made on blood and serum  in 1824
and 1828,1 I inferred that each is capable of absorbing about an
equal volume of this acid gas.  I now find that when pure carbonic
acid gas is brought in contact with blood  or serum over mercury,
and moderately agitated under ordinary atmospheric pressure, the
absorption of gas exceeds  the volume of the  fluid, both  in the
instance of blood and serum.  The results of some experiments are
exhibited  in  the following table.  The majority of them  were
obtained between a temperature of 40° and 45° ;  the three last  at
about 51°.  When the venous and arterial blood, and the serum
tried, were from the same animal, the  numbers expressing the
results are entered in the same line.

   1 Philosophical Transactions for 1824.  Edinburgh Medical and Surgical
Journal, vol. xxx.
10-b
6 dav 
' °                  davy's researches.


Volume of carbonic acid gas absorbed by 100 parts of blood and
                           serum.
No.	Animal.	Venous	Venous	Arterial	Arterial
		blood.	serum.	blood.	serum.
1	Sheep	160	—	167	
2	Sheep	155			
3	Sheep	—	—	133	
4	Sheep	142			
5	Sheep	—	—	150	
6	Sheep	166			
7	Sheep	—	—	—	120
8	Ox	194			
9	Ox	181			
10	Man	118			
11	Heifer	120	—	—	117
12	Sheep	14S	125	141	125
13	Sheep	—	118	—	118
14	Man	153			
15	Sheep	160			
16	Sheep	—	—	159	
           The effect of the absorption of the gas to perfect saturation was
        on the  arterial and venous blood the same;  it rendered both very
        dark; the serum it rendered more liquid, which was well  marked
        by diminished tendency to froth on agitation.
           I  shall now proceed to notice the trials which I have instituted
        of agitating blood and serum, to which a known quantity of car-
        bonic acid had been added, with one or more of the gases considered
        by Dr. Stevens as exerting an attraction on carbonic  acid,  and by
        that means expelling it.
           From the experiments which  I have made on serum, it appears*
        in its healthy state incapable of absorbing oxygen, or of immediately' ,
        furnishing  carbon to  form carbonic acid; and in no instance in
        which I have agitated it with common air or  with hydrogen, when*
        obtained from the blood of a healthy  animal, has there been  any
        indication of the disengagement of gas;  it therefore  is peculiarly
        well fitted for the trial in question.
           To nine cubic inches of serum from the mixed blood of the sheep
        one  cubic inch more of serum was added, containing a cubic inch
        of carbonic acid, with which it had been impregnated over mercury.
        The mixture of the  two was introduced into  the double-mouthed
        bottle without  delay, and  well agitated with  twenty-two cubic
        inches of common air.  On turning the stop-cock  there was no
        change  of volume.  The  serum was  transferred, and there  was
        added to it, with  as little motion as possible, another cubic  inch of
        serum, containing the same quantify of carbonic acid. Now poured
j        back into the bottle and agitated, on opening the stop-cock  a little
        air was disengaged; it was  collected  and found equal to T$oths
        cubic inch.  The serum was left exposed to the action'of the air in 
                 experiments on the blood.              79

the bottle over night, the stop-cocks closed; the following morning
on opening the stop-cock of the bent tube no air was expelled; on
the contrary, there was a just perceptible rise of water in it.   The
experiment was carried  further:  the  serum was  transferred  to  a
via|  and closed,  and the double-mouthed  bottle  was  filled  with
hydrogen.   The  serum was returned  and well agitated with the
hydrogen.   On turning the stop-cock TWhs of a cubic inch of air
was expelled.   It  was  agitated  a second  time  without further
expulsion of air,  and left in contact with hydrogen for more  than
twelve hours without any further effect.  Thus it appears that of
the two cubic inches of carbonic acid gas introduced into the serum,
only one fifth of a cubic  inch was  expelled by successive agitation
with atmospheric air and with hydrogen.
  One cubic inch of venous blood of a man which had  absorbed
1.2 cubic inch of  carbonic acid,  was mixed  with twelve cubic
inches of similar blood, and agitated with hydrogen in  the double-
mouthed bottle.  A very little air only was expelled,  viz.  Tf „ths
cubic inch.
  To fifty-five measures (I.I cubic  inch) of venous blood of a sheep,
twenty measures  of gas  were added over  mercury, composed of
about equal  parts of oxygen and  carbonic acid.   After  agitation
about seventeen  measures  were  absorbed, and   the  blood  had
acquired a florid  hue; ten measures more of oxygen were added ;
there was  no further  absorption.  The tube  was  transferred  to
lime-water  and agitated; the residual air was  not diminished; it
amounted to thirteen or fourteen  measures (the  froth  prevented
precision in marking the quantity,) which possessed the properties
of oxygen, as tested by the taper.
  To twenty-eight measures of venous blood of a sheep, which had
absorbed twenty-six of carbonic  acid, forty-nine  of oxygen were
added in the graduated tube over mercury : after agitation the blood
had  acquired the florid arterial  hue, and there appeared to be an
expansion of one measure.  Transferred to lime-water there was
an absorption of one or two measures, and no more.
  I shall notice one experiment more, in which blood nearly satu-
rated with  carbonic acid was exposed to oxygen,  a  membrane
intervening.  Forty-seven measures  of venous blood,  which had
absorbed thirty-three of carbonic acid, were  introduced into a glass
tube half an inch in diameter, closed at one end with gold-beaters'
skin, and when filled with  blood,  at the other end also; it  was
placed over  mercury in a small receiver, and thirty-seven measures
of oxygen were added to it. under a diminished pressure of about
one inch.   After twenty-four hours there was no change of volume ;
the  blood in  the tube had acquired throughout the arterial hue ; the
gas, thirty-eight measures, transferred to lime-water and agitated,
diminished to thirty-two.
  The tube was now placed under a receiver, and the air exhausted
by the air-pump; a good deal of air was disengaged in the form of
froth, and the gold-beaters' skin  was so distended that  it appeared 
80
davy's researches.
ready to burst; after three or four minutes air was re-admitted ; a
notable  portion of gas was found free between the membrane and
blood; thus showing, that in oxygen gas carbonic acid gas is less
freely exhaled through a membrane than in vacuo.
  The results of this second set of experiments are in accordance
with those of the first.  The inference I am induced to draw from
both is rather  of a negative kind, and unfavourable to the conclu-
sion of  Dr.  Stevens,  already referred to,  at  least in  a strict and
general  sense.  I think it right  to express myself thus reservedly,
reflecting  on some of  the experiments in which a very little carbo-
nic acid  gas  appeared to be extricated  on  agitating blood  with
hydrogen  ; and believing that  Dr.  Stevens, and  other able inqui-
rers, could  not have  been misled on a point so little exposed to
fallacy.
  Relative to the effects which Dr.  Stevens refers to the attraction
of one gas  for another, they appear to me, from what I have wit-
nessed in  carrying on the inquiry, to admit of explanation on  Dr.
Dalton's theory of mixed gases, and that in no instance is the effect
of disengagement of air from a fluid, agitated with another kind of
air, greater than were it agitated in  a vacuum.

3.— What is the condition of the alkali in the blood in relation to
                         carbonic acid!

  On this point much difference of opinion exists  amongst inqui-
rers;  some  believing that the  alkali, or  at least a portion of it, is
uncombined, or combined merely with water, or with  water and
albumen;  some that it is united to carbonic acid  in  the state of car-
bonate; others that it is saturated with this gas, and in the state of
bicarbonate.
   The subject, it must be confessed, is one of great difficulty, and •-'.;.
very perplexing; partly from the nature of the blood, liable to great  ;
variations during life, and to rapid change after death ; and partly   '.
also from  the  nature of the alkaline carbonates, hardly less disposed  ■'■'■.
to change than the blood itself, from variation of circumstances, and    ,
to pass  from one degree of combination into anoiher.               ''■■
   The  bicarbonate of soda, I believe, like the bicarbonate of am-
monia, can  only exist in perfection in the solid state. In dissolving,
I  find,  when  exposed to the atmosphere, it gives  off a part  of its
acid,and  still  more when it is agitated with common air. and more
still with  hydrogen, and in a greater  degree the higher  the tem-
perature.   This  is not favourable to  the  idea that it exists in the
blood, especially when it is considered that this fluid may be exposed
to  a  temperature  of 212° without disengaging  carbonic acid, of
which I have had proof in several trials.
   Sulphuretted hydrogen does  not expel  carbonic acid  from the
alkalies in  solution  in water.   Bicarbonate  of  soda dissolved to
saturation  in distilled water  absorbs, I  find, 143  per'cent  of its
volume of this gas ; whilst the serum of blood (it was sheep's that 
experiments on the blood.
81
was tried) dissolved 207 per cent., arterial  blood 235, and venous
290.  This, too, is unfavourable to the same  idea;  as  is also  the
large proportion of carbonic acid which blood, it has been shown,
is capable of absorbing.
  Supertartrate of potash occasions an effervescence, when mixed
in substance with  a solution of the sesquicarbonate,  but not of the
carbonate  of soda; and the effect is similar, whether the mixture
be  made.over mercury, air  excluded, or in  an  open vessel exposed
to the atmosphere.  The supertartrate of potash  also, I find, mixed
with blood and agitated with common  air,  acts as with the sesqui-
carbonate, and occasions a disengagement of air, and both from
arterial  and  venous  blood, and from serum;  and the  air I have
ascertained is carbonic acid.
   From these facts, may it not be  inferred that the alkali in  the
blood, in its normal or healthiest condition,  is neither in the state of
carbonate  nor of bicarbonate, but of sesquicarbonate?   The power
of  the blood  to absorb carbonic acid  and  sulphuretted hydrogen
accords  best with  this view, and some other important properties of
the fluid are, I believe, in harmony  with  it.
   The sesquicarbonate, I may add,  seems to be  the state of rest of
the alkali  in combination with carbonic acid, under ordinary cir-
cumstances of exposure  to  the atmosphere.  Thus the native
compound is the sesquicarbonate, as is also, I believe, the effloresced
salt.1  And I find that although a solution of  the bicarbonate may
be brought by the air-pump to  the state of sesquicarbonate, it cannot
be reduced to that of the carbonate ; after it has ceased to give off
 any air  in vacuo, it  effervesces with  the supertartrate of potash;
 and if  evaporated to  dryness over sulphuric  acid  under an ex-
 hausted receiver,  on being  subjected to heat, it disengages carbonic
 acid gas.

A.—Does  the blood contain any gas  capable of being extricated
                        by the air-pump ?

    On this subject also there has been  much difference of opinion.
 Our distinguished countryman Mayow, more than a century ago,
 stated that blood, especially arterial  blood, effervesces  in vacuo,
 which he attributed to the  disengagement  of  air, his spiritus nitro-
 aerius.2   Sir Everard Home, on the  authority of Mr.  Brande, in

   1 On exposing carbonate of  soda in excess  to  carbonic acid gas over mer-
 cury, the gas is rapidly absorbed with the expulsion of part of the water of
 crystallization, so as to  produce  an appearance of deliquescence, and the
 sesquicarbonate is formed.
   *Johannis Mayow, Opera omnia. Hagae Com. 1681, p. 133.  1 he follow-
 ing is the passage referred to—"Si sanguis in vase aliquandiu servatus, in
 vin-um collocetur, ex quo aer per antliam aereara exhauntur, sanguis isle in
 superficie,qua idem colorem floridum obtinuit, lemter effervescet,et in  bullas
 assur<*et.  Sin  autem  sanguis arteriosus adhuc incalescens, in loco aere
 vacuo°positus fuerit, idem mirum  in modum expandetur, et in bullulas pene 
82
davy's researches.
1818, asserted  that  blood,  both venous  and  arterial, under the
exhausted  receiver evolves a large quantity of carbonic acid  gas,
an ounce of blood as much as two cubic inches of gas.1 I repeated
the experiment shortly after, but without confirming the result;
neither by  the air-pump, nor by heat applied even to coagulation of
blood and  serum in close vessels, did  I succeed  in  demonstrating
the extrication  of this acid.8  Since that time the experiment of the
air-pump on the blood has been frequently made, and  by observers
of great accuracy, as by Drs. Duncan  and Christison  in this coun-
try, by MM. Tiedemann, Gmelin, Mitschenlich and  Muller on the
continent, and  recently by MM.  Bischoffand Magnus.  With the
exception  of the last mentioned inquirers, the  results have been
negative.   MM. Bischoff and Magnus, on the contrary, state  that
by careful  exhaustion they have obtained gas from  the blood; the
former a small  quantity of carbonic acid gas from  venous blood,
and a very little gas of a different kind from arterial,  the nature of
which he did not determine ;3 the latter a notable quantity, and from
arterial as well as  venous blood, and not only of carbonic acid, but
also of oxygen  and azote.4
  M.  Magnus  attributes the failures  of former experimenters to
their having used pumps of imperfect exhausting power, or to their
not having carried  the exhaustion sufficiently far.   In  my early
and first trial I employed the air-pump belonging to the laboratory
of the Royal Institution, which was an  excellent one, and which
I then believed was in good order ; but I might have been  mis-
taken.
   To endeavour to satisfy myself on this point, I have had an air-
pump constructed for the purpose, under the direction of an  able
artist, Mr.  Ross, of 33 Regent street, already distinguished for his
excellent achromatic microscopes, and it  has answered  perfectly.
When the exhaustion has been carried as far as possible, the differ-
ence of level of the mercury in the siphon-gauge has  not exceeded
a tenth of an inch, and over water  has not exceeded the quarter of
an inch.
  Experimenting with this machine on blood, collected with such
precautions as  I believe to have  been  adequate  to insure accuracy
of results, in a  majority of instances the disengagement of gas has
been rendered  manifest, and  both  from  arterial and venous blood.
   I shall  briefly  mention the trials which I consider most  con-

infinitas elevabitur:  id quod a pariiculis ejus exaestuantibus, inque motum
positis. partim ab aere particulis ejus interspersis oriri verisimile est."
  1 Philosophical Transactions foi  1818, p.  181.
  2 Ibid. 1823, p.  516.
  3 Cotnmentatio de novis  quibusdam  experimentis chemico-physioligicis
ad illustrandam  doctrinam de respiratione institutis  Heidelb. 1837—p. 9.
et seq.                                 ••'«•
  4 Annales des  Sciences Nat. torn, viii- p.  79, et seq. contain a translation
of M. Magnus's paper, with a figure of the apparatus, &c. used ; the original
appeared in  Poggendorf's Journal, vol. xl. part 3. 
EXPERIMENTS ON THE BLOOD.
83
   elusive, and which satisfied me in spite of an opposite pre-existing
   bias.
     Vials  provided with well-ground glass stoppers were filled with
   distilled water, deprived  as much as  possible  of air by the air-
   pump; they were then placed under the receiver and kept in vacuo
   until all adhering air was removed ;  the stoppers were now  intro-
   duced, all  air being excluded, and they were instantly immersed in
   distilled water, which had  been well boiled.  Thus prepared they
   were taken to  an adjoining slaughter-house, where they were filled
   with sheep's blood in the following manner, without its coming  in
   contact with  the air.   For  venous  blood the jugular vein was
   exposed;  two ligatures  were applied to it; the vein was divided
   between the two, and the upper part, slightly detached, was  intro-
   duced into a prepared vial  under  water the instant the stopper was
   withdrawn, and laid open.  The heavier blood proceeding from the
   vessel of course expelled the water;  and when it was supposed to
   be all expelled, the stopper was restored, and the vial was replaced
   in the water.  In the instance of arterial blood it was collected in
   the same  manner from the carotid artery.   In some trials the blood
   was allowed  to  coagulate undisturbed ; in others the  fibrin was
   detached,  and the liquidity of the blood preserved by agitating it,
   the instant the  stopper was replaced,  with some mercury,  intro-
   duced with the distilled water, and  equally deprived of adhering
   air.
      In  about half an hour from the abstraction of the blood, in every
   instance,  it was subjected to the air-pump.  The instant the stopper
   was withdrawn, the vial was placed in a small receiver on the plate
   of the pump, and covered with a little larger receiver, and  the air
   as  soon as possible exhausted.  No  appearance of disengagement
   of gas was  perceptible  until the  exhaustion was nearly complete;
:.  then  it was sudden, sometimes considerable, even to overflowing,
   in  the form of  bubbles, and it continued some time.  The  results
   were not  distinctly different, that I could perceive, whether venous
   or arterial blood was used; I am disposed to think, on the  whole,
   that less air was disengaged from the arterial blood than from  the
    venous.
      When  blood allowed to coagulate  in the vessels  was tried, the
    results varied a little, and  appeared to me  instructive.   At first, on
    exhaustion, only a few particles of air were disengaged; no more,
    it might be supposed, than were derived from the contact of the end
   .- of the stopper.   In two experiments, such was the appearance for
    at least five minutes, conveying the idea that no air was extricated ;
    then abruptly a bubble  or film burst with some force, as was denoted
    by the scattering of the particles of blood ; and  a bubbling com-
   i menced and continued, rendering the  indications of extrication of
■:*?i 'gas unquestionable. And in conformity  with  this  result,  I  may
?;''r' remark, I have never  succeeded in  obtaining indications of air in
    the blood in operating  on  it by the air-pump, if confined  in a de-
    tached portion of vein, or in the heart of animals, the great vessels. 
84
davy's researches.
 previous to excision, having been tightly secured by ligature.   In
 no instance of this kind have I witnessed any distention, such as
 occurs if air be admitted previous to the application of the ligatures :
 clearly indicative, it appears to me, that a very slight compressing
 force is sufficient to confine the air in the blood ; or rather, I should
 say, prevent its substance assuming the elastic state ; and further,
 the probability, that the quantity of air so condensed is small.
   1 have stated that in the majority of instances the indications of
 the disengagement of  air from blood in vacuo have been manifest.
 Exceptions, however,  have occurred, and those clear and decisive;
 inducing me to believe that  the quantity of air condensed in  the
 blood  is variable; and that there are times when it is in excess,  and
 times  when  in deficiency, and  when totally wanting, connected
 with regularly changing states of the functional system.   1 hope at
 a future time to be able to recur to this part of the subject, on which
 at present I have collected but a few facts.   I may add, that such
 facts tend in part to reconcile some of  the discrepancies referred to
 in the  beginning of this section.

 5.— Of the air or gases contained in the blood  capable of being
                   extricated by the air-pump.

   As already mentioned, M. Magnus has stated that these gases are
 carbonic acid, oxygen and azote in notable quantities.  Taking the
 mean of ten of his experiments on the  blood of the  horse and calf
 (five on arterial and five on venous) the total quantity of the mixed
 gases he obtained was, in the  instance of  arterial blood, 104  per
 cent, per volume, and  in  that of  venous 7*6 per cent.;  the former
 consisting of about

                  65 carbonic acid,
                  2-4 oxygen,
                  1-5 azote;
 the latter of
                  5-5  carbonic acid,
                  11  oxygen,
                  TO  azote.

  On a subject of so much importance, it is very desirable that  the
experiments of M.  Magnus should be repeated and verified;  for
until this is done, considering the  physiological history of the blood,
it will  be difficult to avoid doubt, it will be difficult to  depend on
them with that degree  of confidence which  is justly due  only to
well-authenticated facts.
  The ingenious apparatus employed by  M. Magnus  being of com-
plex construction, and not easily used excepting in a well-appointed
laboratory, I  must  leave  the  repetition of his highly interesting
experiments to those inquirers who are  more happily situated than
myself for engaging in them.   I shall limit myself to the detail pf 
EXPERIMENTS ON THE BLOOD.
85
some experiments  instituted with a view of testing M. Maguus's
general results.
   As a solution  of  potassa has the property of absorbing carbonic
acid gas, it  follows that if mixed with the  blood previous to  being
subjected  to the air-pump, it will prove in some  measure a test of
the kind of  air which the blood is capable of affording.
   With  this intent two  vials were prepared, the same as before
used, one filled with distilled water, the other with a weak aqueous
solution  of  caustic  potash, both carefully deprived of air  by the
air-pump.   Observing the same precautions as before, a portion of
venous blood from  a sheep was received into each  of them.  When
less than half of the water and of the solution, as well as could be
guessed, was expelled, the vials were closed with  the glass stoppers
belonging to them, and instantly immersed in water, and as soon as
possible subjected to the air-pump.  The results of exhaustion in
the two  instances were perfectly distinct.   From the blood mixed
with water gas was disengaged ;  there was a continued ascension of
bubbles.   From the blood mixed with the alkaline solution no gas
was liberated, excepting  a bubble or two,  which might fairly be
considered as entangled air derived from contact of the blood with
the stopper.
   A similar comparative  trial was instituted with  arterial blood of
the sheep,  and  the results  also  were similar and equally  well
marked.
   Considered as test experiments, the first inference  from these
results is, that carbonic acid gas, or an air absorbable by a solution
of potash, is disengaged both by venous and arterial blood in vacuo;
and next, that no  other  gas is disengaged from either of  them,
neither oxygen  nor azote, each  of which is  unabsorbable  by the
solution in question.  I have repeated the experiment twice on the
venous blood of man, and twice on the venous blood of the sheep,
and twice on the arterial blood  of the latter, without variation of
results; and they are more to be depended on, as the alkali has the
effect of preserving  the blood  liquid.
   I may mention another method which I have employed as a test
experiment; and, first, in  relation  to carbonic  acid.  If the  blood
contain a notable portion  of this  gas, capable  of  being extricated
by the air-pump, it  necessarily follows, that, when subjected  to the
action of the air-pump, and deprived as  far as possible of its fixed
air by this means, it will  be capable of absorbing a larger quantity
of carbonic  acid than  previous to the exhaustion.  The following
table contains the results of three comparative trials on the venous
blood of the sheep, its fibrin separated  or  detached in the  usual
manner. 
davy's researches.
Table showing the absorption of carbonic acid gas by
Venous blood subjected to the		air-pump.
Volume of blood used.	Volume of carbonic acid introduced.	Volume of gas ab-sorbed.
27 27 27	46 45 46	38 39 35
Venous blood not subjected to the air-pump.		
Volume of blood used.	Volume of gas in-troduced.	Volume of gas ab-sorbed.
27 27 27	47 45 45	37 39 34
Although I have thought it  right  to  notice  these  results, and
although  they  are  in  accordance with  the  preceding, I do  not
attach value to them, excepting as tending to show that the quan-
tity of carbonic acid gas extracted by the air-pump, when the blood
affords it in vacuo, is small.
  The same mode of reasoning suggested comparative trials of the
absorbent power of arterial blood for oxygen, before and after ex-
haustion  by the air-pump, as a further test experiment, whether
arterial  blood  contain oxygen in a free state, that is,  admitting of
being extricated by the removal of atmospheric pressure.   The re-
sult  of  this trial  also has been  negative;  its  power of absorbing
oxygen  has not appeared to be at all increased  by exhaustion; this
at least  was the result of one experiment carefully conducted.

6.—Is any oxygen contained in the blood not capable of being
                 extricated by the air-pump ?

  Before  I was acquainted with the researches  of M. Magnus,  I
had instituted some experiments to endeavour to determine whether
any oxygen in  a free state, or in a condition approximating to that
state, exists in  the blood, and especially in the arterial,  admitting of
being detected by means of substances possessing a strong-attrac-
tion for  oxygen, or of being expelled by substances of greater solu-
bility in blood  than oxygen.   Hydrogen, phosphuretted hydrogen,
sulphuretted hydrogen,  nitrous oxide and nitrous gas, it appeared 
EXPERIMENTS ON THE BLOOD.
87
advisable to try, as belonging to the first class of substances, and
carbonic acid gas as belonging to the latter.
  The results with hydrogen, sulphuretted hydrogen, nitrous oxide
and  carbonic  acid  gas,  were  of a negative kind.   Neither  using
arterial blood, nor blood  which had been agitated with oxygen, and
which had absorbed or made to disappear a certain quantity of this
gas,  could I detect any  indications of its presence, either by com-
bination or expulsion.   In the instances of nitrons oxide and car-
bonic acid,  however,  it  may be  worthy of remark,  that the  blood
which had  been agitated with oxygen absorbed  less of either of
these gases than it did before it was so treated.1
  The results with phosphuretted hydrogen, the spontaneously in-
flammable species, were of an  ambiguous kind, not  sufficiently
clear to  deduce from  them any satisfactory conclusion.  In one
trial, serum of the  venous blood of the sheep absorbed nine  per
cent, of this gas; venous blood 11-3 per cent.; and arterial 5-8 per
cent.2
   The results with nitrous gas were of a different kind, and may
be deserving of being specially noticed.
   The blood  used was  that of the sheep, prepared in the  usual
manner.  The experiments were made during the very cold weather
Which prevailed  in the  beginning of the year already mentioned,
and  the difference of colour between the venous and arterial  blood
was very strongly marked.

                    (1).— On arterial blood.

   1. Fifty-three measures of this blood were agitated over mercury,
with forty-six measures  of nitrous gas; there was a diminution of
volume of seventeen measures.
   2. Fifty-three measures of the same blood (another portion) were
agitated with  nine of oxygen; two measures were absorbed.
   3. Fifty measures of  this  blood, so treated  with oxygen, were
agitated with  forty-seven of nitrous  gas; there was a diminution
of twenty-two measures.

                     (2).— On venous blood.

   1. Fifty-three  measures of this  blood were  agitated with fifty of
nitrous gas; there was a diminution often measures.

   1 Nitrous oxide, I find, is absorbed in about the same proportion by  venous
and  arterial  blood, and  by the serum of blood, and also in about the same
proportion by water.   Thus,  at the temperature of 45° over mercury, using
the blood and serum of the same animal (the sheep) thirty-two measures of
each absorbed twenty-two measures  of this gas, and thirty-two of distilled
waU?r absorbed 2l#5.
  * Supposing the gas decomposed—the phosphorus uniting with the oxygen
.«Cthe blood-;  the apparent smaller absorption by arterial than by venous blood
is what might be expected, on the idea that the former kind of blood contains
most oxygen. 
88
davy's researches.
  2. Fifty-three measures (another portion) were agitated with ten
of oxygen; five measures were absorbed.
  3. Fifty-one measures of blood so  treated  were agitated with
forty-nine of  nitrous gas;  there was  a diminution of seventeen
measures.
  The residual air in each instance was examined, and was  found
to be a mixture of nitrous gas and azote with carbonic acid gas.
The azote,  it may be presumed, was  introduced  with the nitrous
gas; it was in the same  proportion as that which  adulterated it,
viz. about four per cent.  That the residual air was free from car-
bonic acid was inferred from the circumstance, that in comparative
experiments with and without addition of a portion of solution of
caustic alkali, there was  no difference in the proportion of nitrous
gas absorbed:  and it was  corroborated  by another circumstance,
viz.  that  after the absorption of the  nitrous  gas, the blood was
capable of absorbing seventy per cent, of carbonic acid gas;1 and
farther by the result, that when  nitrous gas is  added not to satura-
tion, the whole of  it is absorbed.2
  As regards  the blood itself, the colour of both venous and arterial
was altered; both were rendered darker and  browner, as if a minute
quantity of nitric acid had been added to them, a change long known
to be occasioned by nitrous gas. In the degree of change there was.
however, a difference; in the instance of arterial and of oxygenated
arterial blood, it was more  strongly  marked than in that of the
venous.
  In  conjunction  with the unsuccessful  attempts with the  other
gases already  mentioned, do not the results just described indicate
that a portion  of oxygen  exists in the blood, not  capable of being
extracted  by the air-pump, and yet capable  of entering into combi-
nation with nitrous gas, and which exists  in largest proportion in
arterial blood?  Unless this conclusion is adopted, it must be sup-
posed either that the nitrous gas which  disappears is decomposed,
or that it combines directly with the red particles;  neither of which
suppositions is well supported by facts.  The circumstance that no
azote is disengaged, is not  favourable to the idea that the nitrous
gas is decomposed; and the difference of effect in the  instances of
venous and arterial blood, and, after and before agitation with oxy-
gen, is not in  accordance with the notion of direct combination.   I

  1  To some venous  blood  of a sheep, which absorbed 182 per cent,  of car-
bonic acid gas,  so much of a solution of pure hydrate of potash was added,
that it absorbed 218 per cent, of the  acid  gas;  seventeen measures of this
blood  with excess of alkali, agitated  with fifty-one of nitrous  gas, absorbed
5"5 measures; sixteen of the blood without the excess of alkali absorbed five
measures:  thirty-four measures of carbonio acid  gas were added to the lat-
ter, the  excess  of nitrous gas being left in the tube; on agitation,  twelve
measures of the carbonic acid were absorbed.
  1 In one experiment eighty-four measures of the venous blood of the sheep
were agitated with ten of nitrous gas over mercury; the whole of the gas
was absorbed: twelve of oxygen were added ; on agitation again there was
no further absorption. 
EXPERIMENTS ON THE BLOOD.
89
may mention another fact which seems to have the same bearing:
serum, which does not absorb oxygen, I find also does not absorb
nitrous  gas, excepting in about  the  proportion  in  which  water
rbsorbsit:  and, further, in  corroboration,  1  may mention, that as
blood putrefies,- whether arterial or venous,  its power of absorbing
nitrous gas diminishes; and that it is also diminished  by being agi-
tated with phosphuretted hydrogen.  Thus the arterial blood of a
sheep, which before agitation  with phosphuretted hydrogen absorb-
ed 45-3  per cent, of nitrous gas, after agitation with it absorbed 7-4
per cent, less; and, after it  had become putrid, it absorbed 20 per
cent. less.  According to my  observations, arterial blood does not
lose its  peculiar florid hue under the action  of the air pump.  Is
not this also in favour of the above inference,  that a portion of oxy-
gen  is retained by the blood  resisting extraction by the air-pump?
1 find also, that when venous  blood  is agitated with oxygen, and
subjected to  the air-pump, it, in like manner, retains its acquired
florid vermilion hue, and likewise a  power of absorbing an addi-
tional quantity of nitrous gas.

7.— When oxygen is absorbed by the blood,  is there any produc-
                         tion of heat ?

   To endeavour to determine this point, of so much interest in con-
nection  with  the theory of animal heat, a very thin  vial,  of the
capacity of eight liquid ounces, was  selected  and  carefully en-
veloped in bad conducting substances, viz.  several folds of flannel,
of  fine  oiled  paper,  and  of oiled cloth.  Thus prepared, and a per-
forated  cork being  provided, holding a delicate thermometer, two
cubic inches of mercury were introduced, and immediately after it
was filled with venous blood, kept liquid as before described.   The
vial was now corked and shaken; the thermometer included was
stationary  at 45°.   After five minutes that it was so stationary, the
thermometer was withdrawn, the vial closed  by another cork was
transferred inverted to a mercurial bath, and li cubic inch of oxy-
gen was introduced.  The common  cork was  returned,  and the
vial was well agitated for  about a minute;  the thermometer was
now introduced;  it rose immediately to  46°,  and continuing the
agitation, it  rose further to 46-5, very nearly to 47°.   This experi-
ment was  made on the 12th of February, 1838, on the blood of the
sheep.
   On the following day a similar experiment  was  made on the
venous blood of man.  The vial was filled with eleven cubic inches
of  this  blood,  its fibrin broken up in the usual manner, and with
three cubic inches of mercury;  the temperature of the blood and
mercury was 42*5,  and  the temperature was the same after  the in-
troduction of three  cubic inches of oxygen.   The temperature  of
the'|oom being 47°, a fire having shortly before been lit, the vial
wa&'taken to an adjoining passage where the temperature of the air
 was 39Y  Here the vial was well agitated,  held in the hand with 
90
davy's researches.
 thick  gloves  on as an  additional protection.  After about  three
 quarters of a  minute the thermometer in the vial had  risen a de-
 gree, viz. to 435.
   On  the 14th of the same month a third experiment was made on
 venous blood  from  the jugular vein of a sheep.  The vial was filled
 with 3 5 cubic inches of mercury and  eleven cubic inches of blood.
 The thermometer in the bottle,  left five minutes, was  stationary at
 49°; the temperature of the mercurial  bath was 49°; the air of the
 room was  52°; a thermometer with its bulb moistened was 45°,
 which I mention because the outer covering of the vial was moist-
 ened with  some  blood  which  had overflowed.   After three  cubic
 inches and a half of oxygen had been  introduced,  before agitation,
 the thermometer  was still 49°.  The bottle was briskly shaken for
 about  half a minute; now, on  observing  the thermometer, it was
 found  at 50°;  the vial was again agitated; there was no further in-
 crease of temperature: after ten minutes it had fallen to 49°.
   I shall relate one experiment more, and that on arterial blood.  It
 was made on  the  14th of February,  and in  the  same manner as
 those on the venous blood. Before and after the introduction of the
 oxygen, the blood,  which was from the carotid artery of the sheep,
 was 45°;  after agitation with oxygen it rose to 455: this was done
 when the temperature of the air was 39°.'
   In a former part  of this paper I proposed to  recur to  the question.
 Is the fixation  of oxygen  in the blood  attended  with the  formation
 of carbonic acid  gas?  The change of colour  accompanying the
 fixation of oxygen by the blood, so different from that produced by
 carbonic acid,  and  the effect of nitrous gas before  and after, seem
 to be most in  favour of the  idea, that the oxygen, in the first in-
 stance, is simply  absorbed, and that the heat evolved is merely the
 effect of its condensation ;  or, that if any of it enters into immediate
 union with the carbon, it  is only a small part  of the whole.

                   8.— Theoretical remafks.

  Should the  results detailed in the preceding pages be confirmed
 on repetition, they can hardly fail to have some effect on the theory
 of respiration and animal  heat.

  1 Sir Charles  Scudamore, in his Essay on the Blood, at page 59,  states
 that venous  blood cools much mote slowly in oxygen gas than in  atmo-
 spheric air; that  the same blood divided into two cupping glasses, "after an
 interval of eight minutes from the beginning of the  experiment," exhibited
 a difference of eight degrees—that exposed  to oxygen  being 85°, that to at-
 mospherical air 77°.  As in this instance, the surface of the blood only was
 exposed, and there was no agitation—the effect described could not have
 been from the absorption of oxygen;—an appreciable portion of oxygen could
not have been absorbed in so short a time.  How it  was accomplished (the
retarded  cooling) I shall not attempt  to explain; I apprehend there must
have been some mistake, or fallacy, either in observing or  recording the
result. 
experiments on the blood.
91
  As regards  the former, they appear to me to tend to  show that
the lungs are absorbing and secreting, and perhaps exhaling organs,
and  that their peculiar function  is to introduce  oxygen into the
blood, and separate carbonic acid from the blood.
  As regards animal heat, they appear to favour the idea, that it is
owing, first, to the fixation or condensation of oxygen in the blood
in the lungs in  conversion from venous to arterial; and secondly,
to the combinations into which it enters in the circulation in con-
nection  with the different  secretions and  changes essential  to ani-
mal  life.
  In illustration  of what I  imagine the secreting power of the lungs,
I may mention the difference of effects in an instance of death by
strangulation, and another by exhaustion of air from the lungs by
the air-pump.   A full grown guinea pig was the subject of experi-
ment in each.   The  one killed by strangulation died in about a
minute  after a cord had  been drawn tightly round its neck;  the
other, placed on the plate of the air-pump, and confined by a re-
ceiver just  large enough  to hold it, lived about five minutes after
the  exhaustion  had been commenced,  the pump the whole time
having  been worked rapidly.  The bodies were immediately exa-
mined.   The heart of the strangled animal was motionless; it was
distended with dark blood; twelve measures of the blood, broken
up and  agitated with  twenty-nine of  carbonic acid gas,  absorbed
eighteen measures, or 150 per cent.  The heart of the other guinea
pig  was also distended with blood,  but of a  less dark hue.  Its
auricles were  feebly acting; the lungs were paler than in the for-
mer, and more  collapsed: ten measures of blood  from  the  heart,
broken  up  and agitated with fifty of  carbonic acid gas, absorbed
thirty-seven measures,  or  370 per cent.!
   Further,  in illustration of this supposed secreting power of the
lungs, I might adduce the condition of the blood in disease, and  in
instances in which I have examined  it after death from disease, in
the majority of which I have found the blood loaded with carbonic
acid, as indicated both by the disengagement of this gas when the
blood was  agitated with  another gas, and by the comparatively
small proportion of carbonic acid which the blood was capable of
absorbing.   This condition of the blood,  in relation to carbonic
acid, I believe to be one of great interest and importance, and capa-
ble,  when further investigated, of throwing light on many obscure
parts of pathology, and especially on the immediate cause of death,
and  that happy absence of pain*in dying which is commonly wit-
nessed.
   As regards an exhaling power, which I suppose the lungs may
possess, I conceive it may be exercised occasionally under peculiar
circumstances—circumstances, in the first instance, favouring an
accumulation of carbonic  acid gas in the blood, as undue pressure
of any kind; and, in the second instance, circumstances of a differ-
ent  nature, connected with the removal of undue pressure, admit-
ting thereby the excess to pass off. 
92                     davy's researches.
   The view which I have alluded to relative to the production of
animal heat, is, 1 believe, capable of explaining very many  particu-
lars of animal temperature in different classes of animals, and both
during life, in health, and disease, and  in a  state of  hybernation,
and after death.  If correct, this it  must necessarily do,  theory being
merely an expression of facts, and truths in nature being perfectly
consistent.


   9.— On the difference of colour of venous and arterial blood.

   Of that difference of colour between  venous and  arterial  blood,
which, it appears, was  first  specially demonstrated by Lower,1 at
least  fifty2 years after the great  discovery of  the circulation  of the
blood  by Harvey,3 two principal explanations have been  offered by

  ' Mayow, the worthy contemporary of Lower, thus notices Lower's obser-
vation  of the difference of colour of  the two  kinds  of blood, in connection
with his peculiar views of its cause:
  "Atque prsedicta,  magis adhuc ex eo confirmantur, quod sanguis, qui sub-
atro colore pulmones intravit, idem magis floridus, rutilusque qualis est san-
guis arteriosus, ex iisdem redit, prout d Clariss. Lowero in vivi-sectionibus
observalum est; idemque ostendit mutationem istam in cruoris massa fac-
tam, non tam a comminutione ejusdem in pulmonibus, quam ab aere ei ad-
mixto provenire: etenim sanguinis veuosi  in vase excepti, superficies summa,
qua? aeri exposita est colorem coccineum, floridumque acquirit;  cum tamen
sanguis iste in fundo vasis sub colore atro-purpureo apparet, qui tamen idem
aeri expositus, post breve  temporis spatium colorem rutilum induet.  Ut
mirandum non sit, si sanguis in pulmonibus, ubi viz. aer per particulas ejus
quasque diffusus, cum  eodem intime permiscetur, per totum floridus redda-
tur."  De sal-nitro  et  spiritu nitro-aereo. cap. viii.  De spiritu nitro-aereo
quatenus ab animalibus hauritur, in  Op. om. p. 131.
  2 The difference of colour of the two kinds of blood  had  been long before
noticed ; in Harvey's time it was a subject of controversy; he admitted the
truth of the then, as now, common remark, that the blood from an artery of
a living animal is more florid than from a vein, which he attributed to acci-
dental circumstances connected with the two, maintaining at the same time,
that the colour of the two kinds of blood was essentially the same,  "  Si san-
guis e resciss& arteriS. libere profluens acetabulo accipiatur, venosus  appare-
nt."  Re adds, "multo floridior sanguis in pulmonibus, et exinde exprimitur,
quam in arteriis reperitur."
   The merit of Lower  consists in having  associated the colour with its
cause, and that not hypothetically;  but experimentally, as described by
Mayow, and as detailed  by himself in his excellent little treatise, De Corde
et de  Motu et Colore Sanguinis, published in 1669.   The following is his
general conclusion on the point in question:—"Q,uare sanguinem in  suo per
pulmones transitu aerem haurire, ejusque admixtioni floridum  suum colorem
omnino debere maxime verisimile est; postquam autem in habitu corporis
et viscerum  parenchymatis aer rursus a sanguine magn& ex  parte avolavit,
atque  per poros corporis tianspiravit,  sanguinem venosum illo privatum ob-
scuriorem et nigriorem illice apparere, rationi pariter consentaneum est."—
Op. cit. p. 170.
   3 In 1615, it appears, Harvey first  publicly taught the-doctrine of the cir-
culation of the blood;  he was then aet. 37; the discovery was probably made
about the time of his return from Italy,  in 1602,  as he told Boyle,  that he
derived the first idea of it from considering the use of the valves, to which h.^ 
experiments on the blood.
93
physiologists.  By the majority, following Mayow,  the bright ver-
milion hue of arterial blood has been attributed to the influence of
the oxygen of the atmospheric air inspired on the darker venous
blood, and  the formation  and separation,  either directly or indi-
rectly, of carbonic acid.  By Dr. Stevens, recently,  a  totally differ-
ent view has  been taken of the subject.  He considers the salts of
the serum more concerned in producing the florid  hue of arterial
blood  than  oxygen,  believing that they impart this colour to  the
colouring matter, hematosine;  that venous  blood acquires its dark
colour in the extreme systematic circulation;  and that it loses  the
dark colour, and resumes the florid hue, in its extreme pulmonary
course;  in the one instance acquiring carbonic acid,  in  the other
losing carbonic acid,  in the latter  expelled  by the attraction of the
oxygen inspired.1
   The results of the experiments  which I have already given,  ap-
pear to me  no wise  reconcilable with  this  theory of  Dr. Stevens;
but perfectly in accordance with the older  views which he contro-
verts.   Of this description  is the fact,  that  venous  blood does  not
acquire the arterial hue when acted on by the air-pump, even when
carbonic acid  gas is disengaged;  and that venous  blood  does  ac-
quire it,  from the absorption of oxygen, without the disengagement
of carbonic acid; and acquires it even when  agitated with a mix-
ture of carbonic acid gas and oxygen  gas,  absorbing a  small  por-
tion of the latter, and a  large portion of the former.
   I apprehend,  that the  circumstances  which Dr.  Stevens  has
brought forward in support of his argument, admit of explanation
consistent  with the commonly received opinion  of the  part  per-
formed by oxygen in respiration.  I shall mention a few, the more
important of them, with  others tending, as I  believe,  to elucidate the
subject.
   Certain agents, as  it  is well known, darken the  blood, whether
venous or arterial, such  as  most of the acids, the fixed alkalies, and
ammonia in aqueous solution, and water itself.  In every instance

attention was probably specially directed whilst  studying  at Pavia, by  Fa-
bricius ab Aquapendente, who  claimed  for himself the discovery of them in
the veins, and sagaciously conjectured their use in the extremities.
  1 The following passage, expressing Dr. Stevens's peculiar views, is from
his paper, entitled "Observations on the Theory of Respiration," in Phil.
Trans, for 1835.
  "I have said that black is the natural colour of the colouring matter;  but
when  this agent is diffused in a saline fluid, such as the serum, it  is of a
bright  scarlet tint,  which  is in fact  the natural colour of  arterial blood.
When carbonic acid is added to this blood in the  extreme circulation, it be-
comes dark red ; but when  this acid is removed  in  the pulmonary organs,
the blood then resumes its natural scarlet or arterial colour; and this, as I
have said, is produced,  not directly by oxygen, but chiefly, if not entirely,
by the action of the saits of the blood on the colouring matter. Oxygen, it is
true, changes the colour from  venous to arterial: this, however, is effected,
not by  any specific  action, but by the  removal of the carbonic acid, which
had been the cause of the dark colour in the venous circulation."
       10—c                                       7 dav 
"n
94                   davy's researches.

in which 1 have examined blood  so  darkened, 1 have found more
or less of  the  colouring matter  dissolved, and  the  form of the
blood-particles, as  ascertained  by the  microscope,  more or  less
altered; commonly, greatly reduced  in  size,  and from discs com-
monly converted into globules.
  Certain  other agenfs  have a contrary effect, and, on immediate
admixture, apparently brighten the blood.  Amongst  the insoluble,
or slightly  soluble substances, may be mentioned, magnesia and its
carbonate,  white oxide of arsenic, boracic  acid, viz. the hydrate in
its crystalline form.  Amongst the soluble substances may be  spe-
cified those well-known  ones,  the neutral  salts, common  salt, the
carbonated alkalies, sugar.
  The first class do not appear to produce any change in the blood-
corpuscles  ; I have not been able to detect any. Probably the effect
is owing partly to  the introduction of air mechanically entangled;
partly to the separating of the blood-particles also mechanically;  and
partly to the white particles of the substances reflecting the colour
of the blood-particles interspersed.
  The second class—(for instance, mixed with the blood in concen-
trated aqueous solution,) do not appear, more than the preceding, to
alter immediately the form of the blood corpuscles (this is the result
of all my trials); but to separate them from each other and prevent
their coalescing.1   And, may it not be to this circumstance, that in
relation to colour, they owe their apparent  brightening agency?
  We know, that  the more  concentrated colouring  matter is, the
darker is its hue;  that the more diffused the colouring particles are,
and the more mixed with white particles; or the purer the white
ground is,  on which they are spread, so much lighter and brighter
is the effect.  The great masters of colouring of the 16th century
practised their art, it is understood, on these simple principles; using
always transparent colours,  and  never  black, and so imitating the
rich mellow, and as it were living colours of natural bodies, amongst
which black is almost entirely confined  to coal and charcoal.2
  I shall give in detail a few observations in  support  of the preced-
ing statement.   In  each trial which 1 shall  mention, the cruor of
blood was used, that is,  blood deprived of its fibrin, prepared in the
manner already described.

                         Experiment 1.

   Equal parts of the cruor of the venous blood of an ox, and water,

  1 It is well known, that when a drop of cruor (serum with blood-particles
 suspended in it) taken from crassamentum, recently formed, is placed under
 the microscope, the  particles collect together in groups and coalesce by their
 broad surfaces, forming little piles, or rouleaux—and  this both in the instance
 of venous and arterial blood—which coalescence (the one alluded to above)
 is prevented by a saline solution.
  2 These  remarks  are applicable to hematosine, which is apparently black
 only in mass; in powder, or seen in small pieces by transmitted  hVht it  is
 red. 
experiments on the blood.
95
were mixed  together.  The colour of the mixture was darker than
that of the cruor alone, especially by reflected  light.   Under the mi-
croscope, no blood discs  could be discovered in the mixture—only
small globules, about one-third of the diameter  of the discs, of faint
appearance, as if transparent.  Solution of salt added  to the mixture
rendered it of a  brighter  red—light  scarlet.  Now,  under the mi-
croscope, the particles  appeared smaller, and  well defined, and dis-
tinct,  so that they  were most  easily seen.  The  distinctness of
their appearance was  not increased by  the  addition of  corrosive
sublimate.1
   In similar trials with solution of ammonia,  of potassa, of hydro-
cyanic acid and  strong acetic  acid, the effects on the blood seemed
to be very similar;  the .appearances were much the same, whether
viewed with  the  naked eye or with the microscope; the colouring
matter was dissolved, the forms of the discs were changed, and a
darkening effect  was produced.2

                          Experiment 2.

   Equal parts of a strong solution of refined sugar and  cruor were
mixed together.   The  mixture immediately appeared of a brighter
hue; at and near the  upper  surface scarlet; towards  the bottom
light brick-red.   After  twenty-four hours,  it appeared generally of
a scarlet  hue, until  it was agitated, when the  interior and central
portion of the mixture was found to be dark.  Under the  microscope
the blood-discs were perceived to be unaltered.  The effect  of ad-
mixture of common  salt, of nitre, of muriate of ammonia, of car-
bonate of potash, was very similar; as viewed with the  naked eye
and  with the microscope.  After twenty-four hours, in the instance
of common salt  and nitre, the solution was  hardly  tinged  by the
colouring matter of the blood, and the blood-corpuscles remained
distinct in form—near the surface, of a vermilion hue—within of a
darker hue.   In  the instance of muriate of ammonia and carbonate

  1 When a portion of crassamentum is put into water, its hue is presently
darkened; and the  same effect is produced  by allowing water to  run over the
crassamentum. Dr. Stevens is of  opinion  that this is owing to  the removal
of the saline matter by the water. According to my observations, in con-
formity with those stated in the  text, it is  occasioned  by a change in the
blood-corpuscles themselves, and a partial solution of  the colouring matter.
When the darkened crassamentum is taken from the water and put into a solu-
tion of salt, it immediately acquires a brighter hue.  This Dr. Stevens
refers to the restoration of the saline matter.  I apprehend it is owing to the
effect of the saline  matter chiefly on the altered blood-corpuscles—by  which
they reflect more light.
  It is surprising how slowly the colouring matter is removed from the cras-
samentum by water, when the mass is not broken up; the water appears to
penetrate  very slowly through il;  and the colouring matter, even when dis-
solved, seems  to be retained  in the mass as in a sponge.
  2 In all these instances, the solution of the colouring matter, viewed by
transmitted light, was  rich red, approaching the ruby  hue; in particular in-
stances, compared one with another, there were slight  differences of colour. 
96
daw's researches.
        of potash, a little of the  colouring matter was dissolved, and the
        colour of the mixture was less  bright, and the blood-discs were a
        little smaller.'

                                 Experiment 3.

          A little muriatic acid and cruor were  mixed together, the former
        not in sufficient  quantity to coagulate  the serum.  The  mixture
        presently acquired a darker hue.  Under the microscope, the blood-
        corpuscles appeared somewhat altered in form—they were less dis-
        tinctly disc-like—they approached  more to the globular, and  had
        minute particles (probably of air) adhering to them.   On the addi-
        tion of more and  of stronger acid—effecting the coagulation of the
        serum—the  blood-corpuscles were  found diminished  in size  and
        irregularly globular; they were  examined in a state of dilution by
        the addition of a  little saturated brine.
          Do not these results warrant the preceding inference?   All the
        facts with which  I am acquainted appear to me to indicate that the
        colour of the  blood, whether  venous or  arterial, that is, dark or
        florid, is independent of the saline  matter in the serum, considered
        in relation to agency; and that according to the commonly received
        view, oxygen is the cause of the bright hue of the arterial fluid—
        and its consumption and conversion into carbonic acid, the cause of
        the dark hue  of the  venous—the  saline serum being negative in
        regard to colour, its chief use being to preserve the  red globules
        from injury, prevent the  solution of their colouring matter, retain
        their forms unchanged, and  to  bear them in  their course through
        the circulation.2
          Why oxygen should render  the colouring  matter of the blood
        scarlet;  why its conversion into carbonic acid should change the
        scarlet to a darker hue; and what is the  true shade of colour, of the
•       colouring matter of the blood, are questions, to which, I believe, the
        present state of our knowledge does not admit of a reply in a satis-
        factory manner.  The colouring principle of the blood-corpuscles,
        in its perfect state, can hardly be  considered precisely the same as
        the hematosine extracted  from  them; the former is not soluble in
        serum—the latter is; nor have I found  the colour of the latter in

          ' I have not found an aqueous solution of hematosine  brightened in colour
        by common salt.   It contains no globular particles suspended in it, like the
        mixture of cruor and brine, to enable the effect to be produced—unless the
        common salt acted chemically, which it does not appear to  do.
          2  The conclusion relative  to the  colour of the blood—and especially its
        modification by neutral salts, acids, and alkalies, and other agents, to which
        my experiments have led me, is very similar to that of  Dr. Wells, deduced
        by him from a somewhat different ttain of experiments and reasoning, more
        than forty years ago, as described in his very  ingenious paper, entitled "Ob-
        servations and Experiments on the Colour of the Blood,"  published in the
        Philosophical Transactions for 1797.  This  paper,  whhh has  been much
        overlooked of late years, is every way  worthy of the very original  mind of
        its author, and will, even now, well repay the perusal. 
EXPERIMENTS ON THE BLOOD.                97
solution affected by oxygen; consequently, we cannot, with advan-
tage, predicate the properties of the one from the other.

           10.—Do the arteries after death contain air?

  Harvey, from the results of his researches, came to the conclusion
that the arteries after death, as well  as during life, are destitute of
air.1  This too, was  the conclusion of Prochaska; he opened  the
arteries  under  water,  and could  find  no air in them.2   Amongst
very recent inquirers, Professor Burdach is, I believe, peculiar  for
maintaining an opposite  opinion.   He says, "Les arteres des cadav-
res  sont vides de  liquide, et par consequent  pleines d'air, qui doit
s'etre degage du sang."3   In support of this inference, he  refers to
the observations of Redi and Caldesi, of Haller, Spallanzani, and of
Blumeubach, according  to which bubbles of air are not uncommon
in the blood of reptiles,  even when circulating in their vessels :  he
adduces the fact of the readiness with which air is absorbed by  the
blood;  and, the  additional  fact,  as  he  believes, of  blood readily
giving offair  under the exhausted receiver.  These are the circum-
stances on which  he founds  his opinion, and comes to the conclu-
sion,  "Si  Prochaska  n'a point vu  de bulles  s'en elever lorsqu'il les
ouvrait sous l'eau, il  faut que quelque erreur d'observation se soit
glissee  dans cette experience."
  Theoretically viewed, especially taking  into account the  great
difficulty  with  which air is separated (when it is possible)  from  the
blood, by  the air-pump, and never, as  far as I have observed,  in its
vessels—this conclusion of Professor  Burdach is open  to  many
doubts; doubts which are not removed by his after reflections.
   The question is necessarily one of difficulty, as well as  of much
physiological interest in relation to its  bearings; and, of a  nature, as

  1  The passages from Harvey bearing on  this,  are  in many respects inte-
resting and instructive.  Discussing the question which was agitated amongst
the ancients, whether the arteries are the channels of air or of blood,  he re-
marks, "Sanguinem in  arteriis contineri, et arterias solum sanguinem deferre
turn experimentoGaleni, turn in arteriofomia, turn in vulneribus manifestura
est- cum ab una arteria dissecta,  hoc etiam Galenus affirmat, plurimis in
locis, unius semihorse spatio totam massam sanguinis ab universo corpore,
magna et impetuosa profusione exhaostam fore.  Experimentum Galeni  tale
est: Si  (inquit) funiculo arteriam utrimque ligaveris, et medio rescisso se-
cundum  longitudinem, quod inter duas ligaturas in arteria comprehensum
erit, nihil prseter  sanguinem reperies:  et  sic piobat  sanguinem solum conti-
nere.  Unde etiam similiter nobis ratiocinari  licet: si eundem sanguinem,
qui venis similiter  ligati>,  et rescissis inest, inveneris in arteriis (quern ad-
modum in  mortuis, et aliis animalibus saepius ego expertus sum)  eadem ra-
tione similiter concludeie nos  possumus, arterias eundem sanguinem, quern
venffi, et nihil prseter eundem sanguinem continere."  Exerc. Anal. Proem.
  2 Disquisitio Anatomico-physiologica organismi  corporis humani ejusque
processus vitals';, p.'S7.
  3 Traite  de Physiologie considered  comme Science d'Obseivation.   1 ra-
duit par A. Jourdan.  Tom. vi. p. 2S5. 
98
daw's researches.
it appears to me, admitting of solution only by accurate and strict
observation independent of speculative views.  If it is a fact, that
the arteries contain air after death, and that air is carbonic acid, it
will be easy to account for it  by the  result adverted to in  the pre-
ceding 8th section.   To endeavour to determine this  point, as  re-  ^
gards matter of fact, I have availed myself of the opportunities which
have offered in the general hospital at Fort Pitt, to institute on the
cadaver  the examination  necessary.   The inquiry was begun  in
the month of September, 1838;  and in every fatal case that after-
wards occurred, with the exception of four, during a period of six
months, search was made for air.  As most convenient for exami-
nation and best fitted  to give  accurate results, the internal jugular
vein (thinking it advantageous to extend the inquiry to this vessel)
and the carotid artery  in the  middle of the neck, were selected  for
the purpose.   In every instance  the vessels were exposed with cau-
tion—as much care as possible being  taken to avoid the wounding
of branches.  To determine if any air was in the vein, not  satisfied
merely with the appearance of the vein, a punture was always made
into it, and some blood pressed out: and.  to determine the same of
the artery, a portion of it,  about an inch  in length, where it gives
off  no branches, was  included between two ligatures; cut out so
secured; and transferred to water and there opened.  The  descrip-
tion of cases in which the trials were made,  is shown  in  the two
following tables, in  which also are noticed some other particulars,
which for the sake of accuracy it appears desirable to specify.
. The results of the examination in the nineteen cases included in
the first  table, were, as far as the artery was concerned,  entirely
negative; not a single particle of air  could be observed, in any  in-
stance, to escape from the vessel, opened under water.  The artery,
in every case, was collapsed; flattened; its upper and under surface
in contact, from atmospheric pressure,1 and eiiher quite destitute of
blood, or it contained only a very  minute portion,  in  the  space of
an inch,  never equal to a single drop.   And, in the  instances of the
vein, with one exception, that  of case  No.  3, the result  was similar,
strongly confirming the absence  of air.
  The trials, the results of  which are given  in  the second table,
were made for the  sake of comparison.   I expected, that in every
instance, air would be found  in  the artery as well  as  in the vein.
The circumstance, that in three  out of the eight cases in which the
experiment was  made, no  air could  be procured from  the artery
opened  under water—shows  (to express  the  fact in popular lan-
guage for the sake of brevity) how feeble  is its  power  of suction;
and how very inadequate, on the principle of removal  of pressure,
to draw air  from  the  blood, according to the idea  involved in the
hypothetical view of Professor Burdach.

  1  When opened, eitfer in the air or under water, in every instance, it im-
mediately recovered its cylindrical form, air or water entering. 
                                                          Table 1.

Cases in which the Carotid Artery and Jugular Vein were examined for air, before the removal of the Calvaria.
No.	Age.
1	26
2	45
3	23
4	37
5	31
6	32
7	31
8	32
9	19
10	34
11	41
12	38
13	22
14	37
15	26
16	27
17	36
18	61
19	33
Fatal disease as determined by
         autopsia.
Time of
 death.
Time of ex-
amination
(in hours)
after death
REMARKS.
Pulmonary hemorrhage  .   .
Inflammation and suppuration
  ofjoints   ......
Phthisis pul.—pneumothorax
Cerebral hemorrhage .  .   .
Ascites: indurated spleen and
  liver.......
Peritonitis......
Phthisis pul......
Chronic dysentery  ....
Phthisis pul......
Empyema—pneumothorax   .
Phthisis P.—pneumothorax
Phthisis—pneumothorax .   .
Pleuritis—peritonitis .  .   .
Pulmonary gangrene .  .   .

Phthisis pulmonalis  .  .   .
Ascites;  ccdema of  glottis;
  bronchitis......
Aneurism of aorta—indurated
  lung.......
Malignant tumour  ....
Ruptured aneurism into tra-
  chea   .......
Sept. 17
Oct.
19
24
25

 7
 7
10
  „  H
  „  18
  „  22
Nov.  7
  „   9
  „  16
Dec.	3
>i	5
)5	18 29
Feb.	27
12

  1
18
12

 H
17
m
 8
 li
 4
 5i
20
12
20

11

 2

 3
20

 H
Vein distended with cruor.

Vein distended with liquid blood, which quickly coagulated on exposure.
Vein distended with cruor, and contained two or three minute bubbles of air.
Vein distended with cruor.
Vein distended with fluid blood;  when opened, it flowed in a jet, it may be in-
  ferred, from abdominal pressure;  it afterwards coagulated.
Very little blood in vein.
A little cruor in vein.
A minute quantity of blood in vein.
A very little fluid blood in vein, which speedily coagulated.
A little very dilute cruor in vein.
Vein moderately distended with liquid blood, which, let out, presently coagulated.
Vein empty.
Vein moderately distended with cruor which did not coagulate.
Vein empty; after removal of calvaria some air in the other jugular vein; none
  in carotid artery.
A little liquid blood from vein, which presently coagulated, and had a buffy coat.
Vein distended; about lib. of blood flowed  from it, when opened, coagulated
  feebly.

Vein moderately distended; coagulated when let out, without buffy coat.
A little blood from vein which did not coagulate.

Blood from vein presently coagulated without buffy coat.
CD 
Table II.
Cases in which the Carotid Artery and Jugular Vein were examined for  air, after the removal of the
                                               Calvaria.
No.	Age.	Fatal disease as determined by autopsia.	Time of death.	Time of ex-amination (in hours) after death.	REMARKS.	
1	18	Phthisis punmonalis . . .	Nov. 14	11	Several large bubbles of air in vein; two minute bubbles	in artery.
2	20	Phthisis pulmonalis . . .	Jan. 3	14	Air-bubbles in vein; none in artery.	
3	21	Phthisis pulmonalis . . .	» 9	33	A little air in vein and artery.	
4	29	Phthisis pulmonalis . . .	» H	11	Some air in vein; very little in artery.	
5	18	Empyema......	!» H	33	A little air in vein and artery.	
6	26	Phthisis pulmonalis . . .	„ 24	27	A little air in vein and artery.1	■
7	20	Phthisis pulmonalis . . .	„ 30	28	Some air in vein; none in artery.	
8	20	Diabetes mellitus & phthisis pulmonalis	Feb. 13	27	A little air in vein; none in artery.	
1 In this instance the thorax and abdomen, as well as calvaria, were opened before the vessels were examined for air. 
OBSERVATIONS ON THE BLOOD.
101
  As the results, which I have brought forward without selection,
are perfectly in accordance with the preceding observations of Har-
vey and of Prochaska—may it not be  fairly inferred, that their con-
clusion is the true one; that the arteries, commonly after death, do
not contain  air; and  that when they differ  from this their normal
state, it must be presumed to be the effect of peculiar circumstances,
requiring special invstigation.
  Whether  the arteries, after  death, usually contain something in-
termediate between fluid blood and elastic air, appears to me ques-
tionable in a very high degree. The distinguished physiologist last
mentioned, appears to beof opinion, that they may, and  that they
partly owe to the vapour, which he infers  they may contain, certain
qualities  peculiar to their vessels, particularly the manner  in which
they contract and shorten when divided.
                              IV.

      OBSERVATIONS ON THE BLOOD AFTER DEATH.

  For many years past, in the post mortem examinations of bodies,
I have been in the habit of paying attention to the condition of the
blood in the heart and great vessels, especially in  relation to coagu-
lation; and  latterly, in conjunction with coagulation, to the effects
of agitation on  the blood in common air, as a test, whether or no it
contain carbonic acid gas  in excess, admitting of being extricated
by this method.
  I shall first give the general results of my observations,  made in
Malta, from the year 1828 to 1835, as an example of the variations
in the appearances of the blood after death, and of their comparative
frequency.   For the sake of brevity I shall present them in a tabu-
lar form.—[See table on next page.]
  The fatal cases, affording the subjects of these observations were,
without exception, soldiers of our regiments, serving in Malta, com-
posed of Englishmen, Scots, and  Irish.
  In  the cool season, the bodies were commonly inspected in from
twelve to seventeen hours  after death;  in  the hot season, in from
three to twelve.
  As the table is brought  forward chiefly as  an axample, intended
to show how various is the condition of the blood after death, I shall
restrict myself  to a very few remarks on the different  appearances
of the blood noticed, and especially in connection  with the fatal dis-
eases.  To do justice to the subject,  it would be necessary to enter
into very minute details, and give a statement of particulars, which
could be collected only by laborious research—and which, at pre-
sent, I am not all prepared to offer. 
©	0000000000000000 COCOCOtOWCOtOfcO	Year.
to	a to »s ui w h tj 50otn«a4i-cjoooo	Total number of fatal cases examin-ed.
OS	1 1 1 to to 1 to 1	Heart collapsed, containing either no blood or a very minute quantity.
«o	1 H » » H H | to	Blood liquid; not coagu'ating on ex-posure to the air.
CO	1 1 1 1 1 - | »	Portly liquid, partly coagulated—the former not coagulating on exposure.
«	1 H- 1 1 1 H » B	Partly liquid, partly coagulated—the former coagulating on exposure.
►^	1 »h| | | U	Liquid and coagulating on expo-sure-
o	i-4 tO H- 1— to	Coagulated and containing fibrinous concretions.
to	1 (!) 6) h w 1 1 1	Coagulated, without fibrinous concre-tions—the coagulum soft.
	1 1 1 1 1 to 1 1	Gri:mous, not distinctly coagulated, without fibrinous concretions.
1—1	I I | | 1 _ | 1	Liquid and frothy—without any fi-brinous concretions.
~	1 I 1 1 1 - 1 1	Blood florid.
	1 ~ I 1 1 | 1 1	Fibrinous concretions with(-ut any enter.
m	| I HK«I 1 1	Blofd coagulated in both ventrirles of heart, and broken up.
-	| h- *>■ 1 Oi i- 1 1	Coagulated and broken up in left ven-tricles, no', in right.
>^	1 1 1 - 1 1 1 1	Coagiiluted in right ventricle and broken up; left ventricle tmpty.
00	^ vl <I 1^ » H 1	Cases in which the state of the blood was not noticed.
■S3H0HV3S3H S AAVd 
EXPERIMENTS ON THE BLOOD.
103
  1. The few instances  in which the heart was found empty, or
containing only a very minute quantity of blood, were chiefly cases
of death from ruptured aneurism.
  2. The instances in which  the blood was  found liquid and not
coagulable on exposure to the air, the fatal event, in the majority of
cases, was referable to the respiratory organs, and was owing either
to drowning, hanging, the fumes of a charcoal fire, or the effusion
of blood into the bronchia or air-cells.  The former occurred in a
case of pneumonia ; the  latter in two cases of sudden death, from
what Laennec has called  pulmonary apoplexy.  The blood's liquidity
in these instances was not a post mortem effect, resulting from pu-
trefaction; this was clearly ascertained.  It was owing either to a
loss of the natural fibrin  or lymph, on which the property of coagu-
lation  depends, or such  an alteration in it, as to deprive the lymph
of this quality.  In one instance, a few days previous to death, some
blood  abstracted  from the patient, exhibited in relation to coagula-
bility  its normal condition.
   3. Relative to the  condition of the blood noticed in the 4th and
5th column, as  either liquid—coagulating on exposure, or partly
liquid and coagulable, I believe, it" depended  (whether one or the
other) on the time after death, when the post  mortem examination
was made: I shall have occasion further on, to bring forward exam-
ples in illustration of this remark.
   4. Of the  1G4 cases in which the state of the blood was specially
 noticed, in 105  instances it was found coagulated, the coagulated
 blood mixed with  fibrinous  concretions, or coagulated lymph, the
 material of the  buffy coat;  and I believe  it was found  in the same
 state in the majority of the 85 cases, in which its condition was not
 specified.
   5.  The instances in which the blood was  found coagulated and
 without fibrinous concretions (the coagula soft) were chiefly cases
 of tubercular phthisis.   In the majority of the fatal cases, however,
 of  this disease, fibrinous concretions occurred.
   6. In one  instance in which  the blood was  found grumous, not
 distinctly coagulated, death  was owing to confluent variola ; the
 lungs were  hepatized.   In  the other instance, the disease was  re-
 turned debility; it was of a very obscure nature, and not connected
 with  any well marked organic'lesion.  Whilst grumous blood was
 found in the cavities of  the heart in this case, fibrinous concretions
 were  met with  in the great vessels.
    7.  In the solitary  case in which the blood was  found liquid  and
 frothy, and  did  not  coagulate  on exposure,  putrefaction was  far
 ndvanced ; and  it is probable that the fibrin had become liquid after
 coagulation  in  consequence  of putrefaction.   In  this instance all
 the parts in  contact with blood  were strongly stained by the colour-
 ing matter of the  blood in a state of solulion  in the serum.  The
 phenomenon of the red stain, as a post mortem effect, is, I believe.
 invariably connected with this condition  of the serum, and which
 itself is connected more or less with putrefaction.   I have never 
104
daw's researches.
yet met with an exception to this remark; wherever I have found
red serum, on microscopical  examination, I  have detected change
in the  form of the red particles, indicative more or less of decom-
position.1
   8.  The single case, in which fibrinous concretion occurred in the
heart without crassamentum or cruor, was one of dysentery.
   9.  The single case in which the blood  was  observed florid, was
an instance of tabes mesenterica, without tubercles  in  the  lungs.
The mesenteric and lumbar glands were vastly enlarged,—some  of
them the size of  pigeons'eggs, and contained  a  curd-like albumi-
nous matter; and tubercles containing a similar  matter existed
under the mucous coat of the transverse colon.   The blood in this
instance was coagulated ; its florid hue was  most strongly marked
in the aorta.
   The broken-up state of the  coagulated blood  referred to in the
three last, columns of the table, to the best of my knowledge, has
not yet been described by any pathological writer. The appearance
exhibited was as if one or both ventricles of the heart had continued

   1 Most animal textures, chemically considered, have  a  strong affinity for
the colouring; matter both of blood and bile,—and for the former  especially
when in solution, that is, separated from  the blood-corpuscles, whether  in
water or serum.  In a paper communicated to the Medico-Chirurgical So-
ciety of London, in 1818, and published in its Transactions,— I pointed out
certain false appearances of inflammation, post mortem effects,  connected
with this quality.   I  then  stated, " these false appearances are in  many
instances so exactly like the true, that I  doubted  if the  most  experienced
anatomist would be able to distinguish between  them:" adding, " that I had
made the trial  with medical friends by asking their  opinion of parts coloured
by immersion in blood, and, without the least hesitation they had pronounced
the parts strongly inflamed :" afterwards in Malta, I continued  the inquiry,
and in  1828, made a series of experiments on the colouring power of blood
and bile on the different textures of the body.  The principal results were,
that the stains of* both  are with difficulty removed  by washing, and from
several textures, even by maceration ; and that by mere colour it is impossi-
ble to distinguish between the post mortem chemical effect,—and  the effect,
during life, of  inflammation.  The  influence of temperature is of the first
importance in  relation  to the production of bloody serum,—that  is. serum
holding in  solution  the  colouring  matter of the blood.   As a temperature
between 80° and 100°, the solution will take place in a few  hours, and the
staining will be produced,—the  pseudo-inflammatory appearances will pre-
sent themselves: on the contrary,at a temperature between 35° and 45°, the
blood-corpuscles will retain  their colouring matter and remain  unaltered,
and the serum untinged for many days, and so long none of the  false ap-
pearances of inflammation alluded  to will be observable.  Another point,
of much importance, is the degree of tendency of the  body after death  to
putrefy.  In some instances, even before death, there appears to be incipient
putrefaction of the blood ; and, in  these  cases, bloody serum  is detected
accompanied with staining of the parts with which  it is in  contact, though
the post mortem, examination may be made before the cadaver has had time
to become cold.  In other instances,—and  they may occur at  the same time,
the tendency to putrefaction is so very inconsiderable, that no indications  of
it are perceptible, even after twenty-four hours,  and sometimes longer; and
in these examples there is a corresponding absence of any false appearances
of inflammation. 
observations on the blood.
105
to act after the coagulation of the blood had taken place within
them.  On no other  idea can  I  account for the phenomenon.   I
never witnessed it  in  the blood-vessels,  or even in the  auricles,
which perhaps may be considered in accordance with the supposi-
tion  respecting its cause.   Of the seventeen instances in which this
condition  of the  blood was detected, death  in  the  majority was
owing to  tubercular  phthisis, viz. in 11; in  two, the fatal disease
was  pneumonia, the  lungs extensively hepatized;  in one, abscess
of the lung accompanied with gangrene;  in one, chronic dysen-
tery  accompanied with abscess in the liver;  and in one the  death
was  from violence, a soldier  in good health was shot through the
head by a comrade.   In  the  majority of the instances,  fibrinous
concretions accompanied the broken-up crassamentum.
   1  shall now proceed, and  briefly  notice some later observations
on the blood after death,  made in  the general  hospital, at  Fort Pitt,
during a period of nine months, viz. from January to September,
 1838, in which attention, as  before  mentioned, was  paid not only
 to the state of the  blood in relation to coagulation, but also to its
state in relation to carbonic acid gas.
   The method employed was  briefly  the  following:  In  every
 instance, after the removal of any fluid that might have been found
 in the pericardium, the  great  vessels within it were divided, the
 blood which flowed out  was collected and put into  a  bottle  and
 secured with a glass stopper for  after-observation and experiment.
 The cavities of the heart and  their contents were next examined.
 Sometimes the blood set apart was seen again the same day, to
 ascertain whether it  had coagulated or remained liquid; but more
 frequently, not until the following morning, when  also commonly
 it was  subjected  to  agitation in  atmospheric air  included  in a
 double-mouthed bottle provided  with stop-cocks, to one of which
 was attached a bent tube for communication with a pneumatic
 trough.
   I shall give the  results in a tabular form  individually, with the
 age and fatal disease, the day of the month  of its termination, the
  interval between the time of death and  post mortem examination,
  and between the latter and the examination of the blood,—circum-
  stances without which little value can be attached to the  record;
  and under  the  head of Remarks,  will  be appended the organic
  lesions discovered, of most importance, characteristic of the disease,
  with occasional notices of lesions of rare occurrence.
   I may premise further, that in  using, for the sake of brevity, the
  term " cruor," I have not employed it to designate merely a mixture
  of  serum and red  particles,  but a mixture of the two in  which
  there may be some  coagulable lymph,  to be  determined by trial.
  The te-ms " crassamentum" and "clot"  I have used synonymously,
  in  their ordinary  acceptation, as applied tothe blood.  The term,
  -fibrinous  concretion,"  I  have employed to  designate masses of
  lymph or  fibrin, in  a coagulated state,  such as used to be  called
  polypi. 
                                       TABLE  II.

Of the condition of the Blood after Death from various Diseases, and its Changes.
19
2 29
Fatal disease
determined by
 dissection.;
3 22
Pericarditis
Phthisis
pulmonalis
Rubeola
Phthisis
pulmonalis
Time of
death
Post mnrt.
 ispection
[hrs. after
death.)
an. 20
" 26
Feb. 3
19
16
18
28
29
General condition of the
  blood in the heart.
Pretty much cruor and
 a little  clot in right
 cavities of heart: no
 fibrinous concretions.
About three ounces of
 cruor and dark cras-
 samentum in  right
 cavities of heart.
Much dark liquid blood
 in right cavities  of
 heart.
After condition of the
  blood set apart.
Two  hours  after,
  the cruor  found
  coagulated  fee-
  bly.
Much  cruor  with  fi-
 brinous  concretions
 in risht cavities.
Six ounees of cruor
  collected,  found
  liquid  20 hours
  after.
Results of agitation of the
    blood or cruor.
Agitated immediate-
ly :  absorbed a little
air:  and  again  the
following day.
Immediately after co-
agulation   gave  off
some air  on  agita-
tion. On 1st Feb. had
an  offensive  smell:
and  on  agitation ab-
sorbed a little air.
Agitated  about   two
hours after, gave off
some air: agitated  a
second  time,  imme-
diately  there   was
slight   absorption  :
rubbed  with  quick
lime, a slight ammo-
niacal odour.
Agitated  20  hours
after, gave off about
half  cubic  inch  ofi
air.
Remarks relative to morbid appearances.
Pericardium nearly an inch thick from deposition
  of lymph: contained 20 ounces of purulent
  serum.  Granular tubercles in the lungs.

The lungs abounded in tubercles and vomicae:
  the left pleura contained 46  ounces of puru-
  lent serum, which, on agitation, gave  off a
  good deal of air.
Bronchia dark red :  engorgement of pulmonary
  vessels, and  some  ecchymosis  in  air-cells:
  death on fourth day.
Lungs abounding in tubercles and small vomica?:
  partially hepatized: partially  cedematous: a
  portion oflarge vein in right lung to the extent
  of about half an inch plugged up with  firm
  fibrin. 
TABLE II. — Continued.
				Post mort.		
		Fatal disease	Time of	inspection	General condition of the	After condition of the
		(determined by	death.	hrs. after	blood in the heart.	blood set apart.
	be <:	dissection.)		death.)		
5	19	Bronchitis	Feb.23	33	Much cruor and fi-brinous concre-tions in right ca-vities: the former of sp. gr. 1045.	Cruor did not co-agulate.
6	20	Phthisis pulmonalis	Mar. 22	30	A good deal of cruor and fibri-	Six ounces of cruor collected,
					nous concretions	on following
		!			in right cavities.	day slightly co-agulated.
7	24	Chronic pericarditis	" 30	14	Some cruor, soft crassamentum, — and a little fibri-nous concretion in	The following morning the cru-or was found feebly coagula-
					right cavities.	ted.
8	70	Chronic i Apr. 13 peritonitis, with abscess		48	Only about three ounces of blood (crassamentum)	
		and gan-			from the heart	
		grene of			without fibrinous	
		lungs.			concretion.	
blood or cruor
Cruor  agitated   on
 28th Feb. gave off
 no  air: three days
 later  it   gave  off
 some  air:  it  had
 then a putrid  smell.
On   agitation,  after
 having been broken
 up, a very slight ab-
 sorption :  agitated
 with carbonic acid,
 it absorbed 116 per
 cent.
On  agitation  pretty
  much  air  disen-
  gaged :  and  also
  from the serum.

Clot broken up  and
  agitated: there was
  a slight absorption
  of air.
Remarks relative to morbid appearances.
The bronchia smeared with pus: an ulcer on  upper
 surface of epiglottis: two small clusters of granular
 tubercles in lower part of superior lobe of right lung.
Cavities and tubercles in both lungs.
Seven pounds of serum in cavity of abdomen : thick-
 ening of the peritoneal covering of most cf the vis-
 cera:  a few clustered granular tubercles  in lungs.
 tubercles in kidneys, prostate and testes: and loose
 putty-like matter in left vesicula seminalis.
A small gangrenous abscess in  right lung:  no tuber-
 cles in either lung: 16 pints  of  serum in  cavity of
 abdomen: some pus  in  cavity  of pelvis.  Liver
 weighed  only21bs.: liver  and pancreas  unusually
 firm.   The serum agitated the following  day gave
 off a  good deal of air: the patient for many  years
 had laboured under amentia. 
TABLE  IL— Continued.
  Fatal diseasi
  ! determined
6 by dissec-
5." lion.)
      | Post mort
Time of inspection
      (hrs. after
      death.)
death.
9  59
10
11
12
13
20 Phthisis
   pulmonalis
21,OEdema
  slottidis
20
29
Bronchitis
chronic
phthisis
pulmonalis
Phthisis
pulmonalis
May 3
"  5
"  6
" 17
26
22
21
48
17  45
General condition of the
  blood in the heart.
Cruor and soft coagula
  in right  cavities of
  heart.
Pretty much cruor and
  fibrinous concretions
  in cavities of heart.
A  good  deal  of dark
 liquid  blood  in  the
 large vessels, and in
 right cavities of heart:
 a small portion of fi-
 brin in right ventricle.
A  good  deal  of cruor
 and fibrinous  concre-
 tions in cavities  of
 heart.
Some cruor and fibrin-
 ous  concretions  in
 right cavities of heart.
After condition of the Results of agitation of the
   blood set apart.       blood or cruor.
Three ounces of
 cruor collected,
 the   following
 morning jellied

The cruor slight-
  ly  coagulated
  the  following
  morning.
After three hours
  continued   li-
  quid.
Remarks relative to morbid appearances.
On  agitation,  after Blood effused on left hemisphere of cerebrum on the
 having been broken
 up, gave off a good
 deal of air.

Broken  up, a  good
 deal of air given off
 on agitation
On agitation gave off
 a good deal of air.
On  agitation imme-
  diately  gave  off
  some air.
On agitation imrae
 diately gave off no
 air:  there was no
 absorption.
 arachnoid membrane: fornix soft.  Inferior lobe of
 left  lung cedematous,  contained two cavities  in
 which a puriform fluid: no tubercles.  A  patient in
 Lunatic Asylum labouring under amentia.
Many clustered granular tubercles, and two or three
 small cavities in superior lobe of left lung:  several
 clusters of granular tubercles in superior lobe of right
 lung: right lung extensively  hepatized:  8 ounces
 of purulent serum  in right  pleura : 3 ounces in left:
 2 ounces in precardium.
Unexpected and almost sudden death from  oedema of
 glottis,  margin of epiglottis and sacculi  laryngis :
 the uvula was also cedematous.
Bronchia  red,  and contained  muco-purulent fluid:
 under-surface of epiglottis  superficially ulcerated:
 an ulcer at base of right arytenoid cartilage: numer-
 ous granular tubercles in both lungs: a small vomi-
 ca in superior lobe of right, and three in the superior
 lobe of left lung. The body little emaciated.

Lungs abounded in tubercles, and contained several
 cavities: large intestines severely ulcerated.  Died
 suddenly in the act of speaking. 
A good deal of coagu-jThe  cruor   put
 lated   blood,  eruor,  aside was liquid
 and fibrinous concre-  the   following
 tions in right cavities
 of heart.
A good deal of cruor,
 coagulated "blood and
 fibrinous concretions
 in cavities of heart.
Cruor  liquid the
 next motning.
Some  crassamentum, Two hours after,
—fibrinous   concre-
tions and a good deal
of cruor in right cavi-
ties of heart.
Six ounces of thin cru-
 or  in  right  pleura,
 with a very small por-
 tion of clot.
a good  deal  of dark
 cruor  and  fibrinous
 concretions  in  right
 cavities  of heart:  a
 mass of fibrin in left
 ventricle.
the  cruor  was
found jellied.
The cruor did not
 coagulate.
The  cruor  (six
  ounces)   was
  found   jellied
  the  following
  day.
On agitation gave off
 a little air.
On  agitation
 off some air.
After   twenty-four
 hours the coagulum
 had contracted : se-
 rum had separated:
 broken up and agi-
 tated,   some   air
 given off.
Agitated   twenty-
 four  hours   after,
 gave off a very lit-
 tle air.
Broken  up and agi-
 tated it gave off a
 little air.
Large cavities and numerous tubercles in the lungs:
 lungs partially hepatized: in the  right ventricle of
 heart were two masses of fibrin closely adhering, in
 each of which was a puriloid fluid, consisting (as it
 appeared  under the  microscope) of a few  blood
 discs, globules very like  those of pus, and of other
 particles less regular, and of various sizes.
Some oedema of left lung, weight three quarters of a
 pound: right lung extensively hepatized, of a fawn
 colour: it weighed four pounds: a slight deposition
 of lithate of soda on cartilages of tibiae and of first
 joint of great toes.   It was reported  that he had
 been'subject to rheumatism.
Cavities and numerous tubercles  in  lungs:  severe
 ulceration oflarynx: in a mass of fibrin in the right
 ventricle was a collection of transparent serum: the
 mass was firmest externally.
A false aneurism close to cceliac artery, with two cir-
 cular openings from aorta within  half an inch  of
 each other:  the  sac having burst,  a large quantity
 of blood was poured out and coagulated in omen-
 tum, &c.: a portion entered the posterior mediasti-
 num and ruptured it.
Several cavities  in lungs, and numerous tubercles
 with some hepatization. 
TABLE  II.—Continued
  I Fatal disease
   (determined
    by dissec-
3|    tion.)
lS;3i; Phthisis
     pulmonalis
20 24
21
Hypertro-
phy of heart
2233 Phthisis
     pulmonalis
23 46 Hydrotho-
24 22 Phthisis
  |   pulmonalis
Time of
 death
July 29
31
Aug.  1
"   5
•t   4
Post mort
inspection
(hrs. after
death.
27
37
32
"   9
29
12
General condition of the
  blood in the heart.
Some cruor and fibrin-
  ous  concretions  in
  right cavities of heart
  and in left auricle.
Some cruor, coagulated
  blood  and  fibrinous
  concretions in right
  cavities of heart  and
  in left auricle.
A good deal of cruor in
  right cavities of'heart
  and some clot.
Much liquid blood in ca
 vities of heart: some
 crassamentum:  no fi-
 brinous concretions.
A  little  cruor  and co
 agulated blood in right
 cavities of heart.
Sixty-three ounces
  collected, which
  coagulated in  a
  few minutes.
About  one  ounce
  only  could   be
  collected: the fol-
  lowing  day cru
  or coagulated.
Pretty much cruor and Cruor did  not co
 fibrinous   concretions!   agulate.
 in  right  cavities  ofj
 heart:  very  little  in
 left.
After condition of the
  blood set apart.
Results of agitation of
   the blood or cruor.
After  twenty-four
 hours cruor slight
 ly jellied.
On agitation gave off
 a very little air.
Agitated  immediate-
 ly,  pretty much  air
 disengaged.
Agitated  immediate.
 ly,  gave off a  good
 deal of air.
Remarks relative to morbid appearances.
Broken up  the  fol-
  lowing day, on agi
  tation  it  gave  off
  pretty much air.
Quantity  too  small
  for trial for air.
The following day on
  agitation, gave off
  pretty much air.
Tubercles abounded in lungs with cavities, partial  oedema
  and partial induration.


Right lung weighed three and a half pounds, partially hepa-
  tized, contained cavities and abounded in tubercles: left
  lung similarly diseased, in a minor degree.
Heart nearly triple its natural size: ventricles most enlarged,
  especially left: aorta much dilated and diseased, an ancu-
  rismal pouch at its base : albuminous matter of the ap-
  pearance and consistence of soft putty in left tunica vagi-
  nalis testis, left vesicula seminalis, in cavities in substance
  of kidneys,  in  ureter of the same  side, and in right vas
  deferens : the left ureter was in several places impervious:
  partial oedema of lungs : no tubercles.
Large excavations and numerous tubercles in  lungs :  death
  probably from suffocation, a vomica bursting and  pouring
  its contents  into bronchia.

54 ounces of serum in right pleura, with flakes of lymph:
  18 ounces in lefl pleura: 6 ounces in pericardium, with-
  out deposition of lymph:  the serum  agitated  gave off
  pretty much air : granular tubercles in lungs and in right
  pleura : 32 ounces of serum in cavity of abdomen :  were
  all the blood in the body collected, it would not have.ex-
  ceeded, it is probably, 4 ounces.
27 ounces of sero-purulent fluid in left pleura: lined with
  false membrane: cavities and tubercles in  both lungs: a
  mass of softened fibrin in right ventricle, which it may be
  inferred existed before death : a mass of firm fibrin in left
  ventricle of heart. 
14
19
24
41
16
A good deal of cruor in
 right cavities of heart:
 a little  soft  fibrinous
 concretion.
A good deal of cruor,
 crassamentum and fi-
 brinous concretions in
 heart.
Cruor found coagu-
  lated  the follow
  ing morning.

Two hours after re
  moval, cruor co-
  agulated and co-
  vered with a thin
  buffy  coat.
Cruor, the  follow
  ing  day found
  jellied.
 Some  cruor,  a  good
  deal of crassamentum
  and fibrinous  concre-
  tions in right  cavities
I  of heart,—some fibrin-
  ous concretions in left.
|  ventricle.
[Some cruor and a goodiThe cruor, the fol-
j  deal of crassamentum|   lowing morning
  in  right cavities  of   pretty firmly co
1  heart.                I   ugulaled
Some cruor  and fibrin-After 2 hours, the
 ous   concretions   in   cruor was found
 right cavities of heart,   coagulated,  and
                        a  sli^lit   buff)
Some cruor in right ca
  vities of  heart,—no
  clot or fibrinous con
  cretion.
  coat on it.
Cruor  liquid   tin
  following day.
Broken  up  and agi-
  tated, gave off pret
  ty much air.

Broken  up  and agi.
  tated  the following
  morning,  gave off
  no air : nor absorb
  ed any.
Broken  up  and agi-
  tated, a  little gas
  was disengaged.
Broken  up  and agi
  tated, it gave off a
  little air.
Broken up  and agi-
  tated the  following
  day, no  air  given
  off:  a very  slight
  absorption.
On  agitation did not
  five  off  any air:
  no apparent absorp-
  tion.
Pus in bronchia of left lung : a portion of its inferior lobe
  hepatized,  another  portion  cedematous:  no   tubercles:
  lumbar vertebrae and right os ilii extensively carious.

Right lung weighed 3i lbs.: its superior lobe  completely
  hepatized: some of its vessels  filled with lymph:  lett
  lung in part cedematous : no tubercles.  The  liver very
  large, not fatty, weighed 13i lbs.: 8 oz.  of serum of sp.
  gravw 1010, without any lymph.
Both lungs contained  numerous tubercles and some cavi-
  ties : arch of aorta considerably enlarged :  two masses of
  fibrin adhered to it internally mid-way, about the size of
  filberts, softening but not pultaccous.
A considerable portion of the left side of  face destroyed,
  with the greater part oi' corresponding  maxillary bones :
  a tumour about the size of a lemon  over the left parotid
  gland, its central patt soft, reddish and  blood-shot: com-
  posed of particles which, under the microscope, appeared
  to be of different sizes;  some of them globular.—Viscera
  tolerably sound.
Large intestines severely ulcerated : a mass of fibrin in lon-
  gitudinal sinus  softening internally.
Vomica?  and  numerous tubercles in  lungs:  appendicula
  vcrmiformis distended with  purulent  fluid  :  ulcerated :
  its opening into coecum perfectly closed by adhesion, (an
  example of mucous surfaces  adhering  by the effusion of
  lymph.) 
TABLE  II— Continued.
Fatal disease
 (determined
  by dissec-
    tion.)
31
32
33
34
       ll'ost mort.
Time of inspection
 death,  hrs. after
       death.)
Phthisis
pulmonalis
10'
41
20 Ascites
45|Medullary
   tumour
■Aug. 19    U
22!    8 S
26;
26    27
Sept.   1
21
General condition of the
   blood in the heart.
I After condition of the Results of agitation of
   blood set apart.      the blood of cruor.
Some cruor  and fibrin-
 ous   concretions   in
 right cavities of heart.

Some  cruor,—a  con-
  siderable quantity of
  crassamentum   and
  some  fibrinous  con-
  cretions in right ca-
  vities of heart.
Some  cruor,—-and  fi-
  brinous   concretion
  and a good  deal of
  crassamentum    in
  right   cavities    of
  heart; little  in left.
No  blood  in   heart.—
  blood  from  jugular
  veins liquid.
A good deal of soft cras-
  samentum, some  fi-
  brinous  concretions
  and a very little cru-
  or in heart.
The     following
 morning the cru-
 or slightly jellied.

The  cruor  after
 two hours jellied.
Remarks relative to morbid appearances.
The  next day the
  cruor was found
  coagulated.
Agitated,  <r;;ve off a Numerous tubercles  in  lung.?, and many minute vomica) :
  Irood deal of air.      disease of bone of right upper extremity :  portion of ulna
                       necrosed : cartilage of head of humerus and glenoid cavity
                       destroyed :  pus in capsule.
Agitated, it gave off a Left lung very small,  many tubercles in  it, and a cavity
  little ai,.,          J   communicating with  pleura : left pleura contained 57 oz.
                    I   of turbid serum,  and a good deal of air:  vomica}  and to-
                       heroics in right lung : the serum from pleura on agitation
                    [   gave off a good deal of air.

Broken up  and  agi-jvomica;, and  tubercles  in both lungs:  left femoral and  iliac
  tated it gave off no   vein with their branches obstructed  by coagulated blood
The following day
  found liquid.
The cruor did not
   coagulate.
and fibrinous  concretions,—tbe  L.tter  in many  places
softening, and in one or two reduced to a pus-like state.
  air, and did not ap
  parently    absorb
  any.

On  agitation  it gave'" pints of turbid serum in right pleura : 84 ounces of clear
  off pretty much air.!  serum in cavity of abdomen : some pus in pericardium
                      with great thickening, partial adhesion:  a  few crude  tu-
                      bercles in lungs, and  one small  cavity; the serum from
                      abdomenwasofsp.gr. 1018: the following day,  it had
                       deposited a very little lymph:  on agitation, it gave off a
                       good deal of air.
                     Masses of cerebriform tumour in left arm, accompanied with
                       much disorganisation  of sjft  parts ;  similar  disease  in
                       substance of left kidney : the  lower part  of  vena cava,
                       the left iliac and  femoral veins and  their branches ob.
                       structed by coagulated blood and fibrinous concretions, the
                       latter in  many  places softened and puriform.
The   quantity  too
  small for trial for
  air. 
OBSUKVAl 1UJS8 ON THE BLOOD.
113
   The  instances in  the first  table were strongly indicative of the
variable quality of the blood  after death, from disease.  The par-
ticular instances just given are as strongly corroborative of the same.
The variable quality, as far as appreciable by the senses, seems to
depend  on the lymph, which  as regards coagulability, has appeared
wonderfully little constant; in some instances retaining its power of
coagulation  more than 26 hours after death,-—in others, coagulating
immediately after the fatal event,—and in  some, previous  to that
event.  In a large number of the cases, the lymph appears to have ex-
isted in the  blood possessed of the quality in  question in different
degrees.  This is clearly to be inferred  from the results of the post
mortem inspections,  viz. from finding at the  same time,  and in  the
same body, in the cavities of  the heart, liquid coagulable cruor, soft
crassamentum, and firm fibrinous concretions.
   The  fibrinous concretions,  which are so frequently found in  the
heart after death, are far from being devoid of interest.   Their ap-
pearance, both as regards form  and consistence, is very various.
They are also very various in relation to the manner in which they
are attached to the heart.  I have mentioned one instance in which
serum  was collected  in the interior of a mass; the inner part was
soft, the outer surface firm.   Some masses seem to have a  certain
regularity of structure ; some  have the appearance of being inflamed,
being blood-shot from entangled red  particles of blood; some  ex-
hibit the appearance  of abscess,  and contain as it were in a sac  a
puriform matter, generated by a peculiar process of softening.  Gene-
rally they tend to give the idea of the operation  of  an organising
principle,—a nisus formativils more  or less active  until putrefac-
tion commence, by which the animal  matter is converted into com-
mon matter.
   The different varieties of fibrinous concretions are admirably illus-
trative  of certain morbid appearances, especially false membranes,
bands of adhesion, the state of the cellular tisstie in different kinds
of oadema and induration, and, I may add, hepatisation of the lung
with and without softening, and a similar state of the spleen, ami
perhaps tubercles and their  softening.  When  I have examined
microscopically  the  matter yielded by the  lung which has been
hepatised, undergoing softening, I have found  it very similar to the
matter into which a  fibrinous concretion is  converted, whether  in
the ventricles of the heart or  in a vein, composed of particles of dif-
ferent sizes, most of them approaching  the  spherical iti  form, and
some of them very like  pus  globules; and  1  have found the same
kind of matter in softened spleen., and also in softened tubercular
matter.
   No subject,  probably, in pathology is  more deserving  of  careful
investigation than lymph, in connection with its varieties, supposing
either that there are many different  species of  it, or that it is liable
to sudden and great changes of quality.  Relative to the  formes,
take for instance the  phlebolite in its different  stages of induration,
from soft lymph becoming of cartilaginous firmness and appearance; 
*I4                  davy's researches.

the fibrinous layers deposited in an aneurismal sac, resisting change
occasionally for years; and fibrinous concretions which are formed
i:i the large veins, especially in phthisis, which so soon soften, and
i:i part almost liquefy:—how great is  the  diversity,—how difficult,
m the present state of our knowledge, is the explanation.
   Nor is the liquid cruor, or the  blood remaining either in part  or
altogether liquid after death,—whether for a definite or  indefinite
time,—without interest and importance, especially as regards patho-
logical research, and the distinguishing between the  effects of dis-
ease and post mortem effects in the inspection of bodies.   As long
as the blood is liquid  after death, it  must necessarily  observe  the
laws to which fluids are subject under similar circumstances ; will
accumulate in the dependent parts, and  where there is  least resist-
ance ; and should there be considerable pressure  exerted  from the
disengagement of air in the stomach and intestines, it will appear as
if injected in the organs removed from  such pressure, whether in-
cluded in unyielding parietes, as  the  brain,—subject  to occupy less
volume from greater reduction of temperature after death,  than  its
solid, and during life cooler case,—or contained in yielding  enve-
lopes, as the lungs in the  pleurae and other parts of the body, gene-
rally in the common integuments, and in their peculiar capsules.
In  a considerable  number of examples  given  in the table,  cruor
was found in the heart more than  twenty-four hours  after death.
This cruor, in  producing false appearances of inflammation and
congestion, would act much in the same  manner as  liquid blood,
and in  estimating the  phenomena which present  on dissection,
much the same allowance should be made for it,—or serious errors
will be unavoidable.1
   From the experiments given in the table, on  the agitation in air
of the blood collected after death, it would appear that in the greater
number of instances, gas was disengaged. In several instances the
sir thus liberated was tried, and was  found to be carbonic acid gas,
—proving that  there was an excess of this acid in the blood.  This
excess, 1 am disposed to infer, especially from the results of experi-

   1 Dr. Yellowly in his valuable paper entitled " Observations on the Vascu-
lar appearance in the Stomach, which is frequently mistaken for Inflamma-
tion of that Organ," published in the Transactions of the Medico-Chirurgi-
cal Society for 1813,  has forcibly called  the attention of medical men to
errors such as those above alluded to.  His remarks  on the stomach are, I
apprehend, applicable to every other vascular organ;  and I am not aware of
any phenomena  pointed out by him  that are  not referable  to the circum-
stances specified above.  The long time that a portion of blood may remain
liquid in the body  after death, does not appear  to have been  known by him;
indeed, previous to the observations which I have given in proof of it, I  be-
lieve it had not been even suspected.
   The false appearances of inflammation described by Dr. Yellowly, are not
to be confounded  with those, the effects of mere staining: in one instance
the vessels merely contain blood or cruoi,  as if injected, and which may be
washed out, leaving the part colourless : in the other instance, the colouring
matter is chemically combined with the vessel or texture, and cannot be re*
moved by simple  ablution. 
OBSERVATIONS ON THE BLOOD.
115
 ments which I have made on healthy blood, as already mentioned,
 is the effect of disease, and is particularly apt to take place, as before
 remarked, in the act of dying, when  the powers of secretion seem
 to be arrested, and carbonic acid probably ceases to be eliminated in
 the lungs.  In  accordance with this, is the uniform dark colour of
 the blood, which is usually observed after death, and equally in*the
 left and in the right ventricle of the heart;  and also the little suffer-
 ing, fortunately; commonly  witnessed in dying,—stupor, or coma,
 usually preceding and ushering in the fatal  event.  From the results
 referred to, and from a few  which I have obtained in  operating on
 blood, taken from persons labouring under  disease, I am disposed to
 think that carbonic acid acts a very important part in the economy
 of life, and is connected, when in excess, if not with the production
 of particular diseases, at least with  their modification  and  progress,
 and the production of certain symptoms,—and that the careful ex-
 amination of the blood, in relation  to this acid, is an inquiry much
 wanted, and is likely to reward richly those who engage in  it.  At
 present there is a great difference of opinion, derived from  experi-
 ment,  respecting the carbonic acid in the  blood : some inquirers,
 as Dr. Stevens, to whom  belongs the merit of  having opened  this
 path of research, considering it, in the healthiest condition, always
 in excess, and  capable of being  liberated from venous  blood,  and
 even from arterial, by the  physical agencies in play in respiration;
 whilst others, as already pointed out, take  an  opposite view,  and
 deny that any free  acid exists  in  the blood, in its healihy normal
 slate, or can be separated  from the blood excepting by processes, in
 which it is formed from its elements.  This discrepancy, the inquiry
 I  have mentioned will probably explain or reconcile.   It will eluci-
 date also,  probably, some other obscure points which might be men-
 tioned, especially where it  extended  to  olher fluids, as the urine
 and bile.   I may mention, incidentally, that whenever  I have ob-
 tained indications of the disengagement of carbonic acid from  the
 blood after death, they have been afforded by the fluids spoken of,
 in a very  limited number of trials, and also by any effused  serous
 fluid, collected at the same time and subjected to the same test.
   In most of the cases brought  forward in  the second table,  the
 blood was microscopically examined,  using the  achromatic  object-
 glass of one eighth of an  inch focal distance, before mentioned.  I
 shall notice briefly some of the results.
   The blood-corpuscles were seldom found perfectly uniform either
 in size or  appearance ; slight differences were perceptible.  In some
 instances they appeared thinner than usual and more expanded  ; in
 some, of perfectly regular outline;  in others, the discs had an uneven
 indented margin, and a puckered surface.  In some, in  the same spe-
 cimen, the panicles exhibited these variations.   In most  cases in
 which  gas was  disengaged from the blood on agitation in common
air, the blood-discs,  under the microscope, appeared to have minute
globules attached to them, and very often, instead of gliding on their
flat surface, or with a revolving motion, they moved in the current, 
116
davy's researches.
passing under the object-glass in a perpendicular position, as if sus-
pended in this manner by particles of  air adhering to their upper
edge.                                           .           ,   .
  Lastly, in every instance, without exception, in which, during
life, there were purulent discharges, or  purulent collections were de-
tected after death, globules, like pus-globules, were visible, under the
microscope, on dilution of the blood with water.
  I make mention of these globules in  a guarded manner, from the
circumstance that I have occasionally seen similar ones, in instances
in which no suppuration  preceded death,  and also  in  the  blood of
the sheep in perfect health.  Thus, in the month  of  April, of the
present year,  (1839,) on  examining, microscopically,  the  blood of
six different sheep  killed  the same day,—without exception, parti-
cles resembling  pus-globules were detected, using ihe same method
as that just described.  In these, and in the former instances of the
absence of  the  suppurative process,  however, it deserves to be re-
marked, that the particles in question were fewer in number than in
the cases first referred to.   Till the exact nature of the pus-like
globules is determined, their pathological influence  must necessarily
be involved in some degree of doubt.
   I  was led to institute these trials, in  search of pus  in the blood,
from some observations made by Mr. Gulliver,  who, I believe,  was
the first to  delect this  substance, or its similitude, in the circula-
tion.1
AN  ACCOUNT  OF SOME  EXPERIMENTS  TO ENDEAVOUR
  TO  DETERMINE  WHETHER  OR  NO, FREE CARBONIC
  ACID EXISTS IN THE URINE OF MAN IN HEALTH.


  M. Proust, many years ago,  maintained  that the human urine
contains carbonic acid;  and  M. Vogel, and Mr. Brande, have ex-
pressed themselves to the same effect.  The  first mentioned inquirer

  1 The observations I refer to, are contained rn a very original and ingeni-
ous paper by this gentleman, which was read before the Royal Society last
spring, and which has since been published under the title of il Researches
on Suppuration," in the Philosophical Magaziue for September, 1838.
  This discovery (supposing that the particles are true pus-globules) which
I attribute to him, of course rests on piecise microscopical observation, and
is not to be confounded with the imagined detection oi pus in the veins, and
its inferred existence in the  blood, in instances designated phlebitis, the ma-
jority of which, hitherto described, I am disposed to believe, were example?
not of true inflammation  of vein, but  merely  o'  obstruction  from the
formation of a fibrinous ccagdum. with a tendency to soften and assume  a
purloid character.                                     ....._ 
                 EXPERIMENTS ON THE URINE.              1 ' '
pip5?7"
was of opinion that this acid exists in excess in the secretion of the
kidneys.—': Nos urines (his words are) en sont  surchaigees."1   The
last, Mr. Brande, has not adopted ihis conclusion ; his own is, that the
quantity is variable;  he  says, "When placed  under the receiver of
an air-pump during exhaustion, the gas escapes,  sometimes copi-
ously, but at other times  in minute quantities only."2
  M. Proust drew his inference from the appearance  of  the froth
which  rises in boiling urine, and from the precipitate  procured  by-
adding lime to the fluid.  His statement on the subject is very brief;
—the  following  is the whole of it.   '-An  moment on  elles (nos
urines) commencent a bouillir, on les voit se  couvrir d'une ecu me
blanche volumiiieuse qui en est gonflee, comme je m'en suis assure.
en recueillant une certaine quantite dans une  cloche.   Si, en outre,
on y jette de la chaux en poudre, la plus grande partie  se change en
carbonate."
  The experiments which I have instituted myself on  this subject,
have afforded results which are not reconcilable either  with those of
M.  Proust, or of Mr. Brande.
  On  the  first it appears to me unnecessary to offer any remarks,
as the  methods employed are of very doubtful accuracy.  In some
carefully conducted trials,  in which lime-water was added to fresh
urine in clos^ vessels, I could detect no carbonate of lime in the pre-
cipitate recently examined and not collected on a filter.  If, however,
many  hours were allowed  to elapse,  then  carbonic acid was extri-
cated from the precipitate on the addition of dilute muriatic acid.
   On  the effects of the air-pump on the urine, which  may be con-
sidered  an unobjectionable test of the presence of a free gas,  or
simply absorbed as the carbouic acid in this fluid has been supposed
to be,"I have made very many experiments, both in Corfu in 1828,
and during the last twelve months in this country.   In the  Ionian
Islands  I used an air-pump, in good'order but not of great exhaust-
ing  power.  Recently the instrument I have  employed has been of
the best  construction, the same  as that referred to at page  82  of
this volume.
   In both  series of experiments, [taking proper precautions as  re-
gards  temperature, and the exclusion as much as possible of atmos-
pheric air  by receiving the urine, as voided, into vials  scrupulously
clean,  and from which distilled water deprived of air by the air-
pump  had been  the  instant before  emptied,] the results obtained
were on the whole clear and satisfactory.
   In ihe majority of instances, when  the exhaustion was  carried as
far as  possible, the urine cooled below 60° remained perfectly tran-
quil,—indicating the total absence of any gas.
   In some comparatively few  instances air was  disengaged.   To
determine the nature of the disengaged air, a little solution of pure

  '^Annates de Chimie ct de Physique, torn. >iv. p. 258.
  'Manual of  Chemistry, vol. iii. p. 192, 2nd  edition.   Mr.  Brande, in  the
last edition of his wotk, that of 1S3S. in mentioning the ingred  ents of hea  ihy
 urine,  includes carbonic acid. 
118
DAVY'S RESEARCHES.
potash was added to the urine, and  the exhaustion was  repeated.
In every example that recourse was had to this test, the disengage-
ment of  air continued, clearly showing that  it was  not  carbonic
acid; and rendering it probable that  it was entangled atmospheric
air,  introduced in  the act  of  filling the vial,—it being  difficult
always to prevent the production of froth in this act in  a  slight
degree.
  In illustration, I may mention four trials of the same urine, made
under circumstances, apparently as nearly alike as possible,—having
been received as the bladder was emptied into  four vials, just emp-
tied of distilled water,  and placed immediately to cool, side by side
in the open air, at a temperature of  about 50°.  In about half an
hour, they had  fallen to about 54°.  Then  they  were in succession
placed under th; receiver,  and the  exhaustion effected.  No.  1,
boiled up very  much.  No. 2, remained perfectly tranquil.  No. 3,
gave  off a very few particles of air.   No. 4, remained  perfectly
tranquil.  In these instances, I did not test No. 1, and 3, by potash,
—the other results seemino- to  demonstrate that the air disengaged
was  adventitious, and derived from the  atmosphere.
  The experiments which I have  made have  been numerous,—on
the urine of the saniii  individual at different hours for  many days
consecutively, and also at intervals at different seasons of the year;
—and further on  the urine  of different individuals  under various
circumstances.   The general  result  has been  as I have stated,
negative, and the more uniformly and perfectly so, the more  accu-
racy has been observed in manipulating,—the greater the precau-
tions taken to prevent the admission of atmospheric air.
  From  what I have witnessed  generally in conducting the inquiry,
I am strongly impressed with the conviction, that in  a state of health,
no free carbonic acid passes  from the blood through the kidneys, or
is conveyed dissolved in their secretion, and consequently that these
organs do not perform  a part in the economy similar  to that of the
lungs, in separating this acid gas from the blood in circulation.
  M. Proust, in remarking on the results which  he obtained, those.
already referred to,—seeming  to  him to show that carbonic acid
gas abounds in the urine, says,  '•' we ought  not to be surprised at it,
as this gas s eliminated from the system  in various  other ways."
" Cet acide, considere com me ejection  ne faut  pas nous surprendre.
Nous en  perdons par la transpiration  par I'exhalation  pulmonaire,
et il  fait partie des gaz  que  la digestion  rejette  par d'autres voies."
  This, fairly considered, does not strengthen his conclusion ; but is
perfectly consistent  with the opposite one,—that the kidneys do  not
belong to its regular channel of outlet. If carbonic acid is capable of
passing through the kidneys in  the state under consideration, it  ap-
peared to me probable  that it might be detected  in  the  urine after
drinking largely of a fluid abounding it.   I have  made two trials
with a view to determine this.   At. Corfu the agreeable effervescing
mineral water of Cilli in Styria, which contains an enormous quan-
tity of carbonic acid, and some carbonate of lime was drunk fasti no-, 
EXPERIMENTS ON THE URINE.
119
a pint at a draught; and recently in this  country about  the  same
quantity of soda water in  the  act of effervescing was used.  The
bladder had been previously emptied. The urine on both occasions,
collected within  an hour after, was  found  perfectly tranquil under
the exhausted receiver; not a  particle of air was disengaged from
it, the exhaustion being as complete as possible.
   If the carbonic acid, when taken into the stomach in large quan-
tity, is not conveyed into the bladder in the fluid which passes  off so
rapidly by the kidneys, but is separated from it, either altogether in
the prima? vice, or  in part in the blood, it seems  highly improbable
that these organs, ever, excepting when  in a diseased state, should
separate this gas from the blood ; and when  the composition of  the
blood is taken into account, and the state in which the alkali it con-
tains appears to exist in it,—namely, as 1 have endeavoured to show,
in that of  sesquicarbonate,—this conclusion  is in a great degree
strengthened ; and it appears to me also much corroborated by keep-
ing in view the peculiar function and structure of the lungs as an
exhaling organ acting exposed to rarefied  air,  and as it were in a
partial vacuum, compared with the kidneys, so differently situated
and  constituted, and having a function to  perform so different.
   The  principal difficulty I have experienced in coming to the con-
clusion which I have  been obliged to draw from  my own experi-
ments has been to account for Mr.  Brande's opposite results.  I can
only reconcile them with those which I have  obtained, by supposing
that he did not give his special attention to the  subject; and  that  the
trials he made of the  effect of exhaustion were conducted  without
those precautions being taken  which I have  adverted to, and which
troublesome  experience has taught me are  absolutely necessary to
guard against fallacy  in the inquiry.
   I  have mentioned as a presumption,  that in disease, the human
urine may  contain carbonic acid.  But whether  it does in reality, I
apprehend  remains to  be proved.   Hitherto, in the trials which I
have made of this fluid in patients  in hospital, I have  not detected
it.   My experiments on it, however,  under the influence of disease,
have been limited, not sufficient to allow me to come to  any  satis-
factory conclusion. After death, I have detected it in the  urine,  the
instant it was taken from the  bladder; in  these  cases it  may have
been generated in the  bladder from a change in  the urea, which is
commonly secreted to the la^t, and  which,  as is well known, in  its
un purified state, is peculiarly apt to decompose and produce car-
bonate of ammonia, which, were any other acid present, would  ne-
cessarily afford carbonic acid gas.
   Whether or no  azote, or any other  gas  is  ever contained free
in the urine,  is a question which  perhaps  cannot  at present  be
answered in a satisfactory manner, and  which can be determined
only by carefully conducted experiments  specially directed to  the
investigation of the doubtful points. 
120                  davy's researches.
                              VI.

NOTICE  OP  SOME  ADDITIONAL  EXPERIMENTS  WITH
  THE AIR-PUMP, ON SOME OF THE OTHGR SECRETIONS,
  AND ON SOME OF THE SOLID PARTS  OF  THE BODY.


                         1.-0/ Milk.

  lam not aware of  any attempts hitherto made to endeavour to
determine, whether milk contains free carbonic acid, or that any
opinion even  has been hazarded on the subject.
  Both at Corfu, and  recently in this country, I have  subjected
milk to the air-pump.  The  results of the best conducted  experi-
ments  have been  negative.   At Corfu, in  1828,  I made trial of wo-
man's  milk, and of cow's milk; only a very few bubbles of air were
extricated on exhaustion ; no more than it might  be  fairly inferred
were entangled in the fluid as it was expressed from the nipple into
the receiving vessel.   In this country  1 have experimented only on
cow's milk.   When precaution was taken to prevent frothing, as by
expressing the  milk from the nipple, immersed in water deprived of
air  by  the air-pump, in the  manner analogous to that used  in the
similar trials  on  the blood,—then, on  subjecting it to exhaustion
when cooled, it remained perfectly tranquil, not a particle of air was
disengaged, even when the  vacuum was as complete as it could be
made.
  At Corfu, I made also some experiments on the new laid  egg  of
the common fowl, and with the same  results; neither its white nor
its yolk afforded  any air in vacuo.  The trials  were made on the
white and yolk apart  under water.1
  Are  not these negative results in the instance of milk and the egg,
such as might be expected, a priori, whether we take into consider-
ation their source, or  their  composition,  or  the objects for which
they are destined?  And, may they not in part tend to account for
some of the peculiar qualities in each in their state of perfect new-
ness, and for  the superior wholesomeness of the former,  when, as
by nature it was  intended,  it is drawn by the  infant or young ani-
mal direct from the breast of the mother?2

  1 When the whole egg was immersed in water,  and subjected to the air-
pump, then indeed it gave off some air, as might he expected ; adhering bub-
bles were detached from  the outer surface of the shell generally ; a current of
bubbles, for several minutes, was poured out from two or three conspicuous
pores in the large end of the egg—air, there is little doubt, which had entered
through the same pores, during  the cooling of the  egg, and its consequent
contraction,—which I infer from not finding any air in this part of  the egs,
when it has been put into water the instant it has been  laid, and examined
under water.
  2 The air which milk rapidly absorbs, on exposure to the atmosphere, and
which is promoted by the frothing in milking, and in the agitation it is com- 
EXPERIMENTS ON serous fluids.            12
                         2.— Of Bile.

   Recently I have subjected, with all possible care, the bile of the
 ox, the sheep, and the pig, lo the air-pump.  As soon as the animal
 was killed, a ligature was applied to ihe cystic  duct, and the gall-
 bladder was dissected out.   In  the instance of the ox, the bladder
 was immersed in water, and brought to me, and the bile, within  a
 quarter of an hour, was received into water that had been deprived
 of air; in that of the sheep the  transfer was made on the spot: but
 in that of the pig it was delayed about fourteen  hours.  In each in-
 stance, no air  could be  extricated by exhaustion; the results  were
 most satisfactory,—not a particle appeared.
   On the bile  of  man, 1 have recently made  only one trial,  con-
 ducted in the same manner  as the preceding: it  was procured  from
 a  body, examined twenty hours after death, in the  beginning of
 May, that had died of tubercular phthisis, complicated with paraple-
 gia,  occasioned by the growth of a tumour of the medullary kind in
 the lower part of the spinal canal.  Although a cavity in the lungs
 was  in a gangrenous state,  the blood  bore  no  marks of incipient
 putrefaction ; and not a particle of air was disengaged from the bile
 in vacuo.
   In Corfu, I made a similar trial of cystic bile, in two other  fatal
 cases, both of chronic dysentery, with the like result; one examined
 13 hours the other 20 hours after death.
   The deduction from these results is obvious:  and, in relation  to
 carbonic acid, as bile is an alkaline fluid, they are such as might be
 expected a priori.
   At page 115, I have  mentioned, that on  trial of bile,  collected
 after death in  instances of disease,  by agitation with  common air,
 gas was frequently disengaged, which it was supposed was carbonic
 acid gas.   In these examples it  is probable that the disengagement
 witnessed was owing to incipient decomposition of the  fluid,  con-
 nected with the putrefactive  process.

             3.— Of synovia and of serous fluids.

  Recently, in two instances, I  have  subjected synovia to the air-
 pump ; in both, it was taken  from the human subject—in  one, three
 hours after death—in the other,  sixteen and a half. The trials were
 made, as already described,  by  introducing  the  fluid, as it flowed
from the joint, through an appropriate opening, into distilled water
purged of air.   In the first example, not a particle of air was dis-
engaged.  In the second, two or  three very small  particles only were
separated, giving the idea of adventitious air, entangled during the

monly subjected  to afterwards  in various ways, conduces powerfully  to its
fermentation—to the formation of carbonic acid and vinegar, and the separa-
 tion of its curd and cream. 
^w                  daw's researches.

passage of the fluid from the capsule to the vial ;  there was not the
slightest general effervescence.  At Corfu, also, I subjected synovia
to "the air-pump, in two different instances—the fatal cases referred
to in  the preceding section—and the  results were equally negative.
  It has been asserted by a distinguished inquirer, that a small quan-
tity of air is not an uncommon occurrence in the synovial capsules:
the words of M. Laennec are—"L'on sait qu'il se trouve souvent,
dans les  capsules  synoviales, une petite quantile d'un  fluide aeri-
forfne.,;i  If so, it  might be expected that air might even more fre-
quently be detected in the synovia itself, on the  removal of atmo-
spheric pressure; and that the results I  have given above are to bo
viewed as exceptions.   But, with a  feeling of the  highest respect
for the individual quoted, I  believe that in this instance he has re-
ceived as  matter of fact what is  not really so, trusting unduly to
loose opinion  founded  on  careless observation.   For many  years,
my attention  has been specially directed  to the subject of air  in the
cavities of the body, and I can, without hesitation, say, that  in no
instance,  out of several hundred, in which  I have  examined the
joints after death, could I detect in them the presence of any elastic
fluid.
  Amongst my notes, bearing the date of Malta, June, 1828, I find
three  cases,  in which careful search was made for air in the cap-
sules of the joints and the sheaths of tendons,  by an examination of
the parts under water—the  bodies having been immersed in a bath
for  the purpose; one six hours  after death, another  eleven,  and  a
third twelve.  In each  instance the result was perfectly negative.
As synovia, from its viscid  nature, is peculiarly apt  to froth  or en-
tangle air, it  is not surprising that such an opinion as that referred
to by the very eminent French pathologist should  have arisen.2

  1 Traite  de I'Auscultation Mediate,  Paris, 1826, torn. ii. 445.
  2 The same opinion is expressed by Laennec in another passage, the cor-
rectness of parts of which are very questionable.  On account of the import-
ance of the subject,  practically as well as theoretically considered,  I shall
quote his words at length:—"Tous les bruits qui se passent flans l'interieur
du corps, et que I'on  peut entendre a l'oreille nue, sont dus aux mouvemens
de quelque substance qui se trouve en contact avec un gaz.  C'est ainsi que
l'on entend les borboiygmes dans  les intestins,  la fluctuation hippocratique
dans le pneumathorax avec epanchemenl liquide,  et meme celle qui a lieu
dans l'estomac, le bruit de la crepitation  determine par l'inspiration ou par
les battemens du coeur dans quelques emphysemes des parois thoraciques, la
craquement des doigts chez certain sujets  dont les articulations contiennent
habituellement un gaz, un bruit analogue et accompagne de  crepitation ma-
nifeste sous la main, dans les  pneumarthroses qui succedent  f'requemment
au rhumatisme articulaire,  et particulierement dans I'articulation du genou."
—Op. cit. ii. 456.  In this  passage,  some  important truths are mixed with
opinions of more or less doubtful accuracy.  As the vibrations essential to
sound can  take place in a fluid,  and an elastic fluid is not absolutely required
there  is no good reason why several  of the  sounds mentioned may  not be
produced without the  presence of air;  I shall notice only one  in particular
by way of  illustration, that of the  cracking of the fingers—"le craquement
des doigts:"—this sound was produced in two of the fatal cases noticed in 
EXPERIMENTS ON THE HUMOURS.
123
  Of serous fluids I have hitherto made but few trials; they have
been confined to the liquor pericardii  and the fluid  of the  lateral
ventricles of  the brain.  In three different  instances (the limit  of
these trials)  in  which these fluids, a few hours after  death, were
subjected to the  air-pump,  no indications were afforded of the dis-
engagement of air, excepting a minute bubble or two,  which, pro-
bably it is right to infer,  arose  from air entangled in  transferring
the fluid from the pericardium  and  the ventricle into  the vessel pre-
pared for it.  In the instance of the former,  it was scooped out with
a gallipot,  from which distilled water, purged of air, had,  the in-
stant before,  been emptied; in  that of the latter, it was allowed  to
run into a vial nearly full of water, purged of air, through an open-
ing in the posterior cornu.
   In a case of abdominal dropsy, in which it was necessary to draw
off the accumulated fluid by the operation of paracentesis, the trans-
parent  serum of sp.  grav. 1011 was agitated with common  air in
the  double-mouthed  bottle already mentioned,  without the  disen-
gagement of any gas;  which  may be considered equivalent to a
negative result  with the air-pump.
   As  the serous fluids are commonly alkaline, [that is, contain  an
alkali not saturated fully with  carbonic acid, and capable of absorb-
ing a considerable additional proportion,] the probability is,  that in
their healthy normal  state, they never contain this acid free or un-
combined, nor is it likely, reasoning a priori, that they contain any
other gas in  a state of freedom or mere mechanical solution.
   In a state  of disease, however,  and especially of  fatal disease, I
believe the  presence of carbonic acid  in these fluids is not an un-
 common  occurrence.  When  treating of the blood after death, I
 have mentioned that I have frequently obtained indications of this
gas in serum effused in  excess into the great cavities,  by agitating
a few ounces of it  in  the dou! le-mouthed  bottle,  with twice or
thrice its volume of common air. In these cases the blood, it should
 be remembered, was  found by  the same test to abound more or less
 in the same  acid gas.  The source of the carbonic acid, in the in-
stances referred to, and whether besides this gas, any other gas is
 mixed with  it, are undetermined points,  and seem to be fit subjects
 for farther and  special inquiry.

                  4.— Of the humours of the eye.

   The internal component parts of the eye being from their nalure
 and situation very suitable for the trials under consideration, I have
 in three different instances subjected them  to the experiment of ihe
 air-pump.   In  each instance,  the  organ was extracted a few hours

 the text, in which the capsules of the joints and sheaths of tendons were
 examined for ait, and without a particle being detected, even in the joints
 which emitted the sound on extension.  And this instance, I apprehend, is
 applicable, by analogy, to all others in which firm or hard surfaces are sub-
ject eiiher to  attrition or concussion. 
124
DAVYr's RESEARCHES.
after death;  a viii  having been prepared full of water purged of air,
the sclerotic coat was partially divided, and the lens and a portion of
the aqueous and of the vitreous humour was received into the water.
On one occasion, a small piece of the retina accompanied the lens,
and  on another, minute  portions of the ciliary processes.  On ex-
haustion,  in  each  example the result was similar: no air was dis-
engaged.  In the last of the  three trials on the eye from different
bodies,  the contents of one eye were examined  three hours after
death, and of the other eye the  following day, twenty hours later:
the result was  the same in  both.   The thermometer dining the
time, in the  room where this body was deposited, was about 58°.
  I am not aware that  air has ever been observed in the eye during
life,  or  that there  is any well-authenticated instance of its having
been detected in this organ after death, excepting in cases of very
advanced  putrefaction.

               5.— Of the solid parts of the body.

  It  would be tedious  to give in detail an  account of the experi-
ments which [  have instituted in quest of air in the solid parts  of
the body.   It may suffice to state the general  result,  or rather the
impression made  by the results on my mind, which is, that no in-
ternal  organ, in its healthy normal  state,  contains air capable  of
being extricated by the removal of atmospheric pressure by the air-
pump,  excepting those [the. lungs especially] which are designed
to be its recipient.  ■**'"
  In no instance in which I have tried the  substance of the brain,
before  putrefaction  had commenced, has any air been disengaged
from it in vacuo—a central  part having been selected,  in  which
there were  no  obvious vessels,  and carefully cut out with a fine
sharp scalpel just dipped  in water purged of air, and as soon as ciit
out, immersed in the same water.
  But, in  the instances of the other viscera, I  have always found
more or less air disengaged, on subjecting portions of them in the
same manner to the action of the air-pump.  The proportion of air
evolved appeared to accord with the degree  of vascularity of the
part.   This,  I  apprehend, is what  might  be expected  a priori,
taking  into account the rapidity  with which air enters the arteries,
when they are divided, owing to their expansion  on  the access  of
air depending on their elasticity.  I shall offer a  partial proof of an
experimental kind.
  Two rabbits of the  same age were  killed:  one by dividing ihe
great cervical blood-vessels, the other by a blow on the occiput.
The thorax of each was opened before they were  cold.' In the
heart of the first  mentioned  there was evidently air, and even  in
the coronary vessels.   In the heart of the second there was  no ap-
pearance of air; it was moderately distended  with blood, and its
vessels were  full  of blood.  A ligature was applied  to  the great
vessels of each, and the hearts were  removed  and put into water. 
EXPERIMENTS ON THE SOLID PARTS.
125
The first swam: the second sank.   Under an exhausted  receiver,
the first was amazingly distended; its blood-vessels also were dis-
tended,  and their  very  minute ramifications were  beautifully dis-
played,  vaiiously anastomosing: very little  of the  air was disen-
gaged.  The second was not at ail distended;  a few bubbles of air
only were given off, and these  came principally from the ends ot
the divided vessels; the coronary vessels did not exhibit the slight-
est change, and not a particle of air could be discovered in them.
   These experiments were made at Corfu.   Recently,  I have insti-
tuted similar ones  (using an air-pump of the best construction) on
the carotid artery,  containing blood secured  by a ligature,  and with
the like result, as has already been described, when treating of the
blood in connection with respiration; and demonstrating, that even
if the blood contain carbonic acid  gas capable of being extricated
by the air-pump, this extrication cannot take place so long as the
fluid  is contained  in the vessels, the pressure of their sides being
sufficient, it would appear, to retain the elastic fluid, when present.
   Prochaska,  in his ingenious treatise on the organism of the  hu-
man  body and its  vital  processes,  whilst he  denies,  as  has been
already mentioned, that air is to be  found in the arteries after death.
yet endeavours to show, that during life, they and other parts of the
body partially owe their distention  to vapour which, as  he supposes,
they contain.   He says: "Si statum sanguinis  in  homine vivo et
rnortuo invicem comparamus, ingens voluminis differentia in utro-
que adparet; nam qui in vivo homine  omnia vasa  a  maximis  ad
minima usque repleveraf, rubore vitali cutim universam perfuderal,
post mortem ex minimis vasis evanescit, cui pallor cutis cadavero-
sus succedit, venae subcutanas collabuntur, et arteria? a minimis ad
maximas usque fere inanes ac vacuae reperiuntur.  Cl. Rosa arteri-
am vivi animalis sanguine repletam in duobus locis ligaverat. qua:
exscissa et refrigerata volumen suum ad £ diminuit, et sanguis hujns
contracfaB arteria3 filum referens tantum idiametri partem explevit;
ex quo  sequitur, quod sanguinis volumen  in arteria viva ad volu-
men sanguinis arterias mortuas se ut 9 ad 1  habeat."1
   The  vapour which Prochaska alludes to, it is hardly necessary
to observe, can only have effect, and indeed can exist only, where
there is free space, as in an artery  not full  of blood—in the pleura
or peritonaeum—not at every point in  contact with their contents.
If such a vapour as he supposes exist in the body, and  if the results
of Rosa's experiments,  quoted by  him,  are owing to  its  action,  it
might be expected to be of a peculiar  kind,  not merely  aqueous
vapour, but of some other fluid capable of  becoming elastic, and of
exerting a distending force at the ordinary temperature  of the blood.
I shall describe what I have witnessed in repeating the  experiments,
made with all the  care I could use, to endevour  to satisfy myself on
a point of very great interest, at least, thus hypothetically  viewed.

   1 Disquisitio Anat. Phys. Organismi  Corp. human, ejusque  Processus Vit.
Auctore G. Prochaska.  Vien. 1812, p. 86.
        10 _e                                       9 dav 
126
DAVY'S RESEARCHES.
                       1st Experiment.

  Laid bare and fully exposed the carotid artery of a sheep, on the
10th May, when the  temperature of the air was about 00°; the
8th nerve was separated from the artery.  Applied loosely two liga-
tures to the exposed part; the superior was first drawn tight;  there
was no apparent increase of the volume of the vessel below.   Im-
mediately after tying tightly the lower one, the included space was
measured by a compass, and found to be exactly 150 inch,  and the
diameter  of  the included vessel  -20 inch.   The part was now cut
out; the  artery was first divided above the superior ligature; blood
flowed moderately as from a vein from  the open extremity; it was
next divided  below, when the  blood  gushed out with violence.
The portion removed was again immediately measured;  its diame-
ter was not  perceptibly changed; but in length,  from  150 inch  it
was contracted to  1-20.  It was instantly placed  in water purged
of air by the air-pump; and about an  hour after, placed  under a
receiver for exhaustion.  On  exhausting  the  receiver, I narrowly
watched  the artery; but could not perceive the slightest distention
of it, such as might be  expected if it contained any fluid more vola-
tile than water;  nor did any take place when the vacuum was as
complete as it  could be made.   Measured again, now it was quite
cold, and after having been  taken  out  of the water,  its diameter
appeared unaltered, but its length a little increased, namely, to 130
inch.

                       2c? Experiment.

   This experiment was conducted precisely in the same manner as
the preceding.  The portion of carotid artery included between the
two ligatures, measured  before excision, was 140 inch in length,
and -20 in breadth.  Immediately after excision the length was 132,
the breadth  remaining unaltered.  It was subjected to the air-pump
in the same manner  and after the  same time, and with the  same
negative  result.  Now, on admeasurement, no change could be de-
tected in  its dimensions, either in length or diameter.
   In both instances, the artery which was  cut out was unusually
tense  and hard; and when  punctured, the contained, and  as  it
would appear, compressed blood, sprang forth with force, and to
the distance of about two feet, as if from an animal alive.
   These results, carefully considered, I apprehend, can in  no wise
be received as favourable to Prochaska's views of the existence and
operation of an expansive vapour in the living body.   As the con-
traction  of the artery  took place immediately on its division and
excision, agreeably to what is known of the properties of arteries,
and was  not increased  by cooling, it is not for, but in opposition to,
the argument used by the learned professor.  The phenomena them-
selves, which he endeavours to  explain by means of his imagined 
MORBID ADHESIONS.
127
cause, do not require it. The heart's action during life seems suffi-
cient to account for the expansion of the vessels, even to the capil-
laries:  and  its cessation  in death, conjoined with  atmospheric
pressure, and the elasticity of the arteries, and  the force of gravita-
tion, to explain the emptying of the arteries and superficial vessels,
and the consequent pallor,  and shrinking of the surface, which is
then witnessed; and as is also witnessed, in a  less degree, in  mo-
mentary syncope,  the  same  cause,  as regards the  heart, taking
effect—although unaccompanied by reduction of temperature, such
as would be  required to affect the condition of vapour, were it in
existence.
  Prochaska makes many  excellent remarks  on  the porosity  and
permeability  of vessels, admitting  of a penetration by moisture,
which, amongst parts in contact, will act the same office as vapour;
indeed, in stating his views  on the subject of the porosity of the  ves-
sels, he has adduced some curious facts, on an extension of which,
recently, the doctrine has been grounded of endosmosis  and exos-
mosis.
  Before coming to a conclusion, it  may be right to notice an ob-
jection which may be made to the results of  my experiments in
search of air in the animal  fluids and solids, and  the inference
drawn from them,  that  no  air in a state capable of  being  removed
by exhaustion exits  in  them.  It  may be  said, that animal  mem-
branes are permeable to air, and that therefore they must contain
it, and not  they alone, but also the fluids within them.  This is
true of the dead membranes—especially the thinnest of  them,  and
after a time.   But it remains to be proved that it is true  of mem-
branes  generally,  and  especially during life: and until  proved, it
ought  not  to be admitted.  But even were proof of it afforded, it
does not necessarily follow that the pervading air should  be found
unaltered within:  the oxygen, it is probable, would combine  in a
peculiar way to the colouring matter of the blood;  and the azote
might  also  immediately enter into combination.   The  effect of
porous  spongy platinum in  effecting the combination  of certain
gases is as well known as  it  is extraordinary;  other matters seem
to have an analogous  effect:  and there is no reason why porous
living  parts should not act  in the same way.
                             VII.

ON THE AGE OF MORBID ADHESIONS, AND OF THE FLUID
      FOUND IN THE PERICARDIUM AFTER  DEATH.

  It is an opinion pretty generally prevalent,  that the age of these
morbid adhesions,1 which are so frequently met with in the dissec-

  1 I use the term in its common professional sense, signifying the  matter
constituting the morbid connection of parts. 
128
DAVY'S RESEARCHES.
tion  of bodies, connecting together  serous  membranes,  may be
guessed at by their comparative degree of strength;  thus, weak
adhesions are usually considered of recent origin—and firm adhe-
sions as being of long standing.  Is this opinion correct; and does
it  agree or not with the properties  of coagulable lymph, ot which
these adhesions are principally formed?
   Many circumstances, of which it  will be sufficient to mention a
few, appear to me decidedly in favour of the negative conclusion.
   Wounds, it is well known, which heal by theirs/ intention, are
often firmly united in twenty-four hours.
   In the same space of time, when inflammation has been artificially
excited, I have witnessed the formation of strong adhesions.  An
instance  may be given.  At Colombo, in the island  of Ceylon, in
January, 1819, I  made  the following experiment on a young dog,
nearly full-grown.  By an opening made with  a scalpel  between
the ribs of the right side of the chest, about a  scruple of ariack was
injected  into the  cavity of  the  pleura.  The  lung was slightly
wounded; air passed freely through the opening, and a little frothy
mucus was discharged.   The animal seemed at first to suffer pain
and to be languid; but left to himself, he gradually recovered,  and
in the course of  the  day took some food.   At the expiration of
twenty-four hours  the dog was hot,  but apparently not suffering
pain ; he was running about, and the  wound was closed. The dog
was  now killed, and  was almost immediately examined.   A good
deal  of coagulable  lymph, which had the appearance of being vas-
cular, was found under the skin round the wound—connecting the
cutis and the intercostal muscles.   The adjoining cellular mem-
brane was inflamed. Some bloody serum was effused into the right
cavity of the  chest.   Many  pretty firm and long adhesions  bad
formed between the pleura pulmonalis and costalis, each of which
was  of a reddish hue.   There were also many adhesions  between
the pleura and pericardium, and the pericardium itself was inflamed
—its surfaces adherent, and, consequently, its cavity obliterated.
   The coagulated lymph of the buffy coat of the blood may be used
as an illustration of the  short time  in which  strong adhesions may
form; and I do not know a better confirmation of the fact.  Liquid,
when the blood is  drawn, coagulable lymph  gradually becomes—
first, viscid, and afterwards solid.  In  the viscid state, as I  have
frequently observed, when it is still transparent, it has  the tenacity
of mucus, and admits of being drawn  out into fibres  and bands,
which soon becoming firm and opaque, very well represent the or-
dinary adhesions of the lungs—and in a very  few hours attain their
maximum of strength.
   This viscidity, which  coagulable  lymph acquires in passing from
a  liquid to a solid form,  has not, that  I am aware, been noticed by
authors; and the formation of adhesions is usually explained  with-
out reference to this quality.1

   1 Vide "The Morbid Anatomy of some of the most important parts of the 
MORBID ADHESIONS.
129
  1. It is believed by many writers, and by some of high authority,
that the small portions of serous fluid which are found after death
in the cavities of serous  membranes,  especially in the pericardium
and the ventricles of the brain, may have been  poured out after the
cessation of life.'  I am not aware that this opinion is supported by
any precise facts. As a theoretical conclusion its correctness seems
doubtful.   I  have endeavoured to put it to the test of experiment,
and the result has been unfavourable.  I have  notes of three differ-
ent experiments on dogs, which were made in Ceylon in 1818—all
of which seem to show that, under ordinary circumstances, no effu-
sion of serum or exudation, so  as to occasion  accumulation,  takes
place after death.  The experiments were briefly the following.  In
each instance a  healthy dog was suddenly killed by a blow on the
occiput; the cavity of the  chest was instantly laid open,  and the
pericardium  inspected; a small  quantity of serum found in  it was
removed by a sponge, and the incisions were then closed by sutures.
At  the end of twenty-four hours the sutures were divided,  and the
pericardium  was again examined. In no instance had a single drop
of fluid collected in the pericardium;  and yet, in two instances, the
right auricle and ventricle were considerably distended with blood.
  If these results be conclusive against fluid being effused  into the
pericardium, after death, in dogs, the  inference from  them admits
of being extended, by analogy, to other cavities of the same texture,
and to man; and I am not acquainted with any pathological obser-
vations in  opposition to  it.   The discovery of serous effusions in
examinations post mortem, no  symptoms of their occurrence or
existence having been noticed during life,  is surely no evidence of
their having taken  place after the cessation of vital  action.  It  is too
well known to be insisted on, that large portions of fluid may accu-
mulate in the pericardium, and even  in the ventricles of the brain,
without a single symptom indicative of the occurrence.
  These remarks were written in 1822, and were published in the
Philosophical Transactions for  that year.   Referring  to an able
work on physiology,  now in progress of publication by Professor
Burdach, I perceive that this ingenious inquirer and learned author
objects to the results of my experiments, on account of the pericar-
dium having been exposed to the pressure of the atmosphere, which,
he is of opinion, would arrest the  exudation,  "le  pericardii  ayant.
ete  ou vert et expose a la pression de 1' atmosphere, la secretion ne
pouvait plus s'y accomplir."3  This objection appears to me rather


Human Body," by Matthew Baillie, M.D. F.R.S. fifth edition, p. 6.  This
reference was made in 1822, in a paper published in the Philosophical Trans-
actions  for that year;  since that time I do not recollect any writer who has
insisted on the above mentioned important property of lymph.
  1 Sauvage's Nosologia Method. Ephialles ex Hydrocephalo. Cours d'Ana-
tomie Medicale. par Antoine Portal, torn. iv. p. 54, 8vo, Paris, 1803.
  1  Traite de Physiologie consideree comme Science d'Observation,  par C.
F. Burdach, Professeur a l'Universite de  Kcenigsberg.  Traduit de  l'Alle-
mande, par A. T.  L. Jourdan, tom.viii. p. 509. 
130
DAW'S RESEARCHES.
specious than well founded.  It is true that the air is excluded from
closed sacs, such  as the pleurae atid pericardium ; but I do not be-
lieve  that  the  pressure of the  atmosphere is prevented, inasmuch
as atmospheric air can  enter  through  the aspera arteria into  the
lungs, and through the mediunr of them, act on the pericardium or
pleurae—yielding  membranes, and ordinarily in contact with  the
organs which they contain—and consequently not offering any true
vacuum or an approach to it, favourable to examination.
  Reasoning on the subject, and considering the relative qualities of
the parts concerned—the heart, the pericardium,  the pleurae, and
lungs—it appeared to me more probable, that the pericardium would
rather lose fluid than gain it after death by exudation, inasmuch as
the external  layer—that dividing it  from  the pleura—is a thinner
boundary, and it may be supposed, more easily penetrated than the
internal, comprehending with it the muscular parieties of the heart
and its inner lining.
  To endeavour to illustrate this view  by  experiments, I have had
recourse to  an  aqueous solution of the triple prussiate of potash'
(ferro-cyanuret of potassium).
  1  The solution of this  salt is peculiarly well fitted for the «bove purpose,
both on account of the facility with which its presence may be  detected in
animal fluids, and its not apparently having any astringent or other effect on
the  delicate textures of the body.  The experiments of Heiing on the injec-
tion of this salt into the veins of horses may be adduced in proof and illus-
tration ; as may also some experiments which Dr. Wollaston made on the
taking of the salt internally in  the yeai 1798, and some others made by my-
self in 1823.   From  Professor Burdach's account of Hering's experiments
given at page 344 of the 8th vol. of his Physiology, it appears that the prus-
siate was often detected in the substance of the kidneys, at the expiration of
a minute  after its injection into the vein ; and that it ceased to be detected
in the blood in from fifteen minutes to five hours—although it continued ap-
preciable  in the urine very many  hours longer, even two days.
  Dr. Wollaston, in his paper "On  the non-existence of Sugar in the Blood
of Persons labouring under Diabetes Mellitus," published in the Philosophi-
cal Transactions for 1811, has noticed the results of  some of his experiments,
when engaged in some  similar trials.  He favoured  me with a copy of his
original notes, which,  as  they may interest the physiological reader, I shall
introduce verbatim.   His not being able  to defect  the salt in the blood, is
explained by the results mentioned  as obtained by  Hering.   It may be pre-
mised that the figures in the first column indicate the time when the salt was
taken and the urine was tested.


                        December 15th, 1798.

      vii.       pruss. gtt. xxv.=gr. iii."i
      vii.  15,  not blue.              I ^
      viii.   5.  rather blue.           f*^*
           25,  blue.                 J
           45,  ditto.
       x.  10,  blue.
       xi.  20,  blue. 
FLUID IX THE PERICARDIUM.
131
                           Experiment 1.

   Two hours after death from pulmonary consumption, the jugular
vein of a  body was opened—six  ounces of blood were allowed  to
escape, and then twelve ounces of the solution1 were injected in the
direction of the heart, and ligatures immediately applied to the ves-


                            December 17,
       ii.  30,  pruss. gtt. xxx. "1
       iii.  20,  Dot blue.     > 1.20 shortest time of observed blueness.
       iii.  50,  blue.         J
       iv.  20,  ditto,
       vi.  30,  ditto, strong.
December 26.
       vi.   50,  pruss. sjss.}
      viii.          ditto.   S2.40.
      viii.   45,     ditto.   J
       ix.   30,  rather blue.
        x.   30,     ditto.
            50,  V. S. not blue, i. e. the serum.
  In my experiments a much larger quantity of the salt was taken, viz. 40
grs. of the crystallised salt dissolved in an ounce and a half of water—and as
might be expected, the results were more decided.  After 15 minutes it was
first detected in the urine, and it continued to be detected for the space of 33
hours. The following is a-copy of the notes made at the time;—
		June 12th, 1833.
xii.	40,	took the salt.
	42,	no effect on urine.
	48,	ditto.
	55,	very slight bluish tinge.
	1-5	slight Mae.
	15,	blue.
v.	o,	ditto.
vii.	o,	ditto.
X.	30,	slight blue. June 13.
viii..		slight blue.
i.	P. M.	ditto.
it.		faint bluish tinge.
X.		very faint. June 14.
viii.	A. M.	no perceptible bluish tin
  I find it remarked, that almost all the urine voided during the 33 hours thai
the salt was appreciable, was tested—and that  the  quantity of iron thrown
down was very small, conveying  the  idea that  only a  small portion of the
triple-prussiate reached the bladder—and giving rise to the conjecture that
the greater part of it was decomposed in  the system.
  I may add by  way of precaution—that  the day after taking the very  large
dose of the triple-prussiate, I felt unwell—experiencing slight vertigo and
tendency to syncope.
  1 3 grs. of the salt were dissolved in 12 ounces of water. 
132
DAVY'S RESEARCHES.
sel.  The post mortem examination was  made  on the following
day, the 23d September, twenty-three hours after death.
  Not quite half an ounce of fluid was found in the pericardium.
On the addition of a little  solution of green sulphate of iron, no im-
mediate change  of  colour was produced ;  on admixture of a  little
nitric acid, coagulation was occasioned, and a faint  but  distinct
greenish hue appeared.1
  There was some  crassamentum and cruor, and fibrinous concre-
tion nearly colourless  in  the  right  auricle  and  ventricle—the
fibrinous concretions chiefly in  the latter.   A portion of this fibrin,
moistened with the solution of sulphate of iron  and a little nitric
acid, became blue.  In the left ventricle there was a little fibrinous
concretion : this tested in the same way, acquired a greenish hue
which was only just perceptible.   Portions of the lungs were  simi-
larly tried.  Some portions became greenish ;  some blue ; the blue
colour appeared chiefly in the course of the blood-vessels: even the
walls of a large  tubercular  excavation,  covered with false mem-
brane, acquired a just perceptible greenish hue.
   These results seem to indicate that  there was a slight exudation
from the heart into the pericardium, but  not exclusively so, nor to
the extent to occasion  the accumulation, which is corroborated by
other circumstances.
   The serum from the blood, which flowed from the jugular vein
after death, (it coagulated and afforded clear serum and well formed
crassamentum) was of a  bright yellow hue;  the  liquor pericardii
was nearly colourless.
   Three drops of the  solution of triple-prussiate  mixed with half
an  ounce of serum, tested  in the  same manner as  the liquor peri-
cardii, exhibited as  nearly as possible the same degree  of colour.
   Whence it  may  be inferred  that  extremely little of the  solution
passed into or was retained  in the  pericardium;  that the  greater
part of it passed into the lungs—and that the liquor pericardii was
not a post mortem exudation, but a vital secretion.

                         Experiment 2.

   On the 15th September, injected into the jugular of a body, ex-
tremely  emaciated, which had  been  dead  nineteen  hours,  nine
ounces of a stronger solution of the  triple-prussiate;2 and made the
post mortem examination two  hours after.   The circumstances of
the case were favourable; there was  no serious disease of the lungs,
none of the heart;  the age of the deceased was  37; the principal
lesions  were softening of the brain, especially of the fornix, and
dropsical effusion into the cavity of the abdomen.
   In the pericardium about an ounce of fluid was found: tested by

   1 Serum prevents the change of colour—the instant coagulation is pro-
 duced by nitric acid, the colour appears.
   1 6 grs. of the salt were dissolved in 12 ounces of water. 
                 FLUID  IN THE PERICARDIUM.              133

the salt of iron  and nitric acid, it indicated the presence of a very
minute quantity of the  triple-prussiate; it acquired a  very light
greenish  hue.
  There were about three ounces of a similar fluid  in the  right
pleura, and the effect of the test on  it was similar: the greenish hue
imparted was perhaps a shade lighter.  There was very little cruor,
crassamentum, or fibrinous concretion in any of the cavities of the
heart, and no appearance of any of the solution.  A similunar valve of
the pulmonary  artery  tested  was strongly coloured bluish-green ;
the substance of the lungs exhibited on trial the same hue in a less
degree, and it appeared even  faintly in the frothy  fluid contained
in the bronchia.
  May not these results be considered a  confirmation of the  preced-
ing, so far at  least as regards  the wide spread of the solution—and
there  being no proof of any accumulation of it in the pericardium.
It may be said, that accumulation  in the pericardium could hardly
be expected, as  the greater part of  it seems to have  passed into the
lungs.  But is it not probable, that when serum separates from the
blood in  the heart after death, it will pass out through that channel,
chiefly, if there is any undue pressure, and that the exudation into
the pericardium will be trifling, and even less than  from the pericar-
dium into the pleura?


                        Experiment 3.

   On  the 18th  September, twelve  hours after death from compli-
cated organic disease of the lungs, introduced about four ounces of
a weak solution of the triple-prussiate into the left pleura, through
an opening made by removing a portion of the false ribs;  the de-
ceased was 26 years of age.   The  usual inspection was made three
hours and a half after.   The pericardium was carefully laid open;
it contained about half an ounce  of fluid, and by the  test before
mentioned, it was proved, that a very lit tie of the solution had pene-
trated into the  pericardium and was  mixed with it; it  acquired a
distinct greenish  hue.   There was a very little fluid in the right
pleura; and this on trial  afforded proof, by the change of colour, of
the saline solution having reached so far.


                         Experiment 4.

   On  the 19th  of September,  an  hour and a half after death,  the
consequence of articular suppuration, after an accident, (the deceased
was 45 years of age,) opened carefully into the pericardium, avoid-
ing the pleurae; and introduced about four ounces  of the solution.
The opening was closed by suture of the integuments.   The post
mortem  examination was made 21 hours after.  The left lung con-
tiguous to the  pericardium was moist;  a few drops only could be
collected from its surface.  This  minute quantity, on the addition 
134
DAVY'S RESEARCHES.
of a drop of the ferruginous  solution,  became  dark-green, and on
the addition of a drop of nitric acid, dark blue.  The blood in the
heart was too thick to admit of being tested.
   All these results incontestibly prove a permeability of the mem-
branes after death, admitting  of the exudation of fluids.   They also
seem to show that the amount of exudation is  inconsiderable;  and
to render it highly improbable, that  in the instance of the pericar-
dium, pleura?,"or  ventricles of the  brain, or indeed in the  instance
of any closed cavity of the body, accumulation (the consequence of
exudation,) should take place.
   Other facts might be brought forward in support and illustration
of the  preceding views.   I shall  very briefly  mention  a small
number.
   1. There is no  relation between the quantity of blood in the cavi-
ties of the heart and the quantity of fluid found in the pericardium.
Of this fact, I have satisfied myself by  very many observations,
taking into account the time  elapsing between death and  the ex-
amination of the body.   Occasionally, the one is large and the other
small, and  vice versa.
   2. There is no relation, as  far as my experience extends,  between
the quality of the fluid in the pericardium, and the serum of the
blood.  I have mentioned an instance in  which one was  colourless,
and the other bright yellow.   I  have witnessed many instances in
which the  serum of the blood in the  heart and great vessels was
coloured red, some of the colouring matter  of the red particles
having been dissolved by it, and in which the same colour was
exhibited  in the inner lining membrane  of  the heart  and great
vessels, the effect of staining, without the liquor pericardii being
tinged.
   3.  Coagulable lymph is very rarely found in the liquor pericardii.
But,  were the fluid a post  mortem exudation, it might be expected,
that  coagulable lymph  would be  very frequently observed in it,
inasmuch as in the majority of instances the blood is slow in coagu-
lating;  a portion  of it is commonly found liquid  in the  heart very
many hours after death, and  which coagulates on exposure.
   4.  The gall-bladder distended with bile, the urinary-bladder with
urine, in fatal cases of apoplexy or palsy, the synovial membranes
with synovia, part with their contents with  extreme slowness.   In
no instance  have I ever  met with synovia in the cellular tissue
adjoining the capsule of a joint abounding in synovia.   I am not
aware of urine having ever  been found  in appreciable quantity in
the cavity of the pelvis  after death with distention of bladder.1 How

  1 On the 11th of October, 16 ounces of a weak solution of triple-prussiate
of potash (strong enough, however, to become dark-blue when  mixed with
a salt of iron) were injected into the  urinary-bladder of a young  man two
hours after death from pulmonary consumption.  The post mortem examina-
tion was made 24 hours after; the cavity of the abdomen was  first opened
into and carefully examined; the  only fluid found was in the  pelvis, between
the bladder and the rectum, not quite half an ounce,  and, tested by iron no 
FLUID IN THE PERICARDIUM.
135
small is the exudation from the gallbladder, and how slow in taking
place.   Were it not for its colouring quality, the exudation would
not be appreciable.
  If these views be correct,  the  question of permeability of mem-
branes and  exudation of fluids  in  consequence, need  not greatly
embarrass the pathological inquirer.  1 apprehend, that if no colour-
ing matter of the blood is found  mixed  with a fluid  in  a closed
serous cavity, it may fairly be inferred, that it was secreted during
life; that if the colouring matter of the blood be found intermixed.
especially in solution,  the inference must  be drawn that an exuda-
tion has taken place,  the  amount of which  may perhaps  be  mea-
sured with tolerable accuracy by the quantity of colouring matter.
  The solution in  the serum of the blood of the colouring matter
belonging to the red particles  is  connected with putrid decom-
position, and is one of the first indications of it.  The permeability
of membranes, if not  another effect of the  same change, is, 1 am
satisfied, greatly increased  by it.   This is very manifest from  the
inspection of bodies at  different intervals after death, and at different
seasons of the year: I believe it may be laid down as a rule that the
circumstances favourable to putrefaction, are equally  so, to permea-
bility and exudation.1
   Professor  Burdach,  when treating on what he considers "secre-
tion after death," adduces the results of the experiments of Segalas,
who, in the examination of animals, found, that if it was delayed to
twenty or thirty hours after the death of the animals,  the blood was
thicker in the right side of the  heart, and  diminished in  quantity
by the delay, and that sanguinolent serum  had  collected in  the
serous cavities, especially in  the pleura.2
   These results, it appears to me, may be considered analogous to
those described in  the first experiment which I have related.  As
in that experiment the greater part of the fluid seems to have passed
info the lungs through the natural channel of the pulmonary artery
 —so in those of Segalas, the cruor might  have had issue in  the
same way, and if putrefaction had commenced, as seems indicated

trace of the prussiate could  be detected in it; it appeared to be a weak serous
fluid—it was rendered turbid by nitric acid.
   1 The difference of effect is well shown in the instance of the urinary blad-
der.  On the 27lh of September, when  th-' weather was  cool, water, urine,
and cruor of blood, were lespectively put into  sheep's bladders, quite fresh,
and suspended in jars, covered from the air.  For three hours not a drop of
either fluid had passed through ;  after twenty-four hours, a small quantity of
each was found in the receivers, and the serum was coloured red, and even
contained red particles. Through a bladder, allowed to become putrid, water
passes as through  coarse filtering paper.  The same  effect of putridity, in
increasing permeability, is strongly marked in the leather made in warm and
in cold climates.   In the former, where it is difficult to arrest the putrefac-
tive process, the leather  is in a high degree porous, well adapted for use in a
high temperature; in the latter, not having suffered from putrefaction, it is
dense and almost impervious.   It is equally well fitted for  use, as a protec-
tion from cold and moisture.
   2 Op. cil. vol. viii. p. 509. 
136
davy's researches.
by the coloured serum, an  exudation might have taken place into
the serous cavities, and especially from the lungs into the pleurae.
                             VIII.

ON THE SPECIFIC GRAVITY OF  DIFFERENT  PARTS  OF
                     THE HUMAN BODY.

  On this subject I was induced to make a set of experiments in
1827, from the belief, that on account of its elementary bearings
and probable applications,  it was deserving of more  extended in-
vestigation than it had then received.
  Most of the experiments  were  made  in  our  military hospitals at
Corfu, where advantage  for carrying on the inquiry  was taken of
the post 'mortem examination of  the bodies of deceased soldiers of
our regiments, who  died tinder medical treatment, and  whose cases,
according to the usage of the service, were recorded.
  The parts  submitted to  trial were weighed  almost  immediately
after they were taken from the body, in every instance in less than
six hours, and generally  within two.  When dissection was neces-
sary, they were carefully dissected out; they were freed as much as
possible from contiguous and adhering textures, and  especially from
fat; and without  being previously washed, they were deprived of
superfluous adhering fluid, by being gently pressed between folds
of blotting paper.
  For the sake of brevity I  shall  give the results in a tabular form:
in expressing.them, distilled water,  the  usual standard of compari-
son, is considered as 1000.   The Roman  numerals in the second
column, indicate the bodies to which the parts  subjected to experi-
ment belonged.
Table of specific gravities of different parts of the human body.
No.	Subject.	Part tried.	Ursult.
1	xi.	Nail of thumb, dissected off entire .	1197
2	n.		1190
3	—	Ditto with adhering cutis.....	1180
4'	XI.	Skin of back of thumb, free from fat, with cuticle undetached	1100
5	in.	Skin of chest, over the pectoral muscle .	1108
6	—	Ditto with a thin layer of adhering fat .	1050
7	IV.	Skin of epigastric portion of abdomen	1103
8	—	A front tooth of a young man, not decayed, extracted be-	
		cause loose, owing to disease of the gum	2-240
9	—	Root of the same, the air which was in its cavity expelled	1950
10	—		2380
 
specific gravity, &c«
137
Table of Specific Gravities—continued.
No.	Subject.	I'art tried.	Result.
11	iv.	First molar tooth of a man, about forty years old, extracted	
		on account of pain, connected with a slight caries	2142
12	—		2113
13	—	The whole of the upper part of the same above the gum .	2313
14	—	The top of the crown of the same, consisting chiefly of	
			2620
15	—	A molar tooth not complete, the roots not formed, from the skull of a young woman of Ipsara, which had been ex-	
		posed about two years to the opon air .	2500
16	—	A portion of parietal bone from the same skull	1944
17	ix.	A portion of pars petrosa of temporal bone	1852
18	iv.	Parietal bone freed from pericranium ....	1772
19	—	Eighth rib freed from periosteum.....	1383
20	iv.	Fat from beneath the integuments of abdomen'	0942
21	—		1090
22	v.	Tunica albuginea testis .......	1088
23	xii.	Sclerotic coat of eye.......	1091
24	—		1076
25	—		1100
26	v.	Ligamentous sheath of corpora cavernosa penis	1097
27	ix.	Aponeurosis covering vastus externns muscle	1080
28	vi.	Anterior portion of last lumbar intervertebral substance .	1092
29	xii.	Anterior and outer portion of intervertebral substance, from	
		the lumbar part of spine ......	1104
30	—	Upper portion of the same, containing some of the articu-	
			1110
31	—	The portion beneath, free from articulating cartilage	1098
32	—	Central parts of the same, soft and pulpy	1062
33	x.		1080
34	vi.	Ligament of patella .......	1104
35	—	Cartilage of knee-joint .......	1073
36	iii.		1054
37	v.	Cellular part of corpora cavernosa penis . . .	1086
38	iv.		1086
39	vi.		1080
40	—	Upper part of femoral artery ......	1071
41	—	Middle part of the same......	1061
42	—	Upper part of the internal iliac artery . .	1060
43	vii.	Half of a portion of aorta, just below its arch, divided Ion-	
			1086
41	—	Other half of the same, its outer fibrous coat detached	1077
45	—	Lower part of aorta, just before its termination	1074
46	vii.	Internal iliac artery.......	1068
47	v.	Abdominal vena cava.......	1061
48	xiii.	Vena cava, close to the emulgent vein ....	1061
49	—		1061
50	—	U pper part of femoral vein ......	1066
51	_	Contiguous vena saphena major .	1071
52	vi.	Two of the largest nerves of the femoral fasciculus in the	
			1111
  1 Its specific gravity was ascertained, indirectly, by means of that of a mix-
ture of alcohol and water, in which, when submersed, it remained stationary. 
davy's researches.
Table of Specific Gravities—continued.
No.	Subject.	Part tried.			Result.
55	iii.	A portion of cerebrum (medullary and cortical substance			
		intermixed) ....«•			1040
54	—	A portion of cerebellum.....			1043
55	iv.	Pons varolii.......			1033
56	—	Medulla oblongata.....			1037
57	i.	Upper part of spinal cord ....			1035
58	v.	Substance of testicle .			1041
59	iii.	Substance of liver .....			1053
60	iv.	Ditto........			1035
61	i.	Ditto.......			1069
62	v.	Ditto (Lobulus Spigelii)			1066
63	vi.	Ditto.......			1050
64	vii.	Ditto (Lobulus Spigelii)			1059
65	viii.	Ditto.......			1042
66	ix.	Ditto.......			1045
67	iii.	Substance of spleen ....			1044
68	iv.	Ditto.......			1064
69	v.	Ditto.......			1070
70	vi.	Ditto.......			1048
71	vii.	Ditto.......			1058
72	viii.	Ditto.......			1061
73	ix.	Ditto.......			1060
74	iii.	Substance of pancreas ....			1047
75	v.	Substance of kidney ....			1050
76	vi.	Ditto.......			1050
77	viii.	Supra-renal gland .....			1048
78	viii.	Thyroid gland.....			1060
79	v.	Concretion of fibrin from ventricle of heart			1057
80	xiv.	Substance of lung.....			1054
81	iii.	Hepatised lung.....			1043
82	vi.	Enlarged lymphatic gland, contiguous to the h abdominal aorta .....	>wer ]	)art of	1046
83	iv.	Muscular substance of left ventricle of heart			1049
84	—	Great pectoral muscle ....			1058
85	vii.	Sartorius muscle.....			1056
86	xi.	Lower part of oesophagus			1040
87	—	Cardiac portion of stomach			1048
88	—	Pyloric portion.....			1052
89	—	Upper part of duodenum			1047
90	—	Upper part of jejunum ....			1042
91	—	Lower part of ileum ....			1041
92	iv.	Middle part of ileum ....			1044
93	xi.	Sigmoid flexure of colon .			1042
94	—	Hair.......			1280
95	—	Ditto.......			1293
96	—	Ditto.......			1278
97	—	Ditto.......			1290
98	—	Ditto.......			1275
99	—	Ditto.......			1345
100	—	Ditto.......			1323
101	—	Ditto . . . . .			1300
 
specific gravity, Sec.
139
  The fatal cases to which the Roman numerals refer were the fol-
lowing.
  i.—Aged twenty-seven years ; was admitted into hospital on 29th
August; and died 11th September of peritonitis which followed per-
foration of the ileum,  the effect of chronic ulceration.  The liver
and upper part of the  spinal cord appeared to be quite sound. The
dissection  was commenced eight hours after death.
  ii.—Aged thirty-nine years; was admitted into hospital 29th Oc-
tober; died 31st October, of remittent fever, complicated with bron-
chitis.   Dissection eighteen hours after death.
  iii.—Aged twenty-eight  years;  was admitted into hospital 16th
July ; died 9th of September of pneumonia.  There was much fluid
in the ventricles, and between the membranes of the brain ; the sub-
stance of the brain appeared to be sound.  The lungs were variously
diseased; hepatised in part, in part dropsical, and tubercular.   The
liver exhibited  slightly  the nutmeg-like section.  The spleen was
not enlarged, but rather of a  brighter red and harder than natural.
Dissection seven hours after death.
  iv.—Aged thirty-four years; was  admitted into hospital  9th of
September;  died 10th  September, of (as it was supposed) remittent
fever.  Blood was found extravasated on  the surface  of the cere-
brum:  the  trachea  and bronchia were redder than natural; the
ossophagus was dark red.   The  liver was of the colour  nearly of
yellow wax; the spleen firmer than  natural.  Dissection sixteen
hours after death.
  v.—Aged twenty-six years; was admitted into hospital 20th Sep-
tember ; died 27th September, of (as it was supposed) remittent fever.
The trachea and bronchia were very red ;  the oesophagus was
highly inflamed.  The bile in the gall-bladder was black and offen-
sive to the smell; the gall-bladder itself was in a state of incipient
gangrene.   The common gall-duct  was  pervious; the liver  and
spleen  were apparently sound.   Dissection  nineteen hours after
death.
  vi.—Aged twenty-two years; was  in hospital 116 days; died 2d
October, of chronic dysentery, complicated with tubercular phthisis,
—that is. with tubercles, and vomica? or cavities in the lungs. The
liver was very voluminous, and rather paler and firmer  than natu-
ral.  The spleen was large and firm.   Dissection nine hours after
death.
  vii.—Aged twenty  years; was admitted into hospital 30th Sep-
tember; died 5th October, of remittent  fever.   No organ but the
spleen was particularly  diseased.  The spleen was of great bulk, of
very soft consistence,  like the stale  crassamentum  of blood ;  and
after three or four  hours'  exposure  to the air, it  became  putrid.
From some experiments which I made on it,  it appeared to contain
a large proportion of  coagulable lymph effused into it, and  a very
small proportion of the  red particles  of the blood.1   This state of
  1 It probably also contained pus as well as coagulable lymph ; in softened
spleens connected with other diseases, I  have  recently found distinct pus- 
140
uavy's researches.
 spleen, I may remark, almost always presents itself in the fatal cases
 of remittent fever in the Ionian Islands. The liver was voluminous,
 soft,  and of a brownish  grey colour.  Dissection  12 hours after
 death.
   viii.—Aged twenty-five years, was admitted into hospital 18th No-
 vember ; died 23d November, of (as it was supposed) remittent fever.
 The  lungs, bronchia, trachea, oesophagus, and colon, were more or
 iess inflamed;  the mucous coat of thecolon was in  places gangre-
 nous.  The liver was  rather softer than natural ; the spleen  was
 apparently sound.   Dissection twenty-four hours after death.
   ix.—Aged forty-one  years; was admitted into hospital 26th  No-
 vember; died 27th November, of inflammation of the bronchia  and
 trachea, supervening on latent, tubercular phthisis. The spleen  was
 of natural appearance; the liver exhibited the nutmeg-like section.
 Dissection eighteen  hours after death.
   x.—Aged  twenty-eight years; was admitted into hospital 29th
 September ; died  22d October, of chronic dysentery, after remittent
 fever.  Dissection nine hours after death.
   xi.—Aged thirty-nine years; was admitted into hospital 5th Sep-
 tember; died 13th November, of latent tubercular phthisis, and other
 organic disease, after an attack of remittent fever.  The oesophagus
 was redder than natural, and its epithelium in great part abraded.
 The  jejunum and ileum were rather redder than natural, and  the
 inferior part of the latter was slightly ulcerated.  The large intes-
 tines  generally, with the exception of the sigmoid  flexure  of  the
 colon, were severely  ulcerated.  The spleen was rather smaller and
 firmer than natural; the  liver presented the  nntmeg-like section.
 Dissection seven hours after death.
   xii.—Aged twenty-three  years;  was admitted into hospital 29th
 August; died 8th Dacember, of tubercular phthisis. The bodv was
 extremely emaciated; the lens was unusually soft, and  the'inter-
 vertebral substance perhaps softer than natural.  Dissection twenty-
 nine hours after death.
   xiii.—Aged twenty-seven years;  was admitted into hospital 11th
 December, died 21st  December,  of peritonitis,  the consequence of
 perforation of the ileum, the effect of ulceration.  Dissection  thirty-
 one hours after death.
   xiv.r-Aged twenty-nine years; admitted into hospital 18th Janu-
 ary ; died 7th February, of inflammation of both pleurae.   A collec-
 tion of  pus was found in the anterior mediastinum; about  three-
 fourths of a gallon of serum in the left pleura, and about one-fourth
 of a gallon in the right.   A good deal  of coagulable lymph was
effused  in each cavity, both loose  and adhering.'  The lungs were
very little diseased ; the inferior lobe of the leftlnng which afforded
the specimen, No. 80, the specific gravity of which has been  given.
 was compressed by the effused fluid in a very remarkable manner, and

 globules  on submitting  the pultaceous  matter diluted with water to  the mi-
croscope. 
SPECIFIC GRAVITY, ETC.
Ill
was entirely destitute of air.   Il bore no marks of inflammation or
of hepatisation; and in sulphurous acid, it expanded like the sub-
stance of the corpus  cavcrnosum penis.1
  To these brief notices of fatal cases, it may not be amiss to add
some particulars relative to the different specimens of hair of which
ihe specific gravities are given.   The first three specimens of hair
belonged to English  women  of  the same family,  between the ages
of thirty and  forty  years ;  two were light  brown ; one was  dark
brown ;  all three were fine.   The  hair,  No. 96, belonged to a wo-
man  of  Corfu, aged sixty-six years;  it was gray, and very fine.
No.  97 belonged to a man of the same island, aged seventy-seven
years; it was white and very fine and soft.   No. 98 belonged to an
fpsariot; it was bleached, and probably, in consequence of the de-
struction of its oleaginous  part, its specific  gravity was so high.8
The hair,  No. 99,  belonged to a Hottentot woman, a native of Cape
Town, about twenty'years old;  it was black,  coarse, woolly, and al-
most felted together, admirably adapted  for  protection  against the
sun  ; but it had not been exposed to its action.3   No. 100 belonged
to a young woman  of Pitcairn's Island, in  the  Pacific Ocean, a
daughter of Adam, one of the mutineers  of the Bounty; it was red-
dish brown, partially discoloured by the  action of the  sun's  rays ;
rather coarse, but not in the  slightest degree  woolly.
  On the results generally I shall offer a  few remarks : first, relative
  1 Even when immersed in distilled water deprived of air, and placed under
the  exhausted receiver of the air-pump, it gave off only a few adhering air-
bubbles.  It would  be difficult to explain this by the mere  pressure of the
effi  sed fluid.  Such  a complete absence of air was probably owing to pressure
and absorption acting together; and, in confirmation of this opinion, I may
mention, that  1 have found only a very small quantity of air in the lungs of
animals which have been killed by  strangulation, by the  ligature of the
trachea.
  "This hair was taken from the body of an Ipsariot, which  when I visited
Ipsara, in the  winter of 1826,  was lying exposed with many others, in the
battery, called Fatehio, where they had Allien, making a brave but vain de-
fence against an  overwhelming Turkish force,  by whom, in the short space
of a few hours, this  before flourishing island was made a desert, in the most
literal sense.  Though rather  more than two years had elapsed since the
massacre, when I saw them, the bodies were little changed ;  indeed, the fea-
tures were so distinct, though black and shrunk, that ourguide, (the only living
inhabitant in an  island which before  had  an active population,  exceeding
15,000) recognised each person and called him  by name;  even their clothes
(they  had not  been stripped) had experienced little change.
  The situation of  the place where they fell was dry, and its aspect north-
erly.  In the castle  of Ipsara, on the contrary, which had a southerly aspect,
nothing but whitened bones remained of the numerous victims  of  despair,
who blew themselves up by exploding the magazine, when the  place was
taken.  These facts  strongly exemplify the difference of character of the very
dry  Etesian, or northerly  wind of the  Mediterranean, and of the very humid
Sirocco, or southerly, and especially in the Archipelago.
  3 The effect of the sun's rays on the hair of the negro, is, I believe, analo-
gous to that on the European,  &c. but less powerful: I say, believe, because
I am not quite certain of it.
       10—f                                       10 dav 
142
davy's ueseakuhm.
to the degree of accuracy which may be claimed  for  them; and
secondly in relation to practical use and application.
   As regards accuracy, the results generally can with propriety  be
considered as approximations only to the truth.   The principal
sources of error were two—moisture and air, foreign to  the compo-
sition of the part, both of which  it is difficult  to remove with that
precision which is necessary to  insure  perfect correctness.  The
effect of adhering fluid, however, in slight  excess or deficiency
may, I believe, be held to  be of  little  account in  comparison with
the other cause, the air, the difference of weight of which, compared
with that of solids and liquids, is so enormously great. This source
of error exists in different instances in  very different degrees, proba-
bly very nearly  in  direct proportion to the vascularity of the part
tried, and the size of its vessels, and also to its dryness.  This may
be deduced from the experiments already related  on the action  of
the air-pump on animal  textures. Strictly, in experiments on the
specific gravities of bodies, all adhering  air, whether superficially
attachedor contained in the internal structure, should  be removed
by exhaustion.  Whilst  I express regret that circumstances did not
permit my using this precaution as I could have wished,  I shall give
a  number  of examples in  which I have since employed it, from
which some  judgment may be formed of the amount of error at-
tributable to  the presence of air.
   The first instance I shall offer is that of the parietal bone of a
man of middle age, a case of amentia, which  proved fatal in conse-
quence of pulmonary consumption.
   Before being subjected to the  air-pump,  its specific gravity ap-
peared to be  1790 to distilled water as 1000 ;  after exhaustion, 1970.'
The quantity of air disengaged was  very great; and it  required
long-continued pumping to remove it, indeed, after  working the
pump for more than an hour almost interruptedly, a  few particles con-
tinued to be disengaged.
   A portion of the same bone was calcined.   The fixed part, inde-
structible in the fire, consisting chiefly of phosphate of lime, weighed
before  being subjected to the air-pump, appeared  to be  of specific
gravity 2580, and after of specific gravity, 3070.2
   Another portion  of the  same  bone  was kept immersed in dilute
muriatic acid, until all  the calcareous matter was  dissolved; the
residual cartilage was well washed and  afterwards  gently pressed
between folds of linen to remove all  moisture that  could then  be
separated :  thus treated,  before being subjected to  the air-pump, its
specific gravity appeared to be  1070, and after exhaustion, 1119.
  'The bone was dry, prepared for the museum ;  but it contained some hy-
grometric water.  Exposed  to  a temperature of about boiling water for three
hours, it lost 9.61 per  cent, water; making allowance for which, its specific
gravity would  be, instead of 1970, 2200.  This example may serve to illus-
trate the influence of moisture  in ascertaining the specific gravities of animal
structures.
  * The specific gravity of mineral phosphate of lime—apatite, is from 3100
to 3200. 
SPECIFIC GRAVITY, ETC.
143
  The instances of bone in its dry state, and of its calcareous resi-
due after the action of fire, may be  considered perhaps as extreme
ones,—in  relation  to  the  source of error in question,  the hollow
texture of both being peculiarly  well fitted to retain air.   The next
examples  I shall  bring forward, may  he considered, perhaps,  as
rather average ones—namely, the ligamentum nuchas of the ox, and
the middle coat of the arch of the aorta of the ox.  The former, be-
fore being subjected to the air pump, appeared to be of sp.  grav.
1130, and after being so subjected, of sp. grav. 1134;—the latter, in
the first instance, of sp. grav. 1073, and in  the second of sp.  grav.
1077.
  The substance of the brain may be mentioned as an example  of
a part not subject to the source of error under consideration, for  in
vacuo, as has been already stated., no air is disengaged from it; that
is, if immersed in water, the instant  a portion of it has been cut out
a few hours after death,—before the putrefactive  process has com-
menced.
  Relative  to  the practical  use and application of the results, I
venture to indulge in the hope that the physiologist will  receive
them as a contribution to  his science, considered as a collection  of
facts and of rules deduced from facts; and also that the pathologist
may derive from them a help to  the eye, and a  more certain crite-
rion of organic change than we  yet  possess  in  this  important but
obscure branch of  medical knowledge;  but for this latter purpose
the investigation will require to be prosecuted further.  The quality
of specific gravity will, probably, be most  applicable, as a charac-
teristic to the viscera,—especially the liver and the spleen ; and, per-
haps, the  brain, lungs, and  kidneys.   The results given of the
experiments on the two first mentioned viscera are favourable  to
this conjecture.  These results are very various, and almost demon-
strative that organic disease of the viscera cannot take place without
altering their specific gravity; and,  if so, it is not improbable that
this precise quality may be made an index of the kind and degree of
organic change.   And, a  priori, perhaps, thus much  might be in-
ferred ;  for if fatty matter  is deposited, the specific gravity must  be
diminished; if cartilaginous  matter, it  is probable it will be in-
creased  ; probably it will be variously diminished or increased ac-
cording to the  kind of deposition.   Moreover,  attention  to  these
changes may lead  to more minute observation, and to the collecting
of information curious and useft: .   Every new means of research
is  in this  way indirectly beneficial.   Whoever  employs the stetho-
scope, though he  may not appreciate  its merits in the same  high
degree as  the ingenious inventor of the instrument did, yet he  can-
not fail  to derive instruction from its use, and to become better, more
minutely, more discriminately acquainted with the diseases of the
chest.   The same  remark applies to Avenbrugger's method of di-
agnosis by percussion, and indeed to every other method of investi-
gation,  which directs  and fixes the attention,—drawing it  away 
144
DAVY'S RESEARCHES.
from vague and unmeaning generalities, the bane of knowledge, to
precise and significant particulars,—which are its essence,—and
which are equally important, whether we have in view, during life,
the symptoms of  disease by the bed-side of the  patient;  or,  after
death, on the dissecting table, the organic changes, the effects of dis-
eased action.
  The greater portion of the preceding observations, first appeared
in print in the 3d volume of the Edinburgh  Medico-Chirurgical
Transactions  for 1828.   Recently, on  consulting  Professor  Bur-
dach's Treatise on Physiology, 1 find that the  subject under con-
sideration has, since that time, been investigated by MM. Schubler
and Kapff, who published a work on if, in f832.  Comparing their
table of specific gravities of the different textures of the human body,
contained in the 8th volume of the treatise on physiology already
referred to,—with mine,—some of the results are found  to agree,
others to disagree, as perhaps might be expected, partly from real
differences of specific gravity in  the  same textures in  different
bodies, which  is strongly exemplified in my list, and partly from the
methods of operating and  the interference of  minute and obscure
causes of  disagreement and error, not easily detected, independent
of the two main ones already  pointed out.  The  most striking dif-
ference between their results and mine, presents itself in the instance
of the lungs:  and  I  select it the rather for comment, as it affords
illustration of one of the causes of difference.   According  to  MM.
Schubler and  Kapff, the specific gravity of the substance of the lung
is 645-to water as 1000 ;J  according to the result obtained by me,
1054.  I have stated that  the specimen which  I subjected to exper-
iment was destitute of air:  their specimen, of course, contained air:
and it follows that as the air in the lung is in variable quantity,  its
specific gravity also, unless air be excluded, must be variable  also.
                              IX.

ON THE  EFFECTS  OF DESICCATION. AND THE  PROPOR-
  TION OF WATER CONTAINED IN  THE DIFFERENT TEX-
  TURES OF THE  HUMAN BODY.

  This subject, like that of the specific gravity of the different tex-
tures, may be considered  also as elementary and fundamental;  for
unless it is known with tolerable accuracy what is the quantity of
dry solid matter, each part is capable  of affording, or may be said
to contain, other statical  results will of necessity be  vague and  of
little value.
1 Traite de Physiologie, torn, viii, p. 6. 
EFFECTS OF DESICCATION.
145
  It was  in  Malta, in the summer of 1828, that I commenced the
inquiry, desirous of conducting it on a more extended plan than I
believe had  been previously attempted,  by any one individual; so
that, one  method being employed,  and  the circumstances being
similar, the results might be compared with confidence, and discre-
pancies avoided.
  The method of desiccation which I employed was simply that of
the vapour-bath.  The parts were either placed on paper when not
likely to adhere, in a  Wedgewood evaporating dish, over steam; or
suspended over it  almost touching the bottom, by a fine thread,
when of an adhesive  kind; or, when very soft, they were placed in
it, in platina capsules previously weighed.  They were kept on the
bath till all the  water capable of being expelled by a temperature of
212,° was driven off, which was indicated by their ceasing to  lose
weigfit from further exposure.
   The results,  first published  in  the 4th volume  of the Transac-
tions of the Medico-Chirurgical Society of Edinburgh, are contained
in the following table, constructed  on the  same plan as the  pre-
ceding, in which the Roman  numerals  are designed  for similar
reference.
Table showing the proportion  of dry solid matter  in  different
                  parts of the human body.
			Result
No.	Subject. i.	Part tried.	per ct.
1		Cuticle of sole of foot ......	51.5
2	iii.	Projecting part of the nail of thumb, rather curved as	
			83.3
3	—	Inner part, soft, diaphonous, carefully freed from adher-	
		ing subjacent layer ......	76.6
4	—	Bosjesman's hair.......	91.6
5	—	Hottentot woman's hair ......	92.0
6	—	Kaffer boy's hair .......	92.3
7	—	Young woman's hair of Pitcairn Island	91.3
8	—	Light coloured hair of an Englishwoman	90.7
9	—	Dark coloured ditto.......	90.7
10	ii.	Skin over belly of deltoid muscle .	32.4
11	iv.	Ditto over lower part of scapula ....	35.3
12	v.	Ditto from middle of back .	42.3
13	vi.	Ditto Ditto .......	39.5
14	vii.	Ditto over first joint of thumb.....	39.0
15	—	Ditto of fore-arm just below its bend	32.8
16	—		37 4
17	—		30 2
18	vi.	Cornea .......	27.3
19	—		
20	i.	Fatty matter from beneath integuments of the abdomen	83.9
21	—	Pectoral is major muscle . • . . ■ .	15.6
22	iii.	Muscular substance of left ventricle of heart	20.5
23	—	Pectoralis major muscle.....	24.0
24	v.	Gluteus maximus muscle......	25.8
25	—	Columna carnea from left ventricle ....	21.2
26	iii.	Cerebrum (centrum ovale). .....	I 33.9
27	—		! 20 8
 
116
davy's researches.
*
Table of Specific Gravitif.s—continued.
No.
"28"
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64

 65
 66
 67
 68
 69
 70
 71

 72
 73
 74
 75
 76
 77
 78
 79
 SO
 81
 82
Subject.
  iii.
  v.
  i.
  iii.
  v.
ix.

x.

i.
v.
vii.
vi.
i.
iii.
v.
viii.
i.
iii.
i.
iii.
i.
iii.
iv.
vin.
iii.
i.

i.
iii.
vi.
ii.
iii.
v.
iv.

v.
ii.
iii.
i.
m.
viii.
                      Part tried.
Medulla oblongata
Sciatic nerve     ....
Aorta (inferior abdominal portion)
Diito at its origin
Ditto at its origin
Femoral artery just below the arleria profunda
Ditto            Ditto
Aorta just below its a^ch
Ditto just below the cceliac
Ditto (its  termination)
Common  iliac artery
Basilar artery
Arteria sylvana
Basilar artery
Arteria sylvana
Ascending vena cava.
Femoral vein contiguous to arteria profunda
Ditto a little lower.....
Vena cava ascendens (its commencement)
Superficial vein at the bend of the fore-arm
Thoracic  duct
Substance of liver
Ditto
Ditto (Lobulus Spigelii)
Ditto
Substance of spleen
Ditto
Substance of kidney
Ditto
Substance of lung
Substance of pancreas
Substance of testicle
Great arch of stomach
Upper part of jejunum
Ditto
Dura mater
Pericardium (outer  layer  and a little fatty
  der it detached)
Perichondrium of cartilage of false rib
Ditto
Pleura costalis
Corpus cavernosum penis
Extensor tendon of great toe
Tendo Achillis
Intervertebral substance from last lumbar int
  space, cut out in the form of a wedge
Cartilage of knee-joint
Cartilage of false rib  ....
Ditto.......
Superior part of sternum (spongy portion)
Ditto         (outer table)
Shaft of tibia (outer layer)
Ditto         (inner layer)
Fibrinous concretion from right side of heart
Ditto from left auricle      .
Venous blood, of specific gravity 1061
Serum of blood, of ditto   ditto  1030
matter un-
rtebral 
EFFECTS OF DESICCATION.
147
   The parts submitted to experiment were taken from the following
 subjects.
   i.—Aged twenty-nine  years;  admitted  into hospital  20th May;
 died 2d June, of inflammation of the mucous coat of the ileum and
 colon,  ending in  gangrene.  Dissection  seven  hours and  a  half
 after death ; body  slightly emaciated.
   ii-—Aged thirty years; admitted into  hospital 23d May; died
 30th  May of tetanus, following a fracture of the inferior extremity
 of the radius, and of two transverse processes of the lumbar verte-
 brae.   Dissection  sixteen hours after death;  body very muscular
 and fat.
   iii.—Aged thirty-six years: admitted into hospital 3d May: died
 5th  June,  suddenly, with  tubercular phthisis.   Dissection three
 hours after  death ; body  considerably emaciated.
   iv.—Aged twenty-two years; admitted into hospital 27th April;
 died 9th June, of tubercular phthisis, very far advanced and com-
 plicated.  Dissection seven hours after death; body extremely ema-
 ciated.
   v.—Aged twenty-three years;  admitted into hospital 20ih May;
 died 13th June, from fraclure of the cranium and the  cervical ver-
 tebrae, with effusion of blood on  the brain, and  softening of the
 spinal chord.  Dissection twelve hours after death; body not ema-
 ciated.
   vi.—Aged twenty-two years;  admitted into  hospital 1st July;
 died 4th July, suddenly,  as if from syncope, whilst labouring under
 a frebrile attack, connected with ulceration of the mucous mem-
 brane of the ileum,  and enlargement  and softening of the mesen-
 teric  glands.  Dissection eleven hours after death; body not ema-
 ciated.
   vii.—Aged thirty-two years; admitted into hospital 5th July;
 died 13th July, with febrile symptoms, connected  with  a vast latent
 abscess in  the liver.   Dissection sixteen  hours after death; body
 not emaciated.
   viii.—Aged thirty-three  years;  admitted into  hospital 3d July;
 died 16th July, of acute dysentery,  terminating in gangrene of the
 mucous coat of the  large intestines, with perforation of the colon.
 Dissection seventeen hours after death;  body slightly emaciated.
   ix.—Aged thirty-two years; very stout  and muscular; died sud-
 denly in barracks,  of pulmonary and cerebral ecchymosis.  Dissec-
 tion fourteen hours after  deatli.
   x.—Aged twenty-three years;  admitted into hospital 17th July;
died 30th July, of inflamed and ulcerated ileum.  Dissection twelve
 hours after death;  body considerably emaciated.

   With the exception of the parts taken  from  the body No. 1,
all the  others, the instant  they were  dissected out,  were  gently
 pressed  between  folds of blotting-paper,  to remove superfluous mois-
ture  or  adhering fluids:  and in  an hour,  or two at  farthest, were
placed to dry on  a  vapour-bath, as already mentioned.   In  the 
148
DAVY'S RESEARCHES.
exception above alluded to, the parts were kept together, covered
over, till the following morning,  and then they were washed with
water, and  subjected to pressure with  blotting-paper,  previous  to
drying.
  It may be right  to state, that all the bodies were of British sol-
diers, and that they all died in Malta; and, as will appear from the
dates,  during the hot season;  the thermometer during the whole
time fluctuated between 80° and 90°.
  Of the effects of desiccation on animal textures, remark is  hardly
required, as they are pretty generally known, and are such as might
be expected a priori. The briltleness which the operation imparts,
and its preventing putrefaction, are two of its best defined and most
general effects.   But these effects are  only temporary; as soon  as
humidity is restored, flexibility is also  restored,  and the tendency
to putrefaction and decomposition  returns,  and apparently unim-
paired by suspension.   This property of desiccation in  animal
matter, and in vegetables  also,  though it has been  long applied  to
economical  purposes, for the  preservation of articles  of food, has
not, perhaps, been  used so much as it  deserves; nor has the prin-
ciple,  I believe,  been applied  as generally as  it might  be, to the
solution  of  certain phenomena,  strictly chemical, which occur  in
nature and art.   Does it not serve to explain a fact which, on first
consideration, seems not a  little  extraordinary, that meat will  re-
main  fresh  for  many days in  Egypt,  if  hung up in the  open air,
and exposed to sunshine and wind,  in  the hottest weather;  whilst
it putrefies in a few hours if confined in a close  damp place?  Does
it not afford equally an explanation of the opposite effects  in the
Mediterranean, on dead animal matter, of the southeast or sirocco
wind, and of the  north and northeast winds, of which a remarkable
example has already been given, witnessed in Ipsara?  The  former
wind,  almost saturated with moisture, produces little or no evapora-
tion, or desiccating effect;  whilst  the latter, deficient in moisture,
and sometimes in an extraordinary degree deficient,  occasion rapid
evaporation, and powerfully desiccate; the one acting like confined
moist air of  high temperature, and greatly promoting putrefaction;
the  other operating like  the dry wind of the desert, though in a less
degree, and retarding the change.1  May it  not, too,  serve  to ac-
count  for so many remains of ancient  Egypt, especially of Upper
Egypt and of Nubia, being preserved to the present times, the natu-
ral dryness of the climate having been assisted by various processes
of art?  And is not proof afforded of the correctness of the explana-
tion, in this region being almost  the only one thus spared and cx-

  ' The cooling effect of the wind  is one of the simplest and  most  certain
means of knowing its proportional humidity.  The cooling effect on a ther-
mometer, the  bulb of which is wrapped in moist muslin, of the sirocco wind,
varies from 3° to 6°, and of the northerly winds in summer from 12° to 30°.
This is the result of my observations in the Ionion Islands and Malta, and
it is applicable, I believe,  to the winds named,  in ;he Mediterranean gene-
rally. 
EFFCTS OF DESICCATION.
149
einpted from the general doom of slow and certain change,  almost
amounting  to destruction, which is  manifest  in  other  countries,
where the elements have free play through the intervention of mois-
ture, even in the works of nature?
   Looking over the preceding table of results, it is curious to notice
what little relation there is between the solidity of a part, indicated
by firmness and resistance, and the quantity of solid matter which
it  yields on desiccation.  Who would suppose, a  priori, thai  the
soft flexible  skin contains  more of this solid matter than cartilage;
or that  the delicate serous membranes contain more than the firm
viscera; or  (and it is most remarkable) that the liquid  blood pos-
sesses a larger proportion  of it than some of the solids?
   The  proportional quantity of solid and  fluid  matter constituting
the animal  body, is a question to which considerable attention  has
been paid by physiologists; and it is a  problem still unsolved.   Ac-
cording to some, the proportion of the  former to the latter is as  one
to six;  and according to others, as one to nine.   The results of the
experiments on desiccation which I have given, including those on
blood and serum, may help  to furnish accurate  notions on the sub-
ject;—to show in  the first  place, how extremely  difficult  it is to
solve the problem rigorously, and how impossible it  is to solve it
generally; and, in  the  next  place, to show that,  in  the  adult at
least, the proportion of fluid or of water has been  overrated, inas-
much as in  the blood itself it does not exceed one fifth.
   As my experiments were commenced unconnected with any spe-
culative views, so I shall  endeavour to abstain as much  as possible
from such views,  as they  are very apt to lead astray, and in no in-
quiries  more than in physiological ones, and pervert the judgment,
and even the senses. Deductions  must be drawn from experiments
with great care and hesitation, and not from one or two, but from
many results.  The conclusions  which  may obviously be  made
from the preceding experiments,  it is unnecessary to  point  out in
detail; and  any others I would rather abstain  from drawing,  ex-
cepting  conjecturally,  and for the purpose of leading to further in-
quiry.   Thus, in the instance of the results of  the experiments on
the arteries  and veins, it may be asked, do  they  not  indicate
that the proportion of solid matter in the former decreases with  the
distance from the heart, excepting in the brain, where the  arteries
are very analogous to veins;—whilst,  in the latter,  would it not ap-
pear,  that it observes a contrary  ratio, and increases  with the  dis-
tance?  Should ulterior investigation  confirm  this, it will be an
interesting fact established in physiology. 
150
DAVY's RESEARCHES.
                              X.

  OX THE  ACTION  OF CORROSIVE SUBLIMATE  ON THE
            TEXTURES OF THE  HUMAN  BODY.

  The  power which  corrosive sublimate  possesses,  of preserving
animal  substances, has been known for many years, and has been
taken advantage of by anatomists, both in the  dissecting-room and
the museum,  to promote the objects of each,  as has been well de-
monstrated  by the  minute  and elaborate  labours of Mr. Swan on
the Nervous System. The property also which it has of precipitating
albumen from animal fluids  has been known for  a considerable
time,  and,  as a valuable, test  in analytical  chemistry, has  been
studied  with some care.  But  I  am not  acquainted with any re-
searches hitherto made to  investigate  its  action on  the textures of
the body generally.  Conceiving that  such inquiry was likely to
afford results  which might be interesting and useful, I applied my-
self to it in Malta, in 1828.  I shall describe such of  the experi-
ments which I then made as I believe are  to be depended on;  with
the hope that they  may lead to a renewal of an investigation which
unavoidable circumstances obliged me to leave  in a very unfinished
state.
  The two first I shall mention were of a  preliminary kind, to test
its power of arresting fermentation and  putrefaction.
  On the 15th August,  at a  temperature  between 80°  and 90°.  a
small quantity of aqueous solution of corrosive sublimate was added
to the expressed juice  of the grape in brisk fermentation.  The fer-
mentation was immediately arrested.   The mixture  was put by in
a bottle, loosely corked, not entirely excluding  the air.  Examined
on the 24th  February,  no  further change  appeared  to have  taken
place; the liquid was  clear, and  had the  peculiar smell  of  sweet
must, and the  sediment seemed unaltered.
  On the 10th of August,  a portion of  muscle  putrefying was put
into a solution of  corrosive sublimate.  The  putrid process was
arrested; the peculiar ofFensive odour ceased.   It was then washed
and suspended in water.  Examined on the 24th  February, it was
found unaltered—totally free from any  unpleasant smell.
  On the 15th of April, portions of different textures,  taken  from
the  body of a soldier that had died at  the age of 36, were immersed
in a saturated  aqueous solution of corrosive sublimate, after having
been gently  pressed between folds of filtering paper, and carefullv
weighed.  They were left undisturbed till "the  25th May,  when
they were taken out, examined, and  weighed:  they were then re-
placed.  On the 6th July, they were again  examined and weighed,
first, in  a moist  state,  after  being pressed  between filtering paper;
and afterwards dry, having been thoroughly dried on a vapour  bath! 
ACTION OF CORROSIVE SUBLIMATE.
151
The following table  exhibits the  results;  the column under 15th
April  gives the weight of the portions tried before immersion;  and
the two following, the weights of the same, after continued iminer-
sion.
						Dry
No.	Texture tried.	April	Mav	July	Dried.	matter
		15.	25-	6.		per ct.
		grs.-	grs.	gis.	grs.	grs.
1	Costal cartilage	17-8	1S-6	18-7	7-7	43-2
2	Intervertebral substance	19-6	19-6	19.2	5-4	27-5
3	Rib .	17-2	14-2	13-2	7-9	46-2
4	Upper part of spinal cord .	14	J4.4	13-5	5-3	37-8
5	Pectoralis major muscle	45	26	27	12-6	28
6	Liver :	23	20-4	19-4	8-4	36-5
7	Spleen ....	26	18-5	17	7	27
8	Dura mater	9-8	8-9	8	3-05	31
9	Pia mater	4-2	3.4	3-1	1-5	35-7
10	Lung	19-8	12-5	11-6	4-6	23-2
11	Cellular structure	2-9	2-4	2.4	1-3	44-8
12	Fatty matter	6-6	6-3	6-6	5-8	88
13	Kidney ....	40	30	24.3	6-9	17-2
14	Pancreas	25	15-2	14-7	6-1	24-4
15	Fibrinous concretion .	10-3	8	7-4	3-7	36
16	Vena cava .	14-2	11-5	10-6	3-9	27-4
17	Aorta ....	10-1	8-2	8-1	3-2	31-6
. 18	Corpus cavernosa penis	15-8	9	—	3-3	20-9
19	Cuticle of sole of foot .	6-4	16-6	—	4.3	67
20	Cutis vera .	11-9	10-5	—	4-3	36-1
  It is noted down at the time, that when the different parts above
mentioned were examined on the 25th of May, they were all com-
paratively pale, appeared to be condensed,  and  emitted  no unplea-
sant smell, and were perfectly distinguishable:  a little calomel had
formed on the sides of the glass  vessel in which the experiments
had  been made.   And, also, that  when examined on the 6th July,
they appeared  to be exactly in the same state.   The solution itself
seemed to be  but little  altered;  it contained only a very trifling
sediment.  Evaporated to dryness, it yielded a fawn-coloured resi-
due, which, strongly heated, first gave off fumes of corrosive subli-
mate; next,  whiter and denser fumes, as if of calomel;  and, lastly,
an  ammoniacal vapour:  a small quantity of carbonaceous  matter
remaining.
  On examining the  subjects of  the experiments, after they had
been dried, with a powerful lens, minute crystals of corrosive, subli-
mate were perceived  in  several of them, principally in those the
weight of which was  most increased.  To separate the loosely ad-
hering salt, they were immersed and  left in water, form the 8th to
the 15th July,  during which time the water was frequently changed.
They were then again weighed, after thorough drying on a vapuor
bath.  The  following table exhibits the results:— 
152                  DAVY5S RESEARCHES.
No.	Texture tried.	Dried.	Dried matter percent-40-45 26 43-8 34-3 25-1 34.3 24-6 29 34-5 21-2 45 68-2 15-5 23-2 30-6 24-6 29-7 20 56-2 34-4
* 1 2 3 4 5 6 ? 8 9 10 11 12 13 14 15 16 17 18 19 20	Costal cartilage -Intervertebral substance -Rib -Upper part of spinal cord -Pe^toralis major -Liver -Spleen -Dura Mater ... Pia Mater -Lung -Cellular structure - - -Fatty matter - - -Kidney -Pancreas - - - -Fibrinous concretion - - -Vena Cava -Aorta - - - - -Corpus cavernosum penis -Cuticle of sole of foot Cutis vera - - - -	7-2 5-1 7-5 4-8 11-3 7-9 6-4 2-85 1-45 4-2 13 4-5 6-2 5-8 3-1 3-5 3 3-1 3-6 4-1	
  It may be remarked, that none of the textures during this second
immersion in water, showed the slightest signs of putridity, or ten-
dency to decay; this indeed might have been expected, considering
the result of severer trials.   The  white parts generally, especially
the cutis, blood-vessels, and  membranes,  absorbed water, and be-
came  more  or less flexible, well adapted to display their form and
texture  in a class-room.  The portions of lung,  kidney, and liver
remained firm; the pancreas and muscle were  softened and  ren-
dered flexible in an intermediate degree.
  Comparing the results contained in the last table with those in a
former table, showing the effects of desiccation, it seems very doubt-
ful  if the corrosive sublimate combines with the textures generally,
or with any one texture entirely.  Probably it unites  only with a
part of  each, that part on which  putrefaction chiefly depends, and
which,  it may be conjectured, is essentially albuminous, and not
very different in  its  nature from the  albumen ovi,  for which the
chloride has a strong affinity.  The proportionally increased weight
of the fibrinous concretion, of the liver, and muscle, is in favour of
this conclusion.
  It may be asked, does corrosive sublimate combine directly  with
albumen—as from the manner of expressing my  opinion in the last
paragraph, seems to be taken for granted?  My belief is, that it does
so combine.  This was  the original  view of Dr. Bostock, as stated
in his  ingenious  paper on animal fluids,  published in Nicholson's
Journal for June, 1806,  in which it is also taken for granted,  as
most natural, and in  accordance  with  facts.  It  appears to me pre-
ferable to the later conclusion of M.  Orflla, that the compound pre-
cipitated from white of egg by corrosive sublimate, consists of calo- 
              ACTION OF COKKOSIVE SUBLIMATE.           153

niel and albumen;  and preferable also to the more recent conclusion
of Rose, that  it  is composod of albumen and  oxide  of mercury.
Orfila drew his inference  from the products of  the destructive dis-
tillation of the compound1—results ill adapted for forming an opinion
on the subject.   Moreover, at that time, viz. in 1814, the old hypo-
thesis respecting the compound nature of chlorine still  prevailed  in
Paris.   The data on  which Rose  reasoned I am  not acquainted
with;  I have not seen his original paper—merely a reference to  it
in the edition of Dr. Turner's Elements of Chemistry  for 1824.
   The facts which induce me to adhere to the early opinion of Dr.
Bostock, are chiefly these:—
   1. When corrosive sublimate and albumen ovi combine, there is
no disengagement or production of muriatic acid, as  might be ex-
pected—whether it contained calomel or oxide of mercury.   In one
experiment,  in which the whites of  two  eggs were mixed  with  a
drachm of corrosive sublimate, and after coagulation at a tempera-
ture of about  120°, washed with a small quantity of water, and
filtered, the water which  passed  through  the  filter  had no well
marked acid property, and did not occasion any effervescence when
mixed  with a solution of carbonate of potash.
   2dly, I have  not been  able to combine  calomel and  albumen.
When  I have triturated together the white of egg and  calomel, the
latter has become gray, almost black, as if from the formation of a
little protoxide of mercury from the action of the alkali  contained
in the white of egg: but the white of egg itself has undergone no
change.
   3dly, and lastly, The attempts I have made to combine albumen
and oxides of mercury directly, both the protoxide and peroxide
have been equally unsuccessful.
   The properties, too, of the compound appear to me  most favour-
able to the idea which I have advocated of its nature.  Its properties
are strongly marked, and are indicative of energetic union—being
tasteless, insoluble in water,  and not decomposable either by the
muriatic acid, or by an alkali, or by lime;  whilst  it  is soluble  in
an aqueous solution of the former, whether of  soda,  potash,  or of
ammonia, and also in a slight degree in the liquid albumen ovi.
   Dr. Bostock, from his experiments, concluded  that the compound
of albumen and corrosive sublimate contains from £ to £th iis weight
of the latter.  From various circumstances, it  is difficult to ascer-
tain the exact  proportions of the two, as he himself has pointed out.
The estimate can only be considered as an  approximation :  I men-
tion it chiefly in application to the preceding results.
   These results, practically considered, are not  without interest, as
confirming the general antiseptic power of corrosive sublimate—
preventing,  it would appear, putrefaction from taking place in every
instance in which  it was tried—arresting it when in progress, and
equally arresting vinous fermentation.

              1 Traite des Poisons, torn. i. part 1, p. 47. 
154
davy's researches.
  Mr.  Swan,  in his "Account of a  new method of making dried
Anatomical Preparations," published in 1820 —which I have only
recently seen—has shown  how usefully corrosive sublimate may
be employed in  the dissecting-room; in consequence  of its sreat
antiseptic  power for the purpose of carrying on minute dissections,
and for making dried preparations.  He employed it in solution in
spirit of wine,  (2 oz. of the chloride to  16 oz. of spirit of wine,) or
in water wilh the addition of muriate of ammonia (2  oz. of the chlo-
ride, 70 grains of the muriate, and a pint of water).  The latter is
recommended  by  its cheapness.  For the details of Mr. Swan's
method, 1 must  refer to his work on the subject, which is very de-
serving of the notice of the practical anatomist.
  Corrosive sublimate  in solution has  also been employed for pre-
serving moist preparations; but hitherto not successfully. In 1823,
I saw several preparations preserved by means  of if,  in the mustunj
of the  late Mr. Brooks, and in the collection of Mr. Carpue.   Mr.
Brooks informed  me, that after steeping for a  certain time the pre-
paration in an aqueous solution of the chloride, he transferred it to
proof-spirit, covering the jar in the usual manner. All the prepara-
tions which  he showed were more  or  less injured  by a white de-
posite encrusting them: and in some instances, the  insides of the
jars  were  so encrusted as to  have  become quite opaque,  hiding
completely the object Within. From some experiments which I then
made on two preparations  which had there suffered, which he was
so good as to entrust to me for examination, I found the encrusting
matter to  be chiefly calomel—whether on the preparation itself, or
on the interior of the  containing vessel: the latter  deposit was in
one instance mixed with a little fat and other animal matter.
  From a set of experiments which I made on corrosive sublimate
in 1S22, and which were published in the  Philosophical Transac-
tions for that year, I showed, that under certain circumstances of
complicated  affinity, corrosive sublimate is very apt to be decom-
posed  by exposure to light, and calomel precipitated; and that the
effect may be prevented by adding a substance which has a strong
affinity for the chloride, such as muriatic acid, or muriate of am-
monia, in  a saturated solution  of which it was, I found, seventeen
times more soluble than in water alone.
  Such complicated affinities,  I have no doubt, were exercised in
occasioning  the  precipitation of calomel,  in the  instances of the
spoilt  preparations to which I  have alluded: and  it is  highly pro-
bable that the bad effects  might have been prevented by certain
precautions, tending to oppose those affinities,  as  by immersing
them after steeping in the chloride solution  in dilute muriatic acid,
or in a solution of muriate of ammonia;  or  placing them imme-
diately in  a compound  solution of the muriate  and chloride.   The
few experiments I  have made of this mixture have given favourable
results; but they have  not  been carried sufficiently far, or  made
with suffi:ient precision, to enable me to give a decided opinion on
its permanent efficacy.  This I regret, considering the cheapness 
ACTIOK uF LIME.
155
of the means, and the promise of success which the method holds
out.  By permanent, I  mean  not a duration of a  few months,  or
even of a few years, but  an unlimited time—in relation to use for
the preservation of valuable preparations in the museum.   To de-
termine this, trials on things of little value ought to be made, with
a careful  record of dates and effects.   With this design, a series of
experimental preparations  have recently been put up in the patho-
logical collection  t.t Fort Pitt, and will, 1 hope, hereafter afford  data
for arriving at the information required.
                                XI.

OF THE ACTION  OF  LIME ON  THE  TEXTURES OF  THE
                         HUMAN  BODY.

  It is commonly asserted  and  believed, that lime exercises a cor-
roding destructive influence on animal matter in general—and that
animal bodies, exposed  to  its action,  rapidly decompose and disap-
pear.  Accordingly, it has been almost invariably recommended, to
add  this earth to graves, in instances in which a rapid decay is con-
sidered desirable—as on  the occasion  of the crowding of grave pits,
with dead bodies, during the prevalency of pestilential diseases.1

  1  The following instance, extracted from the ninth volume of the Philoso-
phical Transactions, abridged, may be given as an  example of the vague,
and, as I believe, erroneous manner of considering the operation of lime.  In
1746, when means for preventing the infection of an epidemic disease, which
then prevailed among the  cattle, were under consideration, burying  them
was thought the mosf effectual method, and the  introduction of lime was re-
commended  "for the more speedy  destruction of the distempered carcases."
But doubts arising  "whether  the  lime might not exalt the putrid particles,
and help to spread the  infection, it was the opinion of several of the learned,
that it was most safe on that account to bury them without it."
  Dr. Parsons, the author of the paper, adds,  "that the question will proba-
bly  be decided by a  fact  that  had  come to the knowledge of one of the jus-
tices, John Milner, Esq., appointed  to inspect into the affair, and will serve
to prevent the practice of burying them with lime for the future, as it  makes
it more than probable that malignant particles (by the operation of the lime)
may be sent up, and spread through the air."
  The fact referred to was the following: "Mr. Stallvvood, a  farmer, at
Hackney,  informs  the  justices to whom the  care of the distempered cattle
was committed ; that he had buried thirteen cows, very deep, with the quan-
tity of lime appointed by the justices ; and, observing his dogs to scratch, and
tear up the ground with their  feet, to get  at the cow's flesh, (the lime fer-
menting aud causing a foam as he called it, or strong scent  of meat to arise,
which made ihe dogs so eager to come at it), he beat them off several times;
but the dogs always  returning, as  soon as he was gone, for ?ome time he
hired a boy lo keep them off.  But that he had buried several other cows in
another place, with  their hides cut and slashed, without any lime, and the 
156
davy's researches.
  From the results  of many experiments which I have  made with
lime, on animal substances, I have been compelled  to come to the
conclusion, that this opinion is  not well founded  in fact—indeed,
that it is altogether  erroneous.
  The experiments were commenced in Malta, in  the  summer of
1829, and they were carried  on during the following year.   The
method  observed, was to  immerse the animal matter for  trial, in
cream of  lime, or  rather a  paste of lime, contained  in a wide-
mouthed bottle, well corked,  and covered with cerate cloth, to ex-
clude the  ingress of atmospheric air, and so preserve the lime in its
caustic state.
  One of the  first  experiments  tried was  commenced  on the 27th
August.   A portion of muscle, rectum,  verge of  anus,  urinary
bladder, prostate gland, vesiculae seminales, a portion of jejunum,
the gall-bladder, and the  gall-ducts, were  immersed as  mentioned
above.  They  were taken from  a subject in a  state of incipient pu-
trefaction, and  they exhaled  a  fetid  smell.  On immersion in the
lime and water, as might be. expected, they  gave off a strong ammo-
niacal odour.  They were first examined on the 24th of September.
They were then all in excellent preservation;  swollen, but not cor-
roded, nor their delicate tissues injured. They were next examined
seven months after, viz.  on the 5th of May of the year following
The report was equally favourable; it is stated  that they were much
in the same state as before—the texture of each part distinct—and
the part, as  a whole, easily distinguishable. They were left undis-
turbed  nearly two  years —until  the  6th April, 1832, when, on ex-
amination, they were  found  to  have  undergone material  change.
The cuticle had become soft and  transparent, as had also the  dura
mater, admitting of being torn  with the greatest ease.  The muscle
appeared  to be converted into  adipocire, which was quite white—
had no  unpleasant  smell—was  friable when dried, and burned  with
a bright flame, without any unpleasant smell. The other parts  were
not distinguishable.
   The  second  experiment recorded, was commenced in the begin-
ning of October.   Portions of aorta, dura mater, intestine, skin, cel-
lular tissue, muscle and tendon, were similarly treated.  The results
were examined on  the 5th of May following.  Then, on  opening the
bottle, an  ammoniacal but no putrid smell was perceptible. The parts
were found well preserved, excepting  the fatty matter contained in
the cellular tissue,  which It ad  become of an opaque white and fri-
able, from combination with the alkaline earth and conversion into
soap.   The tendon, it is  mentioned, was somewhat distended and

dogs never attempted to scratch or tear up the ground there."   Two bushels
of lime  were allowed to each cow.  With lime, the bodies were buried ten
feet deep; without lime, eight feel deep.
   Relative to the explanation of the fact—was  not  ihe difference observed
in the two instances owing to this—that in the  one the dogs were attracted
by  the smell of the meat preserved  by the lime—and not in the other, where
it was not so preserved, and where it was undergoing putrefaction? 
ACTION OF LIME ON THE TEXTL'RFS.
157
rendered more  transparent, but  rot gelatinised; and  so  also, in a
less degree, were  the dura mater and cutis;  and the last was de-
prived of its cuticle and hair.
  Some other experiments were made, but, as the results were very
similar, it would  be tedious to describe them.   I may state, gene-
rally, that with  the exception of cuticle, nail, and  perhaps hair,"lime
exerted on the different textures, on which it was tried, no destruc-
tive  power,  but,  a contrary influence—and more particularly  a
well marked antiseptic one.  It has been stated  how certain parts,
in the first  experiment,  lost the  putrid  odour which they had
acquired, when  immersed in lime and water.  Moreover, it appears
from notes of experiments, that after animal  substances have been
fully subjected to  the  action of lime, they ceased to be putrescent;
they resisted  putrefaction, whether placed in air, or plunged and
kept in common  water.   I shall mention one instance.  On the
13th of May, 1830, a portion of ileum, with mesentery attached, and
a portion  of muscular part of heart, with chorda; tendineas, were
placed in a large  jar of transparent lime water,  and covered with
cerate cloth.  Examined nine months after, on the 16th of Febru-
ary, they were found in good preservation, and without any putrid
or unpleasant odour.  The only change perceptible was, that the
portion of heart and intestine  had acquired a light greenish hue,
and the tendon  an opalescent hue; and all were a little softened.  A
crust of carbonate of lime had formed on the water, which still re-
tained some caustic lime.   They were then transferred to a jar of
common water—where, after four days, they continued unaltered.
I may add, that a portion  of cutis, similarly treated, placed in con-
fined air in a bottle, after a whole  month, emitted no unpleasant
odour, and appeared to be unchanged.
  I have observed, that  cuticle, hail, and perhaps  hair, are to be
excluded from the list of animal substances, not materially altered
by the action of lime.   On the cuticle its action is powerful, and, I
apprehend, in consequence of the chemical combination  between
them being formed.  It is well known  how lime has the property of
rendering the cuticle easily separable from the cutis vera,  and how,
in the art of tanning, it  is applied  to this purpose.   The human
cuticle, that, for instance, of the sole of the foot, I find, becomes soft
and gelatinous from immersion in lime and water.  After drying, a
portion  thus tried (well  washed  previous to drying) was white,
semi-transparent and brittle; incinerated, it yielded seventeen per
cent, of ash, which consisted principally of lime and carbonate of
lime.
  The effect of lime on nail is similar to that  which it exercises on
cuticle, but not  so strongly marked.   A portion of nail of great toe,
macerated in lime and water, from  the 7th of June to the 18th of
August, was rendered soft and friable—a little swollen and disposed
to separate or break up  in layers.   Dried,  it exhibited  the same
character as cuticle,  and when incinerated, burned  in  a similar
manner, and left a considerable ash, consisting of a small proportion
       10— g                                     11 dav 
158                  davy's researches.
of phosphate of lime, which pre-existed in the nail, and a large pro-
portion of lime—with which, during the change from maceration,
it may be inferred, it combined.
  On hair, the effect of lime appears to be more destructive; but, in
what manner it acts, I have not attempted to ascertain.  A portion
of human hair of the head, which had been kept in lime and water
about three months, was partially decomposed.  At the bottom of
ihe vessel there was a little black sediment.  The hair, which  was
black, had acquired a just  perceptible reddish shade, and had be-
come much finer, as if wasted, and more feeble, so as to be easily
broken.
  Relative to the results of the experiments generally, they appear
to me to bear me out in  the remark with which I prefaced them,
viz. that lime does not exercise a destructive  corroding power on
animal substances generally, or one promoting  their decomposition;
but, on  the contrary, a preservative and decidedly antiseptic power,
arresting putrefaction, even  when commenced, and retarding de-
composition.  What new arrangements of the elements of animal
matter may take place under the influence of lime, is a subject for
further inquiry.  Probably the effects of lime  on cuticle, nail, and
hair, on which in the arts its operation has been best known, led to
the ideas of its agency on animal substances generally, which I have
been under the necessity of combating.
   It was my intention to have instituted a set of experiments on the
effects of the  other earths, and also of  the  alkalies on animal tex-
tures; but this I have only very partially accomplished.
   From the first few trials which  I have  made with  barytes and
magnesia, the action of the former on animal  substances generally,
and also on  the  cuticle and nail appeared to be similar to that of
lime, but  more energetic; whilst that of the  latter appeared very
much less, not arresting the putrefaction  of the soft parts, and having,
if any, an obscure and slight effect on cuticle and nail.
   The effects of the alkalies,  as might be expected, were sufficiently
 well marked.
   Ammonia, in the form  of aqua ammonise,  acted very like lime.
 Portions of skin, of sole of foot, nail, hair, intestine, dura mater, after
 having  been  a  fortnight  in  this liquor, had  very much the same
 appearance as if they had been immersed in lime water.  The cuti-
 cle was detached; it was  quite  pnlpy;  it offered no resistance to
 pressure, and in consistence was not unlike  starch gelatinised by
 cooling.   The other parts,  not  including the nail and hair, were
 rather soft and swollen, but  not materially changed; the hair and
 nail  showed no alteration, with this exception in regard to the lat-
 ter, that its inferior stratum—its tinder surface, was softened, like
 cuticle.  After another fortnight, the cuticle was found to be quite
 dissolved; the other parts, including nail  and hair, remaining as
 last  noticed: nor  after another month were they  found further
 altered, excepting  that they  were softer, especially the skin, which
 had  become very flexible, and no longer retained the hair. 
EFFECTS OF TANNIN.
159
  Weak solution  of potash, in the form of aqua potassae, tried on
the substances last noticed, had very little effect on any of them; it
prevented indeed  their putrefaction, and softened  them,  but no
more; after a fortnight, they appeared unaltered, and the cuticle
was not detached.
  A strong solution of potash, formed in the proportion of a dram
of the hydrated alkali  to an  ounce of water, acted  powerfully on
them; the cuticle was first rendered gelatinous, and afterwards re-
duced to a blackish powder, as  if entirely decomposed,  and after
about a month's action on the other parts, they too had disappeared,
a little viscid mucus-like  matter  having taken their place, and a
black  matter subsided.   These few experiments  on  ammonia  and
potash were made in Malta, in the summer season,  at a tempera-
ture between 80° and 90°.
                             XII.

ON THE  EFFECTS OF TANNIN ON THE  DIFFERENT TEX-
               TURES OF THE HUMAN BODY.1

  The question, are there any other textures besides  the  cutis,
which have the power of combining with tannin,—led me, whilst
stationed in Corfu, and in Malta, in 1837-38, to institute some experi-
ments on the subject, believing that there would be no difficulty in
arriving at  satisfactory results, and hoping, that even unexpected
results, as so often happens in experimental research,  might be ob-
tained, which might prove both curious and useful.
  The first set  of experiments I undertook, was commenced on the
1st of November, of the year already mentioned, at  Corfu.   The
parts  employed were from the body of a young man, who had died
of remittent  fever; they were kept  in  a tanning infusion  until the
23d of June.  The second set of experiments entered  on, was com-
menced in Malta, on the 15th of April  following.  Most of the parts
employed  were from the body of a man, aged thirty-five years, who
had died from the effects of a severe injury, occasioned  by a  fall;
they were kept immersed until the 4th of July.
  The parts subjected to the experiments, the instant they were
separated from  the body, were deprived of superfluous moisture, by
pressure between folds of blotting paper, and then carefully weighed,
and immediately after put into a strong infusion of catechu, with
some  catechu in powder.  In every instance, putrefaction to a cer-
tain extent took place;  after a while it diminished and ceased.   The

  ' First published in the  fourth volume of the  Transactions of the Edin-
burgh  Med. Chir. Society. 
160
davy's researches.
infusion was changed once or oftener in  the course of the experi-
ment, according to circumstances; or, if the part was very small,
not at all.  The experiments were continued till a full effect appeared
to be produced; to ascertain which the parts were occasionally
taken out and  examined, and partially dried by  blotting paper, and
weighed.  The following table shows the quantity of solid  matter
per cent, which each afforded, when dried on a vapour-bath, as in
the experiments on desiccation.   The increase of weight  it was
supposed, when it could be clearly established, would serve to indi-
cate the quantity of combined  tannin.
) Besidue				
No.	Part tried. [Per cent-			
1	Skin of thumb, afforded			55.6
2	Cuticle of sole of foot, most of the cuti	s removed		53.4
3	Pleura costalis	,		83.3
4	Lower part of ileum		.	38.5
5	Upper part of jejunum			34.4
6	Aorta ....			52.3
7	Muscular part of diaphragm, neither it lining removed	s peritoneal or	pleural	55.3
1	Rib, afforded			58.8
2	Cartilage of false rib		.	57.0
3	Intervertebral substance			41.7
4	Dura mater			53.0
5	Pia mater			53.4
6	Cellular structure			69.3
7	Perichondrium of cartilage of false rib	,		72.2
8	Cornea		,	55.5
9	Sclerotica	, ,	.	70.0
10	Corpus cavernosum penis			45.7
11	Medulla oblongata	, ,		43.4
12	Pectoralis major muscle		.	36.4
13	Aorta ....			47.1
14	Vena cava		, ,	40.2
15	Thoracic duct .			53.5
16	Liver ....		,	27.6
17	Spleen ....			28.3
18	Lung ....	.	.	23.1
19	Kidney		.	17.4
20	Pancreas	.		16.4
21	Fibrinous concretion from ventricle of heart			45.6
  I have stated, that putrefaction took place in every instance, in a
greater or less degree, and that after a time, on changing the infu-
sion, it  ceased.  Some animal matter,  too, in each "instance, was
separated from the part, and deposited.  At the same time the infu-
sion of catechu had its strength impaired; some of the catechu ap-
peared to be precipitated in  the sediment, a part  of it in  most
instances seemed to  combine with the texture, and another part of
it rose to the surface, in the form of a thick pellicle having under-
gone some change.
  The animal parts  which seemed to suffer most from putrefaction, 
EFFECTS OF TANNIN.
161
were the liver, spleen, pancreas, and kidney.  The cuticle was the
only part that did not appear to combine in  the smallest proportion
with tannin, or to be preserved by it.   After long immersion in the
infusion, it was as it were  rotten,  the particles of it  hardly  held
together, and were most easily detached, and, when dried, their co-
hesion was almost entirely destroyed. This, however, strictly applies
only to the outer layer, not to  the inner, and there appeared to be a
gradation from  it.   The  nearer it approached  the cutis the  more
coloured it had become and  compact, and the more it seemed to par-
take of the nature of this membrane, when  converted  into leather.
All the other parts when  more or  less indurated, and rendered more
compact and firin, and all of them were more or less coloured. When
dried, they were all comparatively rigid, with the exception of the
pleura and pia mater.  When immersed in water, they imparted to
the water a brown colour.   The  colouring matter thus withdrawn
when exposed to the air was gradually precipitated, and became in-
soluble like vegetable extractive, and when burnt it emitted a mixed
fume  of  vegetable and animal  matter,—the  former predominating;
and, by its  abstraction, though the colour of the different textures
was very little altered, yet they were all rendered more  brittle, even
the pleura, when dry, lost almost entirely its  flexibility.   I tried the
effect  of water in this manner only on the parts employed in the first
set of experiments.   The loss each part sustained, per cent, when
dried  on  the vapour-bath, was as follows:—
No.	Part tried	Per cent.
1 2 3 4 5 6 7	Cuticle of sole of foot ...... Skin of thumb ....... Pleura costalis . . . . • Lower part of ileon ...... Upper part of jejunum ..... Aorta ........ Muscular part of diphragm .	21.8 7.3 25.0 9.7 9.0 6.0 3.4
  The great loss  sustained by the cuticle was probably chiefly in
consequence of the tannin and colouring matter which it had merely
imbibed, when distended by the infusion like a sponge, being washed
out, and from some of its particles having been detached, in conse-
quence  of its  decayed state already alluded  to.  None of the parts
showed the least tendency to putrefy during this immersion in water,
though  the temperature of the air at the time was high, often above
90°, and they were exposed to the air.
  Considering all the circumstances of these  experiments, the loss
of a portion  of animal  matter  from putrefaction,1 the apparently
  11 Delieve the degree of putrefaction and effect produced by it, is in some
measure proportional to elevation of temperature, and that this is a principal
cause that the leather is so well fitted  for the climate  in which it is made.
Made in a hot climate, it is  soft and very porous,  allowing  heat and perspi- 
162
DAVYTS RESEARCHES.
great increase in weight in  several instances, and the change of
properties produced in all, tending to the preservation of the part,
with the exception of the cuticle,! think it may be fairly inferred,
that the cutis is not solitary in its power of combining with tannin
and forming leather; on the contrary, that the fibrin of the blood,
in the form of a fibrinous concretion, or the buffy coat; and that the
fibrous and serous textures,  and the vessels,  including each  kind,
possess this power in a still more eminent degree,—and that the mu-
cous membranes possess it in an equal degree;  and may not the same
conclusion be extended  to muscular  fibre 1   Relative to  the  liver,
spleen, pancreas, and kidney, their power of combining with tannin
is problematical.   That a portion of each of these viscera does com-
bine with it and the colouring matter of catechu, is  pretty  certain,
and most likely it is the connecting cellular structure which enters
so largely into the composition of their substance. I am disposed to
think that this remark does not apply to medullary matter; it seems
in a certain  manner to be preserved by tannin, without entering into
distinct combination with it.
   After having obtained the preceding results,  the  idea naturally
occurred that other textures of animals besides the cutis, might be
subjected advantageously to the process of tanning for various uses.
It seemed not improbable that some  parts  might be useful in the
form of tubes, as the intestines thus converted into leather. Farther,
it seemed highly probable that the art of tanning might be applied
to the making of certain anatomical preparations, in a dry state, for
the purpose of public demonstration, and that it might also be turned
to account in the art of embalming.   The few experiments which I
have hitherto made in relation to these applications, are as favoura-
ble as could be expected, and  make me sanguine, that whoever
undertakes to push them farther, and give them a fair trial, will be
eminently successful.  Some preparations which I have made of
the larger blood-vessels  and  of the intestines, display their parts per-
fectly in a dry state, and when immersed in water and distended by
the absorption of this fluid, they even display very well the differ-
ent coats of which they are  formed.   I suspect that, anciently in
Egypt,  tannin  was employed in embalming.  Some years ago, I
recollect having examined  a heart, and the fluid in which it was
found preserved, in an  alabaster vase, lined  with a substance like
petroleum.  It had been brought, I believe, from Thebes, in Upper
Egypt, and, if I am rightly informed, it is deposited, by Dr.  Bree, to
whom it belonged, in the Museum of the College of Physicians, of
London.  The heart had the appearance of being  tanned, and the
fluid in which it was preserved was chiefly water, holding in solution
some animal matter and a vegetable principle, analogous to tannin,
both in very small quantity.   It is probably the most ancient moist
preparation  known, and it is well adapted to show  the preservative

ration to escape; made in a cold and temperate climate it is strong and dense,
excluding moisture and retaining heat. 
EFFECTS OF BOILING WATER.
163
powers of a fluid ; and that if air be excluded, there is scarcely any
limit to the durability of bodies so protected.
                            XIIL

ON THE EFFECTS OF BOILING WATER, AND OF BOILING,
  ON THE  TEXTURES   OF  THE  HUMAN  BODY  AFTER
  DEATH.

  The majority of the experiments which I have to detail on this
subject,  were made in  Malta, in  1828-29.  They were instituted
chiefly for the purpose of testing in part the correctness of Bichat's
theory of membranes,—in the developement of which, in comparing
different textures, he lays much stress on the effects in question.
  I shall first notice the effects witnessed from the application of
boiling water to portions of different textures, of small bulk, so small
as to have their temperature almost immediately elevated to that of
the scalding  medium.   The trials were made  in a very plain and
easy manner.  In each instance, the animal matter was placed  in
a Wedgewood-ware evaporating dish, and water boiling from the fire,
in a common tea-kettle, was poured on it, in a continued stream,
for a few seconds, until its  own temperature, it was supposed, was
imparted.
   1. Cerebrum, medulla oblongata, deprived of their membranes,
did not  appear to contract or undergo any change of form, neither
the cortical nor  medullary part:  they were  rendered,  however,
weaker, as  if the cohesion of their particles was diminished,—giving
way when  an attempt was made to raise a portion  with the forceps;
and yet  they were not sensibly softened.
  2. Muscle; a portion of  gastrocnemius contracted pretty much,
and apparently in all  its dimensions.   Portions of other muscles
were tried,  and with like effect.   At the same time,  that they ap
peared to be condensed, they became comparatively pale;  and also
rather hard, seeming to retain their strength of fibre.
  3. Liver, spleen, kidney, lung; each of these experienced contrac-
tion, and all of them became friable.   The portion of lung, when
covered  with hot  water, quite effervesced, so much air was  disen-
gaged, partly, no doubt, from the expansion of the contained air from
heat, but, chiefly probably from contraction of the  air-cells.
  4. Cartilage;  a superficial slice  of the  investing cartilage of pa-
tella, contracted pretty  much and became  bent, forming nearly half
a circle: the next slice contracted and  was bent much less, giving
rise to the  idea that the greater effect on the former was owing to its
possessing  a delicate membrane,  liable  to greater  contraction from
heat, than the substance of cartilage alone.1

  1 There is a preparation, in the Museum of the Army Medical Department, 
164
davy's  researches.
  5. The tendo achillis became shrivelled and appeared to contract
in all its dimensions.
  6. The dura mater became corrugated and appeared to be much
contracted ;  from shining silky white, its natural colour, it became
dull white, wi'h a yellowish tint.
  7. The pericardium became shrivelled and  appeared to  be  con-
tracted ;  its  inner surface exhibited corrugation, and seemed dis-
tinctly fibrous; there was no appearance indicative of its having a
serous membrane.
  8. The skin, contracted very much; the surface of the cutis vera
became rough, as if glandular;  the cuticle was rendered weak, al-
most pulverulent, scarcely offering any  resistance.
  9. The transparent  cornea  became  corrugated  and apparently
opaque.
  10.  Stomach and  intestines; their lining  membrane was  very
much  contracted and corrugated, and so altered  in appearance,  as
not to  be distinguishable; it was rendered also very weak, so  as to
be easily rubbed off.  The same changes occurred in the peritoneal
and muscular coat in  a less  degree.  The  glandular structure,
especially of the duodenum, appeared more distinct.
  11.  Aorta;  its outer membrane contracted and was very much
corrugated ;  its inner, [tried when detached,]  very slightly, and  its
strength appeared  to be very  little diminished; the middle layer
curled a very little, and uncurled when put  into cold water,—and
its strength was not apparently diminished.
  12.  A portion  of vena cava became  condensed and  corrugated,
curling, spirally, outward, from the greater contraction  evidently of
the  outer fibro-cellular coat; the wrinkles  appeared in the inner
coat; there was no distinct loss of strength.   A portion of the  vena
portae, was very much corrugated ; one  portion of its inner coat was
suddenly rendered gelatinous;  another  and contiguous  portion,
harsh  and friable.
  13.  The thoracic duct contracted, and was very much shrivelled.
  In a few instances  I endeavoured to determine, by measurement,
the degree of contraction.  A portion of dura  mater, after the action
of boiling water, was  found contracted about one  half its length and
width ; but increased in thickness; a portion of tendo achillis gave
nearly the same results ; a small fasciculus of fibres, from gastrocne-
mius externus muscle, contracted  less in length,  only about one
third.   To  try to determine whether  the  contraction, in certain
directions, was connected with a general condensation of substance,
E ascertained the specific gravity of some of the textures before and
after the  scalding  agency, subjecting them, on  each occasion, as
nearly as possible, to  the same degree of pressure between folds of

at Fort Pitt, made by Mr. Gulliver, clearly demonstrative of the existence of
such a membrane, extended from the synovial fringes over the cartilage in
question.  In an instance of partial absorption of the cartilage of the patella,
producing a small cavity, I found it covered with a  'delicate  membrane, the
normal one, I believe, unaltered. 
                 EFFECTS OF BOILING WATER.              165

blotting paper before weighing  them.  The results obtained are
shown in the following table.
	Specific Gravity	1 Specific Gravity
Texture tried.	before scalding.	after scalding
Spleen	1041	1060
Dura mater j	1047'	1058
Pericardium	1059	1074
Lower portion of thoracic aorta	1065	1075
Ditto, just below the arch deprived		
of its outer coat.	1070	1072
   These results would seem to show that condensation attends the
contraction,—that the bulk of the part acted  on is actually dimin-
ished.  This is also  indicated, and  I  apprehend very clearly,  by
the effect on certain parts,—especially on the penis,—which, per-
haps  from its structure, is better  adapted than any other to display
it.  Under the influence of boiling water, this crgan becomes hard,
and tense, and rounded; and from the blood pressed out, evidently
of diminished volume.
   Before passing to another part  of the subject, I  may  mention  a
small number of trials which I made to endeavour to  determine at
what  temperature  the corrugating power of hot water commences,
Dura mater was selected for the experiment.  Water of  the tempe-
rature of  140°,  poured on it, had  no apparent  effect; at 150° it was
doubtful; at 155°, there was a perceptible corrugating effect; at
170°  it was considerable; and at 212° the effect was at its  maximum.
   1 shall  now describe the  effects witnessed  on different textures
from  the operation of long continued boiling.  As  a  preliminary,
the effects of this agency on the  principal constituent parts of the
blood, or  those  into which it is resolved, when  abstracted, may be
mentioned.
   1.  Some serum of blood was coagulated by immersion in boiling
water.  The coagulum was inclosed in  a linen  bag and kept in
boiling water over a slow  fire, for twenty-four hours.  The matter
of the coagulum was not in the least softened ; showed  no tendency
to become gelatinous; it was firmer and more brittle than when first
coagulated, breaking with  a conchoidal fracture.   Wiped with blot-
ting paper to remove adhering moisture, it was  found  to be of spe-
cific gravity 1031.  This  low specific gravity, perhaps, might have
been  expected,  as when  the serum  was first caagulated  by heat,
ihere  did not appear to be any condensation ;  the vessel  which was
filled  with the serum, was equally filled with the coagulum; nor from
long boiling was there any very distinct appearance of contraioctn.
  2.  A portion  of fibrin  of blood, the colouring  matter  and the
serum separated  by washing,  was plunged into boiling water;  it

  1 This low specific gravity of  dura mater, was probably the effect of dis-
ease; in the body from which it was taken, fluid was found effused between
the membranes. 
166                   DAVY'S RESEARCHES.

immediately contracted,  and apparently very  much.  The water
was kept boiling for twenty-four  hours.  The  fibrin was not ren-
dered gelatinous ;  nor did it appear diaphanous in  the slightest de-
gree.  It was not entirely deprived of its elasticity ; it was perhaps
a little softer, but not distinctly so. Pressed between folds of blotting
paper, it was found to be of specific gravity, 1067.1
  3. A mixture of red particles and  serum,  after the separation  of
the fibrin, by being pressed through linen cloth, poured into a vial,
was immersed in boiling water;  the  cruor immediately coagulated
pretty firmly.   The water was kept boiling for 24 hours.   The co-
agulated cruor was rendered  softer and more  friable than the coagu-
lum of serum ;  its colour was a dull brick red, which it had after the
first impression of the heat.  Pressed between folds of blotting paper,
it was found of specific gravity 1090.
   In the following trials the operation of boiling was carried on un-
interruptedly for ten  hours.   The parts subjected to it  were im-
mersed in  the  water  already in  ebullition.   They were all from a
body 21 years  of age at the time of  death.   It may  suffice to state
briefly the principal appearances observed in each texture, or in each
compound organ, at the end of the operation.
   1.  Cerebrum.—Both  medullary and cineritious matter, seemed
rather contracted,  was  rather  harder and  more  friable, and felt
greasy.

  1 In another trial, made on a fibrinous mass from the right ventricle of the
heart, boiled for about twelve hours, its specific gravity was found to be 1049.
  Considering the effect, above described, of a boiling  temperature many
hours continued  on the  fibrinous part of the blood, it is very curious that
coction  or digestion of  fibrin at a comparatively low heat, viz. about 99°,
should afford a very different result: thus, if the blood-heat coction be con-
tinued for 48 hours, without stop, the fibrin is reduced  to a semi-fluid state,
coarsely resembling pus, and very closely  resembling the puriloid matter into
which fibrinous concretions formed in the heart, or blood-vessels,  during life,
are in part converted under peculiar circumstances.  To  Mr. Gulliver I ap-
prehend belongs the merit of having first observed this peculiar effect of coc-
tion at a blood-heat on fibrin, and the analogy between its  product and the
result of the softening process on fibrin in the living body.*  The analogy,
however, il is right to observe, is not altogether perfect.  In Mr. Gulliver's
experiments on the coction of fibrin,  I believe, without any exception, marks
of putrefaction were developed in the fibrinous mass, which may  conduce to
the disintegration of  the fibrin, and its reduction to a pultaceous state; far-
ther on, it will be seen how rapidly at a  temperature between 80° and 90°,
fibrin partially liquefies in undergoing putrefaction; but in the fibrinous con-
cretions, when undergoing softening,  I have never observed any well-marked
signs of incipient putrefaction ;  the softened  matter has  never, that I have
witnessed, emitted an offensive smell, and when it  has been mixed with lime
or caustic potash, it has  yielded a very slight odour only of the volatile alkali.
The softening of the fibrin, in the living  vessels, centrically, [as is invaria-
bly the case, as far as my experience extends,] whilst the surface of the mass
is hardened so as to assume the appearance of a sac or inclosing  membrane,
does not seem to admit of explanation on any known principle:  it is an im-
portant problem  in relation to its pathological relations, and  deserving of
minute inquiry.
♦London Medical Gazette, vol. i. New Series, p. 874. 
EFFECTS OF BOILING WATER.
167
   2.  Dura mater, was thickened, rendered  more transparent and
elastic; it was easily stretched and broken.   Its outer surface was
shrivelled.  It admitted of being easily divided into two laminse;
the exterior  of which was thinnest.  The  direction  of the fibres
was horizontal.  No appearance of arachnoid  membrane, or of a
membrane reflected over its inner surface was perceptible.
   3.  The external investing membrane of the heart was rendered
soft and imperfectly gelatinous.
   4.  The lining membrane of the cavities of the  heart was ren-
dered slightly gelatinous.
   5. The cordae tendineae were rendered soft, not  in the slightest
degree  viscid, but very friable ; they  were pellucid, and like cold
jelly.
   6. The valves appeared  contracted and  corrugated;  they were
very friable, and slightly gelatinous;  their base was more so than
their  free  margin.
   7. The muscular substance of the heart was rendered very friable
and soft.  It showed a disposition to  come away in spiral masses,
when pulled  asunder.
   8. The outer coat of the pulmonary artery and of the aorta was
rendered softer, and somewhat gelatinous, and slightly viscid, so as
to be  slightly ropy when drawn out.  It could be traced down to
the valves ; showing, as it appears to me, and as is confirmed  by the
effect of maceration, that the semilunar valves  of both great arte-
ries are connected in part with this outer coat.
   8. The middle coat of both vessels was  rendered more friable,
but not transparent, and not in the least gelatinous  r1 it was  much
less weakened and altered than muscle.
   9. The inner coat too was rendered more friable, more difficult
to separate as a continuous membrane, indeed it could be separated
only in  fine shreds, and it did  not appear at all gelatinous.
   10. The pleura was rendered soft,  rather gelatinous and a little
viscid.
   11. The substance  of the lung had become firm, compact, very
friable, and of a greasy feel.
   12. The liver, kidney, and  pancreas, were rendered very simi-
lar ; and  their investing membrane  had become  very like  the
pleura.
   13. The inner coat of the stomach and intestines was very  much
corrugated;  it had not become in the  least gelatinous, but very fri-
able and easily separable from the cellular coat by rubbing.
   14. The cellular coat, between the inner and muscular, was ren-
dered very soft, somewhat gelatinous and  viscid: it felt granular, as
if it contained mucous glands.

  1 I have found the effect of long-contiuued boiling on the  substance of the
ligamentum nucha? of  the ox similar, and  also similar on the  thick, very
elastic middle coat of the aorta, as in the arch, where this structure is most
strongly marked in the ox. 
168
DAVV!S RESEARCHES.
  15. The muscular coat had become very friable;  not at all gela-
tinous ;  the muscular fibres were very distinct.
  16. The peritoneal coat generally  was rendered soft;  in  some
places it was rather gelatinous and slightly viscid, in others friable.
  17. The inner coat of the urinary bladder and of the upper part
of the urethra, had become slightly gelatinous and diaphanous.
  18. The muscular coat of the former was delicately displayed;
its fibres appeared very  distinct; they were friable.
  19. The cuticle of the tongue was rendered soft and very triable,
and was very easily detached.   It  was  thick  above and  spongy;
extremely thin below, and over the frsenum indistinct.  I attempted
to trace it in continuation.  Over the cryptae of the amygdalae I
could not detect it;  nor in a satisfactory  manner in the  pharynx,
in the immediate vicinity of  the amygdalae.  The cryptae and con-
tiguous lining membrane had become  gelatinous.   In the oesopha-
gus, the cuticle was very manifest,  easily separable, indeed scarcely
adherent,  and very friable.
  20. The  cutis of  the under surface of the tongue, extremely
thin, was  rendered slightly gelatinous and semi-transparent.  The
thick cutis of upper  surface had  become rather friable, especially
the papillae, as if composed  chiefly of vessels.  When it was  re-
moved,  gelatinous projections were seen rising from the  muscular
coat corresponding to the papillae.
  21. The mucous  coat of oesophagus had become rather friable;
some gelatinous matter  appeared to be diffused through it.  The
sub-mucous, cellular, and the mucous coats were affected much in
the same manner as those of the stomach  and intestines.
  22. No cuticle or epithelium was discoverable in the larynx, or
in any  part of the aspera  arteria.   It was very carefully sought
after, on  the supposition,  that  it  might  exist  of a very delicate
nature.
  The  lining membrane of the  larynx was found to be semi-trans-
parent,  elastic and  gelatinous ; the cordee vocales were similar, as
also the connecting membrane of the cartilages of the trachea.
  23. The cartilages of the larynx had become much swollen and
broken; portions of them were projecting out.   They were very
soft, nearly transparent,  and quite gelatinous.  The change in  the
epiglottis was less strongly marked than in the firmer cartilages; it
was less uniformly swollen, soft, and transparent.   The  perichon-
drium generally was rendered gelatinous.
  24. The cartilage of patella was  found soft and semi-transparent,
like stiff jelly.
  25. The lining membrane  of the capsule had become soft, rather
gelatinous, and slighfly  adhesive.
  26. The cellular membrane, surrounding the bursa, between  the
patella and the skin, was found soft, gelatinous, and ropy, admitting
of being drawn out into  threads possessing some elasticity.
  27. The  cutis over  the patella was much corrugated ; it had
become  soft, friable, and a little gelatinous; one surface was  more 
                  EFFECTS OF BOILING WATER.               169

gelatinous, the other  more friable.   The outer surface was rough,
from little protuberances of a gelatinous kind.
  28. The  skin  of the scrolum appeared somewhat similar, but
without the insulated little masses of jelly on its surface.
  29. Its cellular membrane had become soft, gelatinous and ropy.
The tunica vaginalis was very similar; it was equally gelatinous
and soft.
  30. The albuginea was rendered soft and friable, not viscid.  In
appearance, it approached somewhat to the cartilage of patella, but
was less transparent.
  31. The testicle was found firm and very friable.
  32. The conjunctiva  of eye had become rather gelatinous, soft,
and adhesive.
  33. The  cornea was  rendered translucent, and friable, like the
albuginea.
  34. The  sclerotic coat was  similar: the  cornea and  this coat
were not  separable.1
  35. The  lens  had become opaque white, firm and very friable,
—not in the slightest degree gelatinous : it broke up into concentric
laminae.
  36.2 The articular cartilages  investing the ends of the bones of
the foot were rendered semi-transparent; soft, like stiff jelly.
  37. The tendons of the foot had become similar ; the tendo  achil-
lis was  also gelatinous,  but less  completely so; there were whitish
portions observable in it, as if from minute vessels.
  38. The  pancreatic duct  was found changed in a  manner re-
sembling tendon ;  it had become uniformly transparent  and gela-
tinous.
  39. The  outer coat  of the  ductus  communis choledochus, was
rendered  very  like the  corresponding  coat of the aorta;  its  inner
coat was  less' altered ;  it had  become diaphanous, slightly elastic,
and imperfectly gelatinous.
  40. The cutis of body of penis  had become soft, gelatinous, and
elastic.

  1 An eye, an  inch in  diameter, measured from the entrance of ihe optic
nerve to the cornea, and transversely, immersed in boiling water  about ten
minutes, was found contracted to a diameter of ffths of an inch ; and the
cornea from ffths to ||-ths; the latter was  not corrugated or diminished in
transparency.  The boiling was then continued about ten hours;  the globe
was still more contracted,  but the sclerotic  having burst, it was not easy to
measure it; the cornea was reduced to i^ths of an inch. It and the sclerotic
had become soft, not gelatinous; the one retained a considerable  degree of
transparency, and the other had acquired it.
  2 This and the following trials were made on parts of a limb, amputated
on account of extensive  disease of the knee joint, following a fall; the
patient was 21  years of age.  The amputated  limb was boiled eight hours.
It was curious to see the general disruptive effect.  All the bones of the feet
were dislocated; the tendons broken; the cuticle  almost entirely detached.
The toes and metatarsal bones were bent downwards. 
170
davy's researches.
  41. The tendinous sheath of penis  was affected very like dura
mater; but was rendered softer; it admitted of separation in layers.
  42. The corpus cavernosum and spongiosum had become very
friable, slightly elastic, and  only slightly diaphanous.   No  epithe-
lium could be detected, continued from the cuticle of the gland into
the urethra.   The  lining membrane of the urethra was rendered
gelatinous.
  43. The glans penis  throughout had  become soft,  elastic and
gelatinous.  Its  cutis was very gelatinous; minute  papillae, semi-
transparent points, appeared regularly distributed over it.
  In  many instances, the specific gravity of the parts  was ascer-
tained, after the operation of long continued boiling.  The following
table exhibits  the results obtained.   The number in the table, cor-
responds with the preceding numbers.

Table showing the specific gravity of different textures after long
                            boiling.
No. j Description of Texture.		Sp.Grav.
2 Dura mater		1023
7	Columna carnea of left ventricle of heart -	1052
8	A section of aorto (including all its coats) close to the coro-	
	nary arteries --------	1061
12	Liver --------	1046
—	Lung --------	1061
—	Kidney -------	1071
—	Spleen _._.-._	1070
19	Muscular substance of tongue -	1062
23	Thyroid cattilage ------	1012
31 Substance of testis		1070
36 Cartilage of os calcis -		1020
37	Tendo Achillis, close to its termination	1034
A	Cutis of heel1 -------	1029
B	Cuticle from heel ------	1076
	Dura mater - - -	1030
	Abdominal vena cava -	1040
	Its outer coat detached -	1034
	Thoracic aorta just below the arch -	1068
	Duodenum close to common biliary duct	1050
39	Common biliary duct, with a portion of pancreatic duct at-	
	tached .--.-._	1033
40 [Cutis of dorsum penis		1033
41 Tendinous sheath of dorsum penis -		1044
43 'Glans penis - ...		1045
  All these results, received even favourably, can  be  considered
only as  approximations.   They would be more valuable for  the
purpose of comparison, had  the specific gravity of each part been
ascertained before being subjected  to boiling.  However, imperfect

 1 These parts, to which a letter is prefixed, were portions of the amputated
limb: those without the prefix of a letter or number, were taken from a body
aged about 21; the latter were boiled eight hours. 
EFFECTS OF BOILING WATER.
171
even as they are, I hope they  may not be without  use as data
for  reasoning  on, in  forming general views of the analogies of
textures.
  The results generally are not so accordant with those of Bichat,
as described by him in his Anatomie Generale, as might be expect-
ed : nor are they, in my opinion, favourable to his views of distinct
differences in the qualities of certain membranes, which characterise
his  theory.  He states that cellular membrane, and fibrous  mem-
brane are  very differently affected by coction.  In my trials  it did
not so appear.  Judging merely  from the effect of coction, the con-
clusion, which seems  most legitimate is, that  which  harmonises
with the  views of Haller,—that the majority of the white  mem-
branous and fibrous parts, are of analogous composition, differing
rather in degree than  kind ;  and not essentially different from cel-
lular tissue ; and each differing in like manner in degree in different
situations, so  as  not  to allow  of any  individual membrane or
continuity of surface  throughout its course being considered iden-
tical.   Farther on I shall have occasion to recur to this subject.
  When  engaged in this inquiry, I  had intended to investigate
more in detail the effects of coction, and I commenced making ob-
servations on  the  comparative  tendency to putrefaction  of the
textures subjected to the boiling process.  From the partial trials
then made, it appeared that all those parts which were much soft-
ened and  gelatinized by boiling, had become by the change  much
disposed to putrefy.  It was remarkably the case in the instance of
tendon, cartilage,  and fibrous membrane.  After being boiled, they
underwent the putrid liquefaction even  more readily than muscle:
the effects in these instances, as  in  muscle, liver, lung, spleen, &c.
in which, at least in the  majority, there appeared to be an augmen-
tation of specific  gravity, rather than a diminution, was less clear:
and I am  doubtful, whether the  coction really increased or dimin-
ished the  putrefactive tendency.
  A few experiments  about the same time were made on the fitness
of boiling, as an aid in the preservation of anatomical preparations.
The result was favourable, showing that those parts which contain
much blood, and  which are themselves but little altered by a short
application of the boiling temperature, may immediately be put into
spirit of  wine, and kept without its being  necessary to change it.
Thus, in  February, 1829, a portion of blood coagulated by heat,—
a portion of liver and spleen, merely indurated by immersion in
boiling water, were placed in proof spirit. In May of the following
year, they were found in excellent preservation,  the  spirit clear,
without sediment, and only very slightly coloured. 
172
davy's researches.
                             XIV.

ON  THE AGENCY OF  ATMOSPHERIC  AIR  ON  DEAD ANI-
 MAL MATTER; AND ON THE PUTREFACTIVE  PROCESS.

  Amongst  many questions  of interest  involved  in  the subjects
enumerated above, there are  two which stand forward in a promi-
nent manner; viz. whether dead animal matter before putrefaction
commences has the power of absorbing air; and whether the putre-
factive change is attended with elevation of temperature.   Bearing
on these points, although not exclusively so, I shall relate three sets
of experiments which  I have made:  one on the agitation of fresh
animal matter in atmospheric air; another, on its exposure to this
mixed air, confined without agitation ; and a third, on exposure to
the atmosphere, under circumstances  favourable to putrefaction:
and, I shall conclude with some  general remarks on the putrefac-
tive  process.
  My attention was first specially directed to the inquiry in Malta,
in 1829.  Of the results then obtained and published  in  the Edin-
burgh Medical  and Surgical  Journal, 1 shall  now give only such
as, on revision, I believe to be correct, and liable to no serious ob-
jection.

1.— On the agitation of dead animal matter in atmospheric air.

  The results of the latest experiments which I have  made on the
agitation of blood and serum in air, have already been  stated, show-
ing,  that, independent of putrefaction, both venous  and arterial
blood have the power in question ; but that serum does not appear
to possess it, in an appreciable degree.  Respecting serum, I  think
it right to express myself in this qualified manner "in consideration
of the well  established fact,—first, I believe, pointed out by Dr.
Priestley,'  that  venous crassamentum, when  guarded  from the
atmosphere  merely by a thin covering of serum, acquires super-
ficially the arterial hue; indicating the passage, if not the absorp-
tion, of oxygen gas.
  To  try the effect of the solids,—two substances  have been se-
lected as best fitted to give decisive results, viz. cerebral matter and
muscular fibre.  The experiments on the agitation of these sub-
stances have been made in a manner very similar to those  described
on blood and serum.   The brain of a sheep was used—its masseter
muscles and tongue. As soon as the animal was killed in  the usual
way, its  head was removed and brought from the slaughter-house.
The  brain was extracted  whilst  still  warm, and  immediately im-
mersed in  water,  just in sufficient quantity to  cover it: it was

  ' Experiments  and Observations on different kinds of Air • bv Jo^enh
Priestley, Birmingham, 1790, vol.  iii. pp. 365, 370. 
                agency of atmospheric air.             173

cooled rapidly by placing the vessel containing it in runnit g water;
and quickly broken up and reduced to the state of an emulsion. In
this state, with as little water as possible, it was  poured into the
double-mouthed  bottle of the capacity of 32 cubic  inches, provided
with  stop-cocks  and a bent tube, as already mentioned, and well
shaken in atmospheric air for about two minutes.  On turning the
stop-cock, with the bent tube attached connecting it with water, the
water did not rise  in the  tube,—on the contrary, a few bubbles of
air escaped.  The result obtained, using rather more than a quar-
ter of a pound of the masseter muscles, cut into very small pieces
under water, was similar; as it was also, employing the whole of
the tongue divided in the same manner.  The cerebral emulsion,
and also the first mentioned muscle was allowed to remain in  con-
tact with the air  in the bottle for nearly twenty-four hours, without
further agitation; after which, on  turning the stop-cock, there was
a slight rise of the water in the tube; but, I apprehend, not more
than might be fairly attributed  to a change of temperature which
had taken place in  the air of the room in the interval; a fall, name-
ly, from 55° to 51°.  What was the  kind of air disengaged, 1 did
not attempt to ascertain.  It might have been common air expelled,
owing to expansion from  perhaps  a little heat produced  by the fric-
tion of agitation.   Be this as it may. the quantity  expelled was so
very small, that  the  determining  of its nature  would  have been
attended with extreme difficulty.
  As regards the conclusion to  be drawn from these expc riments,
the same I apprehend may be admitted as in the instance of serum;
viz. that  neither muscle nor the cerebral substance perfectly fresh,
have the  power  of absorbing oxygen  in an appreciable quantity;
and judging analogically, it may be  inferred, at  least  as  highly
probable, that the other textures less prone to change, are also desti-
tute of this power.

2.—On the exposure of dead animal matter to atmospheric air,
                    at rest in confinement.

   As  bearing on the subject of putrefaction, as well  as in part on
the last, in relation  to the  animal textures,—I shall give the  par-
ticulars of many experiments made at Malta during the summer
season, on the exposure of dead animal matter to  measured quan-
tities  of atmospheric air, confined in  jars over mercury, at a tem-
perature between 80° and 90°, a heat at which animal matter, as is
well known, is peculiarly liable to change and become putrid.  I
shall first  notice  the results obtained, using blood and its  principal
constituent parts, physiologically considered.
  The blood subjected to  experiment was venous blood.  It was
placed in a receiver over  mercury in a measured quantity of com-
mon air, a few minutes after it had been drawn, having been quickly
coDled by immersion in water.  During the first twelve hours the
volume of air over it was not sensibly changed.  Soon  after there
       n__n                                    12 dav 
174
daw's researches.
^
was a diminution of the bulk of the air, and this diminution gradu-
ally increased.   When greatest, it was nearly equal to the volume
of the blood.  This was accompanied by a change of form of the
crassamentum;  it, as it were, dissolved away, and  an apparently
homogeneous fluid was formed.  And  next there was an augmen-
tation of the bulk of the air.   By examination at different  times,
I found that the volume of air remained unchanged until putrefac-
tion commenced ;l that carbonic acid was formed and  absorbed  by
the blood ;  that the diminution of the  volume of air continued till
the blood was saturated with carbonic acid ; and that its augmen-
tation was owing to further evolution of this  gas, connected with
the formation of ammonia, and the progressive changes of the pu-
trefactive decomposition.2
   The air  over serum of blood confined over mercury  in the same
manner, remained many days without undergoing  any change of
volume; and so  long, the  serum  retained its transparency.   At
length a turbidness appeared in  it,—putrefaction had  commenced,
and the volume of air diminished, owing to the  absorption of car-
bonic acid  gas which had formed.  When the serum was saturated
with carbonic acid gas,—the putrefactive process continuing, the
volume of air slowly increased.
   Results  very similar were obtained, with  the  colouring matter
alone; or (which is more correct)  the mixture of serum  and  red
particles, obtained by pressing  the  crassamentum genlly in  linen.
The changes in this instance were much the same  as  in  the pre-
ceding; they took place more slowly than when blood with all  its
ingredients was employed, and  less slowly than when the serum of
blood was  used.
   The  changes exhibited by the fibrin of the blood  were the most
rapid of all.   In less than twelve hours it lost its firmness; a small
diminution of the volume of air had taken place; a little carbonic
acid gas was found in the residual air, and oxygen had disappeared
about equal in volume to the loss by absorption, together with the
acid gas generated.  In twenty-four hours or little more, the fibrin
had become  semi-fluid or pultaceous;  the oxygen of the  air had
disappeared entirely, or nearly so,  and its place  was  supplied  by
carbonic acid gas, excepting a diminution (which it may be inferred
was carbonic acid gas absorbed) very nearly equal  to  the volume

  ' This may appear contrary to what has  been already stated relative to
the absorption of oxygen by blood ptevious to putrefaction :  but is not in
reality; without agitation, the putrefaction  of blood,  I  believe, commences
[at least at a high temperature,] before the absorption of air by it, is demon-
strable.
  2 The products of the putrefactive decomposition are, I believe, very much
modified by  temperature; so that were the results obtained in  summer and
winter compared, they would be found greatly to differ.  At a low temper-
ature, as between  40° and 45°, in  many instances, I have found both the
blood of man, of the shepp, and of the ox,  to decompose without  evolving
any air: there was a continued  absorption of oxygen, and the  formation of
a large quantity of carbonate of ammonia. 
agency of atmospheric air.
175
of the semi-fluid formed. As the putrefactive process proceeded, the
fibrin divided into two parts—one pultaceous and a  little frothy,
occupying the spot where the fibrin was first put,—the other liquid
surrounding the pultaceous matter ; and the volume of air gradu-
ally increased, carbonic acid gas  being evolved, attended with the
formation of ammonia and the other changes belonging to advanced
putrefaction.
  I shall next mention the results obtained in similar trials on dif-
ferent textures taken from animals just killed, as the rabbit and ox,
—or from the hum n subject a few hours after death.  Paying as
much attenlion as possible to uniformity of temperature, and watch-
ing  the  experiments  carefully, 1 have never been able to observe
any immediate absorption of air. In several instances, as of muscle,
liver, intestine,  &c, there was no diminution but a  progressive
increase of volume from the evolution of air.  In the few instances
in which a diminution of volume did take  place, it  was very incon-
siderable;  and as  this  was accompanied by incipient putrefaction,
and generally attended with the appearance of some carbonic acid
gas, is there not  good reason to infer, that  it was entirely owing to
the  absorption   of  carbonic  acid gas formed, especially as the
moisture of the  part or the fluid which it contained was sufficient
to account for it, and the oxygen which disappeared was equal to
the absorption added to the carbonic acid gas remaining? In corro-
boration of this view,  I may  mention  the  difference of results
obtained,  when  animal  substances were  exposed to putrefaction
under  increased and under  diminished  pressure  by means  of  a
column of mercury acting on the air, in which the substances were
confined,—in one  instance, in the closed  end of  a tube bent up-
wards;  in  the other, in the  closed end of a straight tube, both of
course  placed perpendicularly.   When  the pressure  had  been
increased by the weight of eight inches of mercury, and diminished
by a counterpoise  of sixteen inches, the results were well marked,
especially when  using  very pufrescible substances, as the fibrin of
the blood and muscular  fibre.   With the  increased pressure, at  a
temperature of about 76°, fibrin  being  used, in  twenty-four hours
there was a small diminution of volume of the  air, with just sen-
sible marks of putrefaction having begun  ; whilst  with the dimin-
ished pressure, there was a small increase of volume and a manifest
appearance of putrefaction having  commenced.  Now, it  follows,
of course, that the carbonic acid gas first  formed would be more
powerfully absorbed, and retained with the increased than wilh the
diminished pressure; but if oxygen was absorbed chemically, there
is no reason to suppose  it would produce  any  difference of effect
except in degree.
  The experiments, of which I have just related the  results in
part, were, as already  mentioned, all made  at a comparatively high
atmospheric temperature,—favourable to rapid putrefaction.   The
degree  of rapidity of change, I  may remark, varied  according to
the  nature of the  texture.  Brain, muscle, spleen, liver, and  the 
176
davy's researches.
substance of the glands generally, produced the most rapid change.
In a  few hours carbonic acid gas  might be detected in the air
exposed  to them;  and  generally in  less than twenty-four hours
there  was air generated, and an increase in the volume of the  air.
The soft white parts were next in degree of rapidity,—such as the
cutis, periosteum, dura mater, and I  may  add, stomach, intestinal
canal, vein, artery, and  adipose structure.   Over  these, in about
twenty-four hours, carbonic acid gas could generally be detected in
the air; and generally, in about forty-eight or seventy-two hours  a
little  air was generated.   Tendon, intervertebral substance, carti-
lage, cuticle and bone, were slowest in progress.   In two or three
days  carbonic acid appeared in  the  air in which  they were con-
tained ; but  many days elapsed  before there was  any increase of
volume indicating  the generation of  gas,  excepting the  parts
belonging to a young animal.  After the putrefactive process had
commenced, it proceeded, although the oxygen of the atmospheric
air was entirely consumed: carbonic acid gas continued to be dis-
engaged, in which sometimes a little carburetted hydrogen might
be detected, and sometimes a little sulphuretted hydrogen;—ammo-
nia was constantly formed;  but  I have not been able to satisfy
myself that any azote was either  absorbed or evolved, at least in
the early period.   The appearance of carburetted hydrogen was
most  striking in the instance of muscle; it occurred irregularly;
sometimes early in the  process, more frequently at a later period;
one day, it might be  detected in the air generated,  not in the next.
A softening of the parts, like a deliquescence, always marked  the
progress of the change, and most of  them  became  pultaceous.
After about a fortnight or three  weeks, brain, muscular fibre, the
parenchymatous substance  of the glandular structures  and  the
spleen, were reduced to a very soft stale, and on washing them, the
soft matter, the result of putrefaction, was removed, and the vascu-
lar structure of the  part well displayed; and in  the  instance of
muscle, the tendinous attachments also, and the aponeuroses: and
these in their turn yielded  and became decomposed,  the process
being allowed to continue, as I shall  have a  better opportunity of
describing in  the  next  section, when noticing the same  changes
taking place in the open air.

3.— On the exposure  of dead animal matter to the atmosphere,
   under circumstances favourable to putrefaction,—icith a view
   to the question,  Is the putrefaction of animal  matter attended
   with an elevation of temperature?

   I shall give in some detail the  experiments which I have made
to endeavour to determine this question.  It may be premised, that
they were all made at the same  time and place as the preceding;
that the subjects of them, as  soon as possible, after they were taken
from  the body, were put  into glass vessels,  lightly covered with,
and muffled in dry flax, for the purpose of diminishing the  infill- 
AGENCY OF ATMOSPHERIC AIR.            177
dice of the atmospheric air, as a cooling medium; and that a ves-
sel holding water, was placed contiguously, for the sake of com-
parison in  relation  to temperature.   I shall commence  with the
blood and its different ingredients or  parts  into which  it may be
separated out of the body ; and from them proceed to the  solid tex-
tures.
  Blood.—On the 19th August, about a pound and a half of venous
blood, taken from  a young man, labouring under a slight febrile
ailment,  moderately firmly  coagulated, having  been abstracted
about three hours, was broken up, so that the colouring matter, the
fibrin and serum were well mixed, and immediately put into a glass
vessel  in the  manner premised for observation.   On the 20th at
noon, its temperature  did not differ from that  of the wafer  conti-
guous.  At 6 p. m. of the same day, when the  temperature of the
water was 78°, that of the blood was 80°, and its  odour was pecu-
liar and rather offensive.  On the  21st, when the  water  was 79°,
the blood was the same as the day preceding.  On the 22d, when
the water was  80°, the blood at the surface was 82°, and a little
below the surface 81°.  Its smell was offensive and  ammoniacal,
and its  liquidity was  increased.  On  the 23d, the temperature of
the blood was the same as that of the water; and  so it continued,
whilst slowly undergoing decomposition.
   The colouring matter of blood.— About two pounds of the co-
louring maiter  of the blood of an ox, from which the fibrin had
been separated in the  usual way by agitation, but not deprived of
serum, was exposed to observation on the 19th of August.  It was
examined once or twice  daily.  Its temperature never rose percep-
tibly above  that  of the water.  On  the 22d,  it  had an offensive
smell, and mixed with lime, gave off an ammoniacal odour.   In a
few days the odour became more strongly ammoniacal  and less
offensive ; and so it continued afterwards, whilst gradually under-
going the changes peculiar to its very slow decomposition.
  Serum of blood.—The observations which I have made on the
putrefactive decomposition of this fluid, do not  indicate any  sensi-
ble elevation of temperature attending  it: a result,  which  might be
expected, considering that its putrid changes take place very slow-
ly, and that many months are required for its complete decomposi-
tion, whether  the quantity of serum be large or small, and  even
when freely exposed to the air in a damp atmosphere.
  Fibrin of blond.—On the 19th August, at 4 p.  m. the fibrin of
the whole blood of an ox was separated in the usual manner,  by
agitation, and was immediately well-washed and drawn out loosely,
so that its surface might be well exposed to the air.  In its moist
stale, as it was placed  for observation, it weighed about four ounces
and a quarter.   On the following day,  when the water was 78°,
the fibrin about an inch below the surface was 85°; its odour was
peculiar but not fetid ; this was about  noon.  At 2 p.  m. the  water
being of the same temperature, the fibrin was 90°; iis odour was
peculiar and  rather offensive.   At 6 p. m. the water the same, the 
178                 davy's researches.
fibrin had fallen to 87°.  It had become soft, as it were melting or
deliquescing, and in consequence had subsided so much, that it oc-
cupied only about half the space it did when first introduced, and
of course was much  less exposed to the action of  the air.   It was
slightly alkaline, and a  little  of it, mixed with hydrate of lime,
emitted a distinct ammoniacal odour.   On the 21st, the water be-
ing 79°, the fibrin was only 80°. It was  semi-fluid,  of a light brown
colour,  and had  a peculiar,  rather disagreeable  smell, distinctly
ammoniacal.  On the 23d, its temperature and that  of the water
were the same; it was of a light gray  colour, so  fluid as to admit
of being poured out in drops, and it had a pretty strong and tolera-
bly pure ammoniacal odour.   After  this, there was no sensible ele-
vation  of  temperature attending the  changes which slowly took
place during its progressive decomposition.
   These experiments on the  blood  and its ingredients, 1 may re-
mark, are not solitary ones ; they have  been repeated several times;
and the results have been similar;  and similar generally, so far as
I have observed,  whether the  subject  was the blood of the ox or
human blood.
   Muscle.—On the 25th August, the psoas muscle of a man who
died the same day, and of whose case 1  shall take brief notice in an
appendix, as No.  1, was placed for observation.  No change of tem-
perature was observable till the 27lh ;  (hen it was 2° higher lhan
the water ;  its odour was not putrid.   On  the following day, its
temperature was the same ;  its odour peculiar  and disagreeable,
but not distinctly fetid;  its surface  was sprinkled with the ova of
flies, and with  minute larvae.  On  the 29th, it was  3° above the
water.   On the 30th, at the surface, it was 5° higher, whilst about
an inch below, its temperature was the same  as that of the water.
Ou its surface there was some  froth, and larva in great abundance.
Tiie odour of the surface was peculiar and  ammoniacal;  of the
part below  the surface, peculiar, but  not distinctly ammoniacal. On
the 3isf, it was 7° above the water,  when  larvaa abounded, and
were  feeding  voraciously, and there  was a strong ammoniacal
odour.   The experiment was then interrupted by excluding atmos-
pheric air; the froth  subsided, the larvae died, and the temperature
of the  part fell to that of the water.  A  similar experiment was
made with  the ventricular portion of the heart of the same subject,
and with precisely similar results.  Other experiments have been
made in a somewhat  different  form, and results have been obtained
also somewhat different.  When flies have been excluded, muscle
has undergone a  comparatively slow  change;  it has  gradually
softened, become  unctuous, acquired a peculiar odour, lost its co-
hesion, and has become converted into a reddish semi-fluid, not un-
like chyme, with a very strong ammoniacal odour. In one instance,
this change took  place between the 6th and the  21st of August.
The temperature was not elevated more than  2° at its  maximum.
When the muscular fibre was unravelled, and an extensive surface
exposed to  the air, the change was  very much more  rapid : the 
AGENCY OF ATMOSPHERIC AIR.
179
conversion of muscle  into pultaceous fluid took place in six days,
and the temperature was elevated 7°.
  Brain.—I  shall give two different experiments  made on  this
organ entire, or nearly so, deprived of its membranes, belonging to
bodies No.  I and 2.   That on  No.  2/was commenced on the 14th
July.   On  the 15th, its temperature and that of the water were the
same, viz.  76°.  On the 16th, at its surface, it  had risen 3° ;  whilst
the  deeply  seated portions varied according to their depth, from
2° to  1°.   The surface was then  soft, brownish  and fetid ; what
was below  the surface was apparently little altered.  The tempera-
ture of the brain  continued  increasing till the 21st, when  it  had
risen 11°, then its surface was covered with froth; larvae of large
size were in great plenty, and were feeding greedily;  and the odour
was strongly ammoniacal.  From this time the temperature gradu-
ally fell. "On the 31st, it was only 2° higher than the water;  on
the 1st  August only 1°; and on the 4th, there was  no difference,
At this  time, its surface was  gray, soft, of saponaceous appearance,
free from larvae, and emitting a powerful ammoniacal odour ; and
even then,  two inches  below  the surface, it appeared to be but little
changed.   The experiment  with brain No. 1, was begun  on the
25th July.  The highest temperature attained by it was only 1°
above that  of the water; and on the 11th August, it was the same
as that of the  water.   In this instance, the number of larvae gene-
rated on its surface was less  than in the former; their growth was
less rapid ; they  fed with less avidity—the surface  was  compara-
tively  tranquil, and the ammoniacal odour comparatively  faint;
and latterly a rancid peculiar odour was rather predominant.
  Lung.—It belonged to  body No. 1, and was put into the vessel
for observation, divided into  portions not very  small.   The highest
temperature which it acquired was on the  30th July, then the wa-
ter being 77°; its temperature, at  the surface, and  just below the
surface, varied from 78° to 90°.  Where the low temperature  was
observable, there it was  tranquil and  without larva?; where  the
temperature was  high, there  larva?  abounded and  were in great
activity—the  space they occupied  was surrounded by a margin of
froth, the  ammoniacal odour was  strong, and the portion was be-
coming of  a  blackish hue and liquid.  The experiment was then
interrupted by the'exclusion  of air.  On the following day  the
larvae appeared dead,  and the  temperature had fallen to that of the
water.  On the 2d August, atmospheric air was re-admitted. The
temperature of the whole, never  again exceeded that of the water
perceptibly, though it  did partially,  as in poitions where larva? were
collected feeding,"and where froth  was produced: thus, on the 6th
Auo-ust, whilst the surface  in  general was covered  with a grayish
byssus, and w.u- only  at the  temperature of the water, in one spot
about  an  inch in diameter it was 6°  higher, and there in the midst
of froth, there was a  brood of larva? rapidly growing and  eagerly
feeding.  On the 27th August, the whole presented  the appearance
of an inky fluid, of the temperature of the water,  and strongly am- 
180
davy's researches.
moniacal,  apparently deriving its  black colour from carbonaceous
matter liberated  and suspended, mixed  with particles of cellular
tissue, and at  the  bottom with shreds of pleura and fragments of
vessels, which  became apparent on washing.
  Liver.—It belonged to body No. 3,  and was placed for observa-
tion on the 3d  August.   On the 5th, its temperature was the same
as that of  the water; its odour was offensive, but not  ammoniacal;
a good deal of reddish fluid had exuded, and a little air was in the
act of disengagement.  On the 4th, in some places it was  ln higher,
and in others 2°.   Where highest, some froth was produced, and
many small larva?  were feeding.   The  temperature gradually in-
creased till the 10th, when it was raised  12°; its surface was co-
vered with  larva?  feeding  voraciously in froth, and nearly full
grown, and the odour  was powerfully  ammoniacal.  From this
time it gradually decreased, till, on the 13th, it did  not exceed that
of the water ;  most of the  larva?  were dead ; the odour was very
ammoniacal;  the surface was  free from froth, and of a dark brown
colour, in  some places almost black and of a soft pultaceous con-
sistence.   Beneath  the surface the  change decreased with  the
depth; and  in the lower part, the  liver was comparatively little
altered ; its parenchymatous substance was softened, of a gray hue,
and easily removed by gentle pressure, aided by a stream of water;
whilst the vascular structure, (at least all  but the  very minute
branches) retained sufficient strength to resist the pressure and wa-
ter, and accordingly became well displayed by the operation.
   Intestines.—These were from body No. 4, and were  placed for
observation, after  having been washed  out, on the 3d of July.
Their temperature on  the 4th was  the same as that of  the water,
though the odour arising from them was offensive.  On the 5th
their  temperature was 2° higher ; on the 6th the same as  that of
the water; and so it continued, although a great deal of fetid air
was disengaged,  and  the  surface  had  become  pultaceous and
emitted an ammoniacal  odour.  The stomach of  No. 1 afforded
results very similar.  Its temperature never  exceeded that of the
wafer more than  1°, and  that only  partially, where a few larva?
were  feeding,  and  a  little froth  was excited.   And, in both in-
stances, below the  surface two or  three inches, there  was little
change.   After a month, the parts appeared entire;  but, on minute
examination, after having been well  washed, the tissue which re-
mained seemed to  be chiefly the submucous  cellular  and the peri-
toneal; neither the inner coat,  nor  the muscular, could le recog-
nized ; and even the white tissues were, in  part, losing their cohe-
sion, and exhibited  evident marks of slow decomposition being in
progress.
   Cutis of inside of thigh, dura mater, tendo achillis.— These
parts were taken from body No. 1, and were placed together in the
same  vessel for observation.   They  underwent change slowly;
their  temperature  gradually rose  till  it  was  3° above That of the
water,  viz.—on the 31st July, when the odour from them was 
AGENCY OF ATMOSPHERIC AIR.
181
slightly ammoniacal, their surface unctuous, and there were a few
larvae feeding.  After the 2d August, the difference of temperature
was 1°, and it was the same on the  15th of that month.  A good
deal of yellowish  pultaceous  matter was  formed,  by which  the
parts were  hid.  It was washed off, and  the different textures were
found  nearly equally changed ;  their cohesion irregularly  dimin-
ished;  the  fine connecting tissue, or most delicate fibre, dissolved
entirely or  in part;  holes formed in the two  first mentioned tex-
tures, and the coarser fibres, or fasciculi of fibres, separated in the
last.  On the 1st September they were all reduced to an  ammonia-
cal pultaceous state, in which only a few minute tendinous fibres
were distinguishable.
   Aorta.—A portion of this vessel, belonging to body No. 1, placed
for observation, was  1° higher than the water on the 30th July.  It
had a peculiar and  ammoniacal odour, and its  surface was becom-
ing  unctuous, especially its compact fibrous-  sheath, or the third
coat from the inner one.   On the lllh August there was an eleva-
tion of 3°; a good deal  of light brown pultaceous matter had
formed ;  the odour  was strongly ammoniacal,  and many larva?
were feeding.  On the 16th August,  it was entirely  converted into
a semi-fluid opaque mass, of a light  brown  colour, and strong am-
moniacal odour, and its temperature was the  same as that of the
water.   I have also  made trial of the  different coats of the aorta,
placed  apart for observation, viz.—the  loose  outer  cellular,  con-
taining some fatty matter—the adjoining compact cellular, or rather
fibrous—the next commonly called the middle coat, and the inner
coat—taken from body No. 5.   The changes  in  all of  them pro-
ceeded much in the same manner as  has been described in the pre-
ceding instance, with the exception of the  loose  cellular coat,
which, in that instance, was excluded ; it did not keep progress
with the rest.—after a month's exposure it was  very  little changed.
   Intervertebral substance.—A portion from the lumbar spine was
taken from body No. 5, on the 7th of August.  On the 13th, it had
a peculiar odour, neither putrid nor ammoniacal.  After a  month,
it  was  very little changed ;  and, during that time, its  temperature
was not sensibly elevated above  that of the  water.  From other
experiments, I have ascertained, that a  very long time is required
for the decomposition of this substance, and that even after a year,
it  is not very considerably changed.
   Besides  the preceding, I have  made trial of other parts, as the
pancreas, kidney, spleen, prostate.  They have undergone  change
rapidly like the liver; their  temperature  has been considerably
elevated ; they have all softened, as it were  liquefied like fibrin,
and ammonia in great quantity has been generated.
   I apprehend, more than sufficient has been adduced, in  the  re-
sults of the preceding observations, to decide the question proposed
__u Whether or no  the putrefaction of animal matter is attended
with elevation of temperature?"  It  seems proved that those parts
which undergo rapid change, as the  fibrin of the blood, brain, mus- 
182                 davy's researches.

cular fibre, and  the  parenchymatous  substance  of the  glandular
structures, give off a good deal of heat in being converted from the
solid into the liquid form: and, as  other  parts undergo a'similar
change, and  are  ultimately reduced to a  liquid pultaceous state,
and as, in some of them, there is a  small  elevation of temperature,
may it not be  fairly inferred,  that the  apparently inferior degree of
heat generated by them, is  merely  owing  to  slowness of change :
and, accordingly, whatever accelerates the process of  decomposi-
tion, seems to  promote increase of temperature. Minute mechanical
division has this effect in a remarkable  manner, as was witnessed
in the instance of the fibrin  of the blood, and of muscular  fibre ; the
effect is probably owing to the very extensive surface exposed to
the action of atmospheric air.  The presence  of larvae too. has the
same effect very strikingly, and probably in the same way.   They
tend to separate the  parts,  to agitate the surface, and to  introduce
air  beneath  the surface.   It is curious to watch the  progress of
these animals in their growth, and still more so in their operations.
When their food is very nutritious,  the almost microscopic  ova, in
forty-six  hours are converted  into large maggots.  When they have
nearly attained their full size, they feed  with extraordinary vora-
city, as if aware that th^ir lives depended upon their activity. The
whole of a numerous brood might  be observed, side by side erect,
with one extremity in the  ammoniacal pultaceous mass, pumping
up  nourishment, and  with the other and narrower extremity in the
atmosphere, the orifice of its canal dilated, seeming  to pump down
air; and in the act, by the difference of the specific gravities of the
two fluids—it may be inferred that the perpendicular  position of
the larva; is  maintained, whilst probably  by the  action of one on
the other, a compound is formed fit  for assimilation and for forming
a part of the  new animal, the putrefactive  process at the same time
being accelerated.  It appeared probable at first view, that the larva?
themselves might  generate and possess a  comparatively high tem-
perature; but, on the whole, the  observations which I  made to
endeavour to  determine this  point,  are not in favour of the notion.
When  the larvae are distended with  putrid matter, exhaling ammo-
nia  and  rapidly undergoing change,  then  their  temperature, as
might be expected, is always above that of the  atmosphere ;  but,
when they are free  from putrid matter internally and externally,
although collected together in a large number, in a small space, as
in a phial, a delicate  thermometer placed in the midst of them, did
not indicate  the generation of any  sensible degree of heat.   And,
in conformity with this, I found that the larva? by themselves viti-
ated the air very slowly; indeed, I believe that  their dead  bodies
vitiate it more rapidly than their living.  The changes in ihe dead
bodies, in putrefying and becoming  semi-fluid, accompanied  by the
formation of carbonic acid and  ammonia, are more rapid than the
changes in their living  bodies in passing from the larva? through
the chrysalis state to that of the imago, or in becoming as it were
solid, which change seems to be accompanied chiefly by the ex ha- 
                 AGENCY OF ATMOSPHERIC AIR.              183

lation of water, and  the  formation  of a very little carbonic acid
gas.   Mixture  probably is  another  circumstance  which  favours
and accelerates the putrefactive process and the evolution  of heat.
The two circumstances already  adduced may  partly act in this
manner, as well as by exposing a  greater surface to the air. In the
saccharine or vinous fermentation, the  effect of mixture is well
marked.  So long as the sweet vegetable juice  is retained  in the
tubes or cells of the  plant  or  fruit,  it resists  change ; but, the in-
stant the tubes are crushed, and the cells broken down, the fermen-
tation under favourable circumstances commences.  I suspect some-
thing similar to  this happens  with animal matter.  It is known to
every one that bruised  meat putrefies very rapidly.   An egg, care-
fully put by, exposed  freely  to  the atmosphere, without any cover-
ing over its shell,  will remain free from putridity for months ;  and
in a dry atmosphere,  will  lose the  greater proportion  of the water
which it contains, and  on breaking  it, the yolk and  white will be
found dry and  contracted.   But,  if  the  yolk  and  white  are inti-
mately  mixed  by violent  agitation,  then, I believe,  the mixture,
even  in the  shell, will soon  become  putrid.   Cer'ain I  am  that
when freely  exposed to  the air, out of the shell,  the  yolk being
merely immersed in the white, they do not putrefy, though,  if the
two are mixed, in  a short  time they undergo  a change ;  they be-
come highly putrid, and the temperature of the mixture rises seve-
ral degrees.

     4.—Some general remarks on the putrefactive process.

   What is animal putrefaction, or the putrid  fermentation?   I am
not aware that this question  has yet been replied to, in a satisfactory
manner, or that  the present state  of our information is such as to
admit of making the reply free  from many obscurities.   The little
information I have collected bearing on the subject, I shall  bring
forward without hesitation.  Under diminished pressure, conducted
in tubes over mercury,  the  putrid fermentation appears in some of
its changes analogous to  the vinous.  The elements  of vinous fer-
mentation appear to be leaven, which remains  unaltered,1 and sugar
which undergoes change; and  the helping circumstances, a certain
degree of dilution  with  water, and a  certain temperature.   The ele-
ments of the  putrid fermentation are less distinct.   If there be, as
is probable, an animal leaven, it has  not yet been isolated.  Whether
the presence of oxygen is  essential to the commencement  of the
vinous fermentation is matter of doubt. But the presence of oxygen

  1  The same portion of leaven may be  repeatedly used.  I have preserved
the leaven obtained  from the grape for nearly twelve months, by pouring off
the fermented fluid, as soon  as the leaven had subsided, and adding fresh
su"ar and water.   How leaven acts is one of the  mysteries of chemistry,
and there are others of  a  like kind—as the influence of carbonate  of lime in
the formation of saltpetre—of  sulphuric acid in the formation of sugar from
starch, &c. 
184                  davy's researches.

seems  to be undoubtedly necessary to  the commencement of  the
putrid  fermentation, and only to  its commencement, as we have
seen that it goes on over mercury, after atmospheric air has been
entirely excluded.'  The products of the vinous fermentation in  the
simplest form, appear to be very few.   Alcohol is the only liquid
product known—and carbonic acid gas I believe is the only essen-
tial gaseous product.  The disengagement of azote, probably, when
it occurs, is accidental; may it not be referred in the early stage
of the process to the atmospheric air entangled in the materials, and
in the advanced stage to the decomposition of a little leaven?   I have
made many experiments on this subject, which have led me to this
conclusion.  The  products of the  putrid fermentation seem to be
more numerous.   Carbonic acid gas is the  principal gaseous one.
Sulphuretted hydrogen, and  carburetted hydrogen,  may be  occa-
sionally detected.   Azote, I believe, is not disengaged, excepting at
a very advanced period, when,  probably, the products themselves
are decomposing.   The products  not  evolved in  the gaseous state
appear to be chiefly ammonia, kept down in confinement a while by
carbonic acid and water; and a substance, or matter in a semi-fluid
form which has a considerable resemblance to chyme, and which
appears to  be the proper food  of the larvae of many different kinds
of the  extensive genus  Musca—some  preferring the matter from
muscle, some from tendon, &c.  And this  matter itself seems to
undergo decomposition, and to be converted into ammonia, and a
substance more resembling  extractive  matter after  it has been  ex-
posed to the air, than any other with which I am acquainted, except-
ing one, procurable by the spontaneous decomposition of some kinds
of vinegar to  which atmospheric air  is allowed to  have access.
During the decomposition of the  vinegar, carbonic acid is formed
by the union of carbon  with oxygen.  The vinegar gradually loses
its acidity,  and at the same  time a pellicle forms on its surface, and
gradually  increasing,  becomes  a  thick, strong, tough, transparent
membrane—elastic, strong, and transparent when dry, insoluble in
water, and having great power of resisting change, whether acted
on by heat, by acids,  or alkalies.   Very analogous  to this, is  the
substance  alluded  to, which  1  have witnessed on the surface of
serum and fibrin, and of several solid parts in water in experiments
on their putrefaction, continued from six to twelve months.  The
product from vinegar does not contain azote;  that from the animal

   1 From experiments already related, it appears that venous blood as well
as arterial, contains oxygen in a peculiar state of combination associated with
the red particles: this oxygen  may be sufficient to excite putrefaction after
death, in every part  of the body penetrated by the blood independent of the
atmosphere; and  to account for the very rapid manner  in which bodies pu-
trefy, if abounding in blood, as is often the case in instances of sudden death,
and for their putrefying under water in  insfances of death from drowning.
The very tympanitic state  which bodies acquire so circumstanced—indicates,
that their different textures, especially the integuments, are little pervious to
air—which is also in accordance with the results of Priestley's observations
on the power of  bladder when thoroughly wet to confine air. 
AGENCY OF ATMOSPHERIC AIR.
185
fluids and textures  has  afforded ammonia when decomposed with
lime, at a red heat; but, as I am  not sure that any specimen of it
which I have yet examined has  been  perfectly pure/ I cannot be
certain  that this  difference  of  composition  really exists  between
the two.
  Under ordinary atmospheric pressure and exposure to the atmo-
sphere, the results of the putrefactive fermentation are various and
modified; the circumstances become complicated, and the difficulty
of appreciating them is vastly increased.  The gases generated and
absorbed, in part seem  to  react, and to exert a powerful modifying
influence, both as retarding putrefaction and giving rise to combina-
tions which have a similar tendency; and  inspissation at the surface
from evaporation, by forming a crust, more or less impervious to the
air generated beneath, as well as to the  external air, has a similar
effect. Carbonic  acid gas is powerfully antiseptic—so are ammonia,
and carbonate of ammonia, and sulphuretted hydrogen, as I have as-
certained by experiments  made expressly for  the purpose.  Thus,
blood saturated with carbonic acid gas, did  not putrefy so soon, as
another portion to which none of the acid  gas was added. A solution
of the sesquicarbonate of ammonia, in the proportion of three grains
to the ounce of water, prevented the putrefaction of a portion of mus-
cle immersed in it about a month; and a solution of the strength of
five grains to the ounce of water,  preserved a piece of jejunum more
than eight  months, and I know not how much longer; and displayed
the minute structure of the part, in a very striking manner.   Re-
duction of temperature is another  disturbing circumstance, which
tends, I believe, to give rise to new combinations, especially to the
formation of adipocire, and to render the problem as  to the changes
which take place more complicated.1  Even in this view of the sub-
ject, there  is no want of similarity between the putrid fermentation
and the vinous;  and  a considerable degree  of analogy might be
 traced, very far, were  we to consider the particular agents which
 retard or prevent  the two kinds of-fermentation ;  indeed, I am not
acquainted with a single agent, or circumstance, the  effect of which
is limited to the vinous, or to the putrefactive  fermentation.   They
 all appear common to both, and also to the fermentation of vegetable
 matter generally.   Such is the effect  of  corrosive  sublimate, of the
 sulphurous acid, of tannin, of salt, vinegar, alum, spirit of wine, su-
 gar, &c. These circumstances, just related, prove some resemblance
 between the two kinds of fermentation, in their general phenomena
 —in the causes  which promote and  accelerate, and those which
 retard  and prevent them.   The leaven which excites vinous fer-
 mentation, closely resembles an animal substance in composition
 and in many of its properties, and is even analogous to fibrin.  Like

   • Adipocire,  I believe, like peat, never forms where the atmospheric tem-
 perature is  high; I have never witnessed the production of either of them in
 warm climates, excepting, in the  instance of peat, on mountainous regions,
 where the average temperature is moderate, and in that of adipocire, during
 the cool months, in the Mediterranean. 
186
davy's researches.
fibrin, it is capable of undergoing the putrid fermentation;1 and the
fibrin and muscular fibre act as leaven with sugar and water, and
give rise to fermentation.  Whether the fermentation, thus excited,
is similar or not to the ordinary vinous fermentation  remains to be
shown.  I suspect it is  not similar in all its products.   Carbonic
acid gas is disengaged; the muscle or fibrin is prevented from putre-
fying— and if tainted, is corrected; but, I am not aware that alcohol
is formed.  In one instance, the  sugar, by the fermentation, appeared
to be convened into gum. powerfully absorbent  in water—but very
slightly soluble in water.  It was the result of  three or  four days
fermentation of a solution of refined sugar in waler, excited by a
small portion of beef.  It appears  too, not improbable, that a prin-
ciple may exist,  contained in the  fibrin of the  blood, in  muscular
fibre, and in the parenchymatous substance of the very putrescible
organs in large proportion, which may act as leaven in animal coin-
pounds; and I might mention  some facts in support of the notion,
were I not apprehensive of extending this  part of the subject beyond
its due limits, and the more so, as I wish briefly to advert to one or
two  other points of considerable theoretical interest.
  After witnessing the change  which takes place in muscular fibre,
in consequence of putrefaction  giving rise to a fluid very like chyme
in appearance, I was disposed  to ask, may it not  be concerned in
digestion itself, according to the earliest theoretical notions on this
subject? and also, after observing the effects of the putrefactive pro-
cess in  raising the temperature, inquire, may it  not in the stomach
and  intestines, be one of the sources of animal heat?
  Meat slightly putrid, we know, is highly nutritive, and very easily
digested.   When meat is  becoming  tender by  keeping, it is in an
incipient state of putrefaction;  the muscular fibre is losing its cohe-
sion; the textures generally in a very minor  degree  are doing the
same, and carbonic acid gas is forming,  as I have ascertained by
experiment.  Now,  as we know,  that carbonic acid  gas  is formed
in, or disengaged from the  stomach and intestines, even  when the
function of digestion  is apparently in  its  healthy state, it does not
seem unreasonable to consider this gas a product of digestion, almost
as much as of fermentation.  The  other gases, as sulphuretted hy-
drogen, and carburetted hydrogen, occasionally evolved during the
putrid changes, are frequently  generated in the alimentary canal;
and, the contents of the stomach, and of the whole intestines are
seldom, I believe, destitute of  ammonia.   In relation to this last
mentioned  product of the putrid fermentation, I may  mention, that
whenever I have sought for it after  death,  either in the human
stomach, or in  the duodenum, jejunum,  or  ileum, 1 have always

  ' It also promotes destructive decomposition in vegetable matters in them-
selves little prone to change.  I remember witnessing this effect in a striking
manner in a piece of fine table-linen which was sent to the Mediterranean,
with other things, and  amongst them a bottle of yeast, which burst on the
voyage; the damask was to a considerable extent destroyed, but only where
the yeast had come  in contact with  it. 
AGENCY OF ATMOSPHERIC AIR.
187
found if;  and 1 need not add, that I have always  found it in the
large intestines, and in instances in which  the post mortem exami-
nation was made before there were any indications of putrefaction
having commenced  in the solids or fluids generally, and when am-
monia could not be  detected either in the blood,1 the bile, the brain,
or the  muscles.   The result  of  the examination of animals just
killed, and which I have made in relation to this point, has not been
less conclusive.  In one instance, 1 had a hungry dog, fed at three
different times during the twenty-four hours, with fresh beef.  Three
hours after the last feeding, he was killed.   All the meat given him
had disappeared, excepting the last meal; and the portions of beef
of which  it  consisted, were very little  altered: yet,  triturated with
hydrate of lime, they gave off a distinct ammoniacal odour—so did
a little whitish chyme in the pyloric extremity of the stomach;  the
chyme in  the duodenum gave it off more strongly; a thin yellowish
fluid in the ileum  not less so; and the  contents of the  large intes-
tines in a  hardly less degree.   I  examined the blood,  both  venous
and arterial,  the chyle, the bile, and several of the solid parts; but
none of them afforded, by the test of lime, the slightest trace of am-
monia, not even the kidneys,  although  the  urine abounded in am-
moniacal  salts, and emitted on the addition of lime a most powerful
ammoniacal odour.  These circumstances  seem in  harmony with
the old hypothesis—that putrefaction is  concerned  in digestion.
  In opposition, many facts may be stated, tending to show, that
digestion  is a specific action,  or  series  of actions—that its pheno-
mena are  vital,  or in  other words, peculiar, mysterious, and inex-
plicable according to the present state of our knowledge.  Many of
the results of the experiments of Spallanzani,  and Stephens, are of
this character.   Contrary to the idea of putrefaction, the contents
of the stomach are generally acrid ; and the acidity diminishes almost
gradually  from the stomach  to the rectum.  Ammoniacal salts do
indeed exist in  the stomach and intestines; but in a  healthy state, 1
am not aware, that ammonia, or the carbonate of ammonia, has ever
been delected in these organs; and  consequently, the principal pro-
duct of putrefaction  is found wanting.2    Moreover, putridity seems

  ' In the trials referred to above, the blood and other parts were mixed with
quicklime, and the absence of ammonia was inferred, if no ammoniacal odour
was perceptible.   Recently, I have had recourse to a severer test of the vola-
tile alkili, viz.  bringing near the  mixture under trial, a glass rod moistened
with  muriatic  acid,  so diluted,  that no fumes were produced, merely by
aqueous vapour.   Using this  means, in every instance, 1 have detected am-
monia in the  blood, even when it has been extracted from the body very
soon after death.  The degree of effect, however, has very much varied; in
some cases, in which the blood-particles'appeared  under the microscope very
little, if at  all  altered—the indications of ammonia  afforded were only just
perceptible:'on the contrary, when the colouring matter of the blood was par-
tially dissolved in the serum, and the forms of the blood-particles were
altered, then the indications of ammonia were strong.
  2 This, it may be said, is  owing to  the presence of a  stronger acid, such
as the ruuriatic, which seems to be, from the experiments of Dr. Prout, an 
188
davy's researches.
to be corrected in the stomach, and its natural progress stopped.  T
shall not lay stress on meat introduced in a putrid state into the sto-
mach, having been taken out after a time free from taint, as it may
be said, that the  putrid particles may have  been  destroyed, modi-
fied, or removed, as happens when  tainted meat is placed in a sac-
charine fluid in a state of fermentation.   I would rather adduce the
fact, which I have witnessed, that  muscle which  has been in the
stomach  some time, when  taken  out  and exposed  to the atmo-
sphere, does not putrefy more rapidly, but in a remarkable  man-
ner resists putrefaction.  The substance or matter derived  from
muscular  fibre,  undergoing the putrefactive  change,  is  indeed
not unlike chyme in appearance, whether viewed with the naked
eye, or with the microscope—both of them abounding in  minute
particles  and containing some globules.  But of how little value
is such  a remark—and  how little to be  insisted  on !   Many
different semi-fluids  might  be  mentioned bearing as close a resem-
blance.   It is more to the purpose to compare the matter resulting
from putrefaction with chyle.  How great is the  difference of the
two!  The chyle is alkaline, and yet contains no sensible quantity
of ammonia; there is no reason to suppose that it contains any free
carbonic  acid; it seems as if it were altogether a new formation.
Chyle derived  from  the muscular  fibre  of the ox, in the thoracic
duct of the dog, or that of the ox derived from  grass, consists of a
milk-like serum, coagulable  by acids, and of lymph spontaneously
coagulable, resembling  the  fibrin  of the blood in  its manner  of
coagulating, and gradually  contracting,  and resembling it  also  in
its manner of undergoing the putrid decomposition on exposure to
the air by deliquescing, as it were, or becoming semi-fluid.  I will
not say how incompatible all this appears to  be with putrefaction,
but more, how inexplicable in relation to our  imperfect knowledge
of the chemical changes taking place amongst the  elements of mat-
ter destitute of life, or beyond the influence of the vital organs.
   If putrefaction is not  admitted to be concerned in digestion, the
second question asked above is answered as regards it—" Whether
in the stomach and intestines it may not be a source of animal heat?
But substituting digestion for putrefaction, an answer still may  be
required.  The circumstance that some carbonic acid gas is formed
in the stomach and  intestines, (supposing  that which is found, is
formed there,) is favourable to the idea  of digestion being an auxi-
liary source of heat.   The observations  which I have made on the
temperature of the stomach  in animals, is also  in favour of the idea:
I have often found it as high as that of the  heart, and sometimes.
though rarely, a degree higher.  The conversion  of a solid into a
fluid, as of solid  food into chyme,  or  chyle, appears rather an ob-
jection to the notion.   But, I am not sure that is a valid objection,
when properly considered, there being so many remarkable execp-

active agent in digestion, and which of course, if free, would unite  with any
free ammonia formed; so far weakening the above argument. 
AGENCY OF ATMOSPHERIC AIR.
189
tions of the kind, even in instances in which the change of form is
greater, as in that of the conversion of a solid into a gas, accompa-
nied by combustion, without condensation, even  of the supporter of
combustion; and vice versa, of the formation of a solid from the
union of two gases without change of temperature.  Neither am I
aware of any remarkable change of form of an animal or vegetable
substance, which is accompanied either by absorption, or by  evolu-
tion of heat.   The fibrin of the blood appears  to coagulate with-
out change of temperature;  no heat  is evolved when serum is
coagulated  by an acid; none when  a strong solution  of gum is
coagulated  by sugar of lead; none when milk is coagulated  by
rennet.
  The influence of the various secreting organs on the animal tem-
perature  is, no doubt,  highly deserving of inquiry and of experi-
mental investigation.  Were  I to  draw an inference further from
the observations which I have made on the temperature of different
parts of the body. I should be disposed to say, that besides the pri-
ma? via?, there is  no other apparent auxiliary source of heat, (con-
sidering the lungs as the main source)—neither the brain, the tem-
perature of which is comparatively low, nor the kidneys, the fluid
secreted by which appears in  the bladder to be of rather lower tem-
perature than the blood  in the heart and great vessels; nor the liver,
the temperature of which I  have  never seen  above that  degree
which  might be expected, taking into account its proximity to the
lungs, its bulk and the abundant manner in which it  is supplied
with blood.
  In a former  part of this work "on the temperature of the human
body after death," two instances are given of  an  extraordinary high
degree of temperature observed in bodies which had been  dead a
short time; and in both of which the fibrin of the blood had disap-
peared, as it does in  putrefying, and yet the  bodies exhibited none
of the usual signs of the  putrid change having even sensibly com-
menced.   I then concluded  in consequence,  that the unusual tem-
perature  was not  owing to putrefaction—or  a post mortem  effect;
and, reflecting on all the circumstances of these cases,  and  on the
phenomena witnessed in my experiments on putrefaction, I am con-
firmed in that  inference, and obliged to suppose that it either arose
from the ordinary sources of animal heat being more energetic than
usual, or from the cooling process being comparatively inefficient,
or else to imagine some peculiar morbid change in the blood itself,
on  which,  in "common with  the disappearance of the fibrin, the
unusual  temperature may have depended.   In  all the instances
recorded in the preceding pages,  in which, during putrefaction
there was a considerable elevation of temperature, it was at a parti-
cular period of the process, namely, when it was most active, when
the greatest apparent change occurred, before  the oxygen  of the
atmospheric air had disappeared, and when the change was attended
with the formation of carbonic acid  gas, partly at least, by the union
of the oxygen of the air, with the carbon of  the putrefying matter.
       11—_b                                    13 dav 
190
davy's researches.
Whether any heat was produced during the after part of the pro-
cess, when the changes were taking place more slowly, when oxy-
gen was excluded, and carbonic acid gas was formed  from its ele-
ments in  the  compound in the same  manner as ammonia  was
formed, may be matter of question.  The  results themselves were
far from conclusive—rather hostile than favourable to the idea of
heat being thus generated.  The analogy of vinous fermentation,
in which there is a manifest elevation of temperature produced by
the arrangements of the elements in new combinations,  independent
of the presence of oxygen, maybe adduced in support of the notion.
Were the proportion of carbonic acid gas generated in the two kinds
of fermentation similar, then the analogy would be strong; but, in
the putrid fermentation, the quantity of carbonic acid gas formed,
independent of the  oxygen of atmospheric air, is  small,  and the
quantity of ammonia large. If the formation of ammonia, like that
of carbonic acid gas, were usually attended with increase of tem-
perature, then there  would be reason to suppose that the fermenting
process of animal matter throughout is a heating one.   But, I know
no proof, that heat is evolved in the union  of the elements to form
ammonia.  In relation to heat, it  may be remarked, that azote and
ammonia, and the combinations of the  latter,  and of most of the
former, are peculiar  and anomalous.  Elastic fluids are formed by
the sudden decomposition of solid and liquid bodies (the detonating
compounds) with  little change of temperature—and that an eleva-
tion, not a diminution of temperature.  Ammoniacal gas  unites
respectively with the carbonic, muriatic, and fluo-boracic acid gases,
forming solid salts, without the production of  heat; and as during
the slow decomposition of ammonia by electricity,  there is no evi-
dence of change of temperature, so equally there is want of evidence
of the same in its formation.  The probability, therefore, is, that its
elements unite without evolution or generation of heat; and conse-
quently in the putrid fermentation it cannot  be considered as a
cause of  heat.

Appendix,—containing a brief notice of the fatal cases referred to.

  No. 1.—Aged 42, died on 25th July, of an abscess in the liver.
The body was examined ten hours after death.  It was much ema-
ciated; excepting the liver, the lower part of  the  ileum,  and the
upper part of the colon, the parts generally were sound. The por-
tions of the intestines alluded to, were slightly ulcerated.
  2.—Aged 26;  very little emaciated;  died on the 14th  July, of
acute dysentery.   The body was examined  six hours  after death.
All the organs were tolerably sound excepting the large intestines,
which exhibited the worst  effects of the disease mentioned.
  3.—Aged 23; not much emaciated; died  on the 2d August, of
acute dysentery.   The examination was made nineteen hours after
death.  The pericardium adhered to the  heart;  there was an abscess
in the liver contiguous to the gall-bladder; the inner surface of the 
ON MACERATION IN WATER, ETC.
191
gall-bladder was very red, and it contained a serous fluid ; the inner
coat of the colon  was severely ulcerated; the other organs were
tolerably sound.
  4.—Aged 35 ; rather emaciated ;  lower extremities cedematous ;
died on the 3d July, of disease of the heart and brain.  The exam-
ination was made ten hours and a half after death.  Both sides of
the  heart were much thickened,  and their cavities enlarged; the
central parts of the cerebrum were very much softened ;  the other
organs, with slight exceptions, were tolerably sound.
  5.—Aged 26;  rather ^emaciated;  died  on the 7th August, of
acute dysentery. The examination was made six hours after death.
No  lesion was discovered worthy of notice, excepting in  the large
intestines, which were very extensively ulcerated, &c.
                             XV.

 EXPERIMENTS AND OBSERVATIONS ON  THE  MACERA-
  TION  IN WATER  OF DIFFERENT TEXTURES OF  THE
  HUMAN BODY.

  Although the process of maceration by means of water has been
 long in use amongst anatomists in making preparations of particular
 parts, especially of the  more solid ;  and though, of late years, many
 observations have been collected bearing on this operation,  yet I
 am  not aware that any inquirer  has yet engaged in the subject sys-
 tematically,—has attempted to investigate it through the changes
 which it produces, or  even to ascertain with any accuracy what
 changes really are produced.  Nor is  this neglect surprising, con-
 sidering the circumstances attending the maceration of animal mat-
 ter,—the difficulty of procuring subjects,—the conveniences requi-
 site,—the time required,—the  great attention necessary to observe
 the  fleeting phenomena,—the disgusting nature of the experiments,
 —and the idea of danger of health attached to them.
  It was when stationed in Malta, in the year  1828, that I was in-
 duced to engage  in the investigation for the purpose of removing
 doubts, and of gaining information which  was  not to be collected
 from books.  The results then obtained, were published  in the 41st
 volume of  the Edinburgh Medical and  Surgical Journal;  though
 they were far from being so finished as I could wish, I again bring
them forward with the  hope, that as a contribution to anatomy and
 animal chemistry, they may be of use.

       1.__The circumstances attending the experiments.

  The experiments were all made in the laboratory of the general 
192                  davy's researches.

hospital—formerly the hospital of the knights,—a room, by its equa-
ble temperature, well adapted for the purpose, and they were carried
on during a period very nearly comprehending twelve months.  1 he
water used for maceration was aqueduct water, that of the town of
Valetta, which appears to be very much the same in quality through-
out the year; and seems to be variable chiefly in  temperature, from
being conveyed a distance of about eight miles, and  a considerable
part of the way, running very slightly protected  from  atmospheric
influence.  During  the "spring months its temperature varied from
about 55° of Fahrenheit to 65° ; during the summer from about 65°
to 75° ; during the autumnal from about 75° to 65° ; and during the
winter from about 65° to 55°.  In the cool season it was always a
few degrees above the temperature of the room, and in the hot season
a few degrees below it.   But as the water was changed every day,
or every second day at furthest, and as a gallon or two was generally
used for maceration, the alteration of the temperature of the water
during the progress of  the experiments was immaterial and undeserv-
ing of particular attention.  I have said that the quality of the water
was apparently always much  the same.  This I have not proved by
analysis:  it is conjectured from considering that the aqueduct is fed
by springs in  limestone  rock which  are perennial,  and very little
affected by the seasons.   In July, just before I entered on the in-
quiry, I particularly examined the water.  Its  temperature then as
it flowed from the pipe into the room, was  73°, its specific gravity
was 1008; 100 measures of it contained 4  measures  of air, and this
air consisted of 10 carbonic acid  gas, 62 azote, 28 oxygen.
   Its   saline and earthy contents  were very inconsiderable,  not
quite  T^ part, and consisted chiefly of carbonate of lime, dissolved
by carbonic acid, and  of common salt, with  a very little lime and
magnesia, and fixed alkali in  combination  with the  sulphuric and
muriatic acids.  The  vessels in which the parts  were  subjected to
maceration were glass jars, varying  in capacity from one  to two
gallons.   In some instances they were covered slightly to keep out
dust;  in others they were uncovered.   The subjects of the experi-
ments were generally suspended in the water  by  common pack
thread, and to prevent their floating when air was generated, they
were kept under by a counterpoise of glass  attached by the same
kind  of thread to their inferior surface.

2.—A brief account  of the bodies from which the parts, the sub-
              jects of the experiments, were taken.

   It may be remarked generally, that all the bodies were of the male
sex;  and all of  them, with the exception of two, of  soldiers of our
regiments.
   1.—Aged 25 ; died unexpectedly on  the 24th August, 1828, la-
bouring under symptoms of continued fever of five  days' duration.
The body was examined about  five hours  after death.  Nothing
satisfactory wasdiscovered to account for the fatal event.  Blood, in 
ON MACERATION IN WATER, ETC.            193
large quantity, had been abstracted twice, and active purges had
been used.
  2.—Aged 29;  died on the 10th October, 1828.  The body was
examined twenty two hours after.   It was  niuch emaciated;  the
cerebrum was in a very soft state, especially its central parts;  the
lungs abounded in minute tubercles; the superior lobe of the right
lung contained a tubercular excavation ;  and the lower part of the
ileum was slightly ulcerated.
  3.—Aged 23 ; died on the 16th  October,  1828, of  "continued
fever" (as the disease was called) of nine days' duration, with some
anomalous symptoms.  The body  was  examined fourteen hours
after.   The cause of death was  not ascertained  in  a  satisfactory
manner.   Some lymph was found effused in the posterior medias-
tinum, and the lungs contiguous to  the  mediastinum were turgid
with blood, and in a certain degree hepatised;  the spleen was unu-
sually large and soft; and the lower part of the ileum was slightly
and obscurely diseased.
  4.—Aged 24, died on the 4th November, 1829, having  had  the
thigh amputated on the 16th October, and the femoral artery tied
just below the arteria profunda on the 22nd, on account of second-
ary hemorrhage.  The body was examined twelve hours after death.
The crural, and iliac veins of the diseased limb were thickened by
deposition of coagulable lymph.   The lower half of the thigh bone,
which had been  amputated, was  in  a very diseased state, as were
also the tendons and muscles attached, and the whole of the knee,
almost every part of which was altered; whilst the  leg  and  foot,
with the  exception of oedema, appeared to be in a sound condition.
  5.—Aged 56, died suddenly on the 11th November, 1828.  The
body was examined fifteen hours after.   The  heart was unusually
large ; the semilunar valves of the aorta were partially ossified ; the
orifices of the coronary arteries  were very much contracted ;  the
arteria innominata, and the arch of the  aorta were enlarged ;  the
aorta was generally diseased;  its inner coat irregularly thickened,
and its middle coat corresponding, more or less absorbed.
  6.—Aged 18, died on the 12th November, of  dysentery.  The
body was examined twelve hours after.   It was considerably ema-
ciated; and the colon exhibited the  appearances  usual in this  dis-
ease in its severe  chronic state.
  7.—Aged 23, died on the 29th of November, of acute dysentery.
The body was examined five hours  after.  The whole of the left
lung, and the superior lobe of  the right, abounded in small tuber-
cles ; and in the  former were two or three vomica?.  There was a
small ulcer in the duodenum.  There were several ulcers in the
jejunum, and numerous ones in the ileum and colon.
  9.—Aged 32, died on the 26th December.  The  body was ex-
amined twenty-two hours  after.  The liver contained two abscesses.
The large intestines were severely  ulcerated.
   10.—Aged 29, died on the 7th January, of acute dysentery.  The 
194                 DAVY'S RESEARCHES.
body was examined  sixteen hours after.   There  were patches of
coagulable lymph on the lower part of the ileum (its villous coat.)
The colon throughout exhibited the worst effects of acute dysentery.
  11.—Aged 20, died on the 7th of August, 1829, of acute dysen-
tery.  The body was examined six hours after.  The colon was very
extensively and severely ulcerated, &c.
  12.—Died on the 8th August, of dysentery.   The body was exam-
ined nine hours after. The lower part of the ileum was slightly ulcer-
ated.  The colon was extensively ulcerated, &c.

3.— General results of the experiments on the maceration of the
                  different parts of the body.

  The experiments on maceration were commenced  immediately
after the  inspection of the bodies.  The water, as already remarked,
was changed every day or every second day, and the changes  pro-
duced  were  as frequently observed  during the first  four or  six
months, and were noted down from time to time.
  Were I to give a minute account of the observations which 1 have
made on  the different parts of the body, whilst undergoing macera-
tion in water, a volume would be required to contain them, the de-
tails would be extremely tedious, and their utility very doubtful. I
shall endeavour to avoid equally the two extremes of great minute-
ness of description and of excessive brevity, and confine myself as
much as  possible to a narration of the more important results.  I
shall commence with those parts in which the changes  produced by
maceration are most rapid,  and proceed to  those in which they are
least so, but not confining myself to this order, when a natural con-
nection of the parts, or any other reason, renders a deviation from it
useful.
  Fibrinous concretion from the heart.   The water having been
changed  daily from the 4th November to the 12th, the concretion
had become quite white, rather soft, and of a slightly putrid odour.
On the 22nd it was reduced to a kind of pulverulent sediment. The
same change takes place in common fibrin of the blood, whether
separated from the colouring matter artificially or naturally, as in the
buffy coat, and as in the instance above given of the fibrinous con-
cretions formed in  the heart.  The time required for the alteration
is variable according to the degree of firmness of the  fibrin, and ac-
cording to the temperature, being directly as  the one, and nearly
inversely, as the other;  or in other words,  the firmer it is, so much
the longer time is  required ; and  the warmer  the weather, or  the
water, so much the shorter time.
  Muscle—heart.  (4. 8.)—Its muscular substance underwent rapid
change;  it very soon  became putrid atid soft, and was  washed
away in  the form of pultaceous matter, very like  that from  the
fibrin of the blood;  whilst its  enveloping membrane, its valves,
tendinous chords,  and the great  vessels  taking  their rise  from
it, were  but  little  altered.   With  care  at a  particular period  of 
                ON MACERATION IN WATER, ETC.            195

the process of maceration, it was easy to show that the valves of the
aorta and pulmonary artery are connected with the outer fibrinous
sheath of these vessels;  and I am disposed to believe that  these
valves consist of this tissue in greater proportion, than of the  inner
coat, and that they owe their strength and peculiar properties rather
to the former than to the  latter.   It  is  worthy of remark,  that the
thin muscular substance of the auricles underwent change less ra-
pidly than that of the ventricles.   Other muscular parts of the body
were subjected to maceration ; some of them,  as the substance  of
the tongue, and most of the voluntary muscles exhibited  rapid
change, like the ventricles of the heart; others, as the muscular coat
of the prima? via?, and especially of the rectum, and of the urinary
bladder, more resembled the auricles of  the heart in the slow manner
in which they underwent alteration.
   Brain. (1.)—This organ rapidly becomes soft in water, and forms
with  it a kind of emulsion, the consistence of which varies of course
with  the proportion of each.  In the state of emulsion it has a pe-
culiar and  disagreeable odour, but neither  fetid  nor ammoniacal.
As the water cannot be changed, I do  not consider  it necessary  to
give here any particulars  of the alterations which take place in the
mixture left undisturbed for a considerable time.
   Spleen. (6. 7. 8.  10.)—It became  soft very rapidly according  to
circumstances of temperature, (fee. in a space of time varying from
twenty-four hours to three or four days. When an incision was
made into it and gentle pressure applied  under water, the softened
matter (very like that from fibrin, coloured by the colouring matter
of blood) flowed out, fetid, and mixed with some air  bubbles; and
when it was softened throughout its mass, the operation of pressing
it gently, being continued  under water,  the whole of the  softened
matter was expressed, and nothing distinctly remained but the vas-
cular structure of the spleen, contained in its enveloping membrane,
and presenting a beautiful  and instructive appearance, the vessels
anastomosing  very freely, and in a certain regular manner, and re-
taining their strength very little impaired.  Here I may remark, that
with the  spleen thus prepared, I have often endeavoured to discover
the cribriform  structure, of late years attributed by some anatomists
to the splenic veins.   Nowhere could  I observe this structure;
every opening in the sides of the veins which I could detect was an
opening into a branch.  After the separation of the soft matter, when
the maceration of the spleen was continued, it  slowly underwent
change, and wasted away; the more delicate structure disappearing
first, and  the trunks of the vessel, and the including membrane endur-
ing longest, much in the same manner as the larger vessels generally,
and the fibrous and serous membranes,  which  will be considered
hereafter.
  Pancreas.  (2. 3. 7.)—This organ softened nearly as rapidly as the
spleen. When gently pressed under water, the soft fetid matter was
separated ;  and after two or three days, successively renewing the
pressure,  nothing but its vascular structure and its duct remained, 
196                  davy's researches.
 which latter was of great strength, and resisted further maceration
 for a long time.
   Parotid gland. (6. 9.)—It softened much in the same manner as
 the pancreas, and the pultaceous matter derived from it was very
 similar.   After  the separation  of this,  there remained a tissue of
 strong cellular texture, of vessels, nerves, and the branches,vof the
 duct, which, the maceration being  continued, gradually softened
 and were very slowly decomposed.  The duct itself resisted decom-
 position  very powerfully, and so did a portion of the lining  mem-
 brane of the mouth, in which  it terminated, and  from which  in
 minute structure it was not distinguishable.
   Thyroid gland.  (8.)—It underwent the  same  changes as the
 parotid,  and in about the same  time.  When the pultaceous matter
 generated was expressed, there remained also a tissue of nerves, and
 cellular texture.
   Prostate gland.  (12.)—This organ  changed rapidly, and was
 soon reduced to a soft pultaceous mass of a fawn colour, in which a
 vestige only of cellular tissue could be detected, and the remains of
 some small vessels.
   Kidney.  (4.)—It gave off a good deal of the colouring matter of
 the blood, and was soon reduced to a soft mass.  After gentle pres-
 sure under  water, there remained only the  infundibula which had
 a delicate vascular  structure,  a few large  vessels, its enveloping
 coat, and the lining membrane  of the  pelvis, which did not resist
 prolonged maceration for so long a period as the vessels and mem-
 branes of the spleen.
   Liver. (3. 4. 8. 9.)—It underwent change pretty rapidly, and in
 a manner not unlike the kidney.  The  water was  first discoloured
 by blood, next by gray pultaceous matter derived from the softening
 of the substance of the viscus. After maceration for a month or six
 weeks, there remained little besides its vessels, and the branches of
 its duct.  These resisted decomposition  much longer, especially the
 larger vessels, and the hepatic duct,  and some  of  its branches, to
 which adhered, for a considerable time, very minute grayish  or
 brownish granules.
   Lungs. (3. 4.)—The substance of the lungs softened pretty ra-
 pidly, and was easily broken up.  A portion  of it well washed, dis-
 played very prettily the vascular structure of the organs; after about
 a month or five weeks, little remained but the larger vessels, (some
 of which retained their minute  ramifications.) and the  pleura com-
 paratively little altered.  Where there were tubercles, the alteration
 of softening was quickest,  and it commenced  with the tubercles.  It
 was  very difficult to distinguish, during the progress of change,
 between  the  bronchia and the blood-vessels, and decide which un-
 derwent  change most rapidly.
  Arteries.—Aorta, (4. 5.  10.)  Pulmonary  artery, (10.)  Coeliac
 artery, (8.) Femoral artery, (4.)—These  vessels underwent change
 very slowly.  The different coats gradually softened, the inner and
outer coat first.  The inner coat became as it were mucilaginous. 
                ON MACERATION IN WATER, ETC            197

 and was washed off or removed by the gentlest friction.  The outer
 coat resisted longer; it finally became disintegrated, and  reduced
 partly to a kind of mucilage-like  matter, and  partly to its compo-
 nent fibres not distinguishable except ou very  minute examination
 of  the debris.  The middle coat became soft later than the preced-
 ing; it wasted irregularly, becume full of holes and gradually fell to
 pieces. During the change, the outer coat assumed a brownish hue;
 the hue of the inner coat was little altered; the middle coat assumed
 a bright pink colour. The different arteries exhibited some varieties
 of change: the pulmonary artery underwent  it  slowest; the aorta of
 No. 5, which was diseased, also underwent change very slowly, and in
 a peculiar manner.  The inner coat separated from the middle, and
 the middle in places from the adjoining fibrous coat, and ihe middle
 coat where thickest separated into laminae.   These alterations took
 place in a space of time varying  from six weeks  to  eight  months.
 It may not be amiss to remark, that by the fibrous coat of the artery,
 I mean that which is next to the middle, and between  it  and the
 loose cellular  texture,  the  envelope of the vessel  in which there is
 generally some  fatty matter, and which appears to be even  less
 liable to change than the fibrous,  but  subject to the  same  kind of
 alteration.
   Veins.—Vena cava (4. 5.)—It gradually softened ; the outer cel-
 lular or fibrous coat preceding a little -in its change the proper coat
 or coats of the  vein.  The softening and wasting  process went on
 irregularly; one portion  suffering greatly, and another adjoining
 very little ; and the kind of change was not always the same in the
 same texture;  here  a  spot  became  soft,  semi-transparent  and de-
 pressed ;  there elevated and mucilaginous.  In some places it  was
 discoloured  brown, in  others greenish.   Gradually it became ex-
 tremely thin and worn  into holes,—and  the change continuing, it
 was reduced to shreds and particles.
   Thoracic duct, (8.)—It  slowly underwent change  like the vena
 cava.
  Nerves.—I have made  but few observations on this subject,  and
 these have been confined to the crural nerve  (4.)   Its theca gradu-
 ally softened; in about two months the enveloping and connecting
 tissue constituting the  theca was  partially reduced  to a brownish
 mucilaginous state, which was detached on  the slightest  friction,
 and then the nerve separated into its component filaments.  These
 filaments slowly lost their strength, became as it were mucilaginous,
 and fell to pieces.
  Pia mater, and arachnoid membrane, (11.)—The latter  mem-
 brane in this instance was  slightly opaque,  and  consequently the
 better fitted for observation.  In their change from maceration, the
 two membranes kept equal pace;  they slowly lost their strength, in
some  places  more so  than  others;  holes formed  in them, which
gradually increasing in number and  size, in  about  two months re-
duced  them to shreds.   The  small vessels ramifying through the
pia  mater wasted  and  disappeared much before  the larger  ones; 
198                  davy's researches.

these  latter remained to the last, but perforated,  and undergoing
the same kind of change as the membranes themselves.
   Theca spinalis,  (8.)—It underwent change slowly.  In about
six weeks it presented a very varied appearance; in some places
eroded,  as  it were, and become very thin;  in others, holes  had
formed ;  close to them,  there was a conversion into transparent
spots; and generally there  was a fibrous vegetable growth  adher-
ing to the surface from which it  had sprung.  The same  kind of
change gradually proceeding, the membrane was reduced to shreds,
and these ultimately to particles of a fawn colour, easily suspended
in water.
   Dura mater,  (2. 3. 4.  10.)—This membrane, during the  first
two or three weeks, did not appear to undergo any change.  Gradu-
ally its  surface became  slimy, either with  or without discoloration,
but more frequently  the latter.   In different specimens, the  dis-
coloration was very various, as bright  blue, brown, orange,  red,
and greenish.  A wasting of the substance of the dura mater attend-
ed the formation of the slime, or soft mucilage-like matter;  and,
being washed  off as it successively  formed, the membrane became
very thin and corroded  into holes.   The change proceeded very
irregularly.  The wasting was chiefly confined to particular spots,
as so many centres of action, the adjoining  portions remaining little
altered for a long time, and having their strength but little impaired.
In these portions thus exempted in a manner from rapid alteration,
the structure of the tissue was  well displayed—the very delicate
connecting fibres yielding to decay first,  the  coarser fibres  became
so much the  more apparent.  Sometimes the membrane  divided
into  two layers—occasionally into  three or more lamina?; but it
was  always easy in  this  stage  to  effect  its separation  into two.
Progressively every part partook  of the change, and the membrane
was reduced to shreds and particles.  Some of these shreds I have
examined after having been in maceration eleven months.  Inter-
nally, when drawn  asunder,  they displayed the original colour and
lustre and texture of the dura mater, and they themselves appeared
to be in progress to  ultimate decomposition.  It was curious to
observe the different specimens placed under similar circumstances
undergoing change.   Hardly in  any two was the change  exactly
similar, varying  either in the rapidity with which it took place, or
in the discoloration attending it; and this without any apparent
cause,  as if owing  to difference of composition not appreciable by
the eye.  During the early progress of the experiments, 1 have often
sought to discover, on  the  inner surface  of the dura mater, the
arachnoid membrane; but I was never able to succeed in detecting
it.  And I  may here remark, that all the other  attempts which  I
have  made  to demonstrate  it have  been  failures; and  in  conse-
quence, I am disposed to believe that it is not reflected over the
dura mater according to  the ingenious idea of Bichat.
   Pericardium, (3. 9.)—It underwent change like the dura mater;
but rather more slowly in the early  part of the process, and more 
ON MACERATION IN WATER, ETC.            199
 rapidly in the latter,  and without discoloration.   Maceration, I
 may remark, afforded no evidence of its being a compound texture,
 consisting of an outer fibrous and inner serous membrane, of differ-
 ent  characters, as Bichat considered it.  That it is  a fibrous or
 fibro-cellular structure, capable of secreting serum,  seems certain;
 but more than this at present appears hypothetical, and deficient in
 anatomical demonstration.
   Cuticle, (4. 10.)—It became detached from the cutis in from ten
 to thirteen days, and from some parts sooner than from others.  It
 very slowly underwent change.  It  became discoloured, generally
 brownish; in one instance partially blue.  A slimy matter formed
 on it, attended  with softening;  and it  gradually fell to powder or
 small shreds. These changes were best observed in the thick cuticle
 of the sole of the foot, in which instance they occurred in about
 twelve mouths.
   Cutis,  (4.  7. 9.  10.)—The cutis of different parts underwent
 change somewhat differently.  The difference was most remarkable
 iu the very thin cutis,  and in the thick;  as in the cutis of eyelids,
 prepuce,  and scrotum, and  in that round the anus, the chin, the
 abdomen, &c.  The very thin cutis resisted change for a long time;
 the subjacent cellular tissue became distended with water, and then
 it was extremely difficult to say where this tissue terminated, where
 the cutis commenced;  in fact the former passed into the latter, and
 the latter seemed to be merely the boundary surface of the former,
 the fibres only more closely compacted than in the loose tissue, and
 in the instance of the scrotum and the cutis of the penis,  impregnated
 with brown colouring matter.  Maceration being continued, gradu-
 ally the surface became covered with slimy matter, a softening took
 place, the cutis became thin in spots, and holes formed; and at the
 same time the subcutaneous tissue lost  its strength, became slimy,
 its fibres separated, and ultimately both thS cutis and subjacent
 tissue were reduced to a sediment of shreds and particles.   The
 thick cutis underwent change more rapidly at  first,  and  slower
 afterwards. In a short time, as in about a fortnight or three  weeks,
 it became discoloured, of a bright pink or yellow hue, and it ex-
 hibited a cribriform structure, very many small holes having formed
 in it, arranged in a pretty regular manner, penetrating through the
 cutis. What remained, constituting this cribriform texture, was de-
 cidedly fibrous.  The  fibres were more or  less coarse and  inter-
 woven, and had the colour,  lustre, and general appearance of the
 fibres of tendons, or of the dura mater when separated  by macera-
 tion. This rapid change was most distinct in the cutis of the verge
 of the anus.  It may be remarked generally, that the  more the in-
 teguments abounded in the channels of hair and in fatty follicles,
 so much  the more rapid was this first change or conversion into a
 cribriform structure.   After it had formed, further change was very
slow, and in a manner very analogous to that of the thin skin,  or
of the dura mater and pericardium, and required even longer time
for its completion.  Between the two extremes of very thick and 
200
davy's researches.
very thin cutis, there are parts intermediate in degree of thickness,
and  intermediate also in relation to the  follicles, &c. which they
contain, as the skin of the inside of fore-arm, and that covering the
shin-bone, that of the ear,  not including its lobe, (fee.—and these
parts observe also a kind of medium in their rapidity and manner
of change.   When examined in a certain stage of the process, they
appear to consist of the  same kind  of tissue as the subcutaneous,
only a  little  more condensed;  and to the thickest skin the same
remark relative to texture is, I  believe, justly applicable.
  Alimentary  canal, mouth,  and fauces, (7. 9. 10.)—Different
parts of the  lining membrane of the mouth and fauces underwent
change with very different degrees of rapidity.   Where the ducts
of numerous  mucous  glands pass  through  the membrane,  and
where  the membrane is not extremely thin,  as in the roof of the
mouth, it soon acquired a cribriform texture like that noticed under
the head of the cutis, and thus  perforated,  it underwent further
change slowly.  Where comparatively few mucous glands are situ-
ated in the subjacent tissue, and  where the membrane is compara-
tively thick,  as in the side of the mouth, and especially in the neigh-
bourhood  of the entrance of the parotic! duct, there from beginning
to end it suffered change very slowly.   Over  the  tonsils it expe-
rienced the  first or cribriform change very rapidly.   The glands
constituting  the tonsils were soon converted into a semi-fluid fetid
matter, which  was removed by washing,  and there remained only
a tissue of strong white fibres.   Where the membrane was very
thin, and  at the same time penetrated by numerous ducts of  mu-
cous glands, as under the tongue, and especially on each side of its
fraenum, and  in the back part of the fauces, there it underwent
change rapidly, and it  was soon reduced to a mucilage-like  and
shreddy slate.   The  change which slowly took place in the lining
membrane of these pangs, bore a very close resemblance to that expe-
rienced by the cutis, a slimy or mucilage-like matter formed, the part
became irregularly corroded and worn into holes—it lost its strength,
and the whole  was gradually reduced to shreds, and these ultimately
to particles, which indeed throughout the change were constantly
forming, and as they formed  were removed in changing the water.
And I  may remark, that the tissue subjacent to the lining membrane
experienced  the same kind of alteration; and the same  kind  of ob-
servation which induced me to consider the cutis  as the external
surface of the  tissue connected with it, leads  me  also to infer that
this membrane is an analogous boundary of the texture beneath it.
   Tongue,  (7. 8.)—I have  not alluded above to the epithelium of
the lining membrane of the mouth;  it appears to be very similar to
that covering the upper surface of the tongue.  Like that  of the
tongue, it varies in thickness and distinctness in different parts.  It
is very thick on the roof of the  mouth,  and  on  the anterior and
superior part of the tongue;  less thick on the sides of the mouth,
or middle part of the superior face of the tongue; hardly distin-
guishable on the surface of the fauces and the  back of the tongue, 
               ON MACERATION IN WATER, ETC.            201

and not distinguishable on the floor of the mouth under the tongue,
and on the inferior surface of this organ. About the third or fourth
day, this epithelium began to come away,  or was  easily detached ;
but from no part as a continuous membrane, rather like a curd-like
substance, especially from the roof of the mouth. From the tongue,
particularly the apex, it might be detached in small portions, having
some resemblance to cuticle, and bearing the impression of the sur-
face to which it had adhered.  After the separation of its epithe-
lium, the next remarkable change  in the  tongue  from maceration
occurred in its muscular substance, which soon became  soft t.nd
fetid, and  in  this pultaceous state  it was soon washed  away  in
changing the water, when gentle pressure was at the same  time
made to it.  After the removal of this part, there remained its case,
as it were, which varied in texture in different parts.  On the under
surface it was a delicate membrane, apparently composed of cellular
tissue, and which soon wasted away.  Ou the upper it had a mixed
character, as if composed of tendon-like fibres, and of cellular tis-
sue—the former prevailing most at and towards the apex, and the
latter most  towards the base, and round the foramen  caecum, and
in the anterior part surmounted by papilla?, which,  minutely exa-
mined, themselves appeared  to be bundles of fibres. These papillae,
and this  fibrous and cellular tissue, slowly underwent a change
very like that described when treating of the dura mater, skin, &c.
   (Esophagus, (7. 9.)—In the inferior part of  the oesophagus, and
especially just at its  termination, an outer membrane or epithe-
lium, somewhat similar to that of the mouth, was (as it generally
is) distinct;  and it separated in the same manner.   Higher up it
became very indistinct; and I was not able to trace it in a satisfac-
tory manner in the upper portion, and through  the pharynx, where,
as I have already observed,  its appearance is obscure, and its exist-
ence often doubtful.   During continued maceration, the muscular
coat of the oesophagus first disappeared.   The inner or mucous
coat gradually became soft and  corroded.  In about two months in
 winter, its upper part was reduced to shreds, which, stretched under
water, had  the silky lustre and general appearance of cellular tissue,
or of very delicate fibrous structure.   The lower part was stronger,
 and resisted disintegration a little longer.  The submucous  tissue
 also resisted it a little longer; ultimately it was reduced to the  same
 kind of debris, composed of fibres and altered  particles discoloured
 brown.
   Stomach, (4.)—During the first eight or nine days there was no
 distinct softening or change of  any part of this viscus.  About the
 twelfth day, the mucous membrane was  softening in some places,
 and was easily abraded from the subjacent cellular  layer.   This
 layer, where the mucous coat was removed from it, had the appear-
 ance'of peritoneal membrane.  Its tissue was considerably distend-
 ed with water.  The muscular and peritoneal  coats were of a light
 pink hue.  About the eighteenth day,  the mucous coat was soft and
 slimy,  and when gently rubbed, was readily detached.  About the 
202
davy's researches.
 thirty-fifth day, the mucous coat was slimy, and  of the weakest
 consistence;  in many places eroded.  The adjoining cellular coat,
 of a fibrinous reticulated appearance, white, and of a silky lustre,
 had lost much of its strength, and was softening.  The muscular
 coat was not every  where distinct; where distinct, there cellular tis-
 sue appeared intermixed with it, and it was reddish, and extremely
 feeble.   The peritoneal coat, externally light  brown, internally
 white  and silky, was also  softening.   On  the forty-fifth day, the
 change was  in progress in  all  the tissues;  and on the  seventy-
 second the disintegration was nearly complete; and it was difficult
 to recognise any of the coats or layers, excepting the submucous,
 which, though almost deprived  of coherence, yet was still  pretty
 distinct; and the larger vessels  passing  through it were also dis-
 tinct, but in the same soft weak state.
  Small intestines, (3.  10.)—These parts underwent changes very
 similar to those of  the stomach, but rather more slowly.  On the
 thirty-sixth day, in one instance, the surface of the mucous coat of
 the jejunum exfoliated in  soft  brown  lamina?, and left exposed a
 fresh surface,  in which  vessels and  fibres might be seen, presenting
 a very delicate appearance,  derived from the submucous tissue, and
 terminating seemingly in the mucous  or  inner coat, in the form of
 loops,  especially in  the valvula? conniventes, where  this configura-
 tion was most distinctly displayed,  and forcibly gave the idea that
 the mucous coat  is chiefly formed of vessels, ramifying from and
 into the submucous cellular tissue.
  Large intestines, (3. 8.)—The changes which they experienced
 were also of the same  kind, but were even slower in taking place.
 The submucous cellular tissue, especially of the  rectum, where it
 is very thick, retained its form, and considerable strength, after two
 months' maceration. The  mucous  membrane within the verge of
 the anus, like the skin at the line of junction, changed more rapidly
 than the contiguous part of either texture; and in about twenty-one
 days, in the cool season, when the cuticle  was in  the act of separa-
 tion, the softening  process  had  even then commenced.   Minute
 cavities formed both in the  mucous coat and in the cutis, which,
 increasing in number and extent, in about a month nearly effected
 a separation of the two membranes.  This greater tendency  to de-
 compose in this place of junction, I am disposed to attribute to  the
 mucous membrane,  near its termination,  having  beneath it an un-
 usual number of glandules or follicles; and to the cutaneous  mem-
 brane in the same situation having a large supply in  its substance
 of reddish granules, which perhaps are follicles or glandules which
secrete a fluid peculiar to the part.  It may be  remarked,  that  I
could not follow the cuticle beyond the inner verge  of the anus—
that, when  it  terminated, it  seemed, as it were, to overlap, and to
have no junction with  any epithelium similar to that which in the
mouth  connects the  inner surface of that cavity with the outer sur-
face of the lips.
  Gall-bladder and biliary ducts,  (2. 4.)—Both  the gall-bladder 
ON MACERATION IN WATER, ETC.
203
and  the biliary ducts were slow in suffering change from macera-
tion, especially the latter.  After twelve days, in the instance of No.
4, they had undergone no apparent alteration. After eighteen  days,
when a portion of the liver and pancreas attached to them were in
a state of disintegration,  the ducts did not appear  to  be at  all
changed;  but the inner coat of the gall-bladder was softening, and,
when gently rubbed under water, yellow particles  were detached
from it.  After twenty-three days, the inner coat of the gall-bladder
was  slimy, and coming off in flocculi, whilst  the ducts were not
materially altered;  their peculiar structure  remained distinct, the
lancet-shaped  valvular processes at and near the mouth of the com-
mon duct, and the transverse and oblique fibres and chords, which
some anatomists have called spiral laminae, in the cystic duct,  were
as distinct as at first, and not  perceptibly weakened.   The appear-
ance of the inner surface  of these channels bore a strong resem-
blance to  the sinuses of the dura mater; and their general proper-
ties,  and the  manner in which  they long resisted decomposition,
and  the manner in which they very gradually yielded  to it, con-
firmed the analogy.  After thirty-five days, neither the hepatic, nor
the cystic,  nor the common  duct, nor a portion of the  pancreatic
duct attached, was altered, except very slightly; the lancet-shaped
processes above alluded to were gradually wearing  away.  The
cellular or cellular-fibrous  tissue  enveloping the  gall-bladder and
duct had  become  very soft;  yet, when stretched  under water, its
fibres had the peculiar tendinous lustre and appearance.  The  inner
reticulated surface of the gall-bladder still retained its orange hue;
in many places it was of mucous consistence, or reduced to a slime-
like  state.  After fifty-four days, the  ducts exactly resembled the
dura mater; the lancet-shaped processes  were still distinguishable;
the gall-bladder had lost almost entirely its  inner reticulated sur-
face—that commonly called  its mucous coat; and there  remained
little but a tissue of fibres, which, when stretched under water, had
a silky lustre  like  tendinous fibres, and retained a greenish yellow
tinge of bile.  After about three  months there was  little further
alteration, and even after four no very considerable one;  the  ducts
gradually  wasted  like  the dura mater;  a mucus-like substance
formed on them; they became eroded, as it were, and more in  some
places than in others, and worn into holes; and  the investing tissue
of ducts and gall-bladder became soft and incapable of resistance;
and  thus  gradually, in  from  about six to eight  months, they  expe-
rienced a total disintegration, and were reduced to shreds and par-
ticles of a greenish hue.
  Air passages, (7. 9.)—Different parts of the aspera arteria suffer-
ed change very variously in  relation to  time.  In the instance of
No.  7, on  the twenty-first day there was an  appearance of ero-
sion of the epiglottis, and a wasting of the lining membrane of
the trachea,  portions of which were "in a shreddy state; whilst the
whole of  the lining membrane of the larynx  appeared  to be un-
altered, excepting the sacculi  laryngis, the loose tissue  in which had 
201
davy's researches.
become distended with water, producing an appearance like cedema;
and the same was observable round the  rima glottidis.  In the in-
stance of No. 9, on the twenty-eighth day the erosion of the epi-
glottis was very similar, but the alteration in the trachea less.  On
the thirty-second day (in this latter example, to which I shall now
confine myself,) the lining membrane of the epiglottis was  perforat-
ed with small holes, corresponding to glandules underneath, under-
going decomposition, situated in the substance of the cartilage and
in the connecting tissue, performing  the part of its perichondrium;
and similar minute perforations were formed  in  the lining mem-
brane of the trachea, most remarkably in the back or membranous
part of the canal, and I  believe from the same cause, namely, soften-
ing and disintegration of the mucous glandules, situated in the tissue
next to the lining membrane, and communicating by ducts or pores
with this membrane. At this time the muscles of the windpipe and
the thyroid gland  were in a pultaceous  state;  but the inner mem-
brane of the  larynx still remained  apparently unaltered.   On the
fifty-ninth day, the membrane of the epiglottis  had almost entirely
disappeared;  its cartilage was full of perforations, and  its margin
was  much worn and had  become soft.  The lining membrane of
the larynx was  here  and there slightly eroded,  as if ulcerated.
When a portion of it was dissected off. and stretched under water,
it had the appearance of a fibrous membrane.  The chorda? vocales
retained  their original appearance; and their strength was not ap-
parently decreased.  The inner membrane of the trachea had nearly
disappeared;  the shreds of it which  remained  had also the charac-
ter of fibrous membrane when stretched under water, although ex-
tremely delicate.  The back portion of the lining membrane had
most distinctly this character, and  it had now acquired a cribriform
texture,  from the  many cavities formed in it.   Of the changes
which successively took place after the fifty-ninth day, I  have not
any notes.  I may  remark  generally, from recollection of observa-
tions made on other specimens, that the chordge vocales, the lining
membrane of the  larynx,  the tendon by which the epiglottis  is
attached  to the chorda?  vocales at their junction, were the last parts
that underwent decomposition; and that they underwent the change
in a manner analogous to the dura mater, and the tendons of mus-
cles.  The cartilage which yielded  first was  the  epiglottis; next
the arytenoid, and the cartilaginous  rings of the  trachea; and,
lastly, the annular  and scutiform cartilages;  and they underwent
the change principally by a process  of softening,  becoming slowly
converted into a mucus-like substance.   I  may mention  that I en-
deavoured to trace an  epithelium from the tongue into the larynx,
but in vain;  also that I sought for a villous coat in the air-passages,
but in vain.   The lining membrane appeared to me to  be  of the
nature of a  fibrous tissue throughout, and strictly not a distinct
membrane—merely the boundary surface of the  lining tissue and
the component parts. I could detach  no membrane from the chorda?
vocales;  their surface appeared to be the same as their substance— 
               ON MACERATION IN WATER, ETC.            105

closely and very firmly connected  tendinous  fibres.   Nor could I
detach a portion in the form or semblance of a membrane from any
part, except corresponding to a comparatively loose fibrous  tissue,
in which, or beneath which, are situated the glands, which give the
surface the character of a mucous membrane.
   The passages  of the  nose  and ear, and  the cavities connected
with them,, (10.)—I have not  paid minute attention to these parts
during a long period of maceration.  The few observations  which
I have made in one instance, I shall communicate.   Where the
lining membrane of the nares  joins, the cutis, and where the cuti-
cle of skin terminates,  there,  on maceration  during fifteen days, I
have noticed a kind of epithelium, at that time of curd-like consist-
ence, not dissimilar to the covering of the roof of the mouth,  admit-
ting of being scraped off,  rather than detached as a continuous sur-
face.  As  it has proceeded inwards, it  has rapidly diminished, and
I have not been able to follow it more  than half an inch in a satis-
factory manner.   The  lining membrane of the nasal  passages and
cavities has resisted decomposition for a considerable  time, and in
some measure according  to its  degree of thickness.  The same re-
mark is applicable to the lining membrane of the passages  of the
ear.  The membrane of  the  eustachian tube being comparatively
thick, has  borne maceration a very longtime; whilst the extremely
delicate membrane of the tympanum has disappeared rapidly.  Both
the lining  membrane of the nasal passages and  of the ear have ex-
hibited  generally, during maceration, the character  of a fibrous
tissue, with mucous glandules enveloped  in  them, or subjacent to
them.  In the former I have been much at a  loss to distinguish be-
tween the  periosteum of the cavities and  the lining membrane of
the cavities; and in the frontal and maxillary sinuses, and those of
the sphenoidal bone, I am much disposed  to  believe that they are
one and the same membrane, with mucous follicles  intermixed be-
tween their fibres.  The  membrane lining the tympanum, of such
extreme delicacy and  vascular, bears a greater resemblance  to the
pia mater  than to either a mucous membrane or ordinary perios-
teum—yet it seems to perform the function  of both,  though I am
not certain that it is provided with any mucous glandules, or moist-
ened with  mucus.  The membrana tympani appears to be continu-
ous or connected with  it; and also continuous or connected with
the cuticular lining of  the external passage, which is covered with
cuticle, and which seems to  serve  for periosteum to the bony  ring
of the meatus auditorius.
   The eye.—The observations which I have made on  this  organ
and  its appendices during maceration,  have also been confined to
one instance (No. 10,) and have been more hasty than I could have
wished.   During maceration, when the cuticle has separated from
the eyelids, at the inner boundary of the cilia, I have  not been able
to detect  any, the slightest epithelium, on the conjunctiva.  The
conjunctiva has undergone change like cellular tissue; the sclerotic
coat like dura  mater, but more slowly; the cornea has become of a
       \\__c                                    14 dav 
206                  DAVY'S RESEARCHES.
 milky appearance,  has gradually  softened,  and has wasted away
 more rapidly than the sclerotica.   The lens has become soft,  and
 like thick mucus; and the change has gradually  proceeded from
 the circumference to the centre; and the central part,  previous to
 softening,  has  assumed an opalescent and greenish  hue.   The
 membrane of the vitreous  humour, before softening, has, like the
 cornea, acquired a slight degree of opacity, and  in consequence has
 appeared  so much the  more distinct; it has resisted decomposition
 many weeks.   The lachrymal gland has undergone decomposition
 very like  the parotid;  and the lachrymal ducts and sac very  like
 the lining of the nares.
   The urinary and seminal organs.  The bladder, (4. 7. 6.)—In
 the  instance No. 4, this organ was under observation seventy-two
 days.   Marks of change began to appear on the sixth day,  chiefly
 in the muscular coat.   On the twelfth  day, this coat was of a light
 pink hue, whilst the  inner coat was white, firm,  and apparently
 unaltered.   On the eighteenth day, the  inner partially  began to
 soften.  On the  twenty-third day, all the different coats were soften-
 ing;  the peritoneal was white,  the muscular pink, and the inner
 coat  yellowish, with slimy matter of the  same  hue adhering to it.
 On the thirty-fifth day,  they had all  become very soft, and capable
 of resisting little force;  and both the  peritoneal surface anel  the
 inner surface  were slimy.  On the  forty-fifth  day,  the  muscular
 coat  was  reduced to  pale soft shreds; portions only of  the inner
 coat were distinct;  and these, when examined under  water, had
 the lustre and  appearance of the debris  of a serous or fine fibrous
 membrane.  The adjoining cellular  layer, and  the  cellular layer
 connecting the  peritoneal coat and  the muscular, and the peritoneal
 coat  itself, were much in the same state.   On  the seventy-second
 day, very little  remained;  the small  residue not lost in changing
 the water was in the form of a debris, resembling that of a cellular,
 serous,  or fibrous membrane; and I allude to the three, not  know-
 ing well how to distinguish the debris of the one  from the  other.
 The ureters, it  may be remarked,  resisted disintegration  consider-
 ably longer.  During the whole period  of change, they very  much
 resembled the biliary ducts, and gradually wasted like fibrous tissue.
 Whilst the maceration was in progress,  I sought in vain for a  mem-
 brane deserving the name of epithelium in the bladder and ureters;
 and  I was as  unsuccessful in  my search for villi on their lining
 membrane.  I sought  also for mucous glands or follicles, but could
 not detect them in a satisfactory manner in the  bladder, excepting
 a few close to  its orifice,  in the small  triangular space.  In some
 instances  they  appeared indistinctly in the ureters, in  others not.
 I must confess I have doubts if the  lining  membrane of the bladder
 deserves the name of a mucous membrane.   In the dead body I
 have  never found mucus adhering to it; and it is easy to  conceive
 that  the mucus which is  contained  in the urine  may be derived
from the glandules or follicles above alluded  to,  and  from those of
 the urethra.   I  express  these doubts with hesitation; and chiefly 
ON MACERATION IN WATER, ETC.
207
because it  appears wrong to take for  granted that  which is not
proved; and no less so  to  place much  confidence  in  analogical
reasoning, in opposition to, or not supported by, the simple evidence
of the senses.
  Testes,  and their membranes, (7. 12.)—In the instance of No.
7, after eighteen days' maceration, one testis suspended in water,
deprived of its tunica albuginea, had become very soft and weak;
its structure was well displayed,  and its  capillary tubes might be
drawn out to some length. It appeared to  be yielding  pretty rapidly
to decomposition—but to my surprise it continued pretty nearly in
the  same state more than  a month.  On the sixtieth day little  of it
remained, and that was extremely soft.   The tunica  albuginea de-
tached from one testis underwent  change rather more slowly than
the  other not detached.  Both became corroded, gradually perforat-
ed,  covered with  a mucus-like substance,  and a fibrous vegetable
growth.  They underwent change more rapidly than the tunica
vaginalis.   On the eighty-ninth day,  they were full of holes,  and
what  remained was  too  weak to support its own weight; it  was
almost of a mucilaginous consistence, and  had acquired a certain
degree of transparency.  At the same time the tunica  vaginalis  and
the  tissue of the scrotum,  though somewhat wasted, still retained a
certain degree of strength, and when  stretched under water,  had
very much  their original appearance—the appearance of a tissue of
very delicate fibres, with  some coarser ones intermixed, of a silky,
or tendinous lustre.   During maceration, I attempted to divide the
tunica albuginea into two or more  layers,  but could not succeed.
The vas deferens underwent change very  like the tunica albugi-
nea; its inner surface,  near  its termination, which is a reticulated
structure, composed of fine  tendon-like fibres,  resisted disintegra-
tion longest.  The vesicnlae  seminales,  too, underwent a very simi-
lar  change, and their inner fibrous reticulated tissue  also resisted
change the longest.
  The penis, (6. 7.)—On immersion, this organ became distended
with water, especially the loose  prepuce, and  the cells of the cor-
pora cavernosa, and spongiosa.   At  the temperature of about  60°;
after maceration of eight  days, the cuticle almost ceased to adhere,
and might  be detached most easily.   1 carefully traced  it to  the
mouih of the urethra; about a line inside of the orifice it terminat-
ed,  much in the same manner as the cuticle terminates in the anus,
overlapping the membrane of the urethra.  I  have endeavoured to
find an epithelium as a distinct membrane  in the urethra continu-
ous with the cuticle,  but  in vain; nor have I succeeded  in finding
any villi  in this canal.   Few parts  of  the  body resist maceration
longer than the penis; and all its different  textures are in a very
remarkable manner little  liable to change,  as its  skin, its nerves,
and vessels, the lining membrane of the  urethra, and  more espe
cially its  ligamentous sheath.  Many months are required for the
disintegration of any one of these parts;  and  some of them after
twelve months' maceration in water, changed daily, or every second 
208                  DAVY'S RESEARCHES.
day, still retained their form, and were only partially corroded or
wasted; as the skin of the glans penis, and its internal structure,
and as the ligamentous sheath of the corpus cavernosum. The pro-
cess of change in all these parts appears to be very similar in kind
to that of the dura mater, though much slower, excepting the upper
part of the urethra, where that  membrane is very thin, and where
contiguous to it are numerous  mucous glandules, which undergo
change rapidly, and seem to  accelerate its change.  The process of
change appears  to  be by the formation of a mucus-like substance,
which in the penis I have noticed of very various colours, as pink,
dull brown, bright brown, orange, and green.   It is preceded by
softening of the parts; it takes place chiefly at the surface, or in the
portions most exposed to the action of the water; it is not equable;
but, as in the dura mater, spreads as it were from certain points or
centres, reminding one  of ulceration—the  part  affected seemingly
protecting the contiguous part within certain limits from change.
   Tendon,  (4, &c.)—This  part under my observation has under-
gone  change very slowly;  and the less  mixed  it has  been with
other tissues, so much the less prone has it been to  alteration.  A
portion of the tendo achillis of a limb amputated on the  16th Octo-
ber, 1828,  after constant  maceration for  many  months, was little
changed; the longitudinal  fibres were still strong;  and when the
adhering brown mucus-like  substance, which had formed in small
quantity on the surface, was rubbed off, they exhibited their origi-
nal colout and lustre. The connecting tissue of the fibres had been
either destroyed or rendered very soft, and  in consequence the lon-
gitudinal fibres were easily separated.  Tendons,  at their  origins
and insertions, where most mixed with other textures, change more
rapidly; but even in  these it seems to be rather  a disintegration or
separation of fibres, than a decomposition of them, and amongst the
debris tendinous fibres may always  be found, on careful examina-
tion,  little altered; at least so it has happened  in my experiments.
 The  change to which tendon is liable, appears  to be the same as
that noticed under the head  of the penis.
   Synovial membrane, (4. 10.)—This membrane has lost its firm-
 ness  like serous  membrane, and its  surface has  become  slimy.
 With the exception of a few tendon-like fibres, or shreds composed
 of those fibres and cellular tissue, it has disappeared during a course
 of maceration of about four  months; and the  fatty appendices have
 been apparently converted into adipocire.
   Perichondrium and periosteum.—Both these tissues have under-
 gone change in the same manner,  and at  the same rate in  relation
 to time, as  the dura mater, where they have been detached by dis-
 section from the parts which they enveloped.  When they have not
 been detached,  their change has been modified  by the influence of
 the contiguous surface—sometimes apparently retarded, and some-
 times apparently accelerated.   These remarks  apply chiefly to the
 perichondrium of the cartilages of the  ribs, and the periosteum of
 the cylindrical bones. The  perichondrium and periosteum of other 
               ON MACERATION IN WATER, ETC.           209

parts, according to a variety of circumstances, suffer alteration va-
riously, and especially according to their degree of thickness; thus,
when very thin and  loose, resembling cellular membrane, the peri-
osteum of the lower jaw disintegrates rather rapidly, like the ad-
joining cellular membrane, from which  it is  extremely difficult to
distinguish it, and to say where the one begins and the other ter-
minates.
   Cartilage, (4. 10.)—From the observations which  I have  made,
cartilage and fibro-carlilage appear on maceration to undergo slowly
a very similar change, and to waste away gradually, from being
converted into a  mucus-like substance.  During the change, the
colours which I have witnessed in  some parts have been various
and  extremely bright, especially in  the cartilage of the  symphysis
pubis; I have seen it vividly coloured partially brown, orange, blue,
green, and yellow.
   Bone, (4. 10.)—This  structure undergoes change  from macera-
tion  very slowly,  especially  the compact bones which contain few
vessels and little blood.  Changing the water frequently, the animal
matter appears to be slowly removed; for there is a constant exuda-
tion  of a mucus-like substance on the surface, and the brittleness of
the bone gradually increases.   Various  bones, after having been
under observation twelve months, had not  lost the whole of their
animal matter, not even the most delicate,  as the fine plates of the
ethmoid, and the spongy structure of the turbinated bone.
   Intervertebral substance.—I know of no part of the body so little
changed by maceration as this. Portions of it from different bodies,
which had  been  in  water from eight to twelve months,  retained
their form, were very little altered in appearance, and had lost little
of their substance. The central soft part, almost of gelatinous con-
sistence in  the recent subject, was  the part chiefly affected; it, in
the time mentioned, had principally wasted  and disappeared.  The
outer layers,  on the  contrary, suffered least;  after twelve months
ihey retained, as well as  I could judge, their original firmness; and
when the minute quantity of mucus-like substance which had formed
on their surface was washed off, they exhibited their original colour.

             4.— General remarks and conclusions.

   The changes produced by maceration, or during the process, are
referable,  I  believe,  to  three  distinct causes.   1st,  To chemical
causes, giving rise to new combinations of the component elements,
and  to new productions  with the aid of the oxygen dissolved in the
water.  2dly, To insects—those which constitute the family of In-
fusoriaof Linna?us, (many of which appear to be larva?)  feeding on
the animal  matter.  In many experiments, the larvae of the common
gnat of  Malta has been very abundant and active as a  destroying
agent, performing, in relation to change of form of matter, a part in
water similar to that performed by the larvae of flies on dead animal
substances  in the air. 3dly,  To the  operation of vegetation of those 
210
davy's researches.
obscure plants, belemging principally to the confervai of the Swedish
naturalist, and which in my experiments have invariably appeared,
if the process has been at all  protracted;  and commonly either as
fibres shooting from the part in straight lines, sometimes an inch in
length,  or more  obscurely, as a fine  velvet-like  protuberance, or
growth  resembling a byssus.   The  former kind has appeared most
remarkably on the neurilema, on the cutis  of  glans penis,  on its
ligamentous sheath,  on the tunica  albuginea, and on  the  bones,
especially the  spongy bones.   The  latter kind has occurred chiefly
on the debris of  ligamentous and fibrous parts.
  The first, or the chemical causes,  must be considered  as the main
ones; and the second and third only as  auxiliary, and, in relation
to effect, infinitely inferior in activity.  The changes chemically
produced I have not yet attempted to  investigate with any minute-
ness.   I suspect  they are  in most  respects similar to those which
occur during putrefaction in  the open air,  modified,  in a certain
manner by the solvent power of the water, and moreover modified
by the removal mechanically by the water of the particles detached,
and not dissolved.  I have ascertained that the same  gases are dis-
engaged from  the different textures during putrefaction in the atmo-
sphere, and during maceration or putrefaction in wafer; and  as far
as I am able to judge from a slight examination, the  insoluble de-
bris, generally resulting in both, does not materially differ.   The
most striking difference which occurs in considering the two pro-
cesses is in relation to time, most  parts undergoing change more
rapidly in the air than in the water, that is,  when there is as  free
an access of air  as of water.   The difference is probably owing to
the water removing a substance which  may be called animal leaven,
very apt to decompose itself, and to promote the decomposition of
animal and  vegetable  matter  with  which it may be  mixed,  and
which abounds in and forms a considerable part of all the textures
liable to change, and exists more  sparingly in those parts which
are slow in changing.
                             XVI.

GENERAL  REMARKS  ON  BICHAT'S  THEORY  OF MEM-
  BRANES  IN  CONNECTION  WITH  THE  PRECEDING OB-
  SERVATIONS.

  Bichat, in investigating the nature of membranes, paid attention
to the effects of maceration,  and in his Anatomie Generate he has
given the results of his experience.   In some instances 1  perceive
the  results which I obtained accord with his—in  others they vary
slightly, and in some they materially disagree.  I shall notice only
one or two instances of the latter.
  He describes tendon  as undergoing change pretty rapidly from
maceration—at least comparatively.  He  says it undergoes change 
        REMARKS ON BfCHAT's THEORY OF MEMBRANES.    211

more rapidly than cellular tissue.  And  he extends the remark to
analogous textures, as to aponeurosis, and also to the cutis vera,
and to cartilage: he expresses it as his opinion, that if the substance
of these textures were disposed in fine lamina?, like cellular tissue,
and  not compacted together,  he is persuaded that a maceration of
three or four days would suffice to reduce them to a putrid mass.1
  Mucous membranes he describes  as  peculiarly apt to yield to
maceration—more so,  indeed, he asserts,  than  any  other animal
substance, with the exception  of brain;  and he brings forward the
remark, without distinction, without exception, as applicable to the
membranes generally.2
  It would be of little use to attempt to explain  the discrepancy of
these results—I mean of those which I have described as witnessed
by myself, and those referred to of Bichat.  What I have observed,
in multiplied instances, convinces me that pure  tendinous fibre, as
regards tendency to change from maceration,  is  remarkably  prone
to it; and the circumstances which  I have mentioned  in relating
the  phenomena, appear to me demonstrative of  it—especially one,
viz.  when a mass of tendon is disintegrated by maceration, its  mi-
nute fibres, after a very long lapse of time,  may be picked out very
little altered.
   As  regards  his remark on mucous membranes, relative  to the
effects of maceration, it appears to me to be deficient in correctness,
from its extreme generalness.   The observations which I have de-
tailed, show how great is the difference in  different mucous  mem-
branes, and even in different parts of the same canal  in relation  to
the effect of this process.
  When it is considered how rapidly Bichat pushed his researches—
the extent and the variety of his labours—the short period of his pro-
fessional life—whilst one admires his genius, and admires with asto-
nishment his efforts—one cannot be surprised  at  his inaccuracies.3
  ' Anatomie Generate, i. 162                 2 Idem, iv. 21.
  3 This extraordinary man, according to M. Husson, was born on the 14th
 November.  1771; according to  M. Pinel, on the 22d November, 1772.  In
 his 22d or 23d year, viz. in 1793, he went to Paris to finish his medical edu-
 cation.  A month only after his arrival, he attracted the favourable notice of
 Desault, and became his assistant. This great surgeon died in 1795.  Bichat
 then commenced his public life;  he collected and edited Desault s works in
 an incredibly short time, and that same year gave his first course of anatomy.
 In 1800 after eighteen months devoted to research, he  published  his treatise
 on membranes; the same year his treatise on Life and Death;  the follow-
 in^  year his  System of General Anatomy ; and the commencement of his
 Sfstem of Descriptive Anatomy.  On the 22d July, 1802, he died after an
 illness of a few days, supposed to have been owing  in  part to inhaling offen-
 sive  effluvia  in carrying on  some researches  on the putrefaction of animal
 matter  Thus  in the short  period of about nine years he ran his astonish-
 in*  career as an original inquirer.  Pinel, from whose notice of the life of
 Bichat these particulars are chiefly taken, states, that during one winter he
 opened more than six hundred bodies—and immediately  after gave the  re-
 sults of his observations in a course of lectures on morbid anatomy, in which
 he undertook to show that each texture has a peculiar  mode of disease form-
 in°- a part of its peculiar vital character. 
212
davy's UESEARCHES.
   Bichat's propensity to generalisation was extreme; it may be con-
 sidered almost a passion  in him;  all his writings are characteristic
 of it.  It enabled him to form brilliant hypotheses—most extensive
 general views—so much  the  more dangerous on  account of their
 brilliancy—and the ingenuity, and indeed genius displayed in sup-
 porting them. No part of his General Anatomy was more elaborat-
 ed than  that embracing the  mucous system: it well displays the
 disposition alluded to.  Villi and papillae  (uvillosites ou papilles,"
 he did not distinguish between  them,) he considered a part of the
 character of  these membranes—without exception and essential—
 evidently guided by analogy, by what is witnessed in certain organs,
 as in the small intestines, as regards villi, and the tongue and glans
 penis as regards papilla?:  whilst, in point of  fact, instead of  being
 universal in  mucous surfaces, as he  generalised,  it is more than
 questionable  if they are found any where else, at least in man.
   In relation to the general doctrines of Bichat on the subject of
 membranes,  reasoning on the results of the experiments which I
 have detailed on maceration—the conclusion which appears to me
 unavoidable, is unfavourable; and it is supported  by the results of
 other experiments—by those on putrefaction, on the action of heat,
 and  of coction, and of such chemical agents the effects of which I
 have tried, especially of tannin and corrosive sublimate; and also
 by various physiological and pathological facts and considerations—
 altogether constituting the kind  of evidence which Bichat himself,
 after he had  formed his hypothesis, brought  forward to support it.
 Let  us briefly consider the principles of these  doctrines:—
   1st, Relative to pathology; whence the first idea of a classifica-
 tion  of membranes into distinct definite species was derived;  it is
 true, (adopting his distinction  of membranes,) that under the influ-
 ence of disease, the same  membrane throughout is uniformly affect-
 ed;  that similar membranes are similarly affected, and  different
 membranes dissimilarly?
  2d.  Relative to structure:—Is it  true, that there are certain sim-
 ple elementary membranes—as the mucous, the serous, the fibrous,
 &c.  essentially different; analogous  in the organic system to  the
 chemical elements, as  oxygen, hydrogen, nitrogen, &c. in the in-
 organic?
  3d.  Relative to  particular membranes:—to take an  example; is
 it true, of the mucous, as Bichat maintains, that they possess an
 uninterrupted continuity of similar structure throughout?
  1st. Of the pathological argument—originally proposed by Dr.
 Carmichael Smith, adopted by Pinel, and elaborated by Bichat:—
 in the extensive generalisation  to which Bichat carried it, and which
 was  necessary for his grand views, are there not  many well esta-
 blished facts  opposeei to  it?   If his generalisation were  correct,
 would not the spreading of organic disease and its isolation be very
different from what it is found to be?  Would  the inflammation and
 ulceration of dysentery be confined to the large intestines?  Would
there be local inflammations, and ulcerations—not confined to any 
        REMARKS ON BICHAT's THEORY OF MEMBRANES.    213

particular texture  in which they commenced—not spreading along
that texture or membrane—but  extending in a perfectly opposite
manner; in the alimentary canal, for instance, perforating through
all the coats into the cavity of the abdomen, giving rise to  fatal peii-
tonitis;—in the subcutaneous cellular tissue, to  take  anoiher  in-
stance, not spreading  as  in diffuse  cellular  inflammation, through
the tissue  in which the diseased action commenced", but extending
directly outwards, and penetrating through the integuments,  as
happens in common phlegmon?  Would,  in one disease, various
and dissimilar organs  be affected—as happens in so striking a man-
ner in tubercular  phthisis—to the extent, to baffle calculation as to
the limit of complication; and as happens, in  the majority of  in-
stances of  the exanthemata, when they  prove  fatal, especially in
small-pox,  measles, scarlatina, and erysipelas, the fatal  termination
of which is commonly owing to the supervention of disease in some
deeply seated  organ,  frequently  never suspected  during life—not
having been indicated by any well marked symptoms?
   The evidence derived from pathology dispassionately considered,
appears to  me on  the whole far stronger against, than for the pecu-
liar views of Bichat.  Guided by these views, one cannot proceed
a  step in  the  careful examination of disease in  connection with
structure without  encountering difficulties.   I  shall notice  in  the
briefest manner only a very few—and for the sake of briefness in
the form of questions.  Why is the aorta so frequently diseased and
the pulmonary artery so rarely, their structure being similar? Why
is the upper part of ihe duodenum so rarely the seat of ulceration,
and the lower part of the ileum  so frequently, and still  more fre-
quently the vermiform process of the  coecum, all  three being glan-
dular, but the duodenum in the most marked degree? Why in tuber-
cular phthisis are ulcers  so frequently found in the  larynx, and so
unfrequently in the trachea?   Why is the urethra so little liable to
ulcerate?   Why are the ureters almost exempt from ulceration?
   2dly. On the structure of membranes, viewed as elements—sim-
ple and uniform—well marked by their  appearances and  properties
—perfectly distinct from each other,  and incapable of being con-
founded;—in  colour,  thickness,  hardness,  density,  resistance, &c.
nowise similar;—subjected to desiccation, putrefaction, maceration,
coction, &e. offering different results—in brief, according to Bichat's
idea, each  as well characterised as is a simple substance,  or chemi-
cal element:  on this subject it appears to me there is much want of
satisfactory proof, and the weight of evidence is against the conclu-
sion.   How little analogous for instance is the lining membrane of
the ureters and of the small  intestines;  of the  gall-bladder, and of
the urinary bladder;  of the frontal sinuses, and the other adjoining
sinuses, and of the stomach  and duodenum; of  the stomach  and
duodenum, and of the larynx and trachea.  Some of these in struc-
ture  appearance,  firmness, the  manner in  which they undergo
change and are affected by reagents have a greater  resemblance to
fibrous  membranes than to  mucous—especially  the  lining mem- 
211                  davy's researches.
brane of the  ureters, of the larynx, of the sinuses.  In the frontal
sinuses. I have not been able to detach a mucous membrane from
the periosteum; the periosteum and mucous membrane appear to be
one—the mucus I believe being derived from follicles  contained in
the tissue of  the periosteum.  In the ureters, it appears to me very
doubtful, that the lining membrane is a mucous membrane.  In
character it appears to be a delicate fibrous tissue: I have never de-
tected mucous follicles either in  its substance, or beneath it, or mu-
cus in  its canal; and I have often carefully sought for both.1  It
would   be easy  to multiply instances,  of the  deficiency of well
marked  character—subversive,  1  apprehend, of the generalisation
in question.  In the scrotum, the  cutis vera seems to be merely the
boundary of  the cellular tissue of the scrotum, externally; the one
insensibly passes into the  other.  A similar  remark applies to the
periosteum of the maxillae, especially of the inner surface; the mem-
brane there covering the bone, seems cellular membrane only a lit-
tle condensed, and differs  very  little in  character, in the instances
in which I have  examined  it, from the contiguous cellular mem-
brane.
   3dly.  Take the instance of a  particular membrane,  and examine
it according to the views of Bichat—as to the continuity and iden-
tity of structure—and see what will  be the  result in  point of evi-
dence;  and  let it be a mucous  membrane as before proposed.  If
the alimentary canal  be selected,  how very different will  its differ-
ent parts be found ; the oesophagus wilh its epithelium, without pa-
pilla?, without villi;  the duodenum with  a villous surface, over a
glandular structure;  the jejunum with  its villous valvnla?  conni-
ventes,  the colon  without villi or papillae, without valvulae  conni-
ventes,  possessed of solitary mucous follicles.   If the air passages
be chosen, the results of the examination of  the different parts will
hardly be more dissimilar; as of the under surface of  the epiglottis
compared with the corda? vocales; or the surface of these compared
with that of  the trachea beneath; or  that of the trachea compared
with the surface of the bronchial  branches.   In  the different parts
of the mouth, the differences of structure are even more strongly
marked, as the upper and under  surface of tongue—the one covered
with a thick  epithelium—the other I believe altogether destitute of
epithelium.  The surface of the amygdalae presenting fibrous cryptae,
without epithelium; the surface  of the  palate, a dense fibrous struc-
ture, not I believe distinguishable  from the periosteum, abounding
in glandules  covered with a thick  epithelium; that of the uvula,  de-
licate and yielding, little more than loose cellular tissue, connected
wilh muscles; that of the cheeks, firm and dense, and  like the
parotid duct  very analogous to  a  fine fibrous structure.   An exa-
mination of the eye, would call  forth similar remarks: the transpa-

   1 In accordance with this it is liable to adhesive inflammation:—In two
instances I have known the ureter closed by the adhesion of its lining mem-
brane. 
        REMARKS ON BICHAT's THEORY OF MEMBRANES.     215

rent cornea is continuous with the opaque sclerotica; the conjunc-
tival lining with the lachrymal ducts; how strongly are they con-
trasted !   If  from man  the  examination  were extfiidtd to other
animals, the differences presenting in continuous surfaces would le
found to  be even  more striking—as  in the several stomachs of (be
ruminating animals—the gizzard of the gallinaceous  tribe—the
oesophagus of many of the tribe of cartilaginous fishes. How totally
inimical to the doctrine of Bichat, is the second instance  alluded to,
in which the continuity of mucous membrane is entirely interrupted,
and its place  supplied by a horny lining.
   M. Magendie, in his excellent notes to Bichat's Treatise on Mem-
branes, has made remarks to the same effect.   He remarks admir-
ably on this very subject,  "that generalisation carried too far creates
difficulties.   That it  is  clearly useful to  study mucous surfaces as
one and the same membrane extended over different organs;  but,
that when the  examination of the  structure of the membrane  is
minutely investigated in detail, marked differences occur. In truth,
(he adds) mucous  membranes differ  essentially,  according to the
organs, and even the parts of organs  to which they belong.  The
mucous lining of the'oesophagus does in nothing resemble,  it may
be said, that of the stomach  or nose.  The lining membrane of the
small intestines  is totally different from that of the large, or of the
bladder of urine; and it is precisely the points constituting the dif-
ference which ought to be remarked, much more deservedly so than
the points of resemblance, which are very slight.   In animals (he
proceeds) the characters are even  more strongly opposed; in the
stomach of the horse, the splenic portion is entirely different from
the membranous  pyloric portion.  Each of the four stomachs of the
ruminants offers a very different disposition of structure;—to be-
come acquainted with the function  of each,  it  is necessary to study
the peculiar  structure of each.   In general,  it is of much more
importance to  be acquainted with  the differences than with the
analogies of  things."1
   In this note, M. Magendie, it  appears  to me, has designated well
the defective  part of the doctrines of Bichat—generalisation—which
was his strength, indulged in to  excess,  constituting his weakness.
His doctrine  of membranes may be considered as an hypothesis;
such it was originally, and  such  I apprehend it is still.  A few pa-
thological observations  originated the notion of distinct  elementary
membranes;  analogy led to the idea  that they would be found dis-
tinct in structure  mid   properties;  experiments  and observations
were made in expectation of confirming the analogy, and it accord-
ingly was in a certain manner confirmed ; as M. Magendie remarks,
the points of resemblance,  which were slight, having been seized
—those  of difference,  often  great  and  always  more important,
 neglected.

   ' Traite de Membrane*, Nouvelle edit, revue  par M. Magendie. Paris.
 1827.  Note p. 33. 
216
davy's researches.
  Bichat's theory of membranes often reminds me of the antiphlo-
gistic theory of Lavoisier; as simple, as logical, admitting the pre-
mises; and, viewed as an effort of mind, as great an effort of genius;
and  like it a too hasty generalisation,  that is,  instead of being an
induction of facts, it  is in many respects a presumption—the anti-
cipate mentis, built up in great part a priori; and having perhaps
the same tendency to shackle  the  mind and check  free inquiry.
Bacon profoundly remarks, t: Credunt homines rationem suam ver-
bis imperare; sed fit etiam ut verba  vim suam super intellectum re-
torqueant et reflectant  quod  philosophiam et scientias reddidit so-
phisticas et inactivas."
  The investigation of the subject of membranes and  tissues is un-
doubtedly one of great importance, and deserving of most careful
attention.   Something has been done in the  inquiry, but I appre-
hend, little  in comparison with what remains to be done, to bring
it to a satisfactory conclusion.   In proof, it may be mentioned, that
no classification  of membranes yet proposed by the many followers
of Bichat, has been generally received, or has obtained any but par-
tial assent.   Inquirers are divided  even in  opinion  respecting the
nature of particular structures; as  for  instance, that of the middle
coat of arteries—some  considering it analogous in  nature to  the
substance of  the muscles over which the will exercises no control,
and in which the peculiar arrangement or appearance of fibres observ-
able in the  voluntary muscles under the microscope  is not distin-
guishable:  others, holding it to be totally different from muscular
substance,  neither irritable  nor contractile, but elastic,  and  most
analogous to elastic ligament,  as the  ligamentum nucha?.   This
difference of opinion has arisen out  of various research, not carried
sufficiently far;  and is a good example of the state of our know-
ledge of the subject of membranes  generally, in which a no small
number of points are open to question, and comparatively few are
fixed.   Another example presents  itself  in   mucous  membranes,
viewed in the different relation. It  is yet undecided, whether or no
the secretion  from which  they  derive their principal  characteristic
and  their  name,  is solely the  production  of glandules or follicles
disseminated through their texture,  or that of the submucous cellu-
lar tissue; or in part that of the  membranes themselves independent
of such follicles  or glandules.
   In a former section, namely,  on the  effects  of boiling water, and
of long-continued boiling on animal textures, I have expressed the
opinion, that the  results detailed relative to the white membranes
and  fibrous parts, seemed  to me rather  in  favour of Haller's early
view of them, than of the later  and  more elaborate one of Bichat—
not that they are all distinct tissues,  each sui generis —but that they
are analogous in composition, and  differ rather in degree  than iii
kind, and that their basis is cellular tissue.   When their properties
are considered, traced, as it were in transition ; and when it is con-
sidered how  easily animal and  vegetable substances  are modified,
there is little difficulty in arriving at  this conclusion.  StaYch,  it 
DUCTUS COMMUNIS CHOLEDOCftUS.
217
would appear, by some  change of molecular arrangement, its che-
mical composition remaining unaltered, becomes sugar; the change,
as it is well known,  is produced  artificially by boiling it in  water
acidulated with sulphuric acid.  Tendon by simple coction is con-
verted into gelatine;  and all  the other white  fibrous  and  mem-
branous parts by boiling, are more or less similarly changed in their
properties, without being altered, as far as has yet" been ascertained,
in their chemical composition.  And,  the conclusion, I apprehend,
is strengthened, by reference to pathology, physiology, and compa-
rative anatomy, and especially the last. "
  The test of truth is practical usefulness.   No systematic arrange-
ments of membranes  or tissues yet promulgated, based on the  views
of Bichat, can claim  this proof; or be considered otherwise than
hypothetical.   The desideratum now appears to  be a careful and
unbiassed examination of every different animal structure apart as
much as possible from hypothetical views, and the application  of the
inductive method to the results.
                            XVII.

OBSERVATIONS  ON  THE  STRUCTURE OF  THE DUCTUS
  COMMUNIS CHOLEDOCHUS; AND ON THE FLOW OF THE
  BILE.

  Many years ago, when engaged in minutely examining the com-
mon biliary duct and  the  pancreatic  duct in the human subject, I
observed a peculiarity of structure belonging to  the former, and
partly shared  by the  latter—which,  I believe, had not before been
noticed—at least, 1 have not been able to find it described in any of
the works of anatomy, which  I have  consulted expressly wilh this
object in view.
  The  peculiarity of  structure alluded to, may  be  brought into
view, by slitting open the tubes just mentioned and inspecting them
under water,  after the removal of adhering  mucus  by washing.
Thus prepared, the lower parts of the ductus communis choledochus
and of the  pancreatic duct, will  be  seen provided with a  kind of
valvular apparatus, composed of delicate angular  processes or pro-
jections of their inner coat, pointing downwards.
  Since 1827, when  my attention was  first directed to this  struc-
ture, I have examined the ducts in  question  in a large number of
instances: I have invariably found it  to exist;  but  sometimes more,
sometimes less developed.  The processes,  or valvular projections,
commonly  first make  their appearance (tracing  the passage down-
wards from the liver) a little above the place of junction of the pan- 
218
DAVYS  RESEARCHES.
creatic duct,  and are continued to the termination of the common
duct in the intestine.  In the pancreatic duct, they are more limited;
they are confined to its month, and occasionally to a small portion
of the tube adjoining, not more than two lines from its mouth.
  Their valvular  nature  is easily shown  by the introduction of a
probe; directed downwards, towards the intestine, it passes smoothly
without obstruction; 'but  in  the  contrary direction,  towards  the
liver, it is impeded and stopped, arrested by the minute saccnli,
which exist at the base of the processes.
  The use of these processes is  implied  in  their valvular  nature
and situation: whilst they do not stop the  descent of the secreted
fluids, which it is the office of the ducts to discharge,  they are well
adapted to prevent  the pancreatic  juice from ascending either into
the gall-bladder or  the liver, and  the bile from flowing or penetrat-
ing into the pancreas.
  I have been desirous of  learning  if a similar  structure exists in
other animals; but I regret to say, that in  no work on comparative
anatomy which I have yet consulted, whether systematic or special,
have I found the termination of the biliary duct minutely described,
so as to be able to compare  it  with the human.  The few observa-
tions, which I have had an opportunity of making, seem to show
that this duct at and towards  its termination in the intestine in ani-
mals  of different families,  is  somewhat various.  As the varieties
tend to confirm  the use  of the valvular  structure  in  man, I shall
briefly notice them.
  In  the cat,  the  biliary and  pancreatic  tubes are very similar to
those of man in the manner in which  they terminate; and they are
similarly provided with valvular processes, and proportionally, even
more strongly developed.
  In  the ox and sheep, the pancreatic duct terminates apart from
the common gall-duct.  In  the gall-duct of the  former, the  processes
are shorter comparatively than those of man,  thicker  and rounded,
and are confined to the margin of its mouth.   In that of the sheep,
there is hardly a trace of them, even at the mouth of the duct'
  In  the horse and elephant, both  of which, as it  is well known, are
destitute of a gall-bladder, the terminal structure  of the ducts  under
consideration  is very similar.  It is distinctly valvular,  and in  a
manner bringing  to recollection  the valvula? conniventcs of the
spiral intestine of the cartilaginous fishes.2

  1 The pancreatic duct in man, at  least of Europeans, rarely  terminates
apart  in the intestine; in one instance in  which  I  found it  so terminating,
the valvular structure of the ductus communis choledoehus was unusualfv
indistinct.
  2 In the  horse  the hepatic  and pancreatic duct terminate in a sinus or
pouch-like  cavity, which may be  considered as belonging to the intestine—
not unlike  in its conformation the cavity of the caput galiinaginis of the hu-
man urethra.  In the elephant their termination is very similar:  the mouth
of the sinus is circular and sufficiently  large to admit the end of the little
finger; the cavity  is cup-like within. 
DUCTUS COMMUNIS CHOLEDOCHUS.
219
  In the turkey, two or more hepatic ducts enter the intestine direct
and apart; terminating in the form almost of capillary tubes, pro-
minent  and flexible with extremely  small  orifices, in appearance
not unlike the membranous terminal portion of the urethra of the
ram projecting from the corpus spongiosum, they are without a val-
vular structure.
  In the ray (raia batis) the structure of the biliary duct, where it
passes obliquely through the cents of the intestine,  near the pyloric
end of  the  stomach, is distin. fly  valvular, exhibiting transverse
folds or plates,  offering resistance  backwards  only contrary to ihe
course of the bile.
  Besides the use assigned to the valvular processes in man, to pre-
vent the reflux of the fluids which  the biliary and pancreatic ducts
are designed to discharge, they may be auxiliary also, towards two
other objects, viz. in offering an impediment to the contents of the
duodenum entering the common duct—and in retarding the flow of
the bile from the liver into the intestine, and so promoting at certain
times its passing into the gall-bladder.
  In  the examination of  bodies,  I  am  not  aware  that chyme has
ever been found in the ductus communis choledoehus; I have never
seen it there.   And  from  what 1 have  observed, I am disposed to
believe, that the bile,  after  death,  rarely if ever descends into the
intestine, but is retained  in  the  gall-bladder and  ducts above the
entrance of the common duct  between the coats of the intestine.
This I infer from finding the penetrating portion of duct, not stained
with  bile, like the portion above, and therefore it may be presumed
not containing bile.1   I mention  these  circumstances in proof that
the structure of the  terminal portion of the duct is such as to act
in  the  manner above mentioned.  Besides the valvular processes
described, several circumstances without  doubt are involved in the
operation—as the common duct,  previous to entering the intestine
being enveloped in, or attached to a portion of the pancreas; its ob-
lique passage through the coats of  the intestine; the diminution of
its diameter there; and its clitoris-like papilla, protected by a fold of
the villous coat of the duodenum, somewhat resembling a prepuce,
as has been pointed  out  and described by Morgagni:2 and in  rela-
tion to  the gall-bladder, in addition to some of these circumstances,
its  position,  partly protected from the pressure of the abdominal
muscles by the margin of the liver; and,  perhaps, the relative  posi-
tion of  the common duct, having close  to it on one side the hepatic
artery,  and beneath  it the vena porta? : and perhaps also, the some-
what spiral and lamellar structure  of the  cystic duct.3

  ' This portion of the common duct, may be  considered in  function analo-
gous to  the rectum, commonly  empty and collapsed, and distended only just
before, and in the act of evacuation.
  8 Epist. Anat. p. 33.                             ,•••,!
  5 The biliary  ducts exhibit in different subjects, several varieties—indeed,
they are rarely perfectly uniform, either  in dimensions, or  the manner in
which they are connected,  and especially the common duct with the pan- 
220
davy's researches.
  I shall conclude with a notice of some experiments which I made
in 1829  on the dead body, connected with the  points  under con-
sideration.


                         Experiment 1st.

  Applied a ligature to the pylorus, and made  a small  opening in
the hepatic duct, just above the junction of the cystic, and succes-
sively distended by means of a powerful syringe the duodenum with
water and wilh air:  neither passed into the duct.


                         Experiment 2d.

  After the duodenum had been well washed out, it was filled to dis-
tention  with clear  water.   Pressure was  made on the  gall-bladder
and ducts; the water in the duodenum was found strongly coloured
with bile;  and bile  was found to pass when  similar pressure was
used, the duodenum  being distended  with air.


                         Experiment 3d.

  Laid  open the duodenum, so as to expose the papilla of the ductus
communis coledochus, and having tied the  hepatic duct, made pres-
sure on  the gall-bladder :—the common duct was presently distended
with bile, but no bile passed  into the intestine; a considerable de-
gree of pressure was required to  make  it flow  into the intestine.
And the result was the same, and even more strongly marked, when
the hepatic duct was not tied.

creas. In illustration of some of the circumstances  mentioned  in the text, I
shall give the results of a careful admeasurement of one ductus communis
choledoehus—from a man, aged 30, who died  of pulmonary  consumption.
Slit open, the greatest width of the tube, at the junction of the hepatic and
cystic ducts, was tW01^ an inch, its least near its  termination tsq', its length,
measuring from the junction of the tubes, was just three inches ; rather more
than one-third of its  length, viz. Itcto  inch, was hid, enveloped in the pan-
creas and penetrating the coats of the intestine; where it first joined the pan-
creas, its width was tw> lne length of the portion penetrating obliquely the
intestine was tVoj and the longest valvular filament or process was yVV
In this duct, the valvular  apparatus was strongly developed, and when the
processes were distended (as they were by immersion  in dilute sulphurous
acid)—their points ciossed obliquely, completely obstructing  the passage.
Glisson in his Anatomia Hepatis, mentions, or rather infers the existence of,
circular fibres, in the oblique part of the duct, to which he attributes in part
the prevention of regurgitation, "regressu omnis in ductum communem pra?-
peditur a fibris annularibus, quae non modo orificium ipsum, sed et totum ob-
liquum tractum obsident.'" In the duct, just noticed, there was a distinct
appearance  of transverse fibres,  but to a very limited  extent,  close to the
mouth of the pancreatic duct; they had a silky lustre, not unlike the fibre of
tendon or of the dura mater, and their use, it may be conjectured, is to pre-
vent undue  extension of the part.
  '  Anat. Hepai. Cap.  xvi. 
OBSERVATIONS ON PUS.
221
                       Experiment 4th.

  After having laid open the duodenum, and emptied the gall-blad-
der, by a small opening in its fundus, which was closed by ligature,
injected water gently through the hepatic duct, it rose more freely
in the gall-bladder than it passed into the duodenum.

                       Experiment 5th.

  Placed the body in such a  position  that the gall-bladder was
raised above the level of  the mouth of the common duct,  and in-
jected water as before.  Now it flowed into the duodenum, but did
not enter the gall-bladder.

                       Experiment ftlh.

  The body lying on its  back, injected water forcibly, and with va-
rious degrees of  force ;  it flowed freely into the intestine, and rose
in the gall-bladder so as to  fill  it nearly one third full,—and to the
same extent, whatever was the degree of force employed ; and which
appeared to be (as well  as could be judged by the eye) the  level of
the  mouth of the duct, supposing a horizontal line to be drawn from
it to the gall-bladder.
  Whether there is any vital, peculiar force regulating the expan-
sion and contraction of the mouth of the common duct, and conse-
quently the flow of the bile, it  is difficult  to determine.  That  me-
chanical causes must operate powerfully can hardly be doubted :—
the  results which I have described seem to prove it; and such causes
in conjunction with the variable secretion of the biliary fluid, ac-
cording to the degree of activity of the secerning  organ, will proba-
bly  serve to account for most  of the phenomena belonging to the
course of the bile both in  health and disease.
                            XVIII.

                  OBSERVATIONS  ON PUS.

  The observations which I propose to offer on this subject are of a
miscellaneous kind, with the hope of contributing something to ad-
vance our knowledge of this very important fluid.
  L—I have made several experiments to endeavour to determine
if the pus of an  abscess contain air.  In each  instance the pus, as it
flowed from the abscess, carefully opened at the moment, was received
into a vial full of distilled water that had been  subjected to the air-
       \\__d                                     15  dav 
222
davy's researches.
pump until entirely deprived of air;  and as soon as it had acquired
the temperature of the atmosphere, it was submitted to the action of
the pump, the same instrument as before noticed, and in good order.
   The first trial was  on thick pus from an abscess in the neck of a
young man recovering from an attack of erysipelas of the face.  The
quantity received into the water was small ; it  remained at  the
bottom and was perfectly tranquil; not a particle  of air was disen-
gaged from it, when the exhaustion was as complete as possible.
   The second trial was made on pus from an abscess in the arm of
the same patient, opened  the day after the preceding;  and in this
instance also the result was entirely negative.
   A third trial was made on pus  from the same  person, obtained
from an abscess which had formed in the axilla, opened three weeks
after the last, when his convalescence was well advanced; and again
the result was negative, not a particle of air was disengaged from it,
in the most perfect vacuum that could be formed.
   The fourth trial was on pus from an abscess in  the arm of an old
soldier,  after a very severe attack of erysipelas, (diffuse cellular in-
flammation,) which for many days had endangered life.   The  mat-
ter in this instance was rather thick, and it did not subside readily in
the water.  Submitted to the air-pump, three or four bubbles of air
rose from it.   This occurred before the vacuum  was nearly com-
plete ; seeming to indicate, that the air did not belong to the pus, but
was accidentally entangled, in  passing from the  abscess,  into  the
vial; and in confirmation it may be remarked, there was no general
effervescence, or separation of air from the pus, even of the slightest
kind, when the exhaustion was carried as far as possible.
   These trials then tend to prove  the absence of air in pus from an
abscess.  If,  however, air  in any way have access to the purulent
fluid, and it be subjected to the air-pump, the result, as might  be
expected, will be different.  In one instance, I had proof of this in
an experiment with the air-pump on  some pus from the pleura, in a
case of empyema complicated with pneumothorax, of many months'
duration, in which an opening had spontaneously formed in an in-
tercostal space, discharging daily a small quantity of purulent fluid
of good consistence and colour;  although entirely free from fetor,
this pus under the exhausted receiver gave off a good deal of air.1

   'Some pages back I  have given the  results of experiments apparently
showing that air is not contained in the animal solids  and fluids in their
normal state.  I perceive, that Professoi  Burdach has arrived at a different
conclusion, and that he refers to Dr. Dalton in support of it.  In the 8th vol-
ume of his Physiology considered as a Science of Observation (cap. ii. 4.)
he remarks: "There are many inorganic bodies,  especially water and the
earths, which absorb air, and sometimes  even to an extent exceeding their
own volume, and consequently condense and render it latent.  The organic
substance also exhibits an attraction of this kind for air in a very high degree.
Dalton (Bibliotheque Univ. de Gen. t. liv. p. 130) has proved in the following
manner, the existence of a considerable quantity of air in combination in the
human body.
   " The lungs and stomach are the only parts of the body which contain free 
                       OBSERVATIONS ON PUS.                   223

   2.—It is commonly stated that the specific gravity of pus is 1030.'
According to my experiments this quality is far from fixed; I have
found it considerably variable.   I shall state some of the results
which I have obtained.
   i.—From the pleura, in the case already referred to, of empyema,
complicifed wilh pneumothorax, it was of specific gravity 1028; it
was pus ot good quality and  ordinary consistence, "Album, leve et
a?quale."
   ii.—From an abscess in the thigh, not quite  equable, its specific
gravity was 1031.
   iii-—From the axilla,  in convalescence  from  erysipelas,  pretty
equable, of moderate consistence; it was of specific gravity 1029.


air; the former wilh a capacity of ICO cubic inches, the latter of 50; but the
volume of the whole body is about  4500 cubic inches, or setting  aside  the
lungs and stomach, 4350 cubic inches for the whole of the remaining solids
and fluids.  Now, as the mean specific gravity of these is 1050, their weight
for their volume ought to be equal to 4567 cubic inches of water, that is, 164
lbs.; but the real weight of a man alive of the bulk in question is only 146
lbs. that is equal to 4044 cubic inches of water; consequently it is  necessary
that the solids and liquids during  life should be penetrated with air; and that
thus they should attain a specific gravity inferior to that which belongs to
them when examined apart,  detached, after death, when a portion of their
air is disengaged."—"Dalton (he  continues) states further in support of this
argument, that when the hand is  applied to the orifice if a receiver on the
plate of an air-pump, on exhaustion,  it is felt to be drawn in and to swell,
because the air  contained in the part tends to escape."
   Neither the argument used by this distinguished man,  nor the example, I
apprehend, can with propriety be opposed to the results of actual experiments.
But wniving this, are the data on  which  he reasons, established in  fact ?  Is
the mean specific gravity of the solids and fluids so high  as 1050?  And is
the specific gravity of a dead part detached, independent of difference of tem-
perature, higher than before it was detached  and  during life?  1  believe a
sufficient number of accurate experiments have not yet been made to deter-
mine the first question.  The second, I believe, must be answered in the nega-
tive; from all I have witnessed in trials with  the air-pump, I am convinced,
that instead of air being expelled  after the excision of a part and after death,
and the specific gravity of the part increased,  the contrary happens,— air en-
ters into it, especially its divided vessels, and  its  specific gravity  is dimin-
ished.  Even  admitting the data,  the reasoning seems defective,  inasmuch
as though the specific, gravity of the whole body must  be diminished by the
penetration of air,  the weight  of ihe whole  body must  be increased  by it.
Relative to the drawing in of the  hand and its apparent swelling,  in the in-
stance adduced, the  effect admits  of  easy explanation, by refeience  to the
operation  of atmospheric pressure disturbed:  on the side  from which the air
is exhausted, resistance is withdrawn, the hand is  pressed in from the force
acting from without, and if a blood-vessel be opened, [as  is witnessed in the
operation of cupping, the vessels being subjected to pressure on one side and
not on the other,] the blood will flow freely in vacuum.  I  have already given
the result of subjecting portions of vessels containing blood, to exhaustion,
not partial but on every side, indicating no expansion,  no swelling.
  'Dr. Pearson found, in two instances, a certain  relation between the spe-
cific gravity of the pus, and of the serum of the blood of two individuals; in
one, That the pus was of specific sraviiy 103 ., the serum was of specific grav-
ity 1029; and in the other in which the former was 1033, the latter was 1031.
^Phil. Trans,  for 1810, p. 295. 
224
davy's researches.
  iv.—From the arm, also  in convalescence  from erysipelas of a
dangerous character, (before alluded to, as well as the  last,) its spe-
cific gravity was 1036.
  v.—From an  abscess in the back of a young  man, its  specific
gravity was 1040;  it  had a slight reddish tinge, and under the mi-
croscope was found to contain a very few blood corpuscles.
  vi.—From a large cavity in the lung in a fatal case of pulmonary
consumption, its  specific gravity was  1042;  it  was rather thicker
than the healthy pus of an  abscess.
  vii.—From a  vomica in the lung, in another fatal case of pulmo-
nary consumption,  it  was of specific gravity 1021.
  This variableness of specific  gravity is probably owing to two
circumstances, chiefly,—to variable proportions of the ingredients of
the specimens tried, and the variable density of the liquid part.  If,
ca?teris paribus,  the liquid part of the pus predominates, it  will pro-
bably be of comparatively low specific gravity;  if the concrete part
is in excess,  the  pus-globules, it will probably be of high  specific
gravity.1
  The  pus-globules themselves, I believe to be not less heavy than
the blood corpuscles;  I  have come to this conclusion by mixing
small portions of pus  with solutions of sulphate of soda, of different
degrees of strength ; with  one  of specific gravity 1132, the globules
were  for a  time suspended, slowly subsiding  rather  than rising
towards the surface ;  and,  in this instance, when  examined by the
microscope, the  form of the globules did not appear to have under-
gone any distinct change.3
  What the specific gravity of the  liquid portion is.  I  have never
ascertained in any example; it is, indeed, a point difficult to deter-
mine, unless a large quantity  of purulent fluid can be employed for
procuring it; for the concrete  part,  the globules, and the liquid part,
cannot be separated by filtration, owing to the viscid quality of the
latter; and owing to the same quality, the globules on  rest  subside
very slowly, and rarely leave the supernatant fluid perfectly trans-
parent; the supernatant fluid, under the microscope, is commonly
found to contain  globules, the majority of them smaller than the or-
dinary pus-globules, and of a form less uniformly regular.
  3.—As might  be expected, pus  freezes less  readily than water.
In the winter of 1811, I exposed some pus from an  abscess, to the
open  air over night,  when the temperature  was several  degrees
below 32°.  On the following morning,  it had  an appearance not
unlike that of frozen milk, semi-hard, easily  broken,  composed of

  1 Dr. Pearson, in his paper entitled " Observations and Experiments on Pus,"
in the Philosophical Transactions for 1810, notices four kinds of pus.—1.
The cream-like, and equally consistent; 2, the curdy and  unequal in con-
sistence; 3,  the serous and thin kind; 4, the thick, viscid, or slimy.  He
states that he found the specific gravity of each kind very similar.
  2 Concentrated solution of sulphate of soda, imparts viscidity to pus,—but
more slowly and in a  less degree than muriate of ammonia, and appears to
have less effect on the general appearance of the pus-globule. 
OBSERVATIONS on pus.
225
large thin  plates with fluid  intermixed, arranged  vertically.  On
thawing, the pus did not recover its original properties.  Previously
it was not viscid, excepting in a  very slight degree; now it had be-
come so distinctly, and was slightly ropy.  It was also partially co-
agulated ; and it mixed less readily with water.
  4.—Certain fluids, mixed with pus, have the effect of rendering it
viscid, like mucus.  Solution of potash and soda, and ammonia, act
thus in  a remarkable manner, and a solution of muriate of ammonia
and other neutral salts act similarly, but  in a less  degree.  These
are facts which have  been long known.  Two views have been
taken of the effect.
  It was supposed by Mr. Hunter,  who  first noticed specially the
phenomenon,  that it was an instance  of coagulation,1 an opinion
which has been adopted by some recent writers; thus one, deserv-
edly eminent, (M. Andral) in an article on pus in the Dictionnaire de
Medicine, noticing different varieties of purulent fluid,  remarks,—
"Tous  en definitive,  paraissent etre composes de globules  sem-
blables, nageant dans  un fluide, lequel est susceptible de se coagu-
ler, lorsqu' on le  mele a une solution de muriate d'ammonique."
Dr. Pearson, on the other hand,  has denied that it is a coagulation,
and supposes it to be an  inspissation, "seemingly occasioned," as he
says, "by the  solution of muriate of ammonia attracting water from
the pus."2
  From the observations which  I have made, both these modes  of
explaining the effect appear to be inadmissable.  When I had mixed
a little of the  fluid part of the pus,  decanted tolerably clear, with a
solution of muriate of ammonia, no change was produced, not the
slightest degree of viscidity  was imparted; but when some  of the
opaque  part containing globules  was added, it shortly became vis-
cid.   And in  confirmation I may remark, that  when  viscidity  is
imparted to pus either by the saline solution just mentioned,  or  of
common salt, or of nitre, the quality is not destroyed by dilution ;
the greater part of the saline matter may be  removed by  repeated

  'Mr. Hunter  describes pus as a liquid, "composed of  very small  round
bodies, very much like those small globules which, swimming in a fluid,
make cream."   He adds, "these globules swim in a fluid, which we should
at first suppose  to be the  serum of the blood, for it coagulates with heat like
serum, and most probably  is mixed with a  small quantity of coagulating
lymph; for pus  in part coagulates, after having  been discharged from the se-
creting vessels, as  mucus is observed to do.  But  although it is thus far
similar to serum, vet it has properties that serum has not. Observing there was
a similarity between pus and milk, I tried if the fluid part of pus could  be
eoagulated wilh the juice of the stomach of other animals, but found it could
not.   I then tried it with several mixtures, principally with the neutral salts,
and found that a solution of sal ammoniac coagulated this fluid : not finding
that a solution of this salt coagulated any other of our natural juices, I con-
cluded that globules swimming in a  fluid that was coagulable by this salt,
was to be considered as pus, and would  be always formed in sores that had
no peculiar backwardness to heal."—(Treatise on the Blood, &c,  in vol. in.
of Works,  p. 449.)
  'Philosophical Transactions, for 1810. 
226                 davy's researches.

additions of water, and yet the pus will remain viscid;  and further,
that if pus be mixed with a large quantity of water in a tall jar, and
the water be decanted after the pus globules have subsided, and this
repeatedly till the liquid part of the  purulent fluid is entirely re-
moved, the globules collected on a filter become viscid on admixture
with a saline solution, almost as readily as if they had not been so
treated, and not in an inferior degree.
   5. Dr. Pearson makes a statement apparently contrary to what I
have advanced; he says, if the purulent fluid rendered viscid by a
strong solution of muriate of ammonia be agitated in cold water,
"the matters are diffused, and on standing, the pus is precipitated
in its original state;" and also, that viscidity is not imparted  by a
dilute solution  of the salt.  In answer to this, I shall notice the ap-
pearances I  have  observed in making an experiment, to test the
value of his remark.   A strong solution of muriate of ammonia was
diluted with rather more than an equal volume of water, into which,
si diluted,  a little pus  of an abscess was poured, and they were
mixed by agitation. The mixture was of a light grayish hue, trans-
lucent and equable ;  the globules showed no disposition to subside,
marking a slight degree of viscidity, and which, on trying it with a
probe, it was found  to  possess.   It was now thrown  into a large
quantity of water, by which its viscid property  became very con-
spicuous.   It immediately sunk, and  did not  mix  with the water,
keeping together in a mass like the glairy white of an egg, similarly
treated, or like mucus, which, under water, it greatly resembled;
and the resemblance was more striking from filaments being raised
from the general mass,  by minute air bubbles disengaged and sus-
pended in the viscid matter.
   As the concentrated solution of muriate of ammonia and the other
neutral salts, in my experiments, have not rendered the fluid of pus
viscid; as they do not render serum viscid,  and there appears to be
no necessary relation between concentration and  viscidity, the con-
clusion I have come to, and which has been confirmed  by all I have
witnessed, is, that the effect  of viscidity is equally independent  of
inspissation, and coagulation, and is produced on the globules them-
selves, which,  in fact, are the part which exhibit it.  In accordance
with this, when the viscid fluid is examined with the microscope, its
globules have a somewhat fainter appearance,  as if their transpa-
rency were increased;  and they also appear a little expanded,  and
adhering together more or less, and if moved, when in the field  of
the microscope, some of them may be seen to be  a  little elongated.1
   6. According to a recent analysis of pus by Dr. Gueterbock, 100
parts of this fluid from  an  abscess in a mamma, were found to con-
sist of—

   'In accordance with  this view, it may be remarked that the time required
for different varieties of pus to become viscid on admixture with solution  of
muriate of ammonia is  far  from constant; some exhibit the effect almost im-
mediately; others not till after several hours. 
OBSERVATIONS ON PUS.                 227
  86.1  Water.
   1.6  Fatty matter, soluble only in hot alcohol.
   4.3  Substances soluble in  cold alcohol, viz. fatty matter and
          ozmazome.
   7.4  Substances soluble neither in  hot nor cold alcohol, viz.
          albumen,  pyina, and  the  substances of the globules
          ("globuli et grana puris.")
   0.6  Loss.

 100.01

  From my own experiments I am disposed to consider these  re-
sults as correct and deserving of confidence.   They have been con-
firmed generally in two or  three instances, in which I  have sub-
mitted pus of an abscess to  analysis. The method of analysis which
I have followed has been somewhat different from that used by the
ingenious author just quoted.
  First, The purulent fluid was slowly evaporated to dryness, at a
temperature below that of boiling water.
  The yellow residue of a greasy feel, was then  treated with  di-
lute spirit of wine.  The solution thus obtained, evaporated, yielded
a matter of  a light, bright  yellow hue, soluble in water, and par-
tially deliquescent, consisting chiefly of saline  matter and of ozma-
zome.
  Next, pure  alcohol was  used, and heat employed, nearly to the
boiling point.   Whilst hot, the  solution formed was decanted and
evaporated to a small bulk.  On cooling, a notable portion  of fatty
matter was deposited,  also of a light yellow hue.  The residual fluid
decanted and evaporated, yielded only a very little matter of a brown
hue, consisting chiefly of fatty matter, mixed, I believe, with a little
ozmazome.
  The albuminous residue not dissolved  either by dilute spirit of
wine, or  by concentrated alcohol, was in large  proportion, compared
with  the quantity of the  substances mentioned, extracted by  the
spirituous menstrua.   The precise proportions of the  constituent
parts, I  have not  attempted to verify; a great deal, I  apprehend,
remains  to be done,  before this can be  considered of much  import-
ance.
   The. fatty matter, which I have obtained from pus has been sim-
ilar to that described  by ihe author last quoted ; of a butteraceous
consistence ; moderately firm at 60°; semi-fluid at 80° ; and liquid
 at a somewhat higher temperature, according  to Dr. Gueterbock at
about 140°  F. and when pretty strongly heated giving off an ammo-
 niacal smell.   Dr. Gueterbock mentions  that he  could obtain no
 proof of the presence of cholestrine in it, which recently it has been
 asserted  exists in  pus. This substance, he justly remarks, is depos-
 ited  from  hot alcohol in cooling, in the form  of crystalline plates:

             1 De Pure et  Granulatione, p. 17.—Berol. 1837. 
228                  davy's researches.
no such plates appeared  in  any of the  processes with alcohol, to
which pus was submitted in his experiments; and I have the same
remark to make on mine; thus indicating the absence of cholestrine.
Probably the fatty matter is a mixture of  two or more  kinds, one
capable of combining with  alkalies, and forming a soap ; another
not, and so resembling and approximating to cholestrine.   Dr. Gue-
terbock appears to be of opinion, that the fatty matter of pus is free
adipose matter mixed with the purulent fluid, inasmuch as adipose
globules  may be  occasionally (letected in  it with the microscope,
and the paper used in filtering pus is rendered slightly translucent.
  This conclusion does not appear to me very probable,  or well
supported; it seems to me more likely, that the fatty matter belongs
essentially to pus, and enters into the  composition of the  pus-glo-
bule, and that it is to it that the pus owes its colour and  its cream-
like character.  In an instance of phthisis  with much emaciation, I
have detected it in the pus of a vomica; in which it could hardly be
expected  to be found, unless essential.
  Of the substances inferred to exist in pus and not soluble in alcohol,
that which has been  called pyina is the only one on which  I shall
offer any remark.  Dr. Gueterbock, the discoverer of it in pus,  and
by whom  it has been named, considers its characters well marked
as a proximate principle ; namely, solubility in water, insolubility in
alcohol, and acetic acid, precipitation from solution in water by this
acid, and non-conversion into gelatine by long continued boiling.  I
would not wish to appear unduly sceptical; but  I  cannot refrain
from doubt relative to the positive existence of this substance, inde-
pendent of the means employed to procure it.  It is possible that it
may be formed by the action of acetic acid on the albuminous  part
of the pus.  I have stated at page 53 of this volume, that the serum
of the blood is not coagulafeel by strong acetic acid.   I have since
found, that although there is no effect immediately produced,  nor
for many hours, yet that there is in the course of many days,  and
that if the mixture of the serum and acid be kept, after a time it will
be found jellied or feebly coagulated; and farther, that  the  gelati-
nous  compound under  the  microscope  exhibits very minute  glo-
bules.  Now, is it not possible that this acid on  the  serous fluid of
pus may have a more rapid effect, and produce instantly a substance,
a form of albumen, such as  that which has been called pyina? The
properties of animal and vegetable substances are so  easily altered,
by feeble agencies, sometimes with, sometimes without, new arrange-
ments of their  elements, independent of any alteration in their  pro-
portions,  that great caution requires to be  observed  relative  to the
adoption  of new  proximate principles.
  7.—Dr. Gueterbock has given a very good account of the  pus
particles,  under microscopical examination,  with  which my obser-
vations perfectly accord.  After remarking that  they vary  in size,
and that hitherto those of the greatest magnitude only had  been de-
scribed by authors, he adds,—"Corpuscula majora formarn habent
paene rotundam,  et spha?ricam, quam, si aqua  evaporanie magna 
OBSERVATIONS ON PUS.
229
natant celeritate, luculenter videre poles.  Et forma et magnitudine
paulo  discrepant, alia (et  major quidem pars) satis rotunda,  alia
irregularia, marginibus aliorum  acutis, aliorurn crenatis, snperficie
in plerisque rugata, mororum non dissimilis, ita ut, qui primum ea
videant, alia granula minora supersedere credat."1   The same writer
has also described faithfully the  appearance of the individual pus-
globule, when carefully observed and subjected to the action of dif-
ferent agents.   The result of his observations  is that the globule is
composed of two parts,—an involucrum, which is rendered more
transparent by water,  spirit of wine and acetic acid,—and of cen-
tral granules,  on which  the agents  mentioned have not the same
effect;  and,  in consequence, they are rendered by them, more con-
spicuous.
  Mr.  Gulliver, too, has  recently directed his attention to the same
subject, and, quite independently, has arrived  at the same conclu-
sion relative to the compound nature of the  pus-globule.  This gen-
tleman  considers the central granules,  or,  as  he  designates them,
molecules, as composed of a peculiar principle, possessed of proper-
ties similar to  those belonging to pyina.2
  Of the accuracy of the observations generally, on which this con-
clusion is  founded,  I have not the  slightest doubt.  But I am  not
quite free from doubt concerning the inference, viz. that the cen-
tral granules or molecules, are  composed  of  a distinct substance.
Fibrin is not dissolved by acetic acid ; the spermatic entozoa are  not
dissolved by it; coagulated serum is not dissolved  by it;3 nor is fatty
matter; in brief, its  solvent power over animal  substances generally
is very inconsiderable, as 1  have  briefly mentioned, when treating of
the action  of  distilled  vinegar.4  I  have sometimes  imagined that

  1 When pus is mixed largely with water, and thrown on a filter, the greater
part of it is retained on  the filter; a small portion passes through with  the
water; under the microscope, the particles of the latter appear more irregular
in form, and most of them smaller than  those of the former.   Also, when
largely diluted  with water,  in  a tall jar, and set aside at rest,  a difference
will be found in the time of subsidence  of the particles,  some falling down
immediately, others not for many hours; and these last, on microscopical
examination, I have commonly found ill defined in  form,  and  of a looser
texture.
  2 Vide London Medical Gazette, May, 1839, for a notice of Mr. Gulliver's
paper, " On the composition and elementary structure of the  Pus-globule."
  3Contrary to what Dr. Gueterbock mentions, I  have not found the  involu-
crum of the pus-globules  dissolved by acetic  acid ; only rendered more trans-
parent.  If, after the action of this acid, an alkali be added to neutralise it,
oi if a solution  of common salt be mixed with  it, to change the refractive
power of the medium, the involucrum is rendered discernible.
  4 Doubt, perhaps, similar to that which I have expressed, has occurred to
Dr. Gueterbock; this  I infer from his remark relative to  the composition of
pus-globules; that he cannot  venture to determine whether they consist  en-
tirely, or only in part  of fibrin; and also from the notes to this remark, con-
cerning the action of acetic acid :—" Berzelio duce fibrinam sanguinis bovini
et albumen ovi calore coagulatum bene abluta  acido acetico  concentrato
superfudi, ut utrumque inlumesceret, at aqua coquente  tantum vix utrius-
que solutum est, ut solutione  kali feiroso-hydrocianici  parcum fieret sedi- 
230
davy's researches.
the appearance attributed to central molecules might be owing to par-
ticles of air. disengaged by the action  of the acid on  the minute
quantity of carbonated alkali, which there is reason to believe e^,sts
in the pus-globules.   Some facts are not unfavourable to this idea;
thus, though the globules are rendered  more translucent by a solu-
tion  of pitash, soda, or ammonia, the molecules are less apparent
than even when in water, and if either of these alkalies be added to
a mixture of pus and acetic acid, the molecules, before very visible,
become indistinct.   At other times, I have  supposed  that the ap-
pearance in question might be connected  with the existence of par-
ticles of fat in the globules, on which  the acetic acid would have
little effect, and  might render  more conspicuous by increasing the
transparency of the enveloping  part.   The circumstance that alco-
hol does not render  the  molecules  more but less distinct, whilst it
augments the translucency of the involucra, is rather favourable to
this  idea.  I venture to express the foregoing doubts,  and to offer
these conjectures on this obscure subject, with hesitation, and the
hope that they may lead to further  inquiry.  In justice to Mr. Gul-
liver, I should remark, that I have  not read  his paper referred to on
the composition of the pus-globule; the volume of the Transactions
of the Medico-Chirurgical Society,  in which it will appear, not hav-
ing  yet been published.
   8.  Relative to that important question in  pathology, the mode of
formation of pus, it  is matter of very interesting inquiry, whether it
is a  secretion depending on a peculiar state  of vessels in the part in
which the  fluid  is collected, or whether it may not be formed in the
general mass of the circulating blood,  and be poured  out merely
where it is found collected.   The phenomena of ulcers are favour-
able to the first view; and seem at least  to  prove, that in certain
cases its origin is local, and that it is  formed  in  the part where it
presents itself.   On  the other hand, the collections of pus  which so
often occur in  erysipelas in deeply seated  parts, remote  from the
cutaneous  inflammation, and without symptoms of corresponding
local inflammation,  favour  the  latter view.   This view is also fa-
voured by the detection  of globules resembling pus-globules in the
blood during the process of suppuration,—whether in  instances of
superficial suppuration,  as in small-pox, or in  deeply seated, as in
tubercular phthisis, or lumbar abscess;  and  the analogy which there
is in  a certain dpgree  between the  puriloid  matter,  occasionally
found in masses of fibrin, in the  cavities of the heart and of the great
vessels, seems to me likewise to support it.   Inquiry now is happily
directed to pyogenesis,  and with the aids which the collateral sci-
ences are capable of affording, there is good ground for hope,  that

 mentum. Miratus, quod Berzelio teste  in omnibus libris chemicis adnotatum
est,  et fibrinam et albumen  acido acetico solvi, experimentum  sajpius repe-
 tivi, nonnunquam acido acetico diluto adhibilo sed semper idem fuii eventus."
 He justly adds, " Si hsec experimenta probantur, novos in tenebras et confu-
 siones incidimus, et ad novam materierum illorum simplicium disquisiiionem
 excitamur." 
               EXPERIMENTS ON THE TORPEDO.            23

its termination will be successful; and  if successful, that it may be
the commencement of a new era in pathology.
XIX.
 AN ACCOUNT OF SOME EXPERIMENTS AND  OBSERVA-
                 TIONS ON THE TORPEDO.

  The extraordinary property which the torpedo possesses of im-
parting shocks similar,  as far as sensation is concerned, to those of
the Leyden vial, was one of the last suhjects to which the attention
of my brother,  the  late Sir  Humphry  Davy, was given.  In the
memoir which I have published of his  life, particulars are related,
showing how great was the interest he took in the inquiry, and how
anxious he was that it should  be  prosecuted—and how he urged
me to enter on it.   The last  letter he ever addressed to me, written
from dictation when he considered  himself  dying, is strongly ex-
pressive of his  feelings.  I shall insert it—partly as  an expression
of the  feelings, and partly as showing what he considered  one of
the chief desiderata in the inquiry.

                                      Rome, Feb.  25th, 1829.
"My dear John,
  "If  I  had not had this attack, it was my intention to have gone
to Fumicina, or Civita Vecchia, to make some experiments  on the
torpedo.   I  hope you  will take up this subject,  which, both as a
comparative anatomist and chemist, you  are very capable to eluci-
date. You will see my paper on the torpedo in the manuscript book
which I  have left in Mr. Tobin's hands.1   It was my wish to have
exposed an unmagnetised needle to the  continued shocks of a tor-
pedo in a metallic^spiral, making the metallic communication per-
fect with both electrical organs. There is in my  little box an appa-
ratus which I hope you will use.  Large  living lorpedos may be
procured  at  Fumicina or Civita Vecchia.  The  shock from a very
small jar will make a needle magnetic, provided it is entirely passed
through the metallic conductors^;  but I did not find this effect when
there was any interruption by water.  There are many things worth
attending to in the two kinds of torpedinal fishes found  here-the
tremula'and occlnatella.  Pray do not neglect this subject  which
I leave to you as another legacy.  God bless you, my dear brother,
your affectionate friend,                                    ,
'                                                "H. Davy."

  ' This  his last paper and communication to the Royal Society, was pub-
lished  in the Philosophical Transactions for 1829; it was written in the
preceding October; its results were entirely negative. 
232
davy's researches.
   The researches which I instituted in compliance with these his
 wishes, I had  the satisfaction of commencing at Rome, in  his pre-
 sence, and  of  thinking that  they afforded  him  amusement in  his
 last days; they were continued in Malta, and finished in England.
 The  experiments on the living fish were entirely made in Malta,
 under very  favourable circumstances: the anatomical part of  the
 inquiry was commenced at Rome. Most of the results have already
 been  published in the Philosophical Transactions, in two papers—
 the first of which was  read at  the Royal Society in March, 1832,
 and the second in June, 1834.  I may premise that when I entered
 on the inquiry, it had  not been  ascertained  that the electricity of
 the torpedo, considering its peculiar influence to be electrical, had
 either the power  of acting electro-chemically, in  separating the ele-
 ments of any compound bodies; or magnetically, either in affecting
 the needle in the  multiplier, or in imparting magnetism to iron;  or
 lastly, of generating or producing heat: points to which  my experi-
 ments were  particularly directed, and with positive and successful
 results.  I  may further remark,  that in describing the  results  ob-
 tained, I shall not strictly follow the same order as was observed in
 my first publication, or restrict myself entirely to the details given
 in them: what in those were necessarily disjointed, will  here be in-
 corporated;  and I shall make without hesitation  such alterations as
 any additional  knowledge  I  have since been able to attain by  my
 own labours may seem to render advisable.

        1.—Experiments on the electricity of the torpedo.

   From the preceding letter, it appears how desirous my brother
 was  of trying  the effect of the shock of the torpedo on a needle
 placed in a  spiral wire.  The result, he was  of  opinion, would be
 conclusive as to  the  nature of its electricity—that is,  whether it
 should be considered as distinct, and  of a peculiar kind, or merely
 a variety of common  electricity, or  at least analogous to  kinds
 already known.
   Anxious  to  make this trial,  I had an  apparatus in readiness,
 which, with common electricity,  I had found to answer extremely
 well.   It consisted of  a fine copper spiral wire, (the spring of a
 bracer,) about one inch and a half long, and one tenth  of an inch
 in diameter,  containing about  one  hundred  and eighty convolu-
 tions,  and weighing about  four grains and a half.   This was  in-
serted into a glass tube, just large enough to receive it, and secured
by corks.1 The wire passed through the cork  at each end. and was
 connected with strong  wires with glass  handles  for the purpose of
 contact.  The wire intended to be applied to the under surface of
 the fish was one twenty-fifth of an inch in diameter; that intended
 for the upper surface was stiffer, being one fourteenth of an  inch in

  1 The apparatus referred to by my brother, in his letter, did not answer so
 well: the spiral was of silver wire, wound round a  glass tube. 
experiments on the torpedo.
233
diameter; and its greater strength was useful, as it was  necessary
to employ it  occasionally with some force to  rouse the fish when
averse to give  a shock.  The first  trial  I had  an opportunity of
making with this apparatus was  successful.   It  was on  the 3d of
September, 1831, at eleven o'clock at night.1   The fish uced was a
small one, about six inches long; it had been just  caught in a
hand-net, and immediately put into salt water,  and was very active.
A needle, perfectly free from  magnetism, was introduced into  the
spiral, and there confined by the corks, and the spiral was carefully
connected with the insulated  wires for contact.   The fish for  the
experiment was placed in a glass basin,  and was  barely covered
with water.   One wire was applied to the under  surface of  the
electrical organ, and  the other  to its upper surface, and contacts
were  made at intervals during about five minutes, when the fish
seemed  much exhausted by its  exertions. On  taking the needle
out, and bringing it near some fine iron filings, it was found to be
magnetic, and powerfully attracted them.  This experiment I have
repeated  many  times with fishes of different sizes, some larger and
some smaller, and with the same result whenever the fish has been
active, and the contacts similarly made.
  The next trial instituted on  the electricity of the torpedo was on
Ihe multiplier; it was one which belonged to my brother, the needle
was poised on a pivot, and  was not very sensible.  The precaution
was taken to  insulate the instrument well, by smearing with seal-
ing wax the feet of the stand supporting the coil.   The same wires
for contact were used in this as in the former experiments, and  the
junctions were  carefully made.  Applying one wire to the under
surface, and the other to the upper surface, using the fish first men-
tioned, and after an interval of only two hours, I succeeded in  ob-
taining decisive results; the first shock had a  powerful effect,  the
needle made half a revolution: and other trials were in accordance.
The needle, by active fishes, was generally thrown into violent mo-
tion, occasionally describing nearly a circle, and even by the feeblest
it was distinctly affected.   I have met with no  instance  of a fish
which had the  power of magnetising a needle in the spiral wire
failing to move the needle in  the multiplier;  but I have met with
more  than one example of a fish whose electricity was equal to  the
latter effect and not to the former.
  I have not mentioned, in my  paper in the Philosophical Trans-
actions,  that  I  made comparative trials with the same instruments
on the salt water alone by  contact.   Referring to my notes,  I find
this distinctly mentioned,  and  that no  effects  vyere perceptible;
neither the needle in  the  spiral acquired the slightest degree of

  1 It may appear singular that this experiment was  not made before. The
explanation is  easily made.—On my return from Rome to Malta, in June,
1829, I was assured' that the torpedo is not known in the latter place.   It
was not until the summer of 1831  that I found out that I  had been misin-
formed, and lhat, with a little trouble, the fish may be procured alive at all
seasons of the year. 
231                  davy's researches.

magnetic  power, nor did the needle of the multiplier experience
any divergence: fully satisfying me that the effects were owing to
the peculiar power of the fish.  Indeed,  that this power was the
cause, was manifest from the variability of the effects, in accordance
in degree  of strength with the energy of the torpedo,  as  indicated
electrically by the sensation  which its shock imparted.
   The experiments which I  have instituted, with a view to ascer-
tain  if the electricity of the torpedo has any  igniting power, or
power of passing through air, and of  producing  light, have been
attended with less satisfactory results.  Very active fishes were tried
on circles  of perfect conductors,  interrupted only by  a space just
visible with the aid of a powerful magnifier.  The terminal wires,
coated with sealing wax, excepting at their extremities, were intro-
duced through a perforated glass stopple into a small glass globe,
which was held in the  hand of an assistant.   The contacts were
made in the dark; but not the faintest spark could be perceived,
nor could  any ignition be perceived when  the extreme points were
connected with silver wire,  not  exceeding one thousandth of an
inch in diameter.
   When a torpedo was  put  into  a metallic vessel,  insulated by a
glass stand, and contacts were made on its back with the  insulated
wire resting on the edge of the vessel, or at a distance from it, lumi-
nous appearances were frequently produced, sometimes in the form
of sparks,  and sometimes in the form  of flashes,  not unlike summer
lightning on an infinitely minute scale.  At first, 1 was disposed to
consider the phenomena electrical; but, on  reflection, it  occurred
that  they  might depend on the presence of animalcules, which be-
came luminous when agitated.   And this, I believe, is the correct
explanation  of the effects; for when the salt water was  agitated
without the torpedo, sparks  of light  now and then were seen, and
the flashes or corruscations might have been owing either to lumi-
nous matter thrown off from the surface of the fish when  it gave
the shock, or to the shock simultaneously stimulating several par-
ticles, which  in consequence shone for an instant.
  The only positive result which I have  obtained on the passage
of the electricity of the  torpedo  through air, has  been by using a
chain as a substitute for a wire of communication.   It was a small
gold chain,  composed  of sixty  double links,  each circular, and
about one  tenth of an inch in diameter, fastened, unstretched, to a
dry glass rod at each end. Holding the upper portion  of this chain
in one  hand, and the under  wire in the other, (the  hands being
moistened,) I irritated by means of them the upper and under sur-
face of an active fish; the shock which it  gave was pretty strong,
reaching beyond the fingers,  and was felt with  the same degree of
force in both  hands.  This seems to  show that the air is not  im-
permeable to the electricity of the torpedo; and the same conclusion
may perhaps  be drawn from the  facility with which I have found
it  to pass  through a circuit of wire in  which there  have  been no 
EXPERIMENTS on the torpf.do.
235
less than seven joinings, and those made merely wilh ordinary care
with the fingers, without the aid of any instrument.
  In accordance with Mr. Walsh and  my brother, I have in no in-
stance seen the torpedo affect the electrometer, or exhibit any the
slightest indication of a power of attraction and repulsion in air.
  It having been stated on high authority that a  spark  has been
obtained from  the gymnotus electricus,1 I thought  it right, after
obtaining the  preceding results which were detailed  in my first
paper—to  renew the attempts to procure a spark from the torpedo.
I have tried the method which it is said succeeded with Mr. Walsh
in the instance of the gymnotus, namely, dividing with a penknife
gold leaf attached to glass, and connecting the divided parts with
the contact wires.  Using an active fish in this way, I could  neither
observe a spark in the dark,  nor in the light detect the slightest in-
dications of the passage of electricity, either by the galvanometer,
or the test of the sensation or shock.   I have been equally unsuc-
cessful  in using an electroscope, formed on  the principle of Cou-
lomb's, which  displayed sparks when touched either by a small rod
of glass  slightly excited, or of sealing-wax;—even when the tor-
pedo was taken out of water, and all loosely adhering moisture re-
moved, no effect could be obtained, not even the slightest  indica-
tions of attraction.   1  have varied the trials, using highly rarefied
air at ordinary temperatures, and also condensed air deprived  of
moisture, with the same negative result.   And I have been  equally
unsuccessful in substituting flame;  unless the  metallic points were
in contact in the flame of the spirit-lamp,  the  passage of the elec-
tricity appeared to be completely interrupted.   In  very many expe-
riments, employing  the  most active fish, if there were any visible
space between  the ends of the red-hot platina wire, I never witness-
ed  the  galvanometer  in connection with  one wire  affected, nor
could obtain a shock.   Reasoning on  the  subject, this perhaps is
what might be expected, considering  that the  surface of the fish is
a better conductor than air.   One fact, however,  which I had  ob-
served, afforded some encouragement to persist in the trials—the
fact that the  torpedinal electricity passes through distilled water,
which is a worse conductor of it than  its own  skin.
   I thought it possible, that by insulating the  torpedo on a  plate of
dry glass,  and wiping its circumference dry, and  smearing it with
oil, that the galvanometer might be  affected.  But in this, too, I
have been disappointed; not even in flame, when  the  interruption

   1 Mr. Walsh is said to have written to  M. Le Roi to the above effect; and
also that Sir John Pringle and M. Magellan assured M. Le Roi  they had
witnessed the result repeatedly. Vide Bloch's Ichthyologie, p. 1020.  Block
 refers for his information to Rozier's Journal, Ann. 1774. M. De Humboldt
 (Annates de Chemie et de Physique, torn. xi. 427,) states that the  same le-
 sult has  been observed  by M. Fahlberg.  He  refers to Vetensk Acad. ny.
 quart. 2. (1801.) 
236
davy's researches.
 of the circle has been only just visible, has any effect on the instru-
 ment been produced.1
   Mr. Farady, in the third series of his Experimental Researches
 on Electricity,  states, that he has little or no doubt, were Harris's
 electrometer applied to the torpedo, the evolution of heat would be
 observed.2   I  have made very many experiments  on this subject,
 completely establishing Mr.  Farady's  anticipation.   The instru-
 ment employed was similar to  that described by Mr. Harris in the
 Philosophical Transactions  for 1827, differing  merely in the wire
 passed through the  small globe being exceedingly fine, and of pla-
 tina, formed after  Dr.  Wollaston's  method ;3  in  having  a small
 stop-cock for regulating the height of the spirit in the stem; and in
 using as small a quantity of spirit as possible.   The small  globe or
 bulb of the  thermometer was defended from  the variable  tempera-
 ture of the surrounding air,  by being included in a wooden  box.
 The delicacy of this instrument was so great, that the spirit in the
 stem was not  only  moved by a single spark  of the electrical ma-
 chine, but even very distinctly by the electricity of a single voltaic
 combination, composed of a copper and zinc wire, the former l-25th
 of an inch in diameter, the latter l-50th, excited by dilute sulphuric
 acid.
   This instrument  was strongly  affected by active fish, and even
 distinctly by weak ones;—indeed, occasionally, when it formed part
 of a circle in connection with a galvanometer, I have seen it affect-
 ed alone,  the galvanometer affording no indication of the passage of
 the electricity.    Using two air-thermometers of  the same construc-
 tion, each connected with the  wires for contact at one end, and with
 the galvanometer at  the other,  the heating effect of the electricity
 of the torpedo has been apparently diminished, and even more dis-
 tinctly diminished on adding to the circle another link of very fine
 platina wire.   And  at the same time its influence on the galvano-
 meter has been diminished, and its power of imparting permanent
 magnetism to a needle placed in a spiral, both forming part of the

  1 Since the  above remarks were  first  made, M. Matteucci has  obtained
 sparks from the  torpedo, and M. Farady  from  the gymnotus—not indeed
 directly,  as Mr.  Walsh was  supposed to have done,  but by  means of a
 "magneto-electric coil," the object of which, it has been hypothetically said,
 is to prevent the eledtrical principles  from neutralising themselves directly
 through the conducting matter adjoining; and to force them to re-unite at a
 distance, by traversing the thin stratum of air in which the spark was taken.
 Bibliotheque  Universelle de Geneve,  June,  1836, p. 387. The preceding
part of this note was written in December;—I have since learned (now Janu-
 ary 26, 1839,)  that a spark has been taken direct from the gymnotus, in the
 Adelaide Gallery, and that it was accidentally observed  in making an ex-
periment instituted with a different object  in view.  My authority for this
singular occurrence, and one so difficult of explanation,  is the very intelli-
gent  superintendent, Mr. Bradley.
  2 Philosophical Transactions, 1S33, p. 46.
  3 Philosphical Transactions, 1813, p. 114. 
experiments on the torpedo.
237
circie.  When heat has been applied to the entire link of platina by
nutans of a spirit lamp, so as to render it red hot, the diminution of
effect disappeared; and equally so, as well  as I could judge from
many experiments, whether acting on the thermometer, the galva-
nometer,  or the needle in the spiral.
  It appeared not improbable  that a short portion of very fine pla-
tina wire  i><i<rht be  ignited in  the passage of the  electricity of the
torpedo.   1 have made several experiments to ascertain this,  but I
have never witnessed the effectreven in perfect darkness, and  using
fish the discharge of whose electricity at  the same  time converted a
needle  into a tolerably powerful  magnet;  the needle  having been
put into a spiral connected with the fine wire, so as to afford a test
of the strength of the electricity.  This want of ignition may at first
view seem contrary to the effect on the thermometer;  but, perhaps,
it ought not to be considered so, taking into account the rapid man-
ner in which the heat evolved in the fine platina wire must  be
carried off by the adjoining compound wire of platina aid  silver.
  The experiments which I have made on the electricity of the  tor-
pedo as a chemical agent, have been of a satisfactory kind.  A small
glass globe, of the capacity of about half a'cubic inch, was used for
holding the fluid  to be acted  on; and fine wires communicating
with the contact-wires were introduced into it through a perforated
glass stopple, and they were cemented with sealing-wax along their
whole course in the vessel, excepting at their points.  By means of
this little  apparatus, 1 first tried  the effect of a small active fish on
a strong solution of common salt;  the terminal wires were of silver.
The contacts were made on the upper and under surface of the  fish
in the usual manner; minute bubbles of air collected round ihe point
communicating with the  under wire, but none  at the other point.
After an interval of some  hours, fine gold wires were substiti.ted for
the silver  wires: now gas was  evolved from each extremity, but in
largest proportion and in smallest  bubbles from the point connected
with the under  wire.
  The next experiment was made on a strong solution of nitrate of
silver;  the terminal wires were of gold, the effect was distinct;  the
extremity of the under gold wire  became black, and  only two or
three bubbles of air arose from it; the extremity of the upper gold
wire remained bright, and it was surrounded with many bubbles of
air.  A similar experiment was made on a strong solution of super-
acetate of lead, and with results which were similar; but the effects
appeared to be  produced  with  greater difficulty; they were not dis-
tinct till  the fish had  been much irritated and seemed to put forth
all  its energy.
  These electro-chemical experiments on the torpedo were some of
the earliest which I instituted on its electricity;  the  notes of the
first successful  one  bear the date of the 9th of September, 1831.  In
the autumn and early winter of 1833,  I instituted several other
trials, which were amply confirmatory of the preceding.   In these
latter experiments I did not,  as in the former, coat  with sealing-wax
       H__e                                     16 dav 
238
davy's researches.
the wires introduced  into the fluids, leaving the naked points only-
exposed.  Though the wires were naked, and in every instance in-
troduced more than a quarter of an inch into the fluid, and the dis-
tance was at  least a  tenth of an inch, yet satisfactory results were
obtained.  Using either a saturated solution of common salt, or a
mixture of equal parts of sulphuric acid of commerce,  and water,
and platina or gold wires, gas was given off round each wire under
the influence of the discharge of the electricity of an active fish, ono
contact wire being applied to the under surface and the other to the
upper surface of the  torpedo.   When steel needles were used with
the salt water, then gas was disengaged only from the one in con-
nection with the under surface  of the fish,  the other needle becom-
ing oxidated.   Using a strong solution of nitrate of silver, and gold
wires,  silver was precipitated  only ou that  in connection  with  the
under surface; employing strong nitric acid and platina wires, gas
was given off from one only, that  in connection with the upper sur-
face;  using a solution of iodide of potassium and starch,1 the iodine
in combination with  the starch,  as  indicated  by  the discoloration,
was precipitated round the same wire.
  Even the  decomposition of  water  has been effected, when  the
circle has been interrupted  by four portions of the solution of com-
mon salt, contained  in small tubes, with two needles in each,  the
needles  in one connected with  those in the other,  and at the same
time with the galvanometer,—a  spiral holding an unmagnetised
needle,  and an air thermometer.   And  simultaneous with the che-
mical decomposition, the needle in the galvanometer has been
moved,  and the  spirit  in the air thermometer has been  raised, and
the needle in the spiral has been magnetised.
  Mr.  Walsh,  from his experiments, inferred that the two sides of
the torpedo are, when in action, in opposite electrical states.2  The
results just described appear to prove that its tinder surface corre-
sponds to the copper  or negative extremity of a voltaic battery, and
its upper surface to the zinc  or  positive extremity.3
  To ascertain, if they preserve the same relation  to each other,
when the fish is  made to act on  the  multiplier, and on the needle
in the spiral,  the following experiments were made.   Successively
at different times, with  the same fish, and also with different torpe-

  1 When starch, in powder, is added to a saturated, or nearly saturated,
solution  of the iodide of potassium,  a transparent gelatinous mass is formed.
This I  have used in my experiments; a single combination of copper and
zinc wire, acted on by  very dilute acid, occasions, in this compound, a pre-
cipitation of iodine.  The iodine is precipitated round the negative wire, or
that connected with the copper.   The effect is the same, whether platina or
silver is  made to convey the electricity into the saline solution.  The decom-
position  probably is the effect of the hydrogen disengaged; it is not an im-
mediate  electio-chemical effect.
  * Philosophical Transactions, abridged, vol. xiii. p. 475.
  3 In my first paper on  the torpedo, a mistake was inadvertently made rela-
tive to the electricity of the opposite surfaces of the torpedo, which has been
pointed out by  M. Becquerel, in his very able work on electricity. 
EXPERIMENTS on the torpedo.
239
dos, comparative experiments were tried on the course of the needle
in the multiplier, when affected by the electricity of the fish, and by
that of a couple of very small  plates of copper and zinc immersed
in a  weak acid.  .In every instance  the wire communicating with
the under surface of the torpedo, was found to  correspond in its
effect with the copper plate, and that with the upper surface with
the zinc plate; and whether one wire was in communication with
the under surface of the fish,  and the other with  the upper, or the
former wilh  the copper plate, and the latter with the zinc plate, the
deviation of the  needle  was in the same  direction;  its  south  pole
turned to the west, and  of course,  its north to the east;  and if the
lower contact wire was  made  the upper, the effect on the deviation
of the needle was identical with a change of the plates.
  I have found  the same uniformity of result in the polarity im-
parted by the torpedo to a needle in the spiral wire;  the extremity
of it, nearest the under  surface in the circle, has always acquired
southern polarity, and the other extremity of course northern.
  Besides the preceding  results,  I have tnbtained  some others, of a
miscellaneous nature, which, in consideration of the obscurity of the
subject, and its novelty in  many points, I do  not think it  right to
withhold.  By connecting the spiral with the multiplier, and charg-
ing the former with as many small needles as it could hold, namely,
eight, I ascertained  that a single discharge of the electricity of an
active fish moved the needle in the multiplier powerfully, and  con-
verted all the needles  into magnets; and each of them, I  believe,
was  as strong as if one only had been used.
   Using two spirals charged  with  needles, one connected with one
end of the multiplier, and the other with the other  end, the effects of
the discharge were similar to the  preceding, both on the needle of
the multiplier, and on the needles in  the spirals.   In two instances
the needles  in the spiral connected with  the  upper surface, were
most powerfully magnetised;  and in one  instance, the effect was
greatest on the needles in the lower  spiral.  In   this last instance,
nine needles were acted on in the under spiral, and six in the upper:
the fish which  produced the  effect  was,  with one exception, the
smallest that I had ever used.
   In  a few  experiments on metallic conductors,  the effect of the
electricity of the torpedo on the galvanometer appeared to be much
the same,  whatever metals were used, and whether rusty or bright,
provided the junctions were bright.   The mass of metal appeared
to have more influence: the effect, as might be expected, diminished
with the increase of the mass; thus, when a poker weighing about
two  pounds formed part of the circle, the effect on the electrometer,
though distinct,  was less powerful than when it  was omitted; and
when a large copper coal-scuttle was substituted for it, the effect
was  still more diminished, the deviation of the needle  being  only
just  visible.  Extension of surface, as in  the instance of increased
length of wire, had a sensible modifying effect: thus, in an experi-
ment in which about a  thousand feet of wire were used (formed of 
240
davy's researches.
three pieces, two about one-fiftieth of an inch in diameter, the third
piece considerably finer), the motion of the needle was decidedly
slower  than when a short length of wire was employed, though the
space traversed by the needle was not perceptibly different.  I shall
notice only a few of the experiments which I have made on imper-
fect conductors.
  When I have held the contact-wire in the palm of each  hand
wetted with salt water, and  have touched with the fore-fingers the
upper and under surface of a torpedo, I have felt its shock distinctly;
but in no instance when the  multiplier has been connected wilh the
wires has it been  affected;  and when the spirals have been con-
nected with  them I have once  only seen  the needles in them con-
verted  into magnets.  This  effect accompanied a very smart shock
from a young active fish, about six inches long, just taken.
  When the touching ends of the contact  wires have  been covered
with leather soaked in salt water,  or with cotton thread, all the
effects  of the fish, as might be expected, were witnessed, as if these
imperfect conductors had not intervened; the shock was felt by the
hands holding the wires, needles in the spirals were magnetised, and
the multiplier  was moved.
  When a cotton thread, soaked in salt water, or in a strong solu-
tion of salt, was  interposed beyond  the  contact wires,  both the
power  of affecting the multiplier and of giving polarity to the needle
in the  spiral, was  arrested and this was uniformly the result in a
considerable number of experiments made with three different fishes,
of which two were  very active, and with perfect conductors free
from  this  interruption,  produced  both effects  readily.   But the
power of giving a shock was not equally arrested; for on removing
the multiplier and  spirals, and holding with the wet fingers the
wires attached to  the  moist cotton thread, the  shock was several
times distinctly felt on  stimulating the fish.   The space of cotton
thread between the wires was  about one-tenth of an inch, and to
secure its perfect  humidity or wetness, it was enclosed  in a glass
tube, with corks at each end, through which the wires passed.
   When the apparatus, already described in noticing the chemical
effects of the torpedo, was substituted for the wet cotton thread, the
tubes being filled with a strong solution of salt, the multiplier was
affected, and gas was  given off at  each of the points of the gold
wires; and when steel needles  were used, a free current of gas rose
from the point connected with the under contact wire,  and not a
particle  from  the other point.   In these experiments, there were
interposed at  the same time the chemical  apparatus, one on each
side;  the spiral, one also on each side; and the multiplier interme-
diate ; and there were necessarily many junctions of wires.  And in
an after experiment, in addition to  these,  an air thermometer (Har-
ris's electrometer) was introduced,  and very distinctly affected.   I
 scarcely need add, that in  an  experiment made expressly to ascer-
 tain this point, the shock of the fish was felt beyond the saline solu-
 tion;  for it had been previously proved by the experiments of Mr. 
EXPERIMENTS ON THE TORPEDO.
241
Walsh,  that salt water, even in a  long  circuit of imperfect con-
ductors, has a power of transmitting the electricity of the torpedo.
  The tests or  indications of the electricity of  the torpedo, at pre-
sent known, are six in  number; namely, the physiological effect, as
the sensation it  imparts is sometimes  called; the chemical effects,
as the precipitation  of iodine, the decomposition of water, &c;
its effects on the thermometer, on  the galvanometer, and on steel
in the spiral.  These different tests, in point of delicacy, I am in-
clined to believe, are in  the order  in which they are enumerated.
That  the two  first should be placed highest,  and that sensation
should have the precedence,  the  experiments which I  have made
appear to prove independently of all analogy.
   When the human  body has formed part of a circle of communi-
cation between  the two opposite surfaces of a  torpedo, and also a
chemical apparatus with  platina wires and the solution  of iodide of
potassium and starch, the shock experienced by the hands has been
strong, and the  chemical effect either null  or slight; no gas appear-
ing when a strong solution of salt  has been  used, and no precipita-
tion of iodine occurring unless the platina wires were  very nearly
in contact, and  the fish energetic.
   When, besides the human body, and the chemical apparatus, the
galvanometer has been  introduced into the circle with the air ther-
mometer and the spiral, the shock has been experienced as if it had
been received direct  from the  fish; but I have  never witnessed at
the same lime any other effect.
   Not taking the human body into the circle,  in trials on fish of
very feeble electricity, I have witnessed the  precipitation of iodine,
when neither the air  thermometer, nor a delicate galvanometer with
a double needle has been affected.
   The same kind of evidence has been  obtained of the thermome-
trical  test, being next in point of delicacy, inasmuch as I have seen
the air thermometer affected by a fish which had  no influence on the
galvanometer, in connection with  the wire of the thermometer.
   That the  needle in the spiral is the least delicate test  does not re-
quire  to be insisted  on.    The electricity of a  torpedo, of almost
feeble energy, has been  equal to produce all the  effects alluded to at
once,  excepting sensation,  as already explained, and excepting the
imparting permanent magnetism to the steel needle.  The last effect,
as might be expected, has required greater force; a moderate force,
however, has been sufficient when  a very slender needle  has been
used, and a spiral of  fine wire closely coiled, only just capable of re-
ceiving ihe needle.1
   The few experiments which I have made on  the torpedo, analo-
gous to those instituted by Mr. Todd, described  by him  in the Phi-
losophical Transactions for 1816, have afforded  very similar results.
When the brain has been  divided longitudinally, the fish has con-

  1  The spiral wire above alluded to, is fine copper wire guilt, having about
300 convolutions  to the inch; an inch of it weighed four-tenths  of a grain. 
242
DAVY'S RESEARCHES.
tinned to give shocks.  When the brain has been entirely extracted,
the fish instantly lost this power, though the muscles generally con-
tinued to act powerfully;—nor could any shock be procured in this
instance, either by puncturing wilh a sharp instrument the electri-
cal nerves, where they quit the cavity of the cranium, or where they
enter the electrical organs, just after passing between the branchial
cartilages.  On one occasion, however, it may be mentioned, that
when a small portion of the brain was accidentally left, contiguous
to the electrical nerves of one side, and with which they were con-
nected, then the fish, on being irritated (the  remaining portion of
brain was touched) gave a shock to an assistant who  grasped the
corresponding electrical organ.
  M. De Humboldt states, that the shock of the torpedo may be pro-
cured by touching with the  finger or hand, one surface only of the
fish.1 The experiments which 1 have made expressly on this point
have led me to a different conclusion, namely, that it is requisite to
touch the opposite surfaces of the electrical organs or organ, or a con-
ductor or conductors connected with them, to  receive a shock.   In
very many instances that I have irritated torpede>s by pressing with
the finger on different parts  of the back, as the upper surface of the
electrical organs,  and on the margin of the pectoral fins, however
much the fish were irritated, I never had  any sensation excited  by
the electricity which there was reason to believe was  discharged;
though immediately after, on touching the two surfaces, irritating
only the upper, shocks were received.  On some few occasions, I
have perceived a shock, when apparently only one  surface of the
fish was touched;  but I believe in those  instances the discharge
took place  through the water.2  In corroboration 1 may mention,
that in  experiments in which one  surface only has been  touched
and irritated, the fish itself appears to  make an effort  to bring,  by
muscular exertion, the border of the under surface (the  upper being
pressed on) in contact with the offending body; and this I have wit-
nessed as distinctly in the fcetal fish as in the adult; clearly showing
that the effort is instinctive.  The conductor, which  I suppose to
be necessary for  conveying  the electricity, when a shock is  felt
without immediate contact, exists in salt water. The galvanometer
has been affected when the two extremities of it have been  brought
in contact, one with the back of the  fish, and the other with the
water, two or three inches  from the fish.  And, in one  instance I
experienced a shock, although I touched the water alone, close to a
torpedo; it was in removing an active fish, by means of an earthen-
ware dish, from one vessel into another; the hand that  received the
shock grasped the wet margin of the dish just as the torpedo entered
it.  I believe that the torpedo has the power of discharging its elec-

  1  Annales de Chimie et de Physique, torn. xi. p. 430.
  2  The most remarkable example of the kind of which I have  any note, was
that of a young  torpedo, which  gave slight  shocks to the hand on which it  ..
was supported, whether just under the surface of the water, or just after if"<
was taken out of the water into  the air.                             ,v  f: 
EXPERIMENTS ON THE TORPEDO.
243
tricity in any direction  it chooses.   This inference is drawn from
finding that when  one hand, in contact with the opposite surfaces
of the fish, is receiving shocks, the other hand immersed in the wa-
ter close by, has received  no shock.   And, in confirmation of this,
I may mention  (and at the same time to show how the discharge is
connected with  the volition of the animal,) that when I have applied
to the opposite  surfaces of a torpedo copper plates, merely gently
touching, joined together by a  copper wire, and then irritated the
fish with the contact wires in the usual  manner, the galvanometer
attached to the  contact wires has been distinctly affected.
  In my first communication to the Royal Society, it is conjectured,
that the mucus with which  the torpedo is lubricated, may be a con-
ducting medium between  the two opposite surfaces.  This was an
erroneous view.  It  may serve that  purpose to the surfaces indi-
vidually.   Seeing the error  theoretically, I was led to examine the
margin of the fins, and they have appeared to me to have less mucus
adhering to them than any other parts of the  fish, as if intended
partially to insulate the electrical organs.
  In that  communication also, I stated my inability to account for
my brother's not obtaining  any positive  results in his experiments
on the torpedo.  After reconsidering the subject, I am disposed to
think it might  have been  owing to his using large fish, without the
means of  ascertaining their electrical activity, excepting  by the
shock.  And, we have seen, that when the human body forms part
of the circle of communication  with a galvanometer,  the latter is
not affected in  the passage  of the electricity producing the shock;
which may serve to explain his not  having witnessed any effect on
the instrument at Trieste.  As  regards  the electrical energies of
large torpedos, nothing is more  uncertain. There appears to be no
relation between the  muscular and  electrical power.   I have seen
strong vivacious fishes, which  made great muscular  exertions in
the water,  almost or entirely destitute of electrical  power; and, on
the contrary, I  have seen others languid and moribund, which  have
exerted considerable electrical power.  Small fish are almost always
active electrically, and they are greatly  to be  preferred as subjects
for experiments: moreover, they have this advantage—they can be
kept alive  a much longer time.1   Mr. W7alsh noticed,  in the fish on
 which he experimented at Rochelle  and  the Isle of Re, a retraction
of the eyes of  the torpedo,  at the instant it exercised its electrical
function.   This I have not witnessed in the torpedos of the Medi-
 terranean ; nor indeed have I been able to associate any visible sign,
 any apparent movement of the fish, with the electrical discharge.

  1 The torpedo should be kept in an earthenware vessel, not a wooden one,
 which exercises  some noxious influence on the  fish: the water (the purest
 sea-water that can be procured) should  be changed  daily;  and  the coolest
 place should be  selected for il—where the sun never shines. 
244
DAVY'S RESEARCHES.
 2.— Observations on the electrical organs of the torpedo, and on
         some parts of its structure connected, with them.

   The peculiar columnar appearance of the electrical organs of the
 torpedo, and  their great proportional size, the vast proportion of
 nerve with which they are supplied,  the manner  in  which  the
 columns are sheathed in  tendinous fibres, have been dwelt on by
 all inquirers who have paid any attention  to this fish; but I am not
 acquainted with any attempt  to ascertain by experiment what is
 the exact nature of the substance of these organs, or the peculiar
 structure of which they are composed.
   When I have examined with a single lens, which magnifies more
 than two  hundred times, a column of the electrical organ, it has not
 exhibited any regular structure; it has appeared as an homogeneous
 mass, with a few fibres passing into it in irregular directions, which
 were probably nervous fibres.1
   The specific gravity of the electrical  organ, in comparison with
 that of parts of the fish decidedly muscular, is very low; including
 the upper and under boundary of skin, I have  found  it 1026 to
 water as 100Q.   The specific gravity of a portion of the abdominal
 muscles of the same full grown  fish was 1058, and that of the thick
 strong  muscles of the back close to the spine 1 065.
   The loss of weight which the electrical organ sustains by drying,
 is greater than  I  have observed in any other part of the fish.  I
 shall give the results of one trial; the statement will convey an idea
 of the bulk of the different parts of the torpedo, as well  as of the
 proportion of solid matter which they contain.  The subject of the
 experiment, procured fresh from the fish  market at Rome, was eight
 inches long, and across the widest part  five inches broad.   Entire
 it weighed 2065 grains.  It  was carefully divided, and the different
 parts mentioned were found  to weigh  as follows in  their moist
 state:—

  Spleen    ------     5-5  grs.
   Pancreas        -----     50
  Testes    ------     30
  Kidneys  ------     8-0
  A pale cream  coloured oval body close to left kid-
     ney    -----        -     025
  A reddish oval glandular body attached  to the
     large intestine3        -       -       -       -     0 5
  Liver with gall-bladder and ducts       -       -  105-0

  '  Farther microscopic examination has confirmed the above observation.
 The fibres of the voluntary muscles, even after having been four years in
 spirits, exhibited the peculiar transverse striated appearance: no  regularity
 of structure; nothing distinctly characteristic was visible in the tissue of the
 organ in question.
  3 This is found in all the cartilaginous fishes;  it contains a cavity commu-
nicating with the intestine, and abounds in follicles; its function seems to
be similar to that of the appendicula vermiformis of man. 
EXPERIMENTS ON THE TORPEDO.
245
  Heart and trunk of pulmonary artery    -       -    30
  Gills including branchial cartilages      -       -   530
  Gullet   ------   110
  Stomach         _._.._   (35-0
  Upper valvular intestine -                         29-0
  Lower intestine  -----    5^3
  Electrical organs       -                        302-0
  Head separated at first vertebra  -       -       -  165 0
  Thorax consisting of cartilaginous case and mus-
    cles with pectoral fins attached       -       -  670-0
  Abdomen  without its contents    -       -       -  440 0
  Tail separated just below the anus      -       -  1950

  By exposure to the heat of boiling water for about sixteen hours,
the  different parts were completely dried; their total weight was
reduced to  3^2 grains, so that they had  lost  by drying 84-5 per
cent.

  The electrical organs now weighed        -       -   22 grs.
  Head      -       -       -      -      -       -   25
  Thorax    -       -       -      -      -       -   93
  Abdomen   -       -       -      -      -       -   53
  Tail       -       -       -      -      -       -   36
  Liver (abounding in oil)    -      -      -       -   43
  Residue consisting  of other organs, and  extract of
    fluids which exuded during the drying  -       -   50

  From the above loss of weight of the electrical organs in drying,
they appear to consist of 7 28 matter not evaporable at 212 Fahren-
heit, and of 92-72 water, taking it for granted that the loss sus-
tained  is owing merely to  the evaporation of the aqueous part.  I
lay  stress on matter not evaporable, because  I believe that the solid
contents of the moist organs are less, and that the water which they
contain holds in solution various substances.
  This solution  may be obtained  by cutting the electrical organs
into small pieces, and placing them in a funnel.  The fluid part
slowly separates.   What I have thus collected was slightly turbid,
of a very light fawn colour, just perceptibly acrid; it did not change
the  colour of turmeric or litmus paper; a cloudiness was occasioned
by dropping into it a solution of  nitrate of silver, which was not
completely  redissolved by aqua ammonia; it was copiously preci-
pitated by acetate of lead,  and a cloudiness was occasioned  in it by
nitrate of barytes,  and by corrosive sublimate.  By evaporation it
afforded a  residue which  deliquesced  partially  on exposure to a
moist atmosphere, and had an acrid and a bitter saline taste.  The
exact proportion of this weak solution of animal and saline matters
I have not ascertained, and indeed it would  be very  difficult to de-
termine with any accuracy, for only a small portion separates spon- 
246
DAVY'S RESEARCHES.
 taneously; and  if pressure  is used, the fibres are broken, and the
 fluid expressed is mixed with a pulpy matter.1
   When the electrical organs of the torpedo are immersed in boil-
 ing water, they suddenly contract in  all their dimensions, and the
 coiumtisjrom pentagonal, which they generally are, become  circu-
 lar.   In my early experiments at Rome, they were rendered firmer
 by immersion for a few minutes, and the columns appeared to be
 tolerably distinctly  fibrous  and  laminated, bringing to recollection
 the structure  of the  pile of Zamboni.   Latterly I  have not wit-
 nessed this effect; in  a  few seconds the  tendinous fibres  have been
 convertejd  into jelly, and the columns have fallen asunder, having
 the appearance and consistence of a translucent very soft mucilage.
 To what  this difference of effect may  be owing, I am  at a loss to
 conceive;  perhaps the Roman fish were older than the Maltese;  or
 the aqueduct water at Rome may be harder than the rain cistern-
 water of Malta.
   On exposure  to  the air in a damp atmosphere, or by maceration
 in water, changing the water daily, the electrical organs undergo
 change more slowly than the parts distinctly muscular; in putrefac-
 tion  and  maceration  they  resemble less muscular  fibre than ten-
 dinous fibre, which lalter offers great resistance to both these pro-
 cesses.   But I would  not lay any stress on this quality of resistance,
 as it is extremely vague, depending  on circumstances which it is
 difficult to appreciate, as every one must be convinced, who has
 compared  the different  degrees of rapidity with which different
 orders of muscles of man, and the larger mammalia, undergo change
 from putrefaction and maceration ;  for instance, the slowness with
 which the  muscular fibres of the stomach and intestines alter, and
 the rapidity of change of the fibres of the  heart and thick muscles.
   Quitting the organs of the dead fish, I shall now notice the few
 observations which  I have made on them before they have been de-
 prived of their vitality.
   The effect of  the electricity of a small voltaic trough, the shock
 of which I could just  perceive at the  extremities of my moistened
 fingers, was very distinct on the voluntary muscles of a live torpedo,
just taken from the water; but it did not appear to affect in the least
 the electrical organs.  I could not perceive the slightest contraction
 of them in  whatever manner the wires were applied, not even  when
 a minute portion of integument was removed, or when one of the
 wires was placed in  contact with a fasciculus of the electrical nerves.
 Even after apparent death, many of the parts decidedly muscular
 continued to contract  under this stimulus,  especially the muscles of
 the flank, and  the cross  muscles of the inferior surface of the thorax
 and the heart; indeed this latter organ, two hours after it had been

  1 The torpedo is used for food, in the Mediterranean, amongst the lower
 classes; but  the electrical organs are rejected—they are considered unwhole-
 some. 
EXPERIMENTS ON THE TORPEDO.
247
removed from the body, and had  ceased to contract spontaneously,
renewed its contractions under the galvanic influence.
  Other stimulants have been applied to the electrical organs, and
with the same negative result.   Even when punctured, or incised
(a portion of  their  skin having been removed, which appears to be
very sensitive,) no indications whatever were witnessed of their
substance being either sensitive or contractile.
  Reflecting on the facts and observations which I have just de-
tailed,  it appears  to me very difficult to resist the conclusion, that
the electrical  organs of the torpedo are not muscular, but columns
formed of tendinous or nervous fibres, distended  by thin gelatinous
fluid.  Their  situation, too, surrounded  by, and exposed  to  the
pressure of powerful  muscles,  shows, that if condensation  is re-
quired  for the exercise of  the electrical function,  they may experi-
ence it without possessing any muscular fibres  in  their own sub-
stance.   The arrangement of the muscles of the back and  of the
fins, and  of the very  powerful cross-muscles, situated between the
under surfaces of  the electrical  organs,  are admirably adapted  to
compress them.  Without  entering into any minute anatomical exa-
mination  of these  muscles and  their uses, it is only necessary to
compare them in the torpedo, and in any other species  of Ray, to
be convinced  that  they are adequate to, and probably designed for
the effect mentioned.
  Mr. Hunter,1 in his  account of the torpedo, describes the columns
of the  electrical organs as composed of cells  containing a fluid,
divided by horizontal partitions which he was able to count.  This
structure seems very  probable,  and in the specimens I dissected at
Rome,  I saw  what I fancied an  approach to it;  but I have never
witnessed it in a satisfactory manner in the fresh  fish.  Mr. Hunter
inspected large fishes which had been  preserved in spirits.   The
partitions of the columns in them might have  been more visible
(supposing them to exist)  from the action of the spirit on the mem-
brane,  and from the  greater size of  the  specimen: or they might
have been formed  after death in  the spirits,  by a slow deposition of
the animal matter  contained in the columns.
   Next to the nature of the substance of the electrical organs, the
electrical nerves  have occupied  my attention.   Their  three great
trunks have been accurately described by Mr. Hunter;  but this dis-
tinguished anatomist  has very  briefly noticed  their distribution,
which  is curious, and deserving, I believe, of minuter investigation.
I shall attempt little more than an outline of what I have  observed
in some dissections conducted with considerable care.
   In examining the brain, proceeding from the anterior to the pos-
terior portion, after passing the first,  second, third, and fourth pair
of nerves, or the olfactory, optic, motor, and pathetic2 nerves of the

  ' Philosophical Transactions, 1773.
  * The nerves of the fourth pair are so very small  and tender, that it  is
difficult to demonstrate ihem excepting in old and large torpedos. 
248
davy's researches.
eye, the fifth  pair is seen issuing from the medulla oblongata, or
posterior tubercle of the brain.  "After quitting the cranium (con-
fining the description to one side) it proceeds upwards, divides  into
two large branches, which go to clusters of mucous glands situated
in the front of the head, and  at the interior margin of the electrical
organs,  and they appear to be confined  to these parts.  The next
pair, the first electrical, rises  close to the preceding, just behind it,
and in passing out of the cranium is firmly connected  with it;  and
also where it passes out, a  portion of  medullary matter proceeds
from  it into  a cavity filled  with fluid  in  the  cartilage adjoining,
which there is reason to consider as the cavity of the organ of hear-
ing, and the medullary matter the nerve of hearing.  After this, in
passing outwards, it divides into three small branches and two large
ones.  Of the former, one proceeds to the gills, another to the ad-
joining  muscles, and the third to the mouth. Of the great branches,
one ascends, and sweeping round the margin of the electrical organ,
is distributed to the mucous glands which abound there, and  where
some of its twigs inosculate  with twigs of the former nerve.   The
other great branch,  which is inferior, enters the electrical organ,
and ramifies  through its superior portion.  The next pair of nerves,
the second electrical,  rises a  little beyond the preceding.  On leav-
ing the cranium, it divides into two great branches;  these, with the
exception of  nervous twigs  supplying the adjoining brauchias, are
distributed entirely in  the substance of the electrical organ,  and
ramify in all  directions through its middle  portion.  The third elec-
trical rises close to the last, divided only by a very thin plate of car-
tilage.  The principal portion of it passes  into the electrical organ,
and ramifies  through its inferior part.   Besides, it gives off three
small branches, which  are sent to  the adjoining branchiae,  to the
gullet and stomach, and  to  the  tail.  The branch which supplies
the stomach appears to be the principal  nerve of this organ; it de-
scends along the inner and inferior portion of the gullet," and rami-
fies in the direction of the great arch  of  the stomach.   The caudal
branch  (nervus  lateralis) descends in a straight line under the peri-
toneal lining of the abdomen, and under the spinal nerves, without
giving off a single  branch, till it reaches  the tail, in the muscular
substance of  which ii is lost.
   I have not  yet been able to discover any connections of  the elec-
trical nerves  besides those  pointed  out.   It is  an  interesting fact
that the gastric  nerves are derived from them. Perhaps superfluous
electricity, when not required for the defence of the animal, may be
directed  to this organ to promote digestion.   In the instance  of a
fish which I  had in my possession alive  many days, and which was
frequently excited to give shocks, digestion appeared  to have been
completely arrested; when it died, a small  fish was found in its sto-
mach, much in the same state as when  it was swallowed: no  por-
tion of it had been dissolved.
   Though I  have not found the temperature of the electrical organs
higher than that of other parts  of the fish, or the temperature of the 
experiments on the torpedo.
249
fish generally different from that of the water in which it has been
confined, yet it seems probable that as the branchiaB are liberally
supplied with twigs of the electrical nerves, there may be some con-
nection between its respiratory and electrical function;  and I ven-
ture to offer the conjecture that, by  means of its electricity, it may
have the power of decomposing water, and  of supplying itself with
air, when lying covered with mud or sand in situations in which it
is easy to conceive pure  air may be deficient;  and  in  my experi-
ments  I have often fancied that  I have witnessed something of the
kind;  after repeated discharges  of its electricity, the margin of the
pectoral fins  has acquired an appearance as if very minute  bubbles
of air were generated in it and confined.
   Besides the electrical  nerves, there is a  fasciculus of  nerves de-
serving attention, of great magnitude, formed by the junction of the
anterior and  posterior, or upper and under cervical  nerves; of the
former, about seventeen on each side; of the latter, about fourteen.1
It makes its appearance as one trunk just below the transverse car-
tilage which  is interposed between the thorax and the abdomen.  It
sends a recurrent branch to the muscles and skin of the  under sur-
face of the thorax, but its main  trunk ascends along the inner mar-
gin of the  pectoral fin, and  is distributed through it.  On this fas-
ciculus the sentient and motive powers of the parts connected with
 the electrical organs  seem to depend.
   The electrical nerves at their origin are enveloped in a very thick
 fibrous sheath.  As the branches subdivide in the substance of  the
 organ, the neurilema becomes very thin and semi-transparent.   On
 examining a minute branch with a powerful lens, its internal or me-
 dullary substance is not seen in a continuous line, but interrupted,
 as it were dotted, as if the sheath contained a succession of portions
 with a little  space between each.2
    In the anatomical  structure of the torpedo,  the mucous system
 forms a very conspicuous part; it  consists of several  clusters and
 chains of glands, distributed chiefly round the electrical organs, at
 different depths beneath the cutis, and of strong transparent vessels
 of various lengths and sizes opening externally on the skin, for the
 purpose of pouring out the thick mucus secreted by the glands, and
 destined for lubricating  the  surface.  This system  has  not been
 noticed by Mr. Hunter, and it has been but imperfectly described

    1 Towards the origin of the spinal cord, there is a small space, from the
 under surface of which six nerves arise, three on each side; but  none from
 the upper surface—whence the difference of number noticed in the text.
    1 An after examination, using Ross's  microscope, and his  object-glass of
 one eighth of an inch  focal distance,  has not confirmed the above.  Com-
  paring°a fibril of an electrical nerve and of a spinal nerve, taken from a fish
  which had been preserved in spirits four years,  there appeared to be no ma-
  terial difference in their minute structure: each appeared irregularly fibrous—
  that is, composed of fibres not perfectly continuous or exactly parallel,  con-
  nected by a delicate net-like tissue. 
250
davy's researches.
by Lorenzini.1  Though it is not peculiar to the torpedo, it is  much
more strongly developed  in this fish than in  any other species of
Ray with which 1 am acquainted; and the situation of the glands
and  the  distribution of their vessels  are  different.   Whether it is
concerned  in any way with the electrical function of  the torpedo,
is deserving of consideration.  That it is thus concerned in some
way, seerns to be indicate*! not only by the situation of these glands
between  and surrounding the electrical  organs, but still more so by
the manner in which they are supplied with nerves, either from the
first electrical, or from the fourth pair, which is connected with that
nerve.  As the thick semi-transparent mucus  which the glands se-
crete is probably a better conductor of electricity than the skin alone
or than salt water, this mucous system may serve as a medium of
communication, not for the opposite surfaces of ihe electrical organs,
but  for each  surface individually, included  within the line of the
system referred to.2  I shall mention some results  which are favour-
able to this idea.
   When one contact wire was placed underneath an  active torpedo,
just  anterior to  the  mouth, and the other at  the extremity of Ihe
back, out  of the circle of the  mucous apparatus, the  shock  of the
fish  had no effect either on the multiplier or on the needles  in the
spiral.  But when the upper contact wire was made to touch the
back of one electrical organ, the under wire being placed as  in the
preceding  experiment, then  both  effects were simultaneously pro-
duced; and  they were also produced when  the two wires were
brought very close to each other,  one being kept  as before, and the
other moved  immediately over it, in front, each about a quarter of
an inch from the margin, and  not connected with the electrical or-
gans, except  by the common integuments and this mucous appara-
tus.   It  is worthy of  remark, that this  little space in  front,  inter-
mediate between the two electrical organs, so abounding in glandu-
lar structure,  and so  amply  provided  with nerves, appears from
experiments to possess very little sensibility.    This was denoted in
these trials, in which the fish, though exquisitely sensible of pres-
sure on  the  margin of the pectoral fins, seemed indifferent to it
when  applied in  front,  as if the fourth pair, which supplies  this
part, were  destined rather for secretion than for the purpose of sen-
sation.
   The connection between the electrical nerves and  the mucous

  1 Osservazioni intoruo alle Torpedini fatte de Steffano Lorenzini Fioren-
tino. 4to.   Firenze, 1678.  Farther on, a more particular  account will be
given of the structure.
  2 Some comparative experiments which I  have made seem to indicate,
that  the mucus of the torpedo is a better conductor than sea-water; when
the hands were smeared with this mucus, or when a portion of the fresh skin
of a torpedo, with iis natural mucus adhering to it, was wrapped round the
ends of the .contact wires, by which they were held, the shock received ap-
peared  to be stronger than usual. 
EXPERIMENTS on the torpedo.
251
system, even more remarkable  than  between  the former and  the
stomach, may perhaps warrant  the  conjecture that the electrical
function  may not  only  be aided by,  but also aid the secretion of
mucus; and that, as was supposed in regard to the stomach, when
the electricity is not employed,  in repelling an enemy,  in  violent
efforts, it may be exercised gently in  increasing the activity of these
glands.   In support of this notion it may be mentioned, that in the
fishes which I have kept,  in which digestion was arrested,  the se-
cretion also of mucus appeared to be stopped, or considerably dimi-
nished.
   Mr. Hunter, from the examination of a torpedo whose vascular
system was injected, states, that the electrical organs of this fish are
abundantly supplied with blood-vessels.  From what 1  have wit-
nessed in the living fish, and the  fresh fish recently dead, I am com-
pelled  to  conclude  that  the  quantity  of  blood  which  circulates
through  them is very  inconsiderable.   The blood-vessels  which
p?ss into them with the electrical  nerves are small;  the organs are
colourless,  and very few branches  carrying red blood are percepti-
ble extending through them.   The  integuments of these organs,
and the pectoral fins, and  lateral clusters of mucous glands,  are in-
deed abundantly supplied with  blood-vessels;  the contrast  of the
vascularity of these parts, and of the electrical organs, is so strongly
marked as  to suggest the idea  that the latter can possess very little
ordinary vital activity,  and that in  accordance with the common
analogies of living parts, they  must be rather passive than active.
   Some circumstances pertaining to the integuments of the  electri-
cal organs are deserving of notice.  I  have found that the skin
covering these organs above  is not only more coloured, but  also
thicker than that covering them below, and more vascular, and  sur-
rounded by  more  powerful muscles, and supplied with a  greater
quantity of mucus; whilst the under  surface appears  to  have a
larger proportion of subcutaneous  nerves.  This difference of struc-
ture in the two surfaces of the  electrical organs is probably some-
how connected with their opposite electrical states.
   1 may here notice another  peculiarity of organisation in  the tor-
 pedo, which came under my observation in seeking, though unsuc-
cessfully,  for the  great sympathetic, or the analogous ganglionic
 nerves, which Cuvier asserts  to exist in the cartilaginous  fishes.1
 It has very much  the appearance of  a  nervous ganglion, but is in
 reality a blood-vessel, enlarged  into a little bulb, lined with a red-
dish substance, like muscular fibre, giving the idea of a small heart.
 It is situated one on each side  of the aorta,  from whence it proceeds,
just below the great nervous fasciculus which supplies the pectoral
 fin, and the arterial branch derived from it is lost in this fin.   If it
 be muscular, as its appearance denotes, its functions  may be to aid
 in propelling the blood into the pectoral fin, and perhaps into the
 electrical organ.
1 Hist. Nat. des Poissons, torn. i. p. 438. 
252
davy's researches.
                    3.— Theoretical remarks.

   The experiments which I have detailed on the electricity of the
torpedo, confirm those of Mr. Walsh, made in 1772,  showing  its
resemblance to common electricity.  They moreover  show  that,
like common electricity, and voltaic electricity, it has the power of
giving magnetic polarity to iron, and of producing certain chemical
changes.   In these its general effects, it does not seem to be essen-
tially peculiar, but as much allied  tn  voltaic  electricity as voltaic
elecfricity  is to atmospheric,  or atmospheric electricity is to that
produced by contact or friction.   When we examine more minutely
its phenomena or effects, in relation to these different kinds or va-
rieties of electricity, certain points of difference occur.
   Compared with voltaic electricity, its effect on the multiplier is
feeble; its  power of decomposing water and metallic solutions is in-
considerable;  but its  power of giving a shock  is great, and so also
is its  power of magnetising iron.
   Compared with common electricity,  it has a  power of affecting
the multiplier, which, under ordinary circumstances, common elec-
tricity does not exhibit; its chemical effects are more distinct; its
power of magnetising iron1 and giving a shock  appear very similar;
its power of passing through  air is infinitely less; as is also its
power of producing heat.
   There are other points  of difference; I allude chiefly to the re-
sults  obtained  in the experiments already described,  in which the
metallic communication  was interrupted  by a  strong  solution  of
salt.  In this instance the full power of the fish appeared to  pass;
water was  decomposed,  a  shock was received,  needles were  mag-
netised, and the multiplier was  affected.  When the same experi-
ment  was made on the electricity excited by the  small voltaic com-
bination of a single plate of copper and zinc, each less than an inch
in length and  half an inch in breadth, immersed  in an acid, neither
water was  decomposed,  nor was the multiplier affected.   When it
was made on the electricity of the electrical machine by means of a
Leyden jar, all the effects  were  witnessed, excepting the motion of
the multiplier, and the order of succession of  poles^in the needles
magnetised in  the spirals.  How are  these differences  to be ex-
plained?    Do they admit  of explanation similar to that  advanced
by Mr. Cavendish in  his theory  of the torpedo,  and which has re-
cently been ably advocated by Mr. Faraday?  or are they more  in
accordance with the idea which my brother was disposed  to adopt,
that the electricity of the torpedo and of the other electrical fishes

  l There is this difference when two spirals are used, one connected with
the inside of a Leyden jar, and the other with the outside; a needle in each,
similarly placed, acquires  opposite polarities, the north pole  in one bein"
where the south pole is in the other; whilst in the instance of ihe torpedo
they accord, so that a line of needles, passing from one end of the electrical
organ  to the other, would exhibit a succession of similar poles. 
               experiments on the torpedo.            253

is peculiar—a power sui generis? or, lastly, may we suppose, ac-
cording to the analogy of the solar ray, that it is not a single power,
but a combination of powers?
  The first opinion, which is commonly received, is supported by
the majority of facts detailed in the preceding pages.   The circum-
stance principally hostile to it, at  least in appearance, is the inter-
ruption  of the torpedinal electricity by the smallest quantity of air,
and its  waul of the power of attraction and repulsion  in the air.
  These peculiarities are seemingly in favour of the second opinion,
that the electricity of the torpedo is specific and peculiar.   But till
the opposite surfaces of the electrical organs can  be perfectly insu-
lated, so that no  easier mode of communication is afforded than
through the air, they can hardly be considered of much weight.1
  The  third opinion  may be indulged in as an hypothesis; as a
guide to research it may not be useless.  It applies, however, almost
as much to other varieties  of electricity as to that of the torpedo;
all  of which, it is possible, may be compounded, or owe  their va-
rious effects to the union of several powers,  or etherial fluids, and
their peculiarities, compared one with another, to the predominance
in various degrees of these fluids.  What is known of the  solar ray
is  not unfavourable to such an opinion; and  the history of  physi-
cal science, in relation to elementary ponderable  matter, may give
rather encouragement to the notion.
   As regards the mode of production, or the cause of the electricity
of the torpedo, it is unavoidably enveloped in great mystery.   Like
animal  heat, and the light emitted by certain animals,  and  I may
add, the secretions of animals  generally,  it appears to be the result
of living action;  and connected with a peculiar and unusually com-
plicated organisation.   All the attempts  have been vain,  which I
have made, directed to obtain electrical excitement in the fish after
it  had been deprived of life.
   The  observations which I have detailed relating to its anatomical
structure, show  a complicated adaptation of  parts—nerves  of un-
usual magnitude ramifying between apparently insensible columns,
saturated  with a  bad conducting fluid; muscles surrounding these
columns,  and fitted to compress them; and  a system of mucous
glands  and tubes adjoining, well adapted  to be the medium of elec-
trical communication in the surfaces to which they belong.
   When we consider  this structure, it is an .easy matter to trace
rude analogies between it  and the pile of Volta, or between its co-
lumns and a battery of Leyden jars,  such a battery as was formed
by Mr. Cavendish for  imitating the electricity of the  torpedo, com-
posed of a large number of jars of very thin  glass feebly charged.
But these analogies seem  to help very little, if at all, towards the

   1 In the experiments in which  I attempted  to insulate the surfaces, by
means of oil, the probability is that I failed, and that a communication con-
tinued  if not by the outer surface of the skin, at least by its inner;  indeed,
the attempts to insulate these organs, in the  manner desired, seems to be
almost hopeless.
        11__f                                     17 dav 
254
davy's researches.
solution of the  great difficulty; the question remains unanswered,
what is the cause or source of the electricity?   Here analogy fails
entirely; none of the ordinary modes of excitement appear to be at
all concerned—neither friction, nor chemical action, or change of
temperature, or change of form.  Let us consider for a moment a
small torpedo in an active state.   The smallest which I have em-
ployed in my experiments weighed only 410 grains, and contained
only 48 grains  of solid matter;  its electrical organs weighed only
150  grains, and contained only 14 grains of  solid  matter—for to
this  they were  reduced by thorough drying.   Yet this small mass
of matter gave sharp shocks, converted needles  into magnets, affect-
ed distinctly the multiplier, and acted as a chemical agent, effecting
the decomposition of water, &c   A priori, how inconceivable that
these effects could  be so produced !   This fish was about ten days
in my possession, during the whole of which time it ate nothing,
and its bulk was hardly sensibly altered ; and every day it exercised
its electrical powers, and to  the last  they appeared almost as ener-
getic as when it was fresh from the sea.  This adds, if possible, to
the difficulty of explanation.  That this mysterious function is in-
timately connected with the  nerves, and in a manner more striking
than all ordinary secretions,  is manifest.   Beyond this conclusion,
all is darkness.  We have not, as we have in the doctrine of animal
heat,  advanced another step—we have not been able to  connect
it with  changes in  the electrical organs,  as anale)gous to  known
sources of electricity, as the  changes  which take place in the lungs
in respiration  are  to the  known sources of heat or  combustion.
The attainment of this step  is a great desideratum, and  beyond  if,
probably, we shall  never be  able to proceed.
  Without reverting to the conjectures,  which in passing I have
offered on  the  subserviency of the electricity of the torpedo in an
auxiliary manner to digestion,  respiration, and  the secretion of mu-
cus,  I may remark that its chief use appears to be for  purposes of
defence—to guard it from its enemies, rather than to enable it, ac-
cording to vulgar opinion, to destroy its  prey, and provide itself
with food.  Small smelts, which were kept in the  same vessel with
torpedos, appeared  to have no dread of them, and  I believe they fed
on their mucus. And, in an experiment in which, in  a confined
space, an active torpedo was excited  to give shocks, a smelt which
was  with it was evidently alarmed,  and once  or  twice exposed to
the shock,  leapt nearly out  of the vessel;  but  was not  injured by
the electricity.  In confirmation, I may add that ihe electric power
of the young fish,  which most requires it for its  protection, is,  as
already observed, proportionally very much greater than that of the
old,  and can be excited without exhaustion and loss of life, much
more frequently.   After a very few shocks, most of the  old fish
which 1 had have become languid, and have died in a few hours;
whilst young ones  from three to six inches long have remained
active during ten or fifteen days, and  have never failed to show the
effects I have described. 
experiments on the torpedo.
255
4.— Of the other electrical animals compared with the Torpedo.

  The number of animals of this  description  hitherto discovered
and well authenticated is very small; in brief, the Gymnotus Elec-
tricus and the Siluriis Electricus, besides the  torpedo, are the only
ones, the existence of which is certain and free from all doubt;1  and
to these I shall confine the few remarks which I  propose to offer
relative to their comparative powers and structure.
  AH these fishes  have certain points of resemblance.  Independent
of  their electrical powers,  they are peculiarly defenceless;  their
skin is soft—a true mucous  membrane, although  external, totally
destitute, equally of scales and of spines.   Each possesses a supple-
mentary organ with  which  their electrical function is  connected;
and in each the nerves supplying these organs are of extraoidinary
magnitude.
  The electrical organs of the  respective fishes bear to each other
in their structure a general, but not  close, resemblance.  The organs
of the torpedo are distinctly columnar—the columns vety numerous;
those of the gymnotus consist of septa, or of flat partitions with cr(>ss
divisions between them: whilst those of  the siluriis are neither dis-
tinctly columnar,  nor cellular, being formed as it were of a delicate
net-work of tendinous fibres, retaining interposed a soft  gelatinous
matter, somewhat similar  to that contained in the fibrous columnar
or cellular structure  of the organs of the  former fishes.
  The nerves supplying the organs are peculiarly deserving of re-
mark.   It  is a curiouscircumstance, that in each instance their
source is different.
  In the torpedo, we have seen  that they are derived exclusively
from the brain, from its posterior tubercle.

  'In the list of electrical fishes, two others are commonly introduced—the
so named Tetraodon Electricus and Trichiurus Electricus ; but neither on
good authority. The information on which the existence of the first has been
received, is most scanty and  imperfect.   The narrative has a good deal the
manner of fiction.  It is contained in the Philosophical Transactions for 1786,
in a letter from Lieut. William Paterson, of the 98th Regiment, to  Sir Jo-
seph Banks, accompanied with a  drawing.   The  writer states, that when
accompanying  his regiment to India, in the Island of Johanna, where they
touched, he met with a new species of electrical fish, of the genus Tetrao-
don, as he supposes, in cavities on the  shore in the coral rock, and  that in
handling one he received a shock.   He says, he saw several of them, and
lhat the water in which they were was about 55° or 60° of Fahrenheit,
although the island is within the tropics (sea-water of 55° or 60° in lat. 12
 13'south!)
 Regne Animal," remarks, "that the characters and properties  announced
with so much assurance, rest only on a bad figure g.ven by Nieuhoff, and a
transposition of a part of the text which has no reference  to the figure, no
to any trichiurus." Vol. x. p. 348.  How true is the rernark, in natural as well
as in civil history, that "men love to complete what is imperfect, and to re-
alise what is imaginary." 
256
davy's researches.
  In the gymnotus electricus, they do not appear  to  come  at all
from the brain, but entirely from the spinal cord.  This was the
result of Hunter's dissection ; he says, '; the organ is supplied with
nerves from the medulla spinalis, from which they come out in pairs
between all the vertebras of the spine."
  In the silurus electricus, according to the researches of Rudclphi,
they appear to have  a double source; those supplying the outer
organ being derived from the fifth pair;  those supplying the inner,
from the intercostal.
  Moreover, a marked difference appears in the proportional magni-
tude of the  nerves in the several instances.   In the torpedo they
appear to be largest; in the  silurus smallest.   Hunter  says, "if all
the nerves which go to it (the electrical organ of the torpedo) were
united together, they would make a vastly greater chord than all
those which go to the organs of this eel," (the electrical gymnotus.)1
Their comparative smallness in the silurus, I have satisfied myself
of by my own observations, made on a specimen, which through
the kindness of the  American consul at  Malta, I procured from
Egypt,  and which is now deposited in the  museum at Fort Pitt.
  As regards electrical power, it is commonly believed, that it does
not accord with the proportion of nerve;  that it is feebler in the tor-
pedo than in the silurus, and greatest in  the gymnotus.
  In relation to the shock or sensation which  these fishes impart,
the opinion probably is true.  What  I have  heard in conversation
from  that distinguished traveller and  naturalist, Dr.  Rouppell,
would seem to indicate that the shock of the silurus is more ener-
getic than that of the torpedo; and that that of the gymnotus is the
most energetic,  seems not  to admit of doubt, considering the well
authenticated accounts we have of its effects on large animals, such
as the horse, especially as related by M. De Humboldt.
  But it does not, therefore,  necessarily follow, that the power is in
other respects proportional;  for instance, as a chemical, heating, or
a magnetising agent.  Certain  forms of electricity differ in these
manifestations, and why not the electrical power of these fishes?
  The question can only be determined by actual experiments.  The
arrival of a gymnotus in England, with liberal permission from the
proprietors of the Adelaide  Gallery of Practical Science to make
trial of it, has enabled me to do this in a partial manner.  It was on
the  29th of November last, that I made the trial, when I was assured
by Mr. Bradley, that the fish was, as it appeared  to be, in excellent
health.  For the sake of comparison, I used the same apparatus as
I had employed at Malta on  the torpedo, and in  the same manner.
The first experiment attempted  was  on the galvanometer.   The
effect of the electrical discharge  of the fish was very decided ; the
needle made nearly half a circle.   The next experiment was on two
small needles in a spiral connected with the galvanometer.   The
galvanometer was powerfully affected, as in the first instance, but
'Philosophical Transactions for 1775. 
URINARY ORGANS OF SERPENTS.
257
the needles were  not sensibly magnetised;  the trial was twice  or
thrice  made with  the  same  results.   Next, a shock was received.
Mr. Owen, to whose kind offices I was in part indebted for the per-
mission I had obtained, had prepared  me from the mention  of his
own experience to expect that this would not  be contemptible: il
rather  exceeded than fell short of my expectations:  the  sensation
was  rather like that imparted by a  Leyden vial than the voltaic
battery;  more acute, less benumbing  than that of the torpedo; and
it reached higher, even beyond the elbows."   I did not extend the
trials further,  nor  attempt to test it as  a chemical agent, having been
informed that Mr. Faraday, who preceded me in experimenting on
this fish, had  carefully investigated its influence in relation to this
point.
  Since  that  time this gentleman has communicated  the results
which  he obtained to  the Royal Society, from the  proceedings  of
which  it would  appear that, besides the spark, he has witnessed all
the effects known  to have been  produced by the electricity of the
torpedo.
  Reasoning from my own comparative results on the electricity of
the torpedo and gymnotus, it  appears  to me difficult to  avoid the
conclusion, that the power of each, whatever  it may be in essence,
is modified in its manifestations, or effects; the difference between
the electricities of the  two fishes in imparting shocks, and in mag-
netising steel, was too  strongly marked to be in any wise doubtful.2
                              XX.

ON THE URINARY ORGANS  AND  SECRETIONS  OF SOME
                      OF  THE AMPHIBIA.

  During a period of nearly four years that I was stationed in Cey-
Ion, viz.  from 1816 to 1820, I availed myself of the favourable op-
portunities which there offered to  examine the  urinary organs and

  'At the obliging suggestions of Mr. Bradley, by whose directions every
assistance I could wish  was afforded me, the insulated wires  had attached
to them bent pieces of sheet-copper, in the form of a saddle, for better con-
tact with the  fish.  These were used in  the two first experiments, and also
in a fourth, when I had  the pleasure of witnessing ihe production of sparks,
—according to the method by  which M. Matteucci, in 1836, succeeded when
experimenting on the torpedo, and Mr. Faraday, recently on this fish ; in the
third trial, the hands were applied immediately to the surface of the fish.
  1 [The  sections on  the foetal developement of the torpedo, the species of
torpedo in the Mediterranean, and on  the structure of the torpedo, requiring
for their illustration a number of expensive plates, and being withal intended
for the naturalist especially, have been omitted.—Ed.] 
258
davy's researches.
urine of many of the animals comprehended in Linnaeus's class of
Amphibia.
  Previously, the subject had received but little attention ;  the or-
gans had been very imperfectly described, and  no account that has
come to my knowledge, had then been published, of the chemical
nature of their secretion.
  The results of my observations were communicated to the Royal
Society ; they were honoured  with a  place in  the  Philosophical
Transactions;  and were mainly as follows.

       I.— Of the urinary organs and urine of Serpents.

  The kidneys of several different kinds of serpents, which were
submitted to examination, resembled each other generally, although
in each kind there were minute and trifling differences.   In every
instance they were very large, nearly equal in size to the  liver; they
were long and narrow, and very lobulated ; and like those of some
of the mammalia, with conglomerate kidneys, they were destitute
of a pelvis, each lobule sending a small duct to the ureter.  Each
ureter, formed by the union of two branches, terminated in a single
papilla, situated in the cloaca, and a little elevated above  its surface,
the point of the papilla containing its orifice, directed towards a re-
ceptacle, into which the urine entered. The receptacle here alluded
to is a continuation  of the intestine, yet it may be considered distinct
both from the rectum and cloaca, with which it communicated only
by means of sphincter orifices.  This conformation of parts was seen
to advantage in the larger species of snakes; I first observed it in
the python, and  in a large coluber, commonly  called the rat-snake,
frequently met with from eight  to ten feet long.
  The urinary ducts, even in the substance of the  kidneys, were
often observed to be of an opaque white colour, owing  lo a white
matter which they contained, which was visible through their trans-
parent coats, and which could be expressed  from the papilla,  and
collected in  small quantities for examination.   More or less of a
similar white matter was  almost constantly found  in the  receptacle,
generally in soft lumps, rarely in hard masses.   In the receptacle, I
always observed it pure,  and  not entirely free from  fascal  matter.
This solid urine,  for such it was in  reality, had gradually accumu-
lated in the receptacle, until it  formed  the  masses just  described.
From the  observations made on snakes which were watched in con-
finement, it was to be inferred that the masses were a considerable time
in collecting, from three weeks to a month or six weeks.  When the
bulk of the masses was so large as to distend (he part  unduly, they
were expelled by an unusual exertion of the animal, most  commonly
in the act of devouring its food, which  was usually taken periodi-
cally, at intervals of from three to six  weeks.   Ttie  urine,  in the
instances in which it was observed, was voided, accompanied occa-
sionally but never mixed with fasces.  When expelled, it was com-
monly in a soft state, of a butyraceons consistence, which  it lost 
URINARY ORGANS OF LIZARDS.
259
from exposure to the air, when it became hard and in  appearance
like chalk; a change which I believe was owing merely to the eva-
poration of moisture. The quantity of solid urine secreted by snakes,
is very great, even more than might be expected from the size of
their kidneys; I often  saw masses, voided  by large snakes, which
weighed three or four ounces.
  The chemical nature of this urine was such as I expected to find
it: I say expected, because, before  I left  England, I had been told
by Dr. Prout,  that he had examined the excrement of a serpent in
London,  and  had ascertained that it was nearly pure lithic  acid.
Such I found  it in every instance, in at least eight in which I tried
it; and its properties, whether fresh from the ureter, or after it had
collected in the receptacle, or later when voided, were not materially
different, excepting, as  I believe (and this is matter of after-inference
formed on reflection) that the fresh secretion contained  no free am-
monia, or even lithate  of ammonia, the existence of which, I appre-
hend, when it occurs, is owing to partial decomposition. Subjected
to examination before the blow-pipe, it  emitted strong, ammoniacal
fumes, consumed without flame, and afforded only a very minute
quantity of ash, which  consisted chiefly of phosphate of lime, and a
fixed alkaline  phosphate, and a little carbonate of lime.  In  muriatic
acid, it was insoluble.   In warm dilute nitric  acid, it dissolved with
effervescence,  and  the solution evaporated afforded the pink residue,
almost peculiar to lithic acid.   In an alkaline ley, it was soluble,
and  the solution  was precipitated by muriatic acid.  These proper-
ties sufficiently proved that  the nature  of  the urine was  as above
stated.  Besides lithic  acid,  I was  not able  to detect any other in-
gredient, nor  do I believe that the specimens which  I examined
contained any other with the exception of a minute quantity of mucus
with which they were  lubricated and mixed.

       2.— Of the urinary organs and urine of Lizards.
   Whilst in Ceylon, I  examined the urinary  organs of four differ-
ent species of lizard; the gecko, iguana, a large species resembling
the iguana, called  by the  natives kobbera-guion,  and the  alligator.
The shape of the kidneys was found to vary in the different species;
in their general structure they  appeared to be essentially the same.
Each ureter terminated in a distinct papilla, and both  papillae were
situated in the receptacle  itself.  In no other respect was  I able to
discover between the urinary organs of these  lizards, and the snakes
which I dissected, any materiafdifference.  Neither did the urinary
secretion of these  four species,  and of many other species which I
then and have since analysed, differ from that of snakes in its essen-
tial  nature ; in every instance it  proved to be  nearly pure lithic acid.
Two specimens of urine, from different alligators, agreed in this cir-
cumstance; they differed, however, in one  having  no odour,  the
other a strong odour of musk; the former  was from a very young
animal, the other was  from an older one. 
260
DAVY?a RESEARCHES.
 3.—Of the urinary organs and urine of the Turtle and Tortoise.

 .  The only species of Testudo, the urinary organs of which I have
 examined, are the rnydas, geometrica, and grseca ; the two former in
 Ceylon ;.the last, recently in this country.   Their kidneys, in their
 lobulated structure, resemble those of the preceding animals.  The
 proportional size of the kidneys of snakes is greatest, that of  the
 lizards next, and that of the turtle  and tortoise least.  As is well
 known,  these latter animals differ from the former, in  having a uri-
 nary bladder.   The large green turtle of Ceylon has a pear-shaped
 urinary bladder, not unlike that of some of the mammalia, communi-
 cating with the cloaca by a long dilatable neck, or, as it  may be consi-
 dered, urethra, in which, nearer its termination in the intestine than its
 origin, the ureters open by two large prominent papillae.  The Tes-
 tudo greeca has a large bladder, much resembling that of the  toad
 of the like delicate structure,  and divided into two compartments
 posteriorly ; but similar to the turtle, in its communication with the
 cloaca and the termination  of the ureters, with this slight difference
 however, that they are still more distant from the bladder, opening
 close to the extremity of the urethra.                          a
   In  the bladder, both of the turtle and tortoise of Ceylon, I found
 flakes of pure lithic acid ;  but in no great abundance : they were
 suspended m a transparent watery fluid, containing a little mucus
 and common salt, but no urea, or any other substance, which I could
 detect in the small quantity the subject of experiment.
   The  urinary bladder of the Testudo graeca was in a state of dis-
 tention.  Its contents were found to  consist of lithic acid and lithate
 of ammonia, partly in little firm masses, and partly in the form of
 sand and gravel, not crystalline, mixed with a little  urea.   The
 latter was m solution ; it was defected in a very minute quantity of
 brown liquid, the only portion of the urine that was fluid.
   This  tortoise, it may be remarked, was brought from the Mediter-
 ranean (I believe, from the Ionian Islands) in'the summer of 1836.
 It passed the winter, according to  its habit, in a torpid  state. It was
 mi the first of March  following, that  it was subjected to examination.
 Then its period of hybernation was just over; it had be^un to show
 signs of activity.  For several months it had ate nothing, and. it is
 believed, had not voided excrement of any  kind.  The temperature
 of the air of the room at the time was 55°, out of doors 50°  the  ther-
 mometer placed in the rectum fell to 48°, in the blood flowing  from
 the^.ght auricle, it rose to 50°, and in that from  the ventricle to


  4.— Of the urinary organs and urine of the Frog and Toad.

  The examination which I made of the  urinary oro-ans  of these
animals m Ceylon, was confined to one species of each   thl I„it
frog(R,na taurina, Cuv.) and the brown-Ld (BufoS^ Uuren! 
          URINARY ORGANS OF THE FROG AND TOAD.       261

tini.)   The former was procured from the lake of Colombo, where
it occasionally grows to a great size;—the latter from the slreets of
the  Pettah, which it frequents at night.
  The kidneys of the bull-frog, on examination,  were found to  be
apart, one on each side of the spine;—comparatively pretty large,—
very much lobulated,—of a bright red  colour, and rather tender.
The ureters did not terminate in the bladder but in the  rectum, by
two soft pnpilla3, projecting a little;, and situated between the orifice
of the bladder and the anus,—nearer the former than  the latter.
The urinary bladder was of large dimensions, nearly globular, semi-
transparent,  and yet pretty  strong and  contractile, and evidently
muscular.  Il opened into the rectum a few lines behind the anus,
by a large orifice very well adapted to receive the urine, as it flows
from the ureters, when the anus is closed, as it usually is during the
life  of  the animal and soon  after death,  by its powerful sphincter
muscle.
  The urinary organs of the brown  toad resembled in most re-
spects those of the green  frog.   In  two specimens out of many that
I dissected, I  found the kidneys  incorporated  at their  upper ends.
The ureters  had the same  termination  nearly.   The  bladder of
urine appeared  to be double; when distended fully with air, it re-
sembled two oval bags; which, as two compartments, communicated
freely just above the symphisis pubis, to which they were firmly
attached; and they communicated also by a  single orifice with the
rectum.  This orifice was as well suited  as that of the former for
the reception of the  urine as it flows into  the rectum.  The urine of
the bull-frog, taken  from the bladder immediately after the  death of
the animal, varied  a little in its appearance in different instances,
and very considerably in  quantity,  the bladder being sometimes full
almost to distention, and at other times quite empty.  The follow-
ing is a description  of a quantity of urine, which amounted to 300
grains, and which was collected from thirty-six frogs of different sizes.
  It was almost transparent  and like water in appearance   It was
insipid, but was not without smell;  the odour from it was not unlike
that of the serum of blood.   It was of specific gravity 1003. It had
no effect on litmus or turmeric paper.  Slowly evaporated, it afforded
a minute quantity of brownish extract which had the smell of urea
before it was purified.   This deliquesced on exposure to the air.
Decomposed  by heat in a small  glass tube, it yielded a little amber-
coloured fluid and strong ammoniacal fumes, and a  residual coal,
in which was detected a large proportion of common salt and a little
phosphate of lime.
  Another specimen of the urine  of  these  frogs was found to be
more dilute ; it contained a minute portion of common salt and of
phosphate of lime, without any appreciable quantity of urea.
  The urine of the brown  toad was  pretty uniform  in its appear-
ance in different instances ; and in  its composition  also, judging
from the results of the experiments made on it.   From  the bladders
of eio-hty-four toads, 732 grains of urine were collected.  Examined 
262
davy's researches.
when quite fresh, it was  nearly transparent, and would have been
perfectly so, but for a few minute flocculi suspended in it.   It was
of a pretty bright straw-yellow, very like healthy human  urine  in
appearance, with the peculiar smell, and nearly the same taste in a
slight degree.   It was of specific gravity  1008.   It did not alter
litmus or turmeric paper.  Nitrate of silver dropped into it produced
a very copious precipitate of luna cornea.  A solution of corrosive
sublimate occasioned a minute flocculent  precipitate; neutral ace-
tate  of  lead,  a  copious  white  precipitate.  Aqua ammonia, had
no  effect; oxalate of ammonia produced a slight cloudiness; and
a faint  cloudiness was produced  by muriate  of barytes,  which
did not  disappear on the addition of a drop of  nitric acid.   A por-
tion of  this  urine slowly evaporated, afforded a brown  extract,
with a strong  urinous smell.  To  the moiety of this extract of a
syrupy  consistence, a drop of nitric acid  was added; the effect pro-
duced was just  the same as if concentrated human urine had been
the subject of  the experiment; a crystalline compound immediately
formed,  which I could not hesitate  in pronouncing nitrate of urea.
The other moiety, decomposed by heat in a glass tube ctased at one
end, afforded a considerable quantity of yellow oily fluid, strongly
impregnated with carbonate of ammonia, and a residual coal, from
which was obtained a large proportion of  common salt, and a little
phosphate of lime, and slight traces of a fixed  alkaline phosphate.
Another portion of this urine was set aside to undergo spontaneous
decomposition.   After having been  kept eight days, it  became
slightly turbid and emitted a distinct, though not strong, ammoniacal
odour.
   The conclusions to be drawn  from the results of these experi-
ments hardly require  to bo pointed  out, viz. that the  urine of the
bull-frog and of the brown toad contained urea as a constituent part,
and  the latter  rather abundantly.   And reasoning from analogy, it
appears highly probable,  that the urine of frogs and toads in  gene-
ral, is of a similar nature, and not altogether different from that  of
the other amphibia.
   It is seldom that any very abrupt  transitions are to be observed m
nature:  the urinary organs of the turtle and tortoise, on the one hand,
seem to be a connecting link between theise of the reptiles and the
mammalia, especially as regards their form of bladder, and the termi-
nation of their ureters ; and on the other, amongst the reptiles them-
selves, to form a gradation between the snakes and the batrachians.1
   Perhaps additional facts are not required to prove that the nature
of the secretion of the kidneys of animals depends more on the inti-
mate and invisible structure of these organs, than on the kind of food
the animals consume.  Were such facts wanting, there would be  no
difficulty in furnishing them. How different is the urine of the brown
toad and that  of any species of small lizard !   Yet flies are the  fa-
  1 The gradation is even more complete through the Menobranchvs lateralis
of the Canadian lakes: its bladder is very small: its ureters terminate in the
cloaca, close to  the entrance of the bladder. 
FLUID SECRETED BY THE TOAD.
263
vounte and  common diet of  both.  Other remarkable  instances
might be mentioned of similarity of diet, and difference of urinary
secretion ; and vice versa, instances might be afforded of difference
of diet and similarity of urine : I will mention one only; it is that of
parrots and snakes;  their urine, as I have found, being  much the
same, consisting chiefly of lithic acid, though their diet is altogether
different, the  birds  feeding entirely on vegetable  matter,—the rep-
tiles entirely on  animal matter.1   But let me not  be  supposed to
maintain that  the urinary secretion depends entirely on the organ,
quite independent of  the nature of the  food, or  of  the blood, from
which  the elements of the urine are derived.   It appears to be pretty
satisfactorily proved, that, cceteris paribus, there is a certain relation
between the nature  of the food and  of the urine.   Whilst this has
been generally admitted, the relation between the organ and the se-
cretion has been less  insisted on, though perhaps not less curious
and deserving of attention.
                             XXI.

ON THE ACRID FLUID SECRETED BY THE  COMMON TOAD.

  In every country in which the toad is  found,  it is considered
poisonous by the common people; and  the opinion may be traced
back to a very remote antiquity.  Of late years the notion has been
rejected by the professed naturalists, and placed in the number of
vulgar prejudices.   Thus M. Cuvier, in his general remarks on the
species., says " Ce sont des animaux d'une forme  hideuse, degoutant,
que i'on accuse mal a-propos d'etre venimeux  par  leur salive, leur
morsure, leur urine, et meme par l'humeur  qu'ils transpirent."2
  From observations which I made to endeavour to determine this
point in the Ionian Islands, in 1825, I was  obliged to come to the
conclusion, that  the popular opinion was not without  foundation,
and, of the two, the most correct.  The results of  my experiments on
the subject, were communicated to the Royal Society, in the year in
which they were made, and they were published in the Philosophical
Transactions for 1826;  they were limited to  the  common  toad,
(Rana Bufo, L.)  and were nearly as follows:
  In carefully examining the toad, I found it possessed of  a  pecu-
liar fluid, seated  chiefly in the integuments, in follicles,  in the cutis

  ■The land tortoise of the shores of the Mediterranean is another remark-
able instance.  I have mentioned  how I found its urine to consist chiefly of
lithic acid ; yet its food is chiefly, indeed I believe,  exclusively vegetable
matter.
  * " Le Regne Animal," torn. ii. p. 94. Paris, 1817.  The remark is repeated
in the last edition, that of 1827. 
261
DAVY'S RESEARCHES.
vera, beneath the cuticle and the coloured rete mucosum.   i nese
follicles were largest, and  most numerous near the shoulders and
about the neck of the animal;  but  they were far from  being con-
fined to these parts, tiiey were very  generally distributed, and even
on the extremities.  Pressure being applied to the skin, a yellowish
thick fluid, the fluid in question, exuded, occasionally it even spurted
to a considerable distance.  No difficulty was experienced  in col-
lecting it, from large and old animals, in sufficient e^uantity for exa-
mination.  The following are some of the properties of the specimen
which  was subjected to experiment.
  The greater part of it was  soluble in alcohol and water.   The
aqueous  solution  was  slightly viscid,  and did not  pass readily
through a common filter.  It was not precipitated by acetate of lead;
and its transparency was very slightly impaired by a solution of cor-
rosive sublimate.  The substance obtained by evaporation, both from
the aqueous and  alcoholic solution, was light yellow and  transpa-
rent ; had a faint and  peculiar smell different from that of the toad;
and it was slightly bitter and very acrid, acting on  the tongue like
the extract of  aconite prepared in vacuo ; and even occasioning a
smarting sensation when applied to the skin of the  hand ; its effect
lasted two or three hours.    When heated, it readily melted;  burnt
with a bright flame, and did not emit an ammoniacal odour.  It did
not appear to be either acid or alkaline, judging from its not chang-
ing the colour of turmeric, or of litmus paper.  Caustic ammonia
{aqua ammoniai) dissolved it, without depriving it of its acrid qual-
ity.  Nitric acid also dissolved it;  forming a parple coloured solu-
tion, which, neutralised by an alkali, was  less acrid, as  if partially
decomposed.  The small  portion of the fluid, not soluble either in
water or alcohol, and to which it owed its consistence, was probably
a variety of albumen ;  and  iis appearance,  when  burning, would
seem to warrant this idea.
  Though this fluid of the toad was more acrid than the poison of
the most venomous snakes, it did not appear to have any injurious,
and  much less fatal, effects,  when absorbed and carried into the cir-
culation of an  animal  on which it was tried : thus,  on a chicken,
punctured with  a lancet which had been dipped in it, received no
apparent injury.  And, in confirmation of this statement, I may re-
mark, that although, as already observed,  it abounds chiefly in the
integuments, it is not confined to them ; I found it in notable quan-
tity in  the bile, in minute quantity in the viscid fluid lubricating the
tongue, and also in the  urine, and even in the blood.
  In my paper,  presented  to the Royal  Society, I called^this fluid a
poison; considering the properties described, perhaps it may with
more propriety  be called an acrid than a  poisonous  fluid ;  and
rather analogous to that secreted by certain  insects, as the bee, and
scorpion, than to the  more virulent  and less acrid  fluid  of the  poi-
sonous snakes.
  Reflecting on  the use which this  fluid may be of to  the toad,  it 
FLUID SECRETED  BY THE TOAD.
265
occurred to me, that it may answer two purposes, and these of im-
portance to this abhorred but innocent reptile.
  As the external surface of the skin  is  smeared with this  "swel-
tered venom," as  it has been called by our great dramatic poet, it
must serve to defend it from the attacks of carnivorous animals : "a
toad to eat," is a  proverbial  expression well known ; and the facts
adduced show its propriety and force.  1  may here  add, that nature
has given  this sluggish and  helpless animal an additional security
against attack, in providing it with integuments of  great  thickness,
and  strength,  and  hardness; which  last-mentioned  quality is im-
parted by a layer, between the fibrous cutis, (the cutis vera) and rete
mucosum, almost analogous to bone,  abounding in phosphate  and
carbonate  of lime, and carbonate of magnesia, semi-transparent, and
yet so firm,  that it is not  easily cut.1
   As the fluid contains a substance which is very inflammable, and
as it may  be considered excrementitious, though the blood  is very
slightly impregnated with it, it may serve to separate a portion of car-
bon  from the blood,  and thus in its function be auxiliary to the func-

  1 The tegumentary system of reptiles is curiously  varied in structure and
composition; in every instance admirably adapted to the  peculiar habits of
the species.  How  great  is the contrast between the soft mucous covering
of aquatic active frogs, and the  firm, hard, envenomed covering of the slug-
gish land-toads; or of the former, and the  tortoise; or of the different species
of lizards, compared one  with another, in relation to their skin, in connection
with  their  habits and defensive wants against their enemies.  A careful
chemical examination  of the integuments  of reptiles, I have no doubt, would
amply repay and bring to light  many curious and interesting facts. My own
labours in this field have hitherto been very limited and partial. Besides the
skin of the toad, I have  only examined that of two other reptiles, viz. the
python and Indian  alligator.  The first dry, I found  to consist of
                          96.7 animal matter.
                          3.3 earthy matter.

                        100.0
   The earthy matter consisted  of phosphate of lime and silica, the  latter in
large proportion, coloured reddish by peroxide of iron.
   The second dry (a  single plate from the  back which  weighed 88.2 grs.
was the subject of  experiment, and it was further dried at a temperature of
about 212, previous to examination,) was found to contain
                       5.7 water (hygromelric)
                       33.6 earthy matter
                       60.7 animal matter.
   Subjected to a strong  heat in an open crucible, the animal part consumed
with flame, and afforded a residue retaining the form of the plate differing
from the original only in being somewhat shrunk.   This  bony pate con-
sisted principally of phosphate of  lime, besides which it  contained  a little
carbonate of  lime and silica.  On  the  inner  surface of the plate there were
minute concretions of quartz, the largest about the size of  a small pin s head
semi-transparent, but not distinctly crystalline. Their  hardness,  and not
being acted on by an acid, were properties sufficiently characteristic of their

^Whether the presence of  silica in these instances is to be considered as
accidental or the effect of disease, or constant and normal, analogous to what
occurs in the protecting epidermis of some plants, remains to be ascertained. 
266
davy's RESEAKCHES.
tion of the lungs.   In support of this idea 1 may remark, that I have
found the pulmonary arteries of the  toad, each divided into two
branches ; one of which went to its respective lung, and the other,
very little smaller, to the cutis, between t^ie head and shoulder on
each side, and was extensively ramified where the largest  follicles
were situated, and where there was a  plexus of veins  of great size,
as if intended for a reservoir of blood.
   This  last-mentioned peculiarity of structure, and the situation of
it, corresponding to the gills of the tad-pole, would seem to indicate
that the subcutaneous distribution  of the second branch of the pul-
monary artery,  may aid the lungs  further in  their office  by bring-
ing the  blood to the surface to be acted on by atmospheric air.
   I have endeavoured to ascertain if there is any direct communica-
tion by spiracula through  the integuments.  The. results obtained
have been negative.  Air has  been intre)duced by means of a forc-
ing syringe, under the loose skin, through a small incision, also into
the cavity of the abdomen, and into the lungs by the superior glot-
tis; and has been  much compressed, in these parts underwater, yet
it has been completely confined—not even  the smallest bubble was
visible—forced either through  the skin or through the lungs.
   When dried,  the skin of the toad, I find, exhibits two kinds of
pores; one kind, few in number, confined to the tuberosities over the
shoulders, sufficiently large to receive a hog's bristle ; the other kind,
very numerous, scattered over the  whole surface, and  very minute.
Both of them were best seen by holding the skin between  the eye
and a strong light; the smallest appeared as luminous points of a
yellow hue, the largest as indistinct  circles.   Both were covered
externally with  transparent cuticle, and internally by a delicate sur-
face of cellular tissue; some of the largest were also covered with
rete mucosum ; the smallest appeared  to be destitute of this mem-
brane: both, I believe, are destitute of the superficial layer or crust,
already  mentioned, consisting chiefly of phosphate of lime.
   Whether these apparent pores are the medium of communication
between the blood in the subcutaneous capillary vessels and ihe at-
mosphere, or whether they are merely paris of the cutaneous appa-
ratus of secretion and exudation, it is difficult to determine ;  it is not
improbable that they perform  both functions :  the experiments of
Spallanzani, and the very ingenious ones of Dr. Edwards, on  what
has been denominated cutaneous respiration, may be considered as
demonstrative, that they perform at least the first-named function. 
POISON OF SNAKES.
267
                            XXII.

ON THE POISON OF THREE  OF THE POISONOUS  SNAKES
                         OF CEYLON.

   Of twenty different species of snakes which I had an opportunity
of examining in Ceylon, font only belonged to the poisonous kind;
namely, the Hooded-snake, ihe Tic polonga, the carawilla (as they
are called by the natives) and the Trigonocephaly nigro-marginatus,
(the Bodroo Parn of Russel.1)  All these,  with the exception of the
last, of which,  from its extreme rareness, I  could not procure a living
specimen, I tried on animals, with a view to endeavour to ascertain
what  are the effects of their poison.  Owing to an unavoidable in-
terruption, to which medical officers are liable on service, the inquiry
was not carried nearly so far as I could have wished :  I was obliged
to leave it in an unfinished state. However, as the results which I
hud obtained appeared to me to be of some value (as  the results of
all experiments  carefully made  and honestly related, necessarily
must  be) I thought it right to introduce them into my work on  the
Interior of Ceylon, which was published  in 1821.  From that ac-
count the following is an extract.  I am induced to give it, partly
for the  reason  already assigned, and  partly in consideration  that
the work referred to is scarce, and out of print; and, moreover, as it
appears desirable to call attention to a subject of acknowledged in-
terest and importance, obscure and mysterious in itself, and  pecu-
liarly requiring various and multiplied elucidation by experiments.

1.— On  the  poison  of  the  Hooded snake (Naia  tripudians,
                           Mar rem.)

  Experiment 1.—The snake used in this experiment was about
five feet long and about six inches  in circumference in its broadest
part.  It appeared to  be active and in good health.   On the 30th of
November, 1816, at Colombo, a full grown hen was  brought near
it.  After much threatening the snake darted on the hen, and fixed
its fangs in the skin, covering the lower part of the pectoral muscle.
It kept its hold about  two or three seconds, when  I  succeeded  in
shaking it off.
  At  the moment, the hen  appeared to be  but little  affected; she
seemed  rather uneasy and  restless, and was every now  and then
pecking the part bitten.   Some corn being thrown on the ground,
she ate only a very little.  In two hours she was worse;  but even
then the action of the poison was  not apparent from any remarkable
symptom, merely from a certain degree of debility and languor, in-
dicated by her being easily caught, and by crouching when not dis-
turbed.  There was  no  swelling or appearance of  inflammation

               1 Russel on Indian Snakes, vol. i. p. 60. 
268
davy's researches.
round the punctured wound.  Her  temperature, ascertained before
the experiment, and now by thermometer in cloaca, was found to
have fallen from 109° to 108°.  In four hours she was much worse;
her breathing had  become quick  and  laborious;  venous  blood
seemed to predominate in the circulation ; the comb was bluish and
turgid.  There was very great prostration of strength ; she was
unable to  stand.   The  sensorial  functions  were not apparently
deranged ; the pupil was rather dilated than contracted ;  there were
no convulsions ; no rigors.   Several liquid dejections occurred, and
some watery fluid was thrown  up.  H<>r temperature was now re-
duced to  106°.  I was obliged to leave the house; a servant watched
her; during my absence she expired,  eight hours after she was
bitten.
   I examined  the fowl the next morning, ten hours after death. Ex-
ternally there was no appearance of swelling or of inflammation, or
of any kind of change, not even immediately  on the spot wounded.
Beneath the skin,  where the fangs had penetrated, there was much
cellular membrane and a layer of fat, sufficient to  have prevented
the teeth reaching the muscle.   The cellular membrane under the
wound exhibited slight indistinct traces of inflammation.  On the
mucous membrane of  the  intestines there were  a few red spots.
With this exception, the abdominal viscera in general had no unu:
sual appearance.  The brain exhibited no marks  of disease.   Both
ventricles of the heart were empty, contracted and hard ; the auri-
cles contained coagulated blood.  The  lungs were unusually red,
and the air-cells were full of serum, which on pressure, flowed out
copiously.
   Experiment 2.—Three days after, a  powerful cock was exposed
to the same snake.  The snake fastened on his comb, and kept  its
hold with  its fangs for one or  two seconds.  A little  blood flowed
from the wound.
   During the first four hours,  the bird  did not appear in the least
unwell, walking about and  eating as usual.  After the fourth hour
he began to droop and lose his strength.  In eight  hours he appeared
very weak, could scarcely walk; his feathers were ruffled; his eyes
nearly closed ; his breathing laborious.   In this state he continued
about twenty-four hours without eating: he voided much green ex-
crement.   His temperature was reduced from 109.75, which it was
before he was bitten, to 106°.   About the twenty-eighth hour, he
appeared a little better, but still refused to eat:  this was in the even-
 ing ; the next morning (he was in my bed-room in a large basket) I
 was awakened by his loud and vigorous crowing.  He now appeared
 recovered; he had regained his appetite, and his temperature had
 risen to 108\
   Experiment 3.—The day following, the same snake was tried on
 two puppies, both of  whom it bit.  In neither instance was  Ihe
 health deranged ;  nor had its bite,  sixteen days after,  any effect on
 a small full-grown dog. 
POISON OP SNAKES.
269
   Experiment A.—The snake used in this experiment, was of the
same size nearly as the last;—it had been recently taken and was
active and vigorous.  On the 13th of February, 1817, a young cock,
about half-grown was presented  to it, and bitten on the breast;—
the  wound was so very slight, that  it was only just perceptible.
During the first hour the bird walked about and ate, as if  nothing
ailed him.   Then  he gradually  sickened; his feathers  became
ruffled, he ate very little, and remained stationary in one place.  For
a day and half, he continued growing slowly worse; on the morn-
ing of the second day, he was  found lying down, breathing very
quick, and apparently insensible.   He expired about the  forty-third
hour from the time he was bitten.
   On dissection, no diseased appearances could be detected, except-
ing, perhaps, in the lungs, which were a little redder than natural.
   Experiment 5.—A few minutes after the last fowl was bitten,
another young cock, of the same age nearly and size as the preced-
ing, was exposed to  the snake.  The snake fastened on his thigh,
and inflicted rather a severe wound, from which some blood flowed.
The cock became instantly lame,  and  in less than a minute was
unable to stand.   In about five minutes, his respiration  became
hurried and rather laborious; some  alvine dejections took place. In
about ten minutes  he appeared to  be in a comatose state;  and for
about five minutes he continued in this state—his respiration gra-
dually becoming more feeble and laboured.  In seventeen minutes,
when his breathing  was  hardly perceptible,  he was seized with a
convulsive fit, which, in  the  course  of the  next  minute, returned
four or five times, each less violent than the former—and the last
proved fatal.
   The heart was immediately exposed : the auricles were  found still
acting.   The lungs were redder than usual, and turgid wilh  blood
and serum.   The  brain,  carefully  examined, displayed no morbid
appearance.   The thigh bitten was slightly swollen; the skin sur-
rounding the wound  and  the subjacent muscle  were livid.
   Experiment 6.—On the 29th of October, 1816, at Colombo, I
assisted  my friend, Mr. Finlayson, in examining a small  hooded
snake about two feet  long, very soon after it was killed. We opened
the poison-bag and tried the effects  of its poison on a wild dove.
   First, a little of it was applied to the conjunctiva of the eye.  Im-
mediately the eye-lid fell, and the  eye closed as  if from paralysis.
The eye forced open—the pupil appeared much dilated.
   Next, the tongue was punctured  with  a lancet dipped in  the poi-
son.  In a few  seconds, the bird had  lost the use of its legs; it fell,
and in two or three minutes expired,  without apparent suffering or
any  remarkable symptom.
   The body was'immediately examined.  No  visible  lesion could
be discovered in any  of the organs.
   According to the best of my recollection, it was on this occasion
that both my friend and myself tasted the poison of the Naia, apply-
ino- a very minute quantity  which had been  taken from the poison-
      H__g                                    18 dav 
270
davy's researches.
bag, the same as was used in the preceding experiments, to the tip
of the tongue.  It tasted slightly acrid : the impression was of short
continuance; and  besides this  sensation no other effects were  pro-
duced.1

 2.— On  the  poison of the carawilla (trigonocephalus hypnale,
                          Schlegel.)

  Experiment 1.—The snake used in this experiment and the fol-
lowing, was about a foot long, just taken and very active.  At Co-
lombo, in December, 1816, if bit a puppy, about two months old, in
two places—the side of the face, and the foot of one of the hind
legs.  Immediately, judging from his howling, the animal  seemed
to suffer much pain;  he ran away,  when liberated, on  three legs,
making no use of  the wounded leg.  A drop  of blood came from
each wound.   In less than tw^ minutes, the parts wounded  began
to swell,  and to discharge a thin reddish-brown ichor.  In an hour
the swellings were very considerables, and  the  puppy was severely
unwell—crying piteously,  lying down,  and, when roused, hardly
able to stand. " In about twenty-four hours,  the swelling had ex-
tended to the parts adjoining the wounds, having subsided where
it first appeared.  The wounds still discharged an ichorous fluid,
and appeared slightly  livid.  The health of the dog was improved;
he  was able to  eat and move about on  three legs.   In about forty-
eight hours,  the swelling had  nearly disappeared, and  the animal
seemed to  have recovered his  health.  The wounds had sphace-
lated extensively and  deeply, and a  purulent  discharge had com-
menced.   In  twenty-four hours more, a slough had separated from
the wounds, which were now large deep ulcers, of a healthy ap-
pearance, promising  to heal readily by  the  common  process of
nature.
  Experiment 2.—On the same day, another  puppy was bitten by
the  same snake in the fore-foot.  The  parts immediately swelled,
and discharged an ichorous fluid.   From the foot the swelling ex-
tended to the shoulder; and from the shoulder to the integuments
of the chest;  subsiding where it first appeared, as it spread beyond.
The health of the dog was much deranged ;  for two days it could
stand with difficulty, and  ate very little.  It  had frequent small
bloody evacuations, as if the bowels were inflamed.  At the end of
three days there was a considerable improvement; a great  part of

  '  This last experiment was not described in my work. In 1821, my friend
was alive and actively engaged in scientific pursuits  in India. Unfortunately
for  science, he was prematurely cut off, shortly after, on his homeward voy-
age, by pulmonary disease, contracted  in  Ava, where he accompanied, as
naturalist and medical officer, the political  mission under the direction of
Mr. Craufurd,  the able historian of the  Eastern Archipelago.  Mr.  Finlay-
son's Journal of the Expedition, published after his death, bears ample and
equal proof of his zeal, talent for observation and reflection, and rich acquire-
ments. 
POISON OF SNAKES.
271
the skin  of the  leg bitten was now livid, and on  the  fourth day
sloughed off, exposing an extensive healthy ulcerating surface.  On
the fifth day, the animal was still sickly;  the ulcer healed slowly,
and the dog gradually recovered its health.

  Experiment 3.—On  the day following that on  which the two
preceding experiments  had been made, a  half-grown fowl was bit
by the snake just above  the left eye. The  eye immediately closed ;
a watery fluid, like tears, flowed  from it,  and there was  a similar
discharge from the nostrils.  When the eyelid was forced open, the
pupil  contracted  readily on the admission  of stronger light.   The
opposite side of the face soon became  considerably'swollen.   The
fowl drooped, but never lost the use of its legs.  It refused to eat,
and was much purged;  what was  voided had a chalky appearance.
On the third day, it seemed to  recover a little, and ate a small
quantity of grain.  On the fourth day, it was found dead.
  Under  the skin of the part bitten  there  was  some  coagulated
blood,  and the cellular membrane was discoloured.  On the exter-
nal surface of the heart,  within the pericardium, there was a cover-
ing of coagulated lymph, of a reticulated appearance, strongly indi-
cating  recent inflammation of the  organ.   The lungs were rather
redder than natural.  The gall-bladder was distended  with green
bile.  The intestines were not inflamed, and the  other viscera had
a healthy appearance.

  Experiment 4.—On the day following, another fowl, half-grown,
was bitten by the snake  in Ihe comb, which bled pretty freely.  The
comb  and the skin of the head swelled slightly.   For twelve hours
the fowl was sickly, and ate very little.  The next day the swelling
had disappeared, and the fowl was well.

  Experiment 5.—After a month's confinement, during  which time
the snake ate nothing,  it appeared to  be as active and as fierce as
when  first taken.  It now bit a fowl, half-grown,  on the side of the
face, about a quarter of an inch below the eye.   The surrounding
skin immediately began  to swell, and the eye to discharge a copious
watery fluid.  In a few  hours the  eye was  greatly swollen and dis-
tended with  effused coagulated  blood.   During the first twelve
hours,  the fowl  seemed sickly, drooped, and ate  nothing.  It had
numerous white alvine  evacuations.  In about twenty-four hours,
its appetite returned, and it seemed pretty well, notwithstanding the
diseased state of the eye, the sight of which it had lost from ulcera-
tion.

  Experiment  6.—After another  fortnight,  spent in fasting, and
without apparent diminution of activity,- the  snake bit a large frog
on the head.   The skin became slightly swollen, and discharged a
bloody sanies.  The swelling extended from  the head to the trunk.
The animal died in about five hours. 
272
davy's researches.
 3.— On the poison of the tic-polonga {vipera elegans, Daudin.)

  Experiment 1.—This and the following experiments were made
with a tic-polonga, about four feet and a half long, and very thick.
It had just been taken, and was in full vigour.
  In February, 1816, at Colombo, the same fowl was exposed to this
snake that had lost an eye from the bite of the carawilla. It seemed
desirous to avoid the fowl, retiring and hissing with extraordinary
shrillness and loudness; after being irritated very much,  it darted
at the  fowl and  struck it, but did not appear to have wounded  it,
though it really had,  in the slightest manner possible, near the in-
sertion of the great pectoral muscle.   In about a minute the fowl
was seized with violent convulsions, which, in two or three seconds,
terminated in death.
  The chest was immediately opened.   The two auricles, and (he
right ventricle, and the great veins and arteries, were distended with
coagulated  blood.   When first exposed, the heart was  motionless;
after the removal of the  pericardium,  the auricles exhibited, for a
few seconds, a slight  tremulous action.  In  the brain, lungs, and
other viscera, no diseased appearances could be detected.  The ves-
sels generally were distended with coagulated blood.  The muscles
were very flaccid, and could not  be stimulated to the feeblest con-
traction,  immediately after death; even the pectoral muscles, when
divided, showed no signs of irritablity, nor did the intestines.  Where
the wound had been inflicted, the skin and the muscle underneath
were  a little  darker than  natural, as if from a minute portion of
extravasated  blood.  The muscular fibre was extremely soft and
weak; slight pressure on the  muscles occasioned  the exudation
of a little watery fluid, and some minute globules of air.  There
was not the  slightest swelling of the part, or appearance of local
inflammation.

  Experiment 2.—About half an hour after the preceding experi-
ment,  a  full-grown fowl  was exposed  to the snake.   Even  more
provocation was required in  this instance than in the first, to excite
the snake to act;—at length  he bit the fowl  in the wing;  the fangs
penetrated the loose skin, and drew a little blood.   At the moment,
the fowl did not appear to  suffer any pain, or to be  in any way
affected.  In about a quarter of a minute, by a second-watch, its
breathing had become accelerated;  the eyes nearly closed, and the
pupils a little contracted.   In a minute,  the fowl was seized with
convulsions of a very severe kind,—the head was bent down and
fixed on the breast; the legs were drawn up; in brief, every muscle
appeared to be in violent action, and spasmodically contracted. The
convulsions lasted about half a minute, when the fowl expired.
   The appearances on dissection were the same as in the  preceding
instance.  There was no discoloration or apparent change in the
parts surrounding the wound. 
POISON OF SNAKES.
273
  Experiment 3.—Six days after, the snake bit a young dog, nearly
full-grown, in  the hind leg.  A good deal of blood flowed from the
wound.  The dog immediately ran away, howling, with the foot
drawn up.
  During the first ten minutes, he was very restless;  his move-
ments were rather convulsive, particularly the motions of the hind
leg that was not bitten. Sometimes he would lie down and appear a
little composed, and as suddenly start up and re-cornmence a piteous
howling.
  In about fifteen minutes his breathing became hurried, the mus-
cles  became spasmodically affected,  and violently so, particularly
those concerned  in respiration; copious evacuations took  place,
sur sum et deorswm.   His strength was  now much diminished;  he
lay on the ground breathing rapidly and crying shrilly, every now
and then starting up,  as  if from pain, and almost instantly falling
again, as if from inability to support himself.   In about twenty
minutes, he was  apparently almost exhausted;  the breathing was
short and spasmodic, as it were by jerks, and  amazingly rapid—
about  ninety in a minute;  each expiration was accompanied with
a shrill sound, and  now and then there was a full inspiration, fol-
lowed  by a deep  groan.  Even now, the sensorial powers seemed
to be little affected; the poor animal was conscious of what was
passing, and when patted on the head seemed to be soothed.
  In about twenty-six minutes he became insensible and apparently
comatose, not to be  roused by any  means of excitement applied.
The pupils were rather contracted;  respiration was quick, but not
so quick  as  before,  and  more full:  now and then it  was more
hurried, now  and then there was a  deep inspiration and  a moan;
his extremities were nearly cold.
  In about fifty-one minutes his respiration became spasmodic, the
head pulled down  at  each inspiration.  The  respiration became
slower and slower,  and  gradually  more feeble,  till at  the fifty-
eighth minute it ceased entirely.  The pupil was dilated; just be-
fore death there was a slight convulsive motion of the whole bejdy.
  The body was immediately examined.  A good deal  of  serum
was found effused on the surface of the brain, in  its ventricles and
at its base: the surface of the brain (the pia mater) was redder than
usual;  there were air-bubbles in the  vessels of the pia  mater, and
in the  larger veins.  The liver  was  very  red,  and gorged with
blood;  the lungs were rather red, condensed, and contained little
air.   The ventricles  of the heart were  distended with blood, the
right ventricle especially;  the right auricle was less distended, the
left  auricle was  empty.   The  blood in the heart and veins was
liquid; it did not coagulate on  exposure to  the  air.  There were
red spots on the inner coat of the stomach.  The other  viscera ex-
 hibited nothing unusual.  The foot bitten was very slightly swollen,
owing to the effusion of a little scrum and blood.  The muscle
under the wound was nearly black, there were air-bubbles  in  the 
274
davy's researches.
adjoining cellular membrane; there was no offensive smell from it:
the body was still warm.

   Experiment 4.—Thirty-four days after the last experiment, dur-
ing which time the  snake would  eat  nothing, it bit  a  rat.   The
animal  immediately  lay down  motionless; its respiration became
quick and convulsive; and after two  or three slight convulsions of
the body  in general,  it expired.
   The  body was immediately opened.  The heart  had  ceased to
contract;  the auricles did  not contract when  punctured.   The sur-
face of  the  heart was unusually red and vascular, as  if  inflamed;
its cavities  were distended with blood.  The lungs  were rather
redder than natural.   The muscular fibre  in general had entirely
lost  its  irritability.   There were no marks of disease amongst the
abdominal viscera.
   The  first experiment with this snake was made on the  day it was
brought to me,  the 3d of February; the last, which I have now to
describe,  on the 27th and 28th of June,  an interval  of 146 da} s,
which it had passed fasting.   It had refused different kinds of food
offered,  and yet it looked  now  as well as ever, and appeared to be
equally  vigorous; and from the result of the following experiments,
its poison  seemed to be not exhausted or weakened, but concentrat-
ed and more terribly  active.  As I was obliged to leave Colombo at
this time,  I do not know how much longer the snake lived without
eating.

  Experiment  5.—On  the 27th June, the snake bit a full-grown
fowl in  the face. The wound was inflicted in an instant;  the fangs
were instantly disengaged.  In  a few  seconds the fowl  was  con-
vulsed;  every muscle seemed to be thrown into violent spasmodic
action;  the head was drawn down  on  the breast,  the legs were ex-
tended,  and the animal, lying on its belly, was moved about rapidly
and  irregularly by a quick  succession of those involuntary spasmo-
dic actions of its muscles,  till it  expired, which it  did in ralher less
than a minute from the instant it was wounded.
  The body was immediately opened.  The muscles divided by the
scalpel did not  show the slightest signs of irritability,  nor did  the
intestines; the heart contracted very irregularly, and so very feebly,
that  it had no effect  in propelling its contents.  The auricles were
gorged  with  blood,  particularly the right;  the left ventricle was
empty, and the  right  contained only a  small quantity of blood;  the
arteries  and veins were full of blood, which had coagulated firmly,
even in  the minute branches.  There was  no unusual  appearance
in the brain, or  in any of the other viscera, excepting the distended
state of their blood-vessels.  A reddish sanies oozed from the wound;
the skin round  it was discoloured, without swelling;  the muscle
under the skin was blackish and tender, as if severely bruised;  the
adjoining  cellular membrane was slightly emphysematous. 
POISON OF SNAKES.
275
  Experiment 6.—On the  following day,  the  snake wounded
another full-grown  fowl, inflicting with its fang, in the side of the
face, a puncture only just perceptible.  During the first minute and
a half, the fowl did  not appear to suffer in the least, when it was
seized with violent convulsions, which proved fatal in about fifteen
seconds.
  The appearances on  dissection, which was commenced immedi-
ately, were very similar to the last.   The action of  the heart was
perhaps a little less  feeble;  the vermicular motion of the intestines
had not entirely ceased, and the blood was not  quite so firmly coagu-
lated.  All the cavities of the heart were empty, with the exception
of the right auricle, which was distended with blood.

               Conclusions and general remarks.

  From  the  experiments  on  the  poison  of  the hooded  snake,  it
would appear that its  bite  is not necessarily fatal to fowls; that the
effect of the  bite varies a good  deal according to  circumstances
which it is not easy to calculate; that the poison is capable of being
soon exhausted; that  the symptoms produced by the poison, though
not uniformly the same, pretty generally correspond; and that, in
conjunction with the  appearances on dissection, they seem to indi-
cate that the  lungs are the principal seat of the diseased action.
  From  the  experiments  on  the bite of the carawilla, it would
appear that it is rarely fatal to small animals; that its poison is not
easily exhausted; that the symptoms produced by it are pretty uni-
form; that they are different from those produced by the poison of
the hooded snake, the deceased action  being  more local and much
more inflammatory—commencing in the part  bitten, spreading, pro-
gressively, losing its force  as it extends, and probably never proving
fatal, except  it reach a vital organ.
  From the  experiments  with the tic-polonga, it appears  that its
bite greatly exceeds in fatality that of the  hooded snake, or of the
carawilla, and that  the action of its poison is  different and  peculiar.
Judging from the  symptoms and appearances on  dissection, its
poison seems to exert its influence primarily and principally on the
blood and muscular  system, tending to  coagulate the former and
convulse andparalyse the latter.  All the experiments seem to point
directly  to this conclusion, not excepting even the third, the  pecu-
liarities of which may be referred to the reaction, which it may be
conceived took place, the  animal  being pretty large and strong, and
not overpowered by the immediate effect of the poison.
   From the  whole  of the preceding experiments, it may be inferred,
 reasoning from analogy, in relation to man, that the  bite of the tic-
 polonga is most dangerous; that  of the hooded snake is dangerous
 in a tass degree; and  that  of the carawilla, least of all, and  probably
 never fatalT  The result of the inquiries which I made amongst the
 natives,  though not very  satisfactory, tended to confirm these con-
 clusion's: I found them generally of opinion, that the bite of the tic- 
276
davy's researches.
 polonga is unavoidably fatal, but that the hooded snake only occa-
 sionally so.  Perhaps they exaggerated a little in maintaining the
 first part of this statement: the latter part of it I believe to be quite
 correct; for 1 have seen several  men who  had recovered from the
 bite of the hooded snake, and I have heard of two or three only  to
 whom it had proved fatal.
   I regret  that I have nothing original to offer respecting the medi-
 cal treatment of the bites of these snakes.  It was my intention  to
 have made a series of experiments on the subject; indeed, the expe-
 riments  which  I have detailed were merely preliminary  to that
 inquiry, being instituted  to smooth the way,  to determine,  if pos-
 sible, the  mode of action  of  each  poison, and  furnish data for
 inferring what  are  the pure effects  of the  poison, what  of the
 powers of nature opposing its effects, and  what those of  the me-
 dicine administered.    In  no subject  is  discrimination more re-
 quired  than  in  this mysterious one; and  in no one perhaps has
 less judicious discrimination been used.  It has often been taken
 for granted that the poison of all snakes is similar—not differing  in
 its kind, but only in its intensity of  action; and, agreeably to this
 assumption, that the medicine  useful  in one  instance must be ser-
 viceable in all.  And, too often,  medicines  have got  into repute  as
 antidotes from being given in slight cases, in which recovery would
 have taken place without medical treatment—beneficial  changes
 that were due merely to the preservative powers of the constitution.
 The  reputation that  many Indian medicines, and especially lhat
 snake-stones have acquired,  afford striking proof of  the preceding
 remarks; of  three different kinds of  these stones which I have ex-
 amined, one consisted of partially burnt bone, another of chalk, and
 the third principally of vegetable matter; this last resembled a bezoar.
 All of them (excepting the first, possessed of a slight absorbent power)
 were quite inert, and  incapable of having  any effect, exclusive  of
 that which they might produce as superstitious medicines, on the
 imagination of the patient.1
  The probability is, that  the poison of each different  kind of snake
 is peculiar; and that, when fully investigated, the effects of each will
 be found to require a peculiar mode of treatment, the nature of which
 can only be ascertained by actual experiment.   In the mean time,
 I may remark, that fortunately for man, in this great  obscurity, the
immediate  treatment  of all poisoned  wounds,  merely locally con-
sidered, is simple and very similar.   The obvious indications are,
to extract the poison as much as possible, and as speedily as possi-
ble; and to endeavour to prevent its entering the circulation.  The
first indication  is best accomplished  by cutting out the part bitten,
and scarifying the surrounding integument.  If the  person bitten

  1 It  is  the opinion of the natives that these stones are found in the brain
of snakes.  From Sir Alexander Johnson, to whom I was indebted for the
specimens I  examined,  I learnt that those of the first kind are manufactured
by the monks of Manilla, who carry on a lucrative  trade in them with the
merchants of India. 
HEART OF BATRACHIAN ANIMALS.
277
want courage to do this, he should suck the wound well, and after-
wards apply caustic, if at hand.   The second indication mav be
tolerably fulfilled (if the part bitten  admit of the application of a
ligature) by tying a handkerchief very tightly just above the wound.
Respecting the employment of oil, arsenic, and eau de luce, having
no experience of their  effects, I can offer no decided  opinion.   Oil
seems to have been useful, both  applied externally, and taken inter-
nally, in many instances of the bite of the viper; and  arsenic seems
to have done good in some instances of the bite of the  hooded snake.
Eau de  luce does not appear to have deserved the high character
that was first given to it, indeed I am not aware of any satisfactory
proof of its ever having been beneficial.
                            XXIII.

ON THE STRUCTURE  OF THE  HEART  OF  BATRACHIAN
  ANIMALS, ESPECIALLY OF THE GENUS RANA  OF  LIN-
  NAEUS.

  From  the urinary organs of reptiles, my attention, whilst I was
in Ceylon, was directed to other parts  of their structure,  and  espe-
cially to  the apparatus of circulation and respiration.
  It was at that time commonly asserted by the highest authorities
in comparative anatomy,  and generally believed, that the animals
belenging to the genus rana, and  indeed all those included in the
natural order of batrachians of Cuvier, in the conformation of their
heart, differed  from the other reptiles, which possess a bi-auricular
heart; and resembled  fishes—which have only a single auricle as
well as ventricle.
  The close analogy in general structure which exists between the
batrachians and the other reptiles,  led  me to doubt the accuracy of
this  conclusion; and  observations which I had  an opportunity of
making first in Ceylon, and  afterwards in 1824 and 1825, in Ihe
Ionian Islands, satisfied me that my doubt was well  founded.
  Selecting old and large animals, especially the toad, which in the
Ionian Islands often attains a great size, I experienced but little dif-
ficulty in demonstrating the bi-auricular structure of its heart.  It
was best  effected by  making  an  incision into the ventricle, and in-
flating the organ with the  blow-pipe.   By this method, with the aid
of fine probes,  manipulating under wafer, it was clearly proved that
the heart of the animal has  two auricles, which are divided  by a
transparent membranous septum, possessing fibres, which  appear to
be muscular;  that they communicate with the ventricle by a  com-
mon and very short passage, and that they have no communication
with each other, excepting in  the passage above the valves common
to both. 
278
DAVY S RESEARCHES.
   The same fact as to structure, I found might also be demonstrated,
by blowing air through either of the  two pulmonary veins which
return the blood  from the lungs to the  heart; or, by inflating the
sinuses in which  the venas cavse terminate.   By inflation of either
of the pulmonary veins, the pulmonic  auricle was distended, and
not the systemic.   By inflation of the sinuses of the venae cavas, the
contrary effect was produced, showing,  at  the same time, that the
margin of the septum was qualified to act the part of a valve, and
prevent the blood of one auricle from  passing into  the other.
   But even supposing the margin of  the septum  not fitted to per-
form  the function of a valve,  I  apprehend, from what I have ob-
served in watching the  heart's action, that the  blood from one
auricle would not pass into the other,  the  contraction of  the two
auricles being synchronous, the auricles first contracting, next the
body  of the ventricle, and lastly  that part of the ventricle of a coni-
cal shape, which  may be considered almost as a second ventricle.
   This last mentioned part, (to  notice it more  particularly, as I be-
lieve it deserves) appeared from my dissections, to be separated from
the body of the ventricle by three valves, of a semilunar form, one
large  and two small, and  to have attached within it, to the side of
its cavity, a pale fleshy projection, a moveable septum, above which
it gave origin to four great arteries, namely, two pulmonary arteries
and two aortas, the latter considerably larger  than  the former, each
provided with its  own valve.  The  action of this part is not a little
curious:  when I have watched it, it did not appear to contract simul-
taneously, as  a whole, but one-half first, and then the other, as if
intended, in conjunction with the various anastomoses of  the arte-
rial system, to preserve a constant, though small  and feeble current
of blood, to supply all the parts of the body according to their various
demands.
   The same general structure of heart, I have observed in  the bull-
frog distinctly,  and in the common frog also, especially its double
auricle.  Whether  it exists in all the  other species of the genus, I
have not ascertained; most  probably it does.   And reasoning from
analogy, it appeared highly probable, that all the other genera of the
order  batrachia have a similar conformation, both  of this vital orcran,
and of the sanguineous system in general.
   I then  remarked, should this analogical inference prove correct,
and its truth  be established by observation,  these  animals in their
mature state would no longer be  an  anomaly in the classification of
reptiles on account of their hearts, and they would still continue as
a link connecting  the reptiles with  fishes—the perennibranchiate,
through the whole of their existence;  the other species during the
first stage of it,  by the peculiarities of their respiratory organs.
   This conjecture was offered in 1825, in a paper which was pre-
sented to the Royal Society, and which was afterwards published
in the Edinburgh  Journal  of Science, edited by Professor Jameson ;
and I  am happy to have to state, that it has been  amply verified by 
HEART OF BATRACHIAN  ANIMALS.
279
 the able and minute researches of Mr. Owen, as well as by those of
 other inejuirers.1
   I have stated, that when I began my inquiries, and first published
 my observations, all the batrachians were considered by the ablest
 comparative anatomists from the time of Harvey, downwards, as
 analogous to fishes in the auricular structure of the heart.   And, I
 believe I was fully justified in the conclusion, by reference to their
 writings.2  Since  then,  however, I  have learnt,  that  our distin-
 guished countryman, Mr. Hunter, was acquainted with the fact, that
 some of the batrachians have a bi-auricular heart, and that he made
 it in part the basis of a  subdivision of the order.   This I was in-
 formed of by Mr. Owen, who had the  goodness to show me a highly
 interesting document,  preserved  through the  medium of a copy, a
 classification  by our great  physiologist, of the  animal kingdom
 according to  its organisation,  and which Mr. Owen has in part
 given in his valuable prefatory remarks on the physiological labours
 and discoveries of  Hunter, prefixed to his edition of this portion of
 his works.
 .  At what time Hunter ascertained the fact, it is impossible now to
 determine, in consequence of the unfortunate destruction of his MS.
 papers: it is most likely that it was late in life, as there is no prepa-
 ration in  his splendid collection,  in the  Museum of the College of
 Surgeons, illustrative of it;—the  only two preparations of the heart
 of the common toad and frog, left by him, seem from the descriptive
 catalogue published  in 1831, designed to illustrate the commonly
 received idea.3
   The circumstance that Hunter was acquainted with the bi-auri-
 cular structure in question, may  serve to account  for the adoption
 of it by Sir Everard Home.   In his "Systema Regni Animalis,"  in
 the third  volume of his Lectures on Comparative Anatomy, he in-
 cludes  ihe genus Rana in the same class with lizards anel snakes,
 to which  he assigns "Cor uniloculare, bi-'auritum, sanguine frigido

  1 Mr. Owen's observations are to be found  in his paper on the Structure
 of the Heart in  the Perennibranchiate Batrachia, communicated to the Zoo-
 logical Society, April. 1834.
  2 According to  Harvey, "Piscibus, serpentibus, lacertulis, testudinibus,
 ranis et hujusnodi aliis, turn auricula, turn cordis ventriculus unus."  Exer-
 citatio Anatomica de  Motu Cordis, cap. xvii.
  According to Cuvier, " Les Betraciens n'ont au cceur q'une seule oriellette
 et un seule ventricule."  Le Regne Animal, nouvelle edition, Paris, 1829.
  3 The following is the account given of two preparations alluded  to in the
 text:—"175.  The heart of a large toad (Rana Bufo) injected.  It  is com-
 posed  of a single auricle and ventricle ; from the  latter,  the arterial trunk
 or aorta  arises,  and immediately after its origin divides into two branches,
 which ultimately unite into one descending aorta,  at the inferior pari of the
 spine.  Hunterian."
  "176. The heart of a frog (Rana temporaria) injected.   As in fishes, the
 heart is composed of two cavities, a  single auricle, and a ventricle.  Hun-
terian."
  Catalogue of  the Contents of the Museum of the Royal College of Sur-
geons  in London,  Part V. 1831, p. \Q. 
280
DAVY'S RESEARCHES.
rubra;"—but without specification there, or in any of his writings,
of the observations by which the fact was determined.
                            XXIV.

AN ACCOUNT OF SOME EXPERIMENTS ON ANIMAL HEAT.'

  In the present uncertain state of our knowledge of animal  heat,
theoretically considered,  three circumstances  aro  particularly de-
serving of attention, viz.  the  relative capacities of venous and arte-
rial blood for heat, their comparative temperatures, and  the tem-
peratures of different parts of the animal body.
  On the first of these subjects, we possess only the experiment of
Dr. Crawford, which I believe have not yet been repeated, notwith-
standing they  form the basis of his hypothesis.
  On the second, little inquiry  has  been made, and especially of
late years, since the improvement of the thermometer.
  And, on the third, the observations that have been collected are
very few in  number,  and with the exception of those  of Messrs.
Hunter and Carlisle, are  scarcely deserving of confidence.
  Such were  the inducements that led me to the consideration of
each of these subjects apart, and to endeavour to acquire by experi-
ment some more certain  knowledge respecting them.  The experi-
ments that I have made will  be described  in the two following sec-
tions, and in the last will  be offered the few remarks and conclusions
which naturally arise, and are fairly deducible from the  results.

   1.— On ihe capacities of vowns and arterial blood for heat.

   I must premise, that  my  object has been to endeavour to ascer-
tain the relative capacities of venous  and arterial  blood  for heat,
rather than their exact specific caloric.  The latter, from many cir-
cumstances,  is difficult to be accomplished; whilst the former is
comparatively easy, and,  in  a theoretical  point of view,  is probably
equally useful.
   I have employed both  the  methods commonly used. I shall men-
tion most of the experiments  that  I have made, without noticing the
repetitions of them, and shall begin with those on the times of cool-
ing of equal volumes of venous and arterial blood.
   The blood  used was from  the jugular vein and the carotid artery
of a lamb about four months old. It was received in bottles, and,
to remove the fibrin, which is a great impediment in experiments

  1 This paper first appeared in the Philosophical Transactions for 1814;
most of the prefatory remarks are still applicable. 
               EXPERIMENTS ON ANIMAL HEAT.            2S I

of this kind, it was immediately stirred  with a wooden rod.   In
respect to colour, the difference between  the venous  and arterial
blood was not so great as in the sheep's, and this in a great variety
of instances  1 have always observed, the venous being of a less dark
hue.  The specific gravity of  the venous blood, without the fibrin,
was found to be 1050, and that of the arterial 1047.
  A glass bottle, equal in capacity to 2518 grains of water, and weigh-
ing 1332 grains, was filled respectively with water and venous and ar-
terial blood of the temperature of the room 62°, about four hours after
the blood had been drawn, during which time each bottle had been
closely corked.   A delicate thermometer, by means of a perforated
cork, was placed in the middle of the liquid.  The bottle was then
plunged into water of the temperature 140 Fahrenheit, and when the
mercury  had risen to 120, the bottle was quickly wiped, and sus-
pended in the middle of the room; and the progress of cooling was
noticed every five minutes till the thermometer had fallen to 80°.
The following were the general  results obtained:
          Water cooled from 120° to 80° in 91 minutes.
          Arterial blood in     -    -    89   —
          Venous blood in     -    -     88   —
   Considering, therefore, the capacity of water for  heat to be de-
noted by 1000, neglecting the effect of  the glass bottle, producing a
difference only of  about half a  minute, and the same  in each in-
stance, and dividing  the  times  of cooling by the specific gravity,
the relative capacities of venous and arterial  blood,  without  fibrin,
appear to be as 921 and 934.
   In the following experiments,  the same  kind  of blood, and the
same quantity, was used as in the preceding.  The mixtures were
made in  a very thin glass receiver, containing a very delicate ther-
mometer.  The temperature of the room was 66°.
   Hot water, temperature  121°, cold  water  61°.  Mixture of the
two 90°,  after two  minutes 89°, after three 88°, after eight 87°.
   Venous blood 121°, water 62 5, mixture 89°,  after three minutes
88 5, and after seven 87°.
   Now,  allowing about one  degree of the cooling effect to have
been produced by the  receiver,  indicated by the admixture of the
hot and cold water, calculating the quantity of blood used from the
knowledge of its volume and specific gravity, employing the formula
given by Professor  Robinson, which  consists in  multiplying re-
spectively the weight of the water and the blood by the change of
temperature, and dividing the first product by the second, the quo-
tient  or specific caloric for venous blood appears to be as 812, and
for arterial as 814, results very similar to those I have obtained with
the blood of the sheep.
   In the remaining experiments, blood with the fibrin present was
employed, and with this exception, they were perfectly similar to
those already described.
   The  blood, used to  ascertain its time  of cooling, was obtained 
282
davy's researches.
from a sheep;  and one day the vein was opened, and  on the next
the artery.   The capacity of the bottle employed exceeded that of
the first  by one ounce measure of water; but it was equally thin.
The air of the room was of temperature 69°.
         Water cooled from 120° to 80° in  118  minutes.
         Venous blood in     -      -     112
         Arterial blood  in    -      -     113
And hence, as the latter was of specific  gravity 1049,  its capacity
for heat seems to be as 913; and as the former was of specific gra-
vity 1051, its capacity appears to be 903.
   In the following experiment, equal volumes of fluid blood and of
water were  used, which was  easily accomplished  by means of a
thin bottle with a large mouth, to which a cork  was adapted, with
a perforation more than sufficiently large to admit the bulb of a
very delicate thermometer, and of course to allow, when the bottle
was filled to the brim, the excess to flow out on  the introduction of
the cork, which was always similarly  placed.  To  retard the pro-
cess of cooling, the bottle was closely surrounded by a thick layer
of what is commonly  callpd cotton wool.  Its capacity was equal
to five ounce measures of water, or 2400 grains.   It was first filled
with cold water, which, when its temperature had been  ascertained,
was thrown into the  receiver before used; it was next filled with
hot water, of temperature about 1103, so that the heat of the  glass
might  be nearly the same  as that of the blood; and, lastly, when
the vein  or  artery had been opened, the bottle was immediately
emptied and filled with blood—the temperature of which was ascer-
tained by the thermometer  in less than a quarter of a minute.  The
mixture was now instantly made, and by the same thermometer  the
highest temperature of the  mixture was discovered.
   The four following  trials were made on the blood of two lambs,
both about five months old.  The temperature of the air was 60°.
   Cold water 57-5.   Venous blood 100°. Mixture 80°; after one
minute 78-5.
   Water 58°.  Arterial  blood  103°.  Mixture 803;  after one  mi-
nute 79°.
   Water 58°.  Venous blood  101-5.  Mixture 79°;  after one  mi-
nute 78-25.
   Water 57°.  Arterial  blood 1065.   Mixture 81°; after one  mi-
nute 80°.
   The rate  of cooling was not noticed  after the first  minute had
elapsed, as the blood then generally began to coagulate.  The spe-
cific gravity was only ascertained in the  two last trials; that of the
venous blood was found to be  1050, and that of the arterial 1049;
and hence, allowing, as before, one degree of the cooling effect to
be produced by the receiver, the capacity of venous blood for heat
appears to be 852,  and that of arterial blood 839.
   It is evident that these trials admit of less accuracy than the pre-
ceding; and much more confidence, it appears to me, is due to  the 
               EXPERIMENTS ON ANIMAL HEAT.            283

third series of experiments, so that, if required, I should be inclined
to give  the numbers thence deduced as the greatest approximation
to the truth.

2. — On the comparative temperature of venous and arterial blood,
           and of different parts of the animal body.

   To endeavour to ascertain the comparative temperature of venous
and arterial  blood, I have made a  considerable number of experi-
ments;  some of which, on lambs, sheep, and oxen, it will be suffi-
cient for me in this place to  describe.  In each instance a long in-
cision was made through the  integuments, the jugular vein was laid
bare, and the exact seat of the carotid artery found.  The vein was
then opened, and  a  small, delicate thermometer introduced, and
thrust about an inch  up the vessel beyond the wounded part, and
as the bulb of the  instrument was small, the  flow of blood was not
stopped.  When the mercury  was stationary,  its height was marked.
The carotid artery next was  divided, and the thermometer was im-
mersed in the current of blood, and left there till it ceased to rise.
   The following are the results of five experiments made on lambs,
all of which were  about three months old.  The thermometer in the
shade stood at 65°.

        1.  Venous blood 102-5        Arterial blood 104°
        2.     -     -     104°           -    -     105°
        3.     -     -     104°           -    -     105°
        4.     -     -     103-5           -    -     105°
        5.     -     -     104°           -    -     105°
   The following  results were obtained from three experiments on
sheep, the exact age of which I could not ascertain.  The thermo-
meter in the shade was 60°.
        1. Venous blood 103 5        Arterial blood 1045
        2.     -     -     102-5          -    -    104°
        3.     -     -     103°          -    -     104°

   The experiments on oxen were only two in number.  The tem-
perature of the air was 64°.

        1.  Venous blood 100°        Arterial blood 101-5
        2.     -     -     100°           -    -     101°
  In both instances the oxen  were knocked down before the vessels
were opened; and as respiration had ceased  in consequence of the
injury of the brain and  spinal  cord,  no difference of colour,  of
course, was  perceptible between the blood from the jugular vein,
and that from the  carotid artery.
   These results, so different  from what might have been expected,
from the observations of Messrs. Coleman and Cooper, on the tem-
perature of the two sides of the heart, led me to repeat their experi-
ments.   The experiments in which I place most confidence, were 
281
daw's researches.
made on lambs about four months old, and to these I shall confine
myself at present.   In each  instance the animal was killed by the
division of the great vessels  of the neck: an opening was made im-
mediately into the thorax, and a very delicate thermometer was in-
troduced into the ventricles of the heart by means of a small inci-
sion.  The operation occupied so short a space of time, that in three
instances the right auricle had not ceased contracting.

       1.  Venous blood       -       -       -        104°
          Arterial     -                              105-5
          Rectum     -                              104°
          Right ventricle     -       -       •        1055
          Left        -       -       -       -       10?o
       2.  Rectum    -       -       -       -       10^o
          Right ventricle     -       -       -       105°
          Left        -                              106°
       3. Rectum    -                              105°„
          Right ventricle     -       -       -       105f>
          Left        -       -                      106-5
       4. Rectum    -       -       -       -       10»°o
          Right ventricle     -       -       -       106°
          Left        -       -                      107°

   I  cannot well  explain  the difference  which  exists between  the
results of the preceding experiments, and those of Messrs. Coleman
and Cooper, which are directly opposite,  excepting on the supposi-
tion of its  being  connected  with  the  mode in  which the animals
they experimented upon were* killed, viz. by asphyxia. In death by
asphyxia,  there is generally an accumulation of blood  in the right
ventricle, and in  many instances I  have observed, when the right
ventricle has been distended with blood, little difference of tempera-
ture between the two sides of the heart.1
   To describe all the experiments that I have made to ascertain
the  temperature  of  different parts of the animal  body, appears su-
perfluous, especially as the  comparative results were very similar.
It will be sufficient,' therefore, here to notice the observations made
on the human body, and on that of a lamb.
   That the thermometer might  be  equally applied to all  parts of
the surface, its bulb, in form nearly cylindrical, was fixed to a small
piece of cork, hollowed and  lined with fine wool, and thus half its
superficies was applied in  each  instance.  The observations were
made on the naked body at seven a. m. immediately after quitting

   1 In instances of death by asphyxia, theoretically considered,  it  might be
 expected, that the blood returning from the lungs to the left side of the heart
 not having been acted on by air, and there having been no production of heat,
 would necessarilv resemble venous blood, in temperature as well as in colour.
 In this point of view,  the results of the experiments referred to above may
 be considered confirmatory of the hypothesis in which the lungs are held to
 be the chief seat of the heating process. 
EXPERIMENTS ON ANIMAL HEAT.
285
bed.  The temperature of the  air of the room was 70°.   The fol-
lowing were the results obtained.

  At the central part of the'sole of the foot   -       -       90°
  Between the malleolus internus and  the  insertion of the
    tendo achillis, where the artery is felt    -       -       93°
  Over the middle of the tibia        -       -       -       91-5
  Over the middle of the calf        -       -       -       93°
  Over the popliteal artery at the bend of the knee   -       95°
  Over the femoral artery in the middle of the thigh        94°
  Over the middle of the rectus muscle      -       -       91°
  Over the great vessels  in the groin    t    -       -       96-5
  About  a quarter of an inch below the umbilicus   -       95°
  Over the sixth  rib, on the left side, where the heart is
    pulsating       -                                    94°
  Over the same place in the right   -              -       93°
  Under the axilla, the whole  surface of the bulb being ap-
    plied    ------       98°

  About  an hour had now elapsed from the commencement of the
experiment.  The thermometer again applied to the sole of the foot
rose no higher than 85°, five degrees less than at first.  A disagree-
able sensation of cold was experienced, and particularly in  those
parts not supplied with large vessels, and out of the course of the
great arteries.  The body remained unpleasantly chilly till  break-
fast had  been taken, and then a slight degree of pyrexia was per-
ceived; the heat of  surface being increased, the pulse quickened,
and the  mouth slightly parched.  After breakfast the thermometer
was applied to both  hypochondriac regions, and the left was  found
one degree  higher than the right.
  To ascertain the temperature of different parts of the surface be-
neath the integuments, the bulb of a thermometer was introduced
through small incisions about  half  an inch  between the skin and
subjacent parts of a lamb just dead.   The heat of the rectum was
first ascertained, as a means of marking the rate of cooling, and the
different  parts were  then tried in the following order:—

  Venous blood in the jugular vein      -       -       105-5
  Arterial blood from the carotid artery   -              107°
  Rectum  -       -             -      -      -       105o5
  Over the metatarsal bone       -      -       -        97°
  Over the tarsal  bone    -                             90°
  Over the knee joint     -                            102°
  About  the bead of the thigh     -      -      -       103°
  At the  groin     -----       104°

  Nearly a quarter of an hour  had been occupied in making these
observations,  and  the temperature of the rectum was now found
to be 105°.  The three great cavities were next opened in the order,
enumerated.
       £2__a                                    19 dav 
286                  DAVY'S RESEARCHES.

  Near the lower part of the liver -       -       -      106°
  The substance of the liver      -       -       -      106-5
  The substance  of the lung      -       -       -      106-5
  The left ventricle       ....      107°
  The right ventricle     -      -       -       -      106°
  The central substance of the brain      -       -      104°
  Rectum  ------      1045
  Surprised at the temperature of the brain being lower than that
of the rectum, I was led to repeat the experiment. It may be proper
to notice a few of the results, as it is a curious circumstance which
they confirm.  The four experiments I shall mention were made
on lambs.  As soon as the animal was dead, the cranium was per-
forated, and a delicate thermometer introduced into the central part
of the brain.

  1. Brain       -       104°    Rectum       -        104-75
  2. Brain       -       10575   Rectum       -        1055
  3. Brain       -       105-5    Rectum               106-5
  4. Posterior part of the brain 105-5. Anterior 103°. Rectum 106*5.

  The temperature of the air at the time was 68°.   Different parts
of the brain  were found  to vary considerably in temperature; the
anterior, as already noticed, being lower than the posterior, and the
superficial  than the deep-seated parts.

                 3.—Remarks and conclusions.

  That there is no material difference between venous and arterial
blood in respect to specific caloric, excepting what  arises from dif-
ference of specific gravity; that the temperature of arterial blood is
higher than that of venous; and the  temperature of the left  side of
the heart than that of the right; and lastly, that the temperature of
parts diminishes as the distance of parts from the heart increases—-
are the general results of the preceding experiments.
  Admitting the accuracy of these experiments,  and I think that
they will be found correct when repeated, what are their conse-
quences in a theoretical point of view?
  They are evidently in direct opposition to Dr. Crawford's hypo-
thesis, the essence of which is,  that  the capacity of arterial blood
for  heat is greater than that of venous, that there is no difference of
temperature between the two ventricles of the heart, and in fact that
the heat of all parts is nearly  the same.
  They are more agreeable to, and even support, the hypothesis of
Dr. Black, that animal heat is produced in the lungs, and distribut-
ed over the whole system by means of the arterial blood.
  Neither are they inconsistent with that hypothesis which consi-
ders the production of animal heat  as dependent on the energy of
the nervous system, and arising from all  the vital actions constantly
occurring. 
EXPERIMENTS ON ANIMAL HEAT.
287
  Besides the results of the preceding experiments, many  argu-
ments may be advanced in opposition to Dr. Crawford's hypothesis.
  As we never perceive a difference of capacity in bodies without
a difference of form  or composition; and as very slight differences
of the former result only from great changes of the latter, it might
be expected, a priori, as no difference excepting that of colour has
been detected between venous and arterial  blood, that their specific
caloric would  be very similar.   From  analogy, also, it might  have
been expected that the capacity of arterial  blood for heat would be
much less  than that of water,  as water appears  to exceed almost
every other fluid, and as the capacity appears  to diminish as the
inflammability  of compounds increases.   But  the  strongest  argu-
ments  against  this hypothesis are to  be derived from the experi-
ments of MM. Delaroche and Berard.1
  Dr. Black's hypothesis appears to me far more satisfactory than
Dr. Crawford's, and capable  of explaining a much greater number
of phenomena.
  The  last hypothesis which I mentioned, that which  refers  ani-
mal heat to vital action, has many facts in  its support.
  It may be said that the viscera of the thorax and abdomen are of
the highest temperature, because these parts  are, as it were, the
elaboratories of life; and that the heat of the arterial blood, and of
the parts best supplied with this fluid,  is greatest, because they lie
deepest, and  abound most in the principle of life or vital action.
This explanation was suggested to me by my brother, Sir H. Davy.
There are  some facts which I have observed  agreeable  to it, but
not more so than to the hypothesis of Dr. Black.
  I have found the stomach of the ox, the pyloric compartment, of
a higher temperature than the left ventricle itself; thus, when the
latter immediately after death was 103°, the former, full of  food.
was 104-5.  I  have also found the temperature of young animals,
in whom all the vital actions are  most energetic, higher than that
of animals  arrived at maturity.  I may mention here, in illustration
of this  statement, a  few observations  made on  infants, as I am not
acquainted with any yet published.   In one instance  I  found the
heat under the axilla of a child just born 985; after twelve  hours
99°; and after three days  the same, during  the whole  of which
time it appeared in perfect health.
   On five other children of the same age, similar observations were
made.   In  two instances of weak infants, the temperature, one hour
after birth, was found not to exceed 96°,  which is two degrees be-
low the standard  heat  of man in health;  but their respiration was

  ' On the  specific caloric of gases; from which it would appear that the
capacity of  carbonic acid  gas for heat is actually higher than that of atmo-
spheric air;  or in other words, thai the capacity  of the air expired is greater
than that of the air inspired; and consequently,  in this point of view, respi-
ration ought to be, as it was considered by the ancients, a cooling process.—
An. de Chim. lxxxv. 
288                  DAVY'S RESEARCrhW*.
still languid, and the next day the heat of the axilla had risen in
one to 98-5, and in the other to 99°.
  To conclude; as in each hypothesis examined,  difficulties are
found to exist from facts or the results of experiments of an un-
bending nature, we must at present either suspend theory altogether
and search for experimenta crucis, or adopt that hypothesis which
is conformable to the greater number of facts.   The first measure
is certainly most philosophical;  but to the latter we are naturally
most inclined;  and if I were questioned which view is preferable,
I should not hesitate in selecting Dr. Black's, which to me appears
both most simple and most satisfactory.
                            XXV.

OBSERVATIONS ON THE TEMPERATURE  OF  THE BRAIN
 COMPARED WITH SOME OTHER PARTS OF THE BODY.

  From the results  of some observations already detailed (p. 286),
it would  appear that the temperature of the  brain is not quite so
high as that of the  rectum,  in the instance of sheep, and that the
superficial portion of the brain is less warm than the deeply-seated.
  Professor Muller, in his Elements of Physiology,  has called in
question the accuracy of these observations,  and has rejected the
conclusion  to which they led.
  I have been induced, in consequence, to make recently some ad-
ditional trials on sheep, which I shall now relate.
1.—December 4th, 1837, air 44°.   The head of a two-years-
    old wether was cut off, immediately after death by the
    division of the great vessels of the neck.  A thermometer
    plunged into the base of the brain through the foramen
    magnum, rose to -       -       -              -       104°
  Forced in further, so as to be near the surface of the cere-
    brum,  it fell to   -       -       -       -      -       103°
  Now introduced into the rectum, it rose to  -      -       105°
2.—An ewe two years old;  thermometer in recto before be-
    ing killed        ---..       106°
  After decapitation, at base of brain -                     1055
                    near the surface        -       -       104°

3.—January 22, 1838; temperature of air 45°.  Immediately
    after decapitation, base  of brain -                     105°
  Rectum    ------       106°

4.—Before  decapitation, rectum      -       -       -       1035
    After decapitation, brain -                             103° 
TEMPERATURE OF THE BRAIN, ETC.
289
5—Before decapitation, rectum,      -       -      -       104°
    After       -       base of brain -       -      -       105°
                       near surface of cerebrum    -       103°
6.—Before     -       rectum      -       -      -       105°
    After       •-       base of brain -       -      -       105°
                       near surface of cerebrum    -       104°
7.—Before     -       rectum      -       -      -       104°
    After       -       base of brain -       -      -       105°
                       near surface of cerebrum     -       104°
8.—Rectum, before decapitation      -       -       -       105°
  Venous blood; the thermometer placed in jugular vein, the
     blood flowing freely     ...      -       103°
  In current of arterial  blood from carotid artery    -       1055
  In current of mixed blood,  from the great vessels of the
     neck divided in the ordinary manner     -       -       104°
  Brain at base, after decapitation    -        -       -       105°
  Near the  surface of cerebrum      -        -       -       104°
  Right ventricle (some blood  in it)  -       -       -       106°
  Left ventricle (empty)     -                            108°
  Liver       -      -       -      -        -              107°
  Crystalline  humour of the eye            -              102°
  The subjects of these observations, of the 22d January, were vir-
gin ewes  between  tvvo  and three  years old, with the exception of
No. 7, which was a wether.
  These  results are  generally confirmatory of the preceding, al-
though not  without exception in relation  to the base of the brain.
In another place, further on, I shall have occasion to  give some
additional observations on this point.
  That the  temperature of the surface of the brain at  least should
be uniformly  less than that of  the  rectum, appears to me what
might  be  expected  a priori, considering  the comparatively small
supply of blood to that part, and its exposure to cooling  influences.
In the instance of  birds,  the effect is  very strikingly exemplified;
thus, in the  turkey, on the 22d February, when the thermometer in
the open air was 34°, and  the room 46°,  in cloaca  it was 108°, in
the gizzard  109°, under the pectoral muscle 108°,  ai>d in the brain
90°.  The temperature in cloaca was  ascertained during life; the
other observations were made as soon  as  possible after death;  1st,
in the brain;   2d,  under  the pectoral  muscle; and lastly, in the
stomach.
  The effect of cooling influences on the  brain is shown m a very
decided  manner in the instance of the brain of  man  after death.
Excepting the  hands and  feet, the brain  appears to lose its  heat
more rapfdly than anv other part of the body.  Some precise obser-
vations on the  temperature of the brain after death,  compared with
that of other parts, warrant this remark:  they will be given m de-
tail in the sequel. 
290
DAVY'S RESEARCHES.
                           XXVI.

OBSERVATIONS  ON THE  TEMPERATURE  OF  MAN  AND
                     OTHER ANIMALS.1

  In this place I shall give the results of some  inquiries, which
chiefly between 1816  and 1820, I instituted on the temperature of
man and other animals,—a subject, in a  physiological, and in rela-
tion  to man, in a pathological point of  view, deserving, I believe,
of more minute attention than, to the best of my knowledge,  it had
then received.
  1st.  I shall describe the operations I have collected, to ascertain
the variation of temperature to which man  is liable, in passing from
the temperate into the  torrid zone; in descending from a cool
mountainous district into a hot low country ; and in inhabiting a
region where the diurnal vicissitudes of temperature are consider-
able.
  2dly. I shall give an account of the attempts  I have made to
ascertain the temperature of different races of men.
  3dly. I shall relate the results of  my experiments on the temper-
ature of different kinds of animals.
  And, I shall conclude, with  drawing such inferences  as  the
premises may seem to  warrant, and  with  making a few remarks on
animal heat, as a speculative question.


           1.— Of the variable  temperature of man.

  In a voyage from England to Ceylon, in the year 1816, I had an
opportunity of observing the effect of passing from one  zone to
another on the temperature of man.
  It was in winter, in the month of February, that we set sail from
England.  I commenced my observations in March, when we began
to experience the  tropical  heat; and on the 10th of the month,
when our ship was in latitude N. 9° 42', the weather fine, an  agree-
able breeze blowing, and when Fahrenheit's  thermometer, exactly
at noon, tinder an awning, where the passengers were assembled,
was 78°.   The gentlemen who were  so obliging as to allow me to
try their temperature, were all in good health, had breakfasted about
three hours before, had  taken  little exercise, and  though warm in
respect to sensation, they were not  disagreeably so, or sensibly per-
spiring.  In  each  instance  the  temperature  was  ascertained, by
placing a delicate, thermometor under the tongue, near its root, every
precaution  being  taken  to insure accuracy.   The following  were
found to be the temperatures of seven different gentlemen :—

  1 The observations of an earlier date  than 1S20, were first published in the
Edinburgh Philosophical Journal for January, 182G. 
TEMPERATURE OP MAN AND OTHER ANIMALS.      291
No.	Age.	Temp.
1	' 24	99°
2	28	99-5
3	25	98-75
4	17	99°
5	25	99°
6	20	98°
7	28	98-75
  On the 21st of March, in  latitude N. 0° 12', at noon, when the
sun was apparently vertical, the sky clear, a fresh  breeze blowing,
and the temperature  of the air 79-5.   I  repeated my observations
on the same gentlemen, enjoying good health as  before, and not
unpleasantly warm.
                    No.              Temp.
                     1               100°
                     2              99-5
                     3              98-5
                     4              99°
                     5              99°
                     6              99-5
                     7              99°
  On the  4th  of April, in latitude S. 23° 44', at between  twelve
o'clock and one in the afternoon, when the weather was very fine,
a gentle breeze blowing,  and the  temperature of the air 80°,  I re-
peated my observations on the preceding gentlemen,  and on four
more, and on  a little girl and  a boy.  The circuinstances  were
favourable, much the same  as those already described, arid the
individuals not unusually warm, though our sensation of heat was
rather more than was agreeable.
No.	Age.	Temp.
1		99-5
2	-	995
3	-	99-75
4	-	100°
5	-	99-5
6	-	100°
7	-	99-5
8	25	101°
9	40	99-75
10	43	99°
11	40	99-5
12	13	100°
13	4	99-5
  Lastly, oh the 5th of May, in latitude S. 35° 22, after having
been three weeks between this latitude and that of 30°, the weather
damp and cool, I  repeated my observations on a few of the same
gentlemen as before, and at noon when the temperature of the air
was 60°, and when we felt cool, almost cold. 
29.2
DAVY'S RESEARCHEa
                    No.             Temp.
                     1              98-5
                     3              98-25
                     5              98c
                     6              98-75
                     7              98-25
                     8              98°

   I have  had an opportunity of observing the effect of the sudden
change of temperature  on the  heat of man in descending from
Kandy to Trincomalie.
   The town of Kandy,  the capital of the interior of Ceylon,  is
situated in latitude N. 7° 17', and is elevated about 1,500 feet above
the level  of the sea.1  Trincomalie is situated  in  latitude 8° 34.'
Kandy is  surrounded by hills  and mountains, which  are covered
with wood, and frequently enveloped in clouds, and which abound
in springs and torrents.   Trincomalie is, at least, fifty miles distant
from any  mountains.  The intervening country is low, and though
wooded, very dry, being  subject to long-continued  drought.   One
of the consequences of these  peculiarities of situation is, that the
difference  of temperature, between the two places is very consider-
able.   The mean  annual temperature of  Kandy  is  about 735,
whilst that of Trincomalie is about 10 degrees higher; and in the
summer and autumn months the difference of temperature is from
12 to  15 degrees.
   On  the  15th of September, 1818, the day before I left Kandy for
Trincomalie, at eight o'clock in the morning, when the air was 69°,
I ascertained the temperature,  both under the tongue, and  in the
axilla, of six persons who were to accompany me,—one a servant,
the other five, part of a set of palankeen bearers, all natives of the
western coast of the island, all  in good health, cool,  and fasting.
No.	Age.	Temp, under	Temp, in
		Tongue.	Axilla.
1	35	98°	96°
2	20	98°	97°
3	40	99°	97°
4	35	98°	97-5
5	20	98°	97-5
6	24	98°	97°
  On the 3d of October, the day after our arrival at Trincomalie,
 t nine o'clock in the morning, when the temperature of the air was
 3°,  I repeated my observations on the same  men, who  had not
 reakfasted, were  in good health, and were not fatigued, having
 ome the last fourteen miles the day before by water.

  ' This elevation I ascertained by means of the barometer.  For the exact
latitude of Kandy I was indehted to G. Lusignan. Esq. 
TEMPERATURE OF MAN AND OTHER ANIMALS.      293
0.	Temp, under
	Tongue.
1	99°
2	99°
3	99°
4	99-75
5	99-5
6	99-5
                                           Temp, in
                                           Axilla.
                                           97°
                                           97-25
                                           97°
                                           99°
                                           99°
                                           9S°
  Again, on the 19th of October, the day before we set out on our
return from Kandy, at half-past eleven o'clock in the morning, when
the temperature of the  air was 82°, I renewed my observations on
the men, who, since the 3d of the month, had been leading an idle
life at Trincomalie;  they had breakfasted about  two hours before,
and none of them seemed to feel disagreeably warm.
             No.        Temp, under       Temp, in
                         Tongue.           Axilla.
              1           102°             99°
              2           101°             98-75
              3            98-5             97-5
              4            99°             98°
              5            99°             98°
              6           100°             99°
  On the 28th of October,  two days after our return to  Kandy, at
half-past eleven o'clock in the morning, I tried, for the last time, the
temperature of these men, with the exception of  two  who  were
absent.  They were in good health,  though hardly  recovered  from
the fatigue of  a rapid harassing journey, in  cool wet weather.
through a country on  the  eve of breaking out into rebellion, the
temperature of the air  at that time had suddenly  risen to 84° from
69°, which it was at seven a. m.
No.	Temp, under	Temp, in
	Tongue.	Axilla.
1	98-5	99°
2	98°	97°
3	98°	97-75
4	98°	97-5
  Kandy, from its peculiar situation, so near the equator, nearly in
the middle of a large island, elevated as it is above the level of  the
sea, and  surrounded by mountains, is subject to considerable vicis-
situdes of temperature in the course of the day, and, consequently,
is  a place well adapted for making observations on the effects of
these vicissitudes  on animal heat.   In fine weather the temperature
of the air, at sun-rise, is always below 70°,'and I have seen it as
low  as 55°; and  in the afternoon,  in such weather, it is  always
above 76°, and frequently as high as 83°.
  On the 18th of January, 1818, a favourable day, I tried the tem-
perature  of  an individual, at different  hours, and obtained  the
following results. 
294
DAVY'S RESEARCHES.
3our			Temp, i Air.	of
6	A.	M.	60-5	
9			66°	
1	P.	M.	78°	
4			79°	
6			71°	
11			69°	
                              Temp, under      Sensation.
                                Tongue.
                                 98°           Cool.
                                 97-5          Cold.
                                 98 5          Cool.
                                 98-5          Warm.
                                 99°            Warm.
                                 98°            Cool.
  It may be proper to mention how the individual passed the day.
He rose at six a. m.; read till nine a. m.; breakfasted temperately at
ten ;  was engaged in some chemical experiments from half-past ten
to two p. m.; from two  p. m. to five was employed chiefly  in read-
ing;  from five to six took gentle horse exercise;  dined sparingly
between  seven  and eight; drank  only one glass of  wine; and.
lastly, from nine to eleven was most of the time employed  in
writing.
  It  would be  tedious to give  other  instances  illustrative  of the
change of the temperature of man,—increasing with the tempera-
ture  of the air, and  falling as the atmosphere cools within certain
bounds.  The preceding instance, which has been confirmed  by
various experiments I have made, is the most  minute and  satisfac-
tory that I can bring forward. The subject is inconvenient to make
experiments on, and particularly for a  person whose time is not  his
own,  and, as a  professional man, has  seldom a day of leisure, the
whole of which  he can spend as he chooses.   Nor is it easy in this
inquiry to arrive at accurate results,—at  any thing more than  an
approximation to the truth,—in  consequence of the effects of a
number  of circumstances, and particularly  of  health, diet, and
exercise, which  cannot  be duly appreciated  until they have been
more minutely investigated.

        2.—Of the temperature of different races of men.
  At the Cape of Good Hope, at the Isle of France, and in Ceylon,
I have had opportunities of trying the temperature of several dif-
ferent races of men.
  At the Cape, in the winter of 1816, on the 24th of May, at noon,
when the temperature of the air was  about 60°, I prevailed, with
some difficulty, on five Hottentots, to allow me to put a thermometer
into   their  mouths, for  they were  afraid  of the  instrument; and,
when I saw them again, one blamed it for an illness with which he
was  seized soon  after submitting to the experiment.  I  found their
temperatures the following:—
                    No.        Temp, under
                                Tongue.
                      I           98°
                      2          96-5
                     3           96-5
                     4           97-75
                     5           99-5 
temperature of man and other animals.
295
  These Hottentots,  I  may remark, were  in  the  service of ou
government, employed  as artillery drivers.  They were in good
health, and resting at their barrack at the time.   Their ages varied
from twenty-five to forty, judging from their looks, for of  the years
they had  lived,  they themselves had  taken  no account.  Those
whose temperatures were lowest, I may mention, were most meagre
and wretched in appearance ; and, indeed, with the exception  of
No. 5, who was  pretty robust, they were all of a very spare habit
of body.
  At the same time I ascertained  the temperature under the tongue
of three  English artillerymen, in good health  and cool,  who had
served ten years at the Cape, and who were giants'in appearance
when compared with the poor Hottentots.   All three were nearly of
the same age, between thirty and  forty.  The temperature of one of
them was 995, of the other two 99°.
  At the Isle of France, at Port Louis, in June, one of the coolest
months there, when the thermometer was at 74°, I tried the temper-
ature  of three  negroes,  two  natives of Madagascar, and one  of
Mozambique.  Of  these the temperature of the two first  was 98°,
and of the last 99°.  They were house  slaves,  between  eighteen
and twenty years old, well clothed and fed,  and in good health.
  The temperature of an English gentleman, who had been in the
island several years, and of another just arrived, was ascertained at
the same time.  The former was  98-25, the latter 985.
  In the island of Ceylon I commenced my  observations, at Co-
lombo.  Colombo, in latitude N. 6°  56', is situated on the sea-shore,
at the distance of about thirty miles from the boundary mountains
of the Kandian country.  Its temperature is remarkably equal;  in
the hottest day seldom exceeding 84°, and in the coolest night rarely
falling to 70°.   The greater part  of  the  year, the  range of the
thermometer is from 77° to 73°, and the mean annual temperature
is about 79°.
  On the  14th of September, between six and seven o'clock in the
morning, in  a village about a mile from Colombo, when the air was
about 79°, I tried the temperature  of six Singalese, of different sexes
and ages, all cool and in good health and fasting.
            No.      Sex.     Age.     Temp, under
                                        Tongue.
            I       F      50          101°
            2         -         4           101-5
            3        M      29          101°
            4         -        8           101-5
            5         -      40          100°
            6         -       25          100°
  These people  lived in the midst  of a cocoa-nut  grove,  and, like
the Sino-alese in  general, led an easy and indolent life, according to
our notions of activity, and  subsisted chiefly on rice, fruit, and
vegetables.
  The following morning, about  the same  time, and when the tern- 
296
davy's researches.
perafnre of the air was the same, I tried the temperature of four
Albmoes.
             No.      Sex.      Age.     Temp, under
                                           Tongue.
             I        F         5         101-5
             2        -         12         101-5
             3                  23         101-75
             4       M        27         101°
  These Albinoeswere the children of black parents; the two first
were sisters, and they had brothers and sisters of the colour of their
parents.   They were all well made, active, and in good health.1
  On the 12th of October, between six and seven o'clock in  the
morning, while the air  was  between 77° and 79°, I tried  the tem-
perature of a number  of children, at the eirphan school, in  the
neighborhood of Colombo, some  half caste, of Singalese mothers
by English soldiers, others white of English parents.
half  caste.
No.      Sex.

 1        F
 2
 3
 4        M
 5
 6
 7
1        F
2
3
4
5        M
Age.	Temp under	Temp, in
	Tongue.	Axilla.
12	100-5	98-5
14	101°	
17	100°	
14	102c	100°
10	101-5	99-5
14	100°	99°
10	100°	99°
WHITE	children.	
9	101°	99-5
6	101°	98°
9	101°	98-5
12	102°	100°
8	102°	100°
   These girls and boys at the excellent institutions to which they
belonged, were well clothed and fed, as well as usefully educated.
At the time, they were cool, and in good health, and had not break-
fasted.
   In  the  Kandian country, the climate of which  in  general  verv
much resembles that of its capital, I have  at different times ascer-

  1 The young Albino, twelve years of age, in  England, and  certainly in
IMorway, would not be considered peculiar;  for her eyes were light blue and
not particularly weak, her hair of  the colour that usually accompanies such
eyes, and her complexion fresh and rather rosy.   She had considerable pre-
tensions to beauty, and was not without adn>irers amongst her countrymen
It is easy to conceive that an accidental variety of the kind mi^bt propagate
and that the vvh.te  race of mankind is sprung from such an accidental variety!
Ihe Hindus  are of this opinion, and there is a  tradition or story amon^t
tnem in which this origin is assigned us.                     '       °" 
         ^mriitiAiuKii UK MAN AND OTHER AVIMALS.      297

tamed  the temperature  of Kandians,  Vaidas,  Caffres, Ma'ays.
Sepoys, and Englishmen.
  In Saffragam, a Kandian province, on the 17th of April,  1817,
when the temperature of the air was 72° at seven o'clock in the
morning,  ] tried  the  temperature  of an old  Kandian, almost a
century old, and  of a boy  about twelve  years old, both cool, but
not cold :
     Old  man.  Temp, under tongue 95°.   In axilla  93°.
     Boy.       Temp, under tongue 98°.   In axilla  96-5.
  In Dombera, another Kandian  province, on the 5th of September,
at one  o'clock in  the  afternoon, when the  temperature of the  air
was  76°,  I tried the temperature of three Kandians,  stout men in
the prime of life.
       No-       Age.       Temp, under       Temp,  in
                               Tongue.           Axilla.
       1        24             99°            98°
       2        30             99°            98°
       3        33              98°            97-5

  On the  7th  of  the  same  month, and in the same  mountainous
district, I tried the temrerature of three Kandian priests:
           No.            Age.           Temp, under
                                          Tongue.
            1              15                99°
            2              16                99°
            3              30                98°
  At Kandy on the 7th of February, 1S18,1 tried the temperature
of two  young priests  at five o'clock in the evening, when  the air
was  75°.
Jo.	Age.	Temp, under Tongue.
1	15	99°
2	16	98-5
  In the same year, at Kandy, on the 29th of October, I found the
temperature of a  very  old  priest, (about a century old) in the
axilla 98-5.*
  The higher castes of Kandians, I may remark, to which the few
subjects of my experiments belonged, are, for Indians, not only well
formed, but stout and muscular  men.  Their food consists chiefly
of rice and farinaceous fruits, which they use highly seasoned, and
of milk, fowls and game.   Their drink is principally water, the use
of intoxicating liquors  being contrary  to their religion.  Their
ordinary dress is a handkerchief about the head, and a large cloth
folded about the loins, and reaching below the knee,  with the addi-

  1 Advanced old age in this person was well marked.  He complained of all
his senses having become impaired, excepting that of taste; he preferred
animal food to vegetable, and the most savory meats, and ate often. He said
he slept little, and dreamed much; and that his dreams were about the dead. 
298
DAVY'S RESEARCHES.
 tion, in cold weather, of another cloth which  is thrown  over the
 shoulders, and  wrapped  about  the  body.  Their  dwellings are
 comfortable cottages.  Their occupations  chiefly agricultural pur-
 suits.   As they are  stouter than the  lowlanders, so  are they more
 active, and as it appears to me, more acute and intelligent.
   All the priests whose temperatures I tried, I should observe, were
 priests of Boodho,  who dress and  live in a manner peculiar to
"themselves.  Their dress consists of yellow robes,  which, thrown
 over the left  shoulder, and girded about the loins, fall in graceful
 drapery to the feet, covering every part with the exception  of the
 neck, right arm and shoulder.   They wear nothing on their head,
 which, as well as the eye-brows  and the  hairy part of the face, is
 carefully shaved and kept bare.  They profess celibacy, lead an indo-
 lent, quiet life, devoted chiefly to religious duties and literary pursuits,
 (such as they are) and subsist almost entirely on vegetable food.
   At Kandy on the 12th of September.  1818,1  had  an opportunity
 which rarely  occurs,  of ascertaining  the temperature  of  three
 Vaidas.  The  temperature of the air at the time was about 78°.

          No.        Age.     Temp, under     Temp, in
                               Tongue.         Axilla.
           1           60         98°            95°
           2          30         98°            96°
           3          35         98-5           96°

   The ages of these men I was obliged to guess, for they themselves
 could not inform me.  They belonged to a large  party who had
 come to Kandy, with a tribute of dried  deer's flesh and wild honey.
 They were quite naked with the exception of the partes naturales,
 which were concealed by a scrap of cloth.  The hair of their head
 and beard was long and matted,  and  had never been cut or combed.
 Their eyes were lively, wild and restless.  They were well  made
 and muscular, but of a spare habit, and in person  they chiefly dif-
 fered  from the Kandians in the slightness of their limbs, the wild-
 ness ot their looks, and  their savage appearance.   According to
 their own account of themselves, they came from the  neighbourhood
 of the Lake of Bintenne, where they subsisted on game  which
 they killed in  the chase, some  roots, and wild fruits, and  a little
 grain  of their own growing.    They  were profoundly  ignorant,
 could  not  count above  five, were  hardly  acquainted  with the
 rudiments of any art,  and though they feared demons as they did
 wild beasts, they had no knowledge whatever of a Supreme  benefi-
 cent Being, and not the slightest notion  of any state of existence
 after the  present.  Yet, these men considered themselves civilized
 in comparison with the wilder  tribes of  Vaidas, who never leave
 their native forests, and who attack with their sylvan weapons, the
 bow and  arrow, every intruder into their haunts, and whom  I have
 heard  Kandians of a bordering  province  describe as living  almost
 entirely on raw animal food, as going quite naked, as  having no 
TEMPERATURE OF MAN AND OTHER ANIMALS.
299
superstition, and in fact as being in a state very little removed from
that of brutes.1
  On the 17th of December, 1818, when the air was 74°, I tried
the temperature of five African negroes, servants in the military
hospital at Kandy.
No.	Age.	Temp, under	Temp, in
		Tongue.	Axilla.
1	23	98-5	98°
2	35	98-5	98°
3	25	99°	98°
4	34	99-5	98°
5	28	, 99-5	98°
  The ages of these men I conjectured from their looks.  Most of
them  were from  Goa.  They  were of African parents, had not
degenerated, and like African negroes in general, they were  stout
and muscular.  Nos. 4 and 5,1 should remark, whose temperatures
exceeded the rest, were in a state of gentle perspiration produced
by slight exercise.
  On  the 18th of March, 1818, at  noon,  air 81°, at  Kandy, I tried
the temperature of four Malays:—
No.	Age.	Temp, under	Temp, in
		Tongue.	Axilla.
1	17	98-5	98-5
2	35	99-5	97-5
3	22	99°	98°
4	18	98-5	97-5
  These  men  were free Malays, in good circumstances.  Three
were natives of Colombo, and one of Cochin.   They were active,
stout, well made, and very muscular men, all of Javanese parents.
They were dressed not unlike Kandians, but with  less cloth about
their loins, and a eloth most commonly over their shoulders.
  On the 18th of May, in the afternoon,  when the temperature of
the air at Kandy was 80°, I  tried the  temperature of six Sepoys,
belonging to a battalion  of Madras native infantry :
No.	Age.	Temp, under	Temp, in
		Tongue.	Axilla.
1	25	98.5	98°
2	19	99°	96°
3	26	9S-5	97°
4	22	98°	95°
5	38	100°	97°
6	20	98°	97°
  1 The influence of habitual exercise in strengthening any particular set of
muscles, is remarkably illustrated in the Vaida.  I saw one, a young man of
a diminutive and spare form, with slender arms and shoulders, use with the
greatest ease a bow he had been accustomed to, which one of the strongest
of our soldiers could hardly bend. 
300
davy's researches.
  Most of these Sepoys were natives of Madras, or of the adjoining
country.   They were tall, thin, and rather feeble men.   They had
been in Ceylon about three months.
  On the 20th of the same month at between eight and nine o'clock
in the  morning, when the temperature of the  air in Kandy  was
about 75°, I tried the temperature of several English soldiers.
No.	Age.	Years in	Temp, under
		India.	Tongue.
1	24	Oi	98-75
2	99	2	98-5
3	27	2*	99°
4	36	16	99-25
5	28	4	99°
6	34	Oh	99-5
7	25	1	100°
8	23	Oh	101°
9	25	25	99°
10	23	Oh	98°
  The four first were in perfect health ;  the remaining six were in
different stages of convalescence from  intermittent fever.   They
were all cool, and had not breakfasted.

     3.— Of the temperature of different kinds of Animals.

  My observations on the temperature  of different kinds "of ani-
mals have  been  made at intervals, as  leisure  and  opportunity
permitted, in  England, Ceylon, and during a  voyage  to the latter
island.   Though pretty numerous, they are far from complete; the
completion  of the  inquiry demands the co-operation of  many
observers.

          Is/, Of the temperature of the Mammalia.

  I may premise that in  my experiments on the mammalia, with a
few exceptions which will be particularly noticed, the temperature
of each animal was ascertained by introducing a thermometer into
the  rectum ; and I  may extend the remark to the experiments on
birds ;  and  I  may further premise, that,  when the contrary  is not
noticed, the subject of the experiments appeared to be healthy.
  Monkey  {Simla Aygula).—At  Colombo,  on the 30th of May,
air 86°, the  temperature of this animal full grown, in the axilla was
104£°; rectum, only 103*°.
  At Amanapoora, in the Kandian country, on the 1st of June, air
73°, the temperature of another full grown  monkey of the same
kind, in the axilla, was 101.°
  Pangolin  {Manis pentadactyla).—At Colombo on the 4th of
November, air 80°, the temperature of a young pangolin apparently
sickly,  was  only 90°. 
         TEMPERATURE OF MAN  AND OTHER ANIMALS.      301

  Bat.—In the neighbourhood of Colombo, on the 27th of Septem-
ber, air 82°, the temperature of one bat was 100°, and that of another
101°.   The  instant  the animals were killed, the thermometer was
introduced into the cavity of the abdomen.  The species resemble
the Vcspertilio peruviana of Linnaeus, but was much smaller.
   V. vampirus.—At Colombo, on the  15th of October, air 70°, the
temperature  of this  animal, ascertained in  the same  way as the
preceding, was 100°.
  Squirrel {Sciurus getulus ?)—At Colombo, on  the 19th of Oc-
tober, air 81° the temperature of this animal was 102°.
  At the same place, on the 29th of September, air 84°, the temper-
ature of a large black squirrel was 106°, in  the thick fur of the
groin.
  Common  rat.—At Colombo, on the 8th  of February, air 80°,
the temperature of this animal was 102°.
   Guinea-pig.—Female  half grown,  102°;   male  of about the
same age 101°.1  Chatham, 5th  May.
   Common  hare.—At Colombo,  on  16th  of June, air 80°, the
temperature of this animal in the groin was 100°.
   Ichneumon.—At Colombo, on the 4th of November, air 81°, the
temperature of this  animal was 103°.
   Jungle-cat—At Colombo, on the 26th of February, air 80°, the
temperature of a young animal of this species of Vivera was 99°.
   Cur-dog.—At Kandy, on  the 29th of May, the temperature of
an animal of this  kind was 1025, and of  another  103-5, both
nearly full grown.   The temperature of a bull-dog, in  England, on
the 27th December, was 102°.
   Jackall.—M Colombo, on the 9th of April, air 84°, the  temper-
 ature of two young jackalls was  101°.
   Common cat.—In  London, on the 5th September, air  60°, the
 temperature of a full grown cat was 101°, and in Kandy, on the 7th
 April, air 79°, the temperature of another was 102°.
   Felix pardus.—At Colombo, on the 10th of February,  air 81°,
 the temperature of a young fierce animal of this  kind, about four
 months old, was 102°.
   Horse.—At Kandy, on the 14th of June, air 80°, the temperature
 of a horse,  of Arab descent, was 995.
   Sheep.—In Scotland, I have observed the  temperature of sheep
 in summer, to vary from 101° to  104°; at the Cape o f Good Hope,
 in winter, air 67°, in six different instances I found the temperature
 of the  African sheep  to vary from 103° to 104°, and in Ceylon, in
 the neighbourhood of Colombo, air  78°, the temperature of one
 sheep was 104° and that of another 105°.
    Goat.—At MeiuntLavinia, near Colombo, on the 27th December,
 air 78°, the temperature of a full grown castrated  goat was 103°,
 that of a female, about nine months old, 104°.
    Ox,__At Edinburgh, in  summer,  the blood of an ox,  flowing
           ' In abdomen, under liver, 103°.
12__b                                   20 dav 
302
DAVY'S RESEARCHES.
from the carotids, was 100°; in Kandy, on the 28th of May, air
80°,  the  temperature of  an ox, ascertained  in the  same  way,
was  102°.
  Elk.—At Mount Lavinia, on ihe 27th of December, air 78°, the
temperature of a female elk was 103°.
  Hog.—At Hanwille, in  Doombera, on the 26th of November, air
75°, the temperature of the blood of a wild hog, flowing from the
carotids,  was 105°; at Mount Lavinia, air 80°, the temperature of
two young domestic pigs was the same.
  Elephant.—At Colombo, on  ttie 22d of September, air 80°, the
temperature of a full grown, healthy elephant  was 99 5.  It was
ascertained  by placing a thermometer in  a deep abscess in the
back.1
  Porpoise.—In  latitude N. 8°  23', on the 11th  of March, air 72°
sea 74-75, the temperature of a porpoise was 100°.   The  animal
was drawn into the ship alive.  The instant it was killed 1 tried its
temperature, by introducing a thermometer into  the substance of its
liver.

               2.— Of the temperature of birds.

  Falcon {Falco milvusl).—At Colombo, on the 24th of August,
air 77-5,  the temperature of this bird was 99°;  it had been shot a
few hours, and its legs were broken.
  Screech-owl.—In London, in the autumn, air 60°, the temper-
ature of this bird was 106°.
  Jackdaw.—At Attapittia, in the Kandian country, on  the 2d of
June, air 85°, the temperature of this bird, the instant it was  shot,
was 107-75.
  Common thrush.—In London, in the autumn, air 60°, the tem-
perature of this bird was 109°.
  Common sparrow.—At Gompala,  in the Kandian country, on
the 3d of June, air 80°, the temperature of this bird, the instant it
was shot, was 108°.
  Common pigeon.—In  London,  in the  autumn,  air 60°, the
temperature of this bird, confined in a cage,  was 108°.  At Mount
Lavinia,  on the 27th of December, air 78°, the temperature of two
young pigeons, two weeks old, was 1095 ;  and of two, three weeks
old, 109°.

  1 It was necessary to lay open the abscess to effect a cure. The opera-
tion was performed with an amputating knife; a deep incision,  as was
requisite, was made;  the animal was kneeling down for the convenience of
the operator—not tied—his keeper at his head. He did not flinch, but rather
inclined towards the surgeon, uttering a low suppressed groan.  He seemed
conscious, that what was doing was  intended for his good ; no human being,
similarly situated, could have behaved better. I think it right thus torecord
this instance, which I witnessed myself, of this animal's  (may I call it)
reflecting power and conduct, which it is difficult to consider otherwise than
rational.  And so  confident were the natives that he would  behave as he
did, that they never thought of tying him. 
TEMPERATURE OF MAN AND OTHER ANIMALS.      303
  Jungle-fowl—In  Ceylon,  near  Tangalle, on the  20th of July,
air 78°,jhe temperature of one jungle-hen, the instant it was shot,
was 107-5 ; and in the afternoon of the same day, air 83°, the tem-
perature of another was- 108-5.  The jungle-fowl  of  Ceylon,  I
may remark, more resembles the  English pheasant than the barn-
deior fowl.
   Common fowl.— At Edinburgh,  in the winter, air 40°,  the
temperature of a full grown hen was 1085.   At Mount Lavinia, in
December, air 78°, the temperature of two hens was 1.10° (the one,
half, the  other full grown);  that of a  hen  that had been  sitting
on her eggs three weeks 108°; that of an old cock 110°, and of two
chickens, two months old, was 111°.
  Guinea-fowl.—At Mount Lavinia. at the same time, the temper-
ature of a full grown guinea-hen was 110°.
  Turkey.—At the  same time, the temperature of  a full  grown
turkey-cock was 109°, that  of two more of the same age  108-5;
that of a full grown hen 108°; and that of a young cock two
months old, was 109 5.
  Procellari aiquinoctialis.—In latitude N. 2° 3', on the  8th of
August, air 79°, sea  81-5, the temperature of this  bird was 103-5,
and that of another 1055.
  P. Capensis.—ln latitude S. 34° l',on the 11th of May, air 59°,
sea 60° the temperature of two birds of this kind was 1055.
  At Mount Lavinia,on the 27th December, when the temperature
of the air was about 77°, the following observations were made  on
some of the inmates of the governor's poultry-court.
  Hen, half grown     -           -           -       110°
  Cock, ditto          -           -           -       111°
  Chicken, two months old         -           -       111°
  Another, of the same age         -           -       111°
  Hen, full grown, laying eggs      -           -       110°
  Hen, that had  been sitting on her  eggs  about three
    weeks            -           -           -       108°
  An old Malay cock   :           -           -       110°
  A cock, ten weeks old, sickly     -          ' -       108°
  Guinea-fowl, full grown          -           -       H0°
  Turkey-cock, full grown         -           -       108°
  Another,      do.   -           -           -       108°
  Another,      do.   -           -           -       109°
  Turkey-hen         -           -           -       108°
  A young turkey, two months old  -           -       109-5
  A full grown goose   -           -           -       107°
  Another            -           -           -       107°
  A  o-oose, that had been  sitting on her eggs nearly a
    month            -           -           -       106°
  A young duck, twenty days old   -           -       110°
  Another, five weeks old         -           -       110°
  Another, two months old        -           -       110°
  Another, of the same age         -           -       110° 
304
davy's researches.
  Two full grown ducks           -           -       110°
  A full grown drake   -           -           -       110°
  Another, but younger           -           -       111°
  A full grown teal, taken young, tamed        -       109-5
  Another             -           -           -       108°
    Young  snipe.—Colombo,  Ceylon,  September, air  83°, half
fledged; thermometer, between thigh and body, 98°.
  Another, less strong, 97°.  It ate a few worms, seemed distressed,
and lived only about 24 hours after.
  Common hen.—Colombo, November, in recto, 109°; after having
been frightened by a cobra capello, not bitten, 111°.
  At Trincomalie, in the same year, on the 9th of October, when
the  temperature of the  air was 84°, that of five fowls, nearly full
grown, was 107°.  They had  been in confinement  in  a small
hamper two or three days.   On the  18th October, in the same place,
when the  air was 82°,  found the temperature of two full grown
hens, not in confinement, also 107°.
  Plover.—Near Minery, in Ceylon, in September, the temperature
of a plover, just killed, was 105°.
  Common goose.—At Mount Lavinia, in  December, air 78°, the
temperature of two full  grown geese was 107.
  Common duck.—At the same time and place, the  temperature
of a full grown drake, of two full grown ducks, and of four duck-
lings, from  three  to five weeks old, was 110°, and that of a young
drake, full grown 111°.
  Peacock.—At Kornegalle, in July, air 83°, the  temperature of a
full  grown wild peacock was 105°;  of a young pea-hen 10S°.

             Of the temperature of the amphibia.

  Testudo rnydas.—\n latitude N. 2° 27',  on  the 19th of March,
air 79 5, the temperature of a large turtle, caught  a  week before  at
Ascension, was 84°, in recto.  Again, in latitude  S. 2° 29', on the
23d of March, air 80°, the temperature of the blood of the animal
flowing from  the great vessels of the  neck  was 88 5.  The turtle
was sickly, and probably this heat was morbid.  At Colombo, on
the  4th of May, air  86°, the temperature  of the blood of a turtle
that had been caught the day before was 85°.
  T geometrica.—At Cape Town,  in May. air 61°, the tempera-
ture e>f this animal was 62-5.   At Colombo, on the 3d of March,
the  temperature of a larger specimen was 87°, air 80°.
  Rana  ventricosa.—At Kandy, on the 31st of May, air 80°. the
temperature of two frogs of this kind, just  brought from a damp
shaded place,  was 77°.
  Common male frog,  in recto, 64°, immersed in water of 60°,  in
a small pond,  near Edinburgh, June 23, air  60°.
  Another frog, kept in  shade out of water a quarter of an hour in
recto. 63°, air  62°.  A decapitated frog of about the same size, kept
there the same time, 62°, in recto. 
         TEMPERATURE OF MAN AND OTHER ANIMALS.      305

  A frog, just after it was taken, (it had  hopped some way) after
basking  on wet turf, exposed  to the  sun,  occasionally obscured
by light clouds, in recto, 70°;  water of pond 61°.  The same  frog-
placed in the shade, where the thermometer was 62°, after aquarter
of an hour, from 70°  fell  to 63°; and decapitated, and left another
quarter of an hour, the  air continuing  at 62°, it fell to 60°, in recto.
  Another  frog, in a  state of rest, taken from a  shady place, sur-
rounded with  damp plants, in recto, 58°; the thermometer  in the
place from  whence it  was  taken  was also 58°.
  Another  frog, taken from the turf close to the pond, where it had
been  a short time basking, was 68°,  in recto;  the  thermometer
exposed in  the  same place amongst the grass was 65°.'
  Iguana.—At Colombo, 4th  September, air 82°, the temperature
of this animal was 82-5.
  Serpents.—At  Colombo, on the 27th of August,  air 81-5, the
temperature of an  elegant green snake, a  species of coluber, was
88-5, in oesophago.   At the same place, on  the 24th of August, air
825, the temperature of a small species of brown  snake, another
species of  coluber, was 815 in abdomine.  On the 23d of Sep-
tember, air  83°, the temperature of different species of brown snakes
also belonging to the  genus coluber was 90°, in cesophago.
               4. — Of the temperature of fishes.
  Shark.—In  latitude  N. S° 23', on the llth of March, 1816, air
71-75, sea  7475,  the temperature of a  large female shark,  just
taken, and  still alive,  was 77° in the deep muscles near the tail.
  Bonito.—In latitude  S. 1° 14', on the 29th of July, 1816, air 78°,
sea 80 5, the temperature  of the heart  of this fish, which lies very
near  the surface,  was  82°, and of the  deep-seated  muscles  99°.
These observations were made immediately after the fish was taken.
I may remark,  that the  heart and gills of this fish were unusually
large, and the latter of a dark red colour; further, that the muscles
in general, which  were very thick and  powerful, were red like those
of a porpoise, and that  the bonito appears to be as fond of raising
its head above  the water as the  porpoise itself: with these circum-
stances, probably its extraordinary temperature is connected.
  Common trout.—Near Edinburgh, in  the spring,  river 56°, the
temperature of this fish was 58°.
  Common trout, Mount  Cenis,2  in  a tank supplied with  water
flowing perennially from  snow, 1  found at 40°,  at three different
seasons of  the  year, temperature of fish 42°, in excellent condition.
  1  These frogs were all  males (no females were found in the pond), they
were full grown, and active; their testes  large.  In their  stomachs  were
caterpillars and insects,  and in one, two small hard stones.
  My observations  seemed to show,.that their temperature is variable, as
mi^ht be expected, according to the activity of their respiration ; and that,
occasionally, it is at least three degrees higher than the moist body would
be similarly circumstanced, independent of respiration.
  2 The trout at Mount Cenis, in a lake about 5000 feet above the level of 
306                  DAVY'S RESEARCHES.

   Trout, about half a pound weight, in ccsophago, 58°;  water of
river,  flowing  from  Loch  Katrine  into Loch  Vanacher, 56°,
July 5th.
   Eel {M.  laterostris),  Chatham,  May 14.  Temperature in air
51°, in  cesophago,  51°.  The eel had  been out of water several
hours.
   Flying fish.—In latitude N. 6° 57', on  the 12th of March, air
77° sea 77-5, the temperature of this fish, the  instant it fell on the
deck, was 78°.

             5.— Of  the temperature of mollusca.

   Common oyster.—On a rock about a quarter of a mile from the
shore, off Mount Lavinia,  where the water was about  a foot deep,
in December, the temperature of the common oyster was the same
as that of the sea, viz.  82°.
   Snail.— At Kandy, on the 11th of June,  the temperature of one
of a large species of snail that abounds  in the woods of Ceylon,
was 76°, and that of another, 763°, after having been confined eight
hours in a box, the temperature of which  was 76|°.

             6.— Of the temperature  of Crustacea.

   Cray-fish.—At Colombo, on the 16th of September, air 80°, the
temperature of  a  large  cray-fish that had been taken out of the sea
two or three hours  before, was 79°.
   Crab.—In the neighbourhood of Kandy,  on the  25th of March,
the temperature of a small crab, of a species which is common  in
the mountain torrents  of the interior, was the same as that of the
water in which it lived, viz. 72°.

               7.— Of the temperature of  insects.

   Scarabceus pilularius.—At Kandy, on the 30th of June, ail 76°,
the temperature of a beetle of this kind was 77°.
   Glow-worm.—At Kandy, on the same  day, in the morning, air
73°, the temperature of a large species of glow-worm was 740.1

the sea, is  always in season, which perhaps may be owing in part to the
temperature of the deep water being probably always about 40°. In accord-
ance with this, I am informed that the same is the  case with the char
inhabiting the deep waters of Coniston Lake, in Lancashire,  and also it is
said, of the trout of the Sorgue, at Vaucluse, in Provence—a  stream which
bursts out at the base of a  mountain precipice, and the temperature of which
probably  varies very little throughout the year.  On  the 10th of April, 1830,
I found it 54° at its source.
  1 The light of the glowworm does not appear to be combined with beat;
and the same remark applies to the light of the fire-fly,  and, I believe of
other luminous animals.   On the  luminous  matter of the fire-fly, I made
many experiments in 1816, at Colombo. I may mention here a few of the
results.   It is viscid, neither acid nor alkaline, has a  strong  and peculiar 
TEMPERATURE OF MAN  AND OTHER ANIMALS.
307
  Blatta orientalis.—At  Kandy, on the 28th of the same month,
air 83°, the temperature of two cockroaches was 75°; and on the
29th, found  the temperature of two  more the  same, when  the air
was 74°.
   Gryllus hcematopus?—At the Cape of Good Hope, in May, air
62°, the temperature of two locusts was 72-5.
  Apis ichneumonia ?—At Kandy, on the 26th of June, air 75°
the temperature of a wasp was 75°.
   Papillio Agamemnon.—At Kandy, on the  2d July, air 78°, the
temperature of this butterfly, in abdomine, 80°, and in thorace, 81-5.
   A large butterfly not unlike the preceding, in England, Nov. 4th,
temperature of room 74°, thermometer  placed between its wings and
abdomen rose to 81°.
   Scorpio afer.—At Kandy, on the 20th May, at noon, air 79°, the
temperature of a large scorpion was 77-5.1
   Julus.—At Kandy,  on  the 18th  of June, at noon, air 80°, the


 odour; affords  no  ammonia when decomposed by heat; it  yields  a  brown
 empyreumatic oil.   It continues to shine after it has been detached from the
 animal; in one instance, it shone after fourteen hours.  The separation of
 the luminous pait does not immediately prove fatal to the fly ; I have known
 one live twelve, and even eighteen  hours  after.  The luminous matter ap-
 pears to be a  secretion independent of the influence of external light: I kept
 the flies in darkness many days, supplying them with food, and they contin-
 ued to shine.   The life of the animal is more easily extinguished than  its
 luminous property; thus, when plunged  into  carbonic acid, the luminous
 matter continued shining, after the animal was motionless ;  but its duration
 was shot: the same was observed in hydrogen gas.  The luminous  matter
 detached, shines for a brief time in water,  and even in water deprived ot air,
 by long boiling, in alcohol, in aqua ammonise, nitric acid, nitrous acid vapour,
 ammoniacal  vapour, in carbonic acid, and  in  hydrogen.  In the nitric acid,
 and the aqua ammonia;, and  their vapours, and in alcohol, the brightness ol
 the light was  increased  on immersion ; but it was  of only a few seconds
 duration.  In  carbonic acid and hydrogen, it shone longer isolated than when
 forming a part of the insect. Sixteen fire-flies, confined  in  a  small vial
 afforded sufficient  light to enable me with  perfect ease to see the figures on
 my watch.   The gland or organ by which the luminous matter is secreted,
 has a tubular  arrangement,  somewhat perhaps analogous  to the  electrical
 orsrans of the gymnotus and  torpedo.            _    ,
   * The popular idea of the  poison of the scorpion, is  I believe, far from
 correct.  From the  few  experiments I  have  made with  this animal, I  am
 induced to infer that its sting is less severe than that of our honey bee.  A
 fowl wounded by a large  scorpion in the breast, appeared to  suffer little or no
 inconvenience; the punctured part was only very slightly red and just per-
 ceptibly swollen.   I have applied the peculiar fluid  twice to the tongue ; in
 one  instance,  it  occasioned a slightly acrid  sensation; and in themother,
 besides the sensation, it blistered the part slightly ; the effect wa= very trans-
 itorv : in a few hours it had ceased.                        ...
   Even in  Ceylon, the poetical idea, of the  enraged scorpion stinging
 himself to death, is entertained ; but I never witnessed such a result.  On
 on? occasion  I saw the  experiment of encircling a scorpion by fire, confi-
 dently made by an English gentleman, but without effect, no danger from
 ?h ? flames,  no" provocation  could  induce  the  animal to  wound himself.
 Perhaps, occasionally, when extremely irritated, it may do so,-not knowing
 what he is doing. 
308
davy's researches.
temperature of a julus was 78.5.  It was  of that species which
emits a  yellowish fluid,  having the  smell  of iodine, and which
colours the cuticle, not unlike iodine, but has no effect on polished
steel.

               8.— Of the temperature of worms.

   The only worms, the temperature of which  I have tried, were
two kinds of leech, the Hirudo sanguisuga, and a species which
in Ceylon is called the jungle  leech, remarkable for  living out of
water in  damp places.  The temperature of both was  the same as
that of the water and air in which they were confined.
   I  may remark, generally, that  in the few experiments I have
made to  ascertain  the temperature of small animals of the lower
classes, a very small thermometer was used in each instance, intro-
duced through a small incision into the body.

            IV.— Conclusions and general remarks.

   That the temperature of  man increases in passing from a cold or
even temperate  climate, into one that  is warm ;  that  the tempera-
ture of the inhabitants of warm climates is permanently higher than
those of  mild; and  that  the temperature  of different races of
mankind, ceteris paribus, is very  much  alike, are conclusions
which the preceding observations on man seem to warrant.
   The first  conclusion, I  am aware, is  not novel ; but I do  not
know that it was ever drawn before, excepting  from  verv scantv
data.                                     &          y       y
   The second conclusion, though  conformable with the first, is I
believe new; indeed  it is contrary to a received opinion, that  the
temperature of man  in warm climates is  actually lower than in
cold.  The opinion alluded to, I conceive, arose partly from hypo-
thetical views of the subject;  and  if I recollect rightly, it has been
supported only by two or three observations recorded  by Dr. Chal-
mers, in his History of South Carolina, which were made at a time
when thermometrical experiments were  not very common,  and
when the standard temperature of man was rated  much toe) low.
Further  refutation of this opinion is  perhaps unnecessary.  The
experiments I  have  made with all the care in  my power, are so
numerous, and their results are so consistent, that if I do not deceive
myself, they put the question beyond the shadow of doubt,and fix as
a  fact,  that  if the  standard temperature of man,  in  a temperate
climate, be about 98°(which I believe is the greatest approximation
to the truth) in a hot climate it will be  higher, varying with atmo-
spheric variations from 98h° to 101°.
   The third conclusion I  believe  to be perfectly accurate; I  say
believe, because it is difficult, if not impossible, to collect more than
presumptive evidence on  the subject.  However,  may not  the
evidence  be considered sufficiently satisfactory, since the variation 
            ON THE EFFECT OF VIOLENT EXERCISE.        309

of the  temperature of the different races I tried did not exceed, in
degree, what may be witnessed  amongst different individuals of a
ship's  company, all of one nation, or even  amongst different mem-
bers of the same family ?  The similarity of temperature in different
races of men is the more remarkable, since between several of them
whose  temperatures agreed, there was nothing in common but the
air they breathed.—some feeding on  animal food almost entirely, as
the Vaida,—others chiefly on vegetable diet,  as the priests of Boodho,
—and  others, as Europeans  and Africans, on neither  exclusively,
but on a mixture of both.
   Farther, that  the temperature  of birds, of all animals  is the
highest,—that of the mammalia next,—that of the amphibia, fishes,
and certain insects  next in degree,—and lowest of all, that  of the
mollusca, Crustacea, and worms,—are conclusions, with few excep-
tions, that may be deduced from the preceding experiments on the
temperature of animals  in general.
   Moreover, since  in general, so far  as experiment and  observation
have yet gone, there appears to be a decided connection  between the
quantity of oxygen consumed by an animal, and the  animal's heat,
is there not good reason  to consider the  two in the  relation of cause
and effect?
   If animal heat be owing to nervous energy, or any way connected
with the nervous system, why, it may be asked, are birds so much
hotter  than the mammalia?  Why is  the  temperature of most
quadrupeds higher than  that of  man?
   Or, if it be owing to digestion, and secretion, and animal  action,
why is the temperature of the amphibia and of fishes  so low,  whose
powers, in respect to these  functions, are so considerable?
   Or, if it be connected with muscular energy, why are the animals,
whose  muscular powers  are most remarkable (the animals belonging
to all the lower classes), equally remarkable for the lowness of their
temperature?
   Or, lastly, if animal heat at all depend on  peculiarities of struc-
ture or organization, why, it may be asked, is not the temperature
of the  amphibia elevated  like that of birds,—the  structure  of the
respiratory, and  digestive, and  secreting organs of the one class
being so much like those of the other?
                           XXVII.

OBSERVATIONS  ON THE EFFECT OF VIOLENT EXERCISE
         ON THE TEMPERATURE OF THE BODY.

  Whilst  I  was in  Ceylon, I made a  few  observations on the
effect of severe exercise on the temperature of man, which, although 
310
DAVY'S RESEARCHES.
less perfect and extended than I could wish, may be deserving of
insertion here.
  On theSlh of July, 1817, preparatory to setting out on a journey,
I tried the temperature, both under the tongue, and in the axilla, of
six natives belonging to a set of palankeen  bearers, in good health
and quite cool, at about  seven o'clock in  the morning, when the
temperature of the air was  80°.  The results were the following:
No.	Age.	Therm, under Tongue.	Axilla.
1	35	985	-
2	30	99°	97°
3	35	98-5	96°
4	32	98-5	96°
5	35	99°	96°
6	33	100°	98°
  At the end of the 2d day's journey, at four o'clock  in the after-
noon, immediately on halting, I tried the temperature of three of
the bearers.
               No.       Therm, under     Axilla.
                            Tongue.
                1             98°           98°
                3            100°           98-5
                4             98-5          98°
  Before setting out, when at rest, the skin of these men was cool,
it conveyed, indeed, to the touch of another, the sensation  almost
of coldness; now, instantly after rather  severe exercise, when  the
temperature under the tongue was not raised, that of the axilla was
increased and the surface of the body generally felt hot.
  The next trial of temperature, under the influence of exercise,
was made on  the 26th July, on two of the same set of bearers, both
about thirty years of age, both in good health, one stout and robust,
the  other rather slender.  At ten a. m., at Ranne, in the Megam-
pattoo, when  the temperature of the air was 87°, after  resting two
hours, the temperature of the first man was, under the tongue, 99°,
in the axilla 97°;  and that of the second, under  the  tongue, was
98° and in the axilla 97°.
  A few minutes after ten o'clock, I set out for Tangalle. The sun
was bright, the weather unusually hot, and the men, as if impatient,
proceeded with more than ordinary diligence and speed.  At noon,
when the air was 92°, I suddenly ordered them to stop, that I might
ascertain their temperature.   The first mentioned  man, was one of
the  bearers carrying the palankeen, the other had been running by
its side; both were sweating, the latter  most profusely.  The tem-
perature of the first, under the tongue, was 98°, in the  axilla 98-25;
of the second, under the  tongue, 99°;  in  the axilla 96-5.'

  1  I shall mention one observation moie. On the 10th of September, 1817,
after walking four miles  over a very rugged road, in the interior of Ceylon, 
TEMPERATURE OF THE INSANE.
311
  There are,  on record,  many instances of sudden death,—from
drinking cold  water,  or from plunging into  cold  water, after
exhausting fatigue, and when the body  is commonly said to be
heated.   Probably, in  such  cases, in  conformity with the above
observations, the temperature of the body has been actually reduced
below its natural standard, taking the tongue as an  index of the
internal heat, and the fatal effect  may, in part, be the consequence.
This view of the effect was  taken by  the late Dr. Currie, who, in
his  Medical Reports,  in the twelfth chapter, has collected many
examples of  the kind, and, amongst  them, that interesting and
impressive  one of the  catastrophe which befell the army of "Alex-
ander the Great, on the banks of  the river Oxus, where, according
to Quintus Curtius, the loss  of life was actually  greater than had
been experienced in any single battle.   The circumstances  of the
case were, a forced march of forty-six miles, in hot weather, over a
desert; excessive thirst and exhaustion ;  and, in this state, drinking
large draughts of cold water.
                           XXVIII.

OBSERVATIONS ON THE TEMPERATURE OF THE INSANE.

  In the Lunatic Asylum at Fort Clarence, attached to the General
Military Hospital  at  Fort  Pitt, Chatham, it  has  commonly been
believed that  the  temperature of the  insane  is below the average
temperature of man.   This opinion has  chiefly been founded on
thermometrical observations, made many years ago by the late Mr.
Tully, then surgeon to the forces, in medical charge.   As the differ-
ence of  temperature was, in many instances, stated to be of several
degrees, varying  from 92° to 97°,  as ascertained under the tongue,
taking 98° as  the  standard, I could not avoid entertaining doubts
respecting the  accuracy of the results ; and  this feeling induced me
to institute some trials, for the  purpose of endeavouring to arrive at
some  certainty,  on a point not without interest,  and importance,
both theoretically, and in  regard to the management of the insane.
I shall  give two  sets  of observations;—one set made in the  depth
of winter,—the  other  in  the  height  of summer,—under circum-
stances, otherwise, as nearly  like as possible ;—viz. at the  same

and sweating profusely; when the sensation of heat was  greatest, a ther-
mometer, placed under my longue, was 98°, the temperature of the air at the
time was 88°.
  These observations are too few  in number to admit of conclusions being
drawn from them in  a satisfactory manner.  Few, however, as they are, the
results are not uninteresting, especially those indicating a reduction of tem-
perature  under the tongue. 
312
DAVY'S RESEARCHES.
time of the day, between 10 o'clock  and noon, at about ihe same
interval between meals, the  breakfast hour being 8, and the dinner
1,  and after taking on  each occasion about the same degree  of
exercise in the open air.  The winter observations were made on
the 17th  January, 1838, when  the temperature of the atmosphere
was 30°; the summer observations, on the 4th of August following,
when it was 68°;  in  the former instance the temperature of the
room where the trials were instituted, was 43°; in the latter about
the same as the open air.
Table of observations ou the  temperature of the insane  in  the
                winter and summer of 1838.
■m c t> .• . to Species of Winter. Name of Patient. MS r •, c. « cu nu P Insanity. State of health		Temp. under T. 100	Summer. State of health.	Temp-under T.
Pte Henry Dalton 55 Amentia Pretty good			Pretty good	101
— Owen Eagar 63 Mania good		100	good	101-5
SJt. George Bayley 49 Mania | good		100	good	101
— H. Sutherland :31 Amentia rather feeble		99	feeble	101
— John Roarke 41 Mania	good	98	good	101
Pte Sam. Palmer 42A<nenba	good	99	good	100-5
— John Sharpe 50 Amentia slightly ailing		102	good	995
— William Cane 62 Amentia; g00d		98	good	100-5
— Hugh Catlin 69 Amentia feeble		100	feeble	101
— Ad.Walshatskyol Amentia pretty good		99	moderate	100
— William Lyons 34 Amentia pretty good		100	moderate	101
— Jacob Mundy 53 Amentia good		99	good	101
— James Mullins 37 Mania	good	99	good	100
— C.T.Levis 41 Mania		101	obscure dis. of lungs	104-5
— James Davis 41 Amentia	pretty good	99	good	100
— George Roper |64 Mania	good	101	good	101
— John Fielding 45 Amentia	pretty good	100-5	moderate	101
— Luke Reilly 29 Amentia	indifferent	99	indifferent	99
— John Hennessy 57 Mania	good	99	good	100
— Michael Tudor 61 meianch'iia	good	100-5	good	101
— John Mayow 40 Amentia	good	100	good	101
— Ricd. Clements 61 Amentia	good	98	good	100
— Christ. Frisch 47 Amentia	good	101	good	101
— ElijahWalwark 27 Amentia	good	98	good	100
  None of these patients were under coercion ; the majority of them
were chronic cases and incurable, labouring under erroneous ideas
on certain subjects.
  For the sake of comparison, I ascertained at the same time, both
in winter and summer, the temperature of some of the  individuals
belonging to the establishment.
1 Officer	Age. 48	State of health.	Temp, under tongue,' 17 Jan.	Temp. 4th Aug.
		good	98	99
2 Officer	50	delicate	100 5	—
3 Serjeant	53	good	100-5	100-5
4 Serjeant	51	rather infirm	101	101-5
5 Private	41	good	99	99
6 Private	27	good	98	—•
 
TEMPERATURE OF THE INSANE.
313
  From these observations it would appear that the temperature of
the insane, as of persons not so affiicted, varies slightly in different
individuals;  that it is  not lower in the insane, but rather higher;
and that it  varies slightly in summer and winter, being greatest in
summer,—in accordance with the preceding observations, made on
occasions of rapid  transition from one climate to another.
  The tolerance of cold  and of heat by the  insane, is a question
totally different from the  foregoing on their internal temperature.
That they  bear in  most instances degrees of heat and cold, without
complaining, which to sane  persons would  be disagreeable,  is a
well-established fact, however it may be accounted  for.   Probably
neither heat nor cold affects their senses  in the same degree as it
does those in perfect  health.  Agreeably  to this view, it may be
remarked, that certain organic lesions  occur in  the insane, unac-
companied by the  ordinary  symptoms :  thus, tubercles not only
form in their lungs, but also tubercular excavations, often unattended
with cough or difficulty of breathing, as if the parts had lost their
sensibility.  But, notwithstanding no warning is given of the mis-
chief in progress, it runs its course, terminating in death as certainly
and  rapidly  as  if indicated  by the common train  of symptoms.
The analogy may  hold good as regards heat or cold in their influ-
ences on the  constitution of the insane :  whether felt or not,  excess
or deficiency of temperature  may be as injurious  to  them, as to
individuals possessed of the most delicate sense of them.
  Incidentally, 1 would remark, that in  this  class  of maladies in
which the ordinary symptoms of associated  disease are so often
latent, attention  to the  temperature, as well as to the pulse, may be
of great use to the medical attendant.  The pulse and the temper-
ature  may make  him acquainted with the existence of disease,
before not suspected, and may lead to inquiry of a minute kind, by
which the exact species of the adventitious disease may be discovered.
The case of C. T.  Lewis, one of the patients in the lunatic asylum,
whose temperature was ascertained and  given in  the preceding
table, is a  striking example of the use of such observations.  On
the 4th of  August, the temperature under the tongue was found to
be 104 5, and his pulse rapid.  This called attention to his  state ;
and,  although he  made  no complaint,— his  appetite good,—the
functions, as far as was known,'tolerably well performed, it  was
inferred he had obscure disease of lungs.   He died  in  less than a
month, namely, on the  26th of  August.   The  fatal disease was
pulmonary consumption, organically considered, in  an aggravated
form, but  in  relation to symptoms, most mild:  There were ulcers
of larynx without  affection of voice;—most  extensive disease of
lungs, vomicas and tubercles without cough  ; ulceration of intestines
without diarrhoea  ; and  disease of testes, vesiculae seminales, and
prostate, of a severe kind, equally  latent, excepting  in the testicle,
the  hardness  and enlargement of which,  but without pain, were
casually noticed. 
314
davy's researches.
                           XXIX.

OBSERVATIONS ON THE TEMPERATURE OF THE SHEEP IN
                 WINTER AND IN SUMMER.

  The majority of the foregoing observations, seem to  show that
the temperature of man, and birds,  and  quadrupeds, is  somewhat
higher in warm weather than in cool weather,—as in the hot atmos-
phere of the plains within the tropics, compared with the cool air
of the mountains.  The observations, however, made by our enter-
prising arctic travellers, during the depth of winter of  intense cold,
seem  to prove  that the animals  inhabiting the extreme northern
regions  have a high  temperature, perhaps higher than the same
animals in a milder atmosphere.  In illustration, I shall insert here
the results of some trials made on quadrupeds, by inserting a ther-
mometer  several inches into the rectum before the death of the
animals, commonly taken in traps, for which I am indebted to  the
Rev. G. Fisher.

  1821.
Nov. 15,	White Fox		-
Dec. 3, e:	it Cf		-
" n!	cc		.
" 15,	It		-
" 17,	11		-
" 19,	((		-
1822.			
Jan. 3, " 9,	(C it	(female) A White Hare	
c __ " 10,	(( CC	White Fox (male)	
" 17,	<(		((
" 24,	it		ii
u __	It		it
it	tt		1(
" 27,	a		EC
Feb. 2,	A Wolf		-
Fahr.	Air at the
	time.
106-75	+ 14°
101-5	— 5°
100°	— 3°
101-25	— 25°
99-75	— 15°
98°	— 10°
99-75	— 5°
104-75	— 26°
100°	— 25°
100°	— 26°
100°	— 15°
106°	— 32°
103°	— 21°
10o°	— 21°
102°	— 21°
101°	— 27°
105°	— 27°
  The great difference of temperature of individuals of the same
species, may have been owing to. a difference in the length of time
they had been entrapped.
  Considering the highest temperature as nearest the natural tem-
perature, the results are favourable to the notion above alluded to,
that very severe cold may promote the production of animal heat.
And,  theoretically considered,  this appears  nowise improbable.
much less impossible.  Several  circumstances may be supposed to
conduce to it,—sueh as the very warm, or bad-conducting nature 
                 temperature of the sheep.             315

of the thick winter clothing of the  animals, in conjunction with
extreme  dryness  of air,1—the great activity  of the  function  of
digestion,2—the greater activity of the function of respiration, and
the consequent greater degree of aeration of the blood.  As our
fires burn with more intensity in winter than in summer, and give
off more heat,  so  in animals a greater degree of heat  may be pro-
duced under the  circumstances alluded to, when most required.
   With the hope of collecting some satisfactory information on this
point, I have selected the sheep, as a fit subject for trial, and I shall
now record the results which I obtained in winter, and spring, and
summer.
   On the  night  of the 22d  January, 1838, the wind  changed  to
the north, and the  temperature fell  below the  freezing point.  It
continued  so, constantly,  to the 26th of the same month ;  at night
generally below 22°, and  by day, at  or  below 29°.  On the 26th,
at noon,  at  Chatham, I made observations on  three sheep,  ewes,
which, the preceding day, had been driven in  from an adjoining
marsh, and had  been kept, during the night, in a cool out-house,
where the temperature was below the freezing  point.  At the time
of the trials the temperature of the open air was about 29°.
   1.—Rectum        .....    104°
     Blood flowing from jugular vein         -       -    103°
         "         from carotid artery        -       -    105°
     Base of brain    -                                  104°
     Near surface of cerebrum        -        -       -    103°
     Left ventricle    -                                   108°
     Right ventricle (blood in it)      -        -       -    107°
     Liver     ......    107°
   2.—Rectum        .....    104°
     Mixed  venous and  arterial blood  from  great
       vessels of neck         -                           105°
     Brain at base    .....    106°
     Surface of cerebrum      ....    103°
     Left ventricle    -----    108°
     Right ventricle   -----    106°
     Liver                                   -       -    106°

  1 This is very strongly indicated by a circumstance which I  heard related
by Mr. King, the  enterprising  and  very  intelligent medical officer, who
accompanied Captain Sir  George Back,—how, in  the depth of winter, the
blankets exposed to the air  after being frozen, dried so completely, that,
when  brought near a fire,  not  the slightest appearance  of vapour was
observable.
  2 The journals of our arctic travellers  offer very striking examples both
of the  accommodating power of the human  stomach and  the strength  of
digestion.   The quantity of animal food consumed, when there is an  ample
supply, in the high northern  regions, is marvellous.  I have been informed
by Dr. Richardson, that the daily allowance of meat to the servants  of the
Hudson's  Bay Company,  is eight pounds a-man.—Their  food is entirely
animal food. 
316                davy's researches.

  3.—Rectum        -
    Mixed  venous and  arterial  blood from  great
       vessels of neck
    Base of brain
    Towards surface of cerebrum
    Left ventricle     -
    Right  ventricle (blood  in it)
    Liver     -

  From ten to fifteen minutes  elapsed between the examination of
the brain and  heart.   The temperature of the rectum  was tried
during life.  The  head was cut off immediately after the flow of
blood had ceased.  The heart was not taken out till the skin and
abdominal  viscera  had been removed.
  In  the first experiment,  in which  the difference of arterial and
venous blood was tried, the trial was  carefully made, and the result
unobjectionable.  The small bulb of the thermometer was introduc-
ed into the jugular vein, and  the blood flowed freely over it; and,
it was placed in the full stream of arterial blood, close to the  wound
in the carotid artery, after a ligature had been applied to the jugular.
  The following observations were made  on the 29th of January,
between one and two o'clock, p. m., when the air was  about 46°.
It rained the preceding night; froze early in  the  morning; after
eight, a. m. there was a continued thaw.
,—Rectum	-	-	105°
Venous blood, from jugular vein		-	104°
Arterial from carotid artery	-	-	106°
Right ventricle of heart ~	-	-	105°
Muscle of left ventricle, where	thickest -	-	108-5
Left ventricle	-	-	108°
Brain at base	-	-	105°
Near surface of cerebrum	-	-	103°
Interior of globe of eye	-	-	100°
.—Rectum	-	-	105°
Vagina (mucous fluid flowing from it, period of sestus)			10"°
Blood from jugular vein	-	-	106°
" carotid artery	-	-	107°
Base of brain	-	-	106°
Near surface of cerebrum	-	-	105°
Right ventricle	-	-	107°
Left ventricle	-	-	108°
Interior of globe of eye -	-	-	104°
  It was my wish to have examined the heart whilst yet pulsating,
to endeavour to ascertain if any heat is produced by the muscular
contraction of the  organ.   The  chest  was opened  within  five
minutes of the division of the great vessels of the neck; but in
both instances too late,  the heart had ceased to contract.
104°

105°
107°
106°
109°
106°
106° 
temperature op the sheep.              317
    The second sheep was  in an irritable state; the lungs abounded
 m gianular tubercles, yet the animal was in excellent condition.1
    i ne next  observations were made on the 16th of March, when
 the temperature of the air was 51°.

    1.—Rectum        --....     io6°
     Jugular vein     -                              _     jQg0
     Blood from carotid        ...            jq^o
     Right pleura2                                    ~     10To
   2.—Rectum        ....            Iq-0
     Mixed venous and arterial Hood from cervical vessels  106°
     Both lungs       -       .               .            107o
   6.—Kectum        -                                   jq-o
     Mixed blood      -                                   Iq^o
     Lung     ....;;     108O
   4.—Kectum        -                                    10i\°
     Mixed blood      -        .       .         •           iqjo
     Lung    -....;     lfJ9o
     EYe                                                  104°

   These  sheep,  as well as the tvvo preceding, were ewes, about
three years old.  The sex of the following, the subjects of obser-
vation on the 23d of May,  is not mentioned iu my notes; the tem-
perature of the air then was 63°.

   I.—Rectum         -                                    105°
     Mixed venous and arterial blood from neck       -     107°
   2.—Rectum         .....    \{J50
     Mixed blood      -                                    107°
   3.—Rectum         -                                   105°
     Mixed blood      -                                   107°

   The next observations were  made on  the  21st August, between
noon and  tvvo  o'clock  in the afternoon, when  the  temperature  of
the air was between 70° and 72°.
  1 The prevalency of tubercles in the  lungs of sheep is  remarkable.  In
 their granular  state, they do not appear to affect materially  the health or
 condition of the animal; even a few small vomicae seem to have very little
 effect.  I believe it is precisely the same with the  human species; many
 facts which I have collected are in accordance with  it.  The  analogy is in-
 structive and well deserving of being kept in mind.
  1 The temperature of the lung and pleura was found by  introducing a
 thermometer through a small incision in an intercostal space, immediately
 after the division of the great vessels, whilst the heart was  still acting.
  On the 18th March, in  the instance of a full-grown spaniel  bitch, the
 temperature, in recto, was found to be 105°, and in the right  pleura, the lung
 not wounded, 107°.  30 drops of hydrocyanic acid were now introduced into
 the pleura;  in half a minute the bitch expired, convulsed.  The  chest was
 immediately opened, the heart was still acting, the temperature of the right
 ventricle was 104°, of the left ventricle 107°; both ventricles were distended
with blood,  which afterwards coagulated.
       12—c                                       21 dav 
318
davy's researches.
1.—Rectum	.	-	.	-	105°
Mixed blood 2.—Rectum	-	;	-	.	107° 107°
Mixed blood 3.—Rectum	-	-	-	;	108° 105°
Blood	.	.	-	-	106°
4.—Rectum	.	.	-	-	1055
Blood	.	.	-	-	107°
5.—Rectum	.	-	.	-	104°
Blood	.	.	-	-	105°
6.—Rectum	.	.	-	-	105°
Blood	.	.	.	-	106-5
7.—Rectum	.	.	-	-	106°
Blood	.	.	-	-	106°
8.—Rectum	.	.	-	-	106°
Blood	-	-	-	-	106-5
  The two last were lambs about fourteen weeks old.   The  rest
were ewes, about three  years old,  with  the exception  of No. 3,
which  was a  ram of about the same  age.  The  testes of  this
animal  were  comparatively small,  little more than  half their
autumnal  size, yet they  contained a good deal of spermatic fluid,
abounding in the spermatozoa peculiar to the sheep.
  These "sheep had not  been previously driven.   The  subjects of
the following observations, made at one, p. m., on the 28th August,
had been driven ten miles early the  same morning, and had been
exposed to the  sun in the market, and in the butcher's yard.  They
were all ewes, and about three years old; the thermometer at the
time was 79°
—Rectum	-	-	106°
Blood in jugular vein	-	-	106°
Stream of blood from carotid	artery	-	107°
.—Rectum	-	-	105°
Blood in jugular vein	-	-	106°
Ditto from carotid artery	-	-	108°
.—Rectum	-	-	105°
Blood in jugular vein	-	-	106°
Ditto from carotid artery	-	-	107°
.—Rectum	-	-	106°
Blood in jugular vein	-	-	105°
Ditto from carotid artery	-	-	107°
  All these observations were made with  the  same thermometer,
and  consequently they are better fitted for comparison.  But after
comparing them, it does not appear to me that the results are sufii-
ciently consistent to admit of any positive conclusions being drawn
from them.  They seem to show, that the temperature of the body
is a  little  higher  in  the warm  weather of  summer than in  the
moderate degree of cold of our winter;  the heart perhaps being 
temperature of some fishes.
319
an exception.   The subject  demands further inquiry, especially as
regards the effects of extreme cold.—I have brought forward such
observations as I have made, with the hope that they may lead to
others;  and I have given  them, miscellaneous as they are, believ-
ing that they may have some little value  in connection with the
theory of animal  heat generally, which, to be true and permanent,
must rest on a very extensive series of facts—or what  is identical,
be an induction from them.
XXX.
   ON THE TEMPERATURE  OF SOME FISHES OF  THE
                     GENUS THYNNUS.

  It is commonly believed and asserted by naturalists that fishes
generally, without exception, are cold-blooded; thus Linnaeus, in
his  "Regnum Animale," characterises them in relation to their
blood by "Sanguine frigido ;'n and Baron Cuvier,  our latest and
highest authority, not only admits it, but also undertakes  to show,
that it must be so:  thus,'in the chapter of his "Histoire Naturelle
des  Poissons," on the  general  character and essential  nature of
fishes, he says, "ne respirant que par l'intermedc de l'eau, c'est a
dire, neprofltant pour rendre a leur sang les qualites arterioles que
de la petite quantite d'oxigene content!  dans Pair mele a l'eau, leur
sang a du rester froid."2
  It was many years ago, viz. in 1816, when on a voyage to Ceylon,
that 1 first  met  with an  exception to this  universally received
opinion.   It occurred  in  the instance of  the bonito (Thynnus
pelamys, Cuv. and Valen.), the temperature of which, in the deep-
seated muscles, in the  thickest part of the fish, a liltle  below the
gills, I found to be 99°, when the surface of  the sea, from which it
had just  before been taken, was 805, the difference being, the very
remarkable one of eighteen degrees and half.3
  This fact necessarily made a strong impression  on my mind,  on
account of its singularity; at Malta/in 1S33-4, when examining
the heart  and <rills  of the tunnv, of the  Mediterranean, {thynnus
vulgaris, Cuv. and  Valen.) my attention was recalled to it on rind-
inoMhat  the latter were supplied with nerves of unusual magni-
tude;  that the heart, like  that of the  bonito, was very powerful;
that the fish equally, or even more abounded in blood; and that its
muscles  generally,  like  those of the bonito, from the same cause,
were of a dark-red colour.   It immediately occurred to me that Us
temperature also  might be high, analogous  to that of the bonito;
and the result of careful inquiry amongst the fishermen  ot most

               1 Systema Nat. Lib. i. p. 12.
               2 Hist. Nat. des Poissons, Lib. l.  p. 27o-
               3 Vide above. 
320                 davy's researches.
experience  in  the  tunny fishery, confirmed the conjecture.  All
who were  asked, declared that the tunny is warm-blooded;  and
one of the  most intelligent, when questioned as to  the degree of
heat, said,  it was much the same, or little  less than that of the
blood of a pig, when flowing from the divided vessels of the  neck
on  being killed ; and this  man was very  competent to  give an
opinion on  the subject, having been much employed in the fisheries
on the  Sicilian coast, in which the viscera of the  fish are considered
the perquisite  of the common fishermen, and are instantly taken
out by  them when the fish are caught.
  From the tunny, I extended the inquiry to other fish of the same
family; and learnt that the  analogy holds good applied to all the
species of the  genus Thynnus, of Cuvier and Valenciennes, with
which  the  Maltese fishermen are acquainted, viz. T. brevipinnis,
T. thunnina,  T. alalonga, and the two already mentioned ;  all of
which  abound in  blood, have a powerful  heart, red or reddish
muscles, and also, as I have ascertained by particular examination,
have their  gills  amply provided with large nerves.  Not having
been able to procure any of these fish alive, their exact temperature
1 have not been able to determine; but, from  the  reports  of the
fishermen,  it would appear that the common  tunny is the  warmest
of the species,  and  in  accordance with  this,  I have found its
branchial nerves proportionally largest.
   These nerves, immediately after quitting  the cranium, enter or
swell out into  ganglia of considerable size, more or less connected
together, from whence five principal  trunks  proceed; the  first four
chiefly to the  branchia, and are the respiratory nerves; the fifth,
the lowest, to the oesophagus and stomach, and the parts adjoining.
In  point of magnitude, these  respiratory nerves almost rival the
electrical nerves of the torpedo, and their  origin is very similar,
and their  direction and associations, but withthis  marked differ-
ence between  them, that the nerves of the torpedo are entirely
destitute of ganglia.
   The respiratory nerves of the other  species  of thynnus  which
I  have examined, very much  resemble  the  preceding.  Those
which are smallest  belong  to  the thynnus brevipinnis; and yet
even in  this  fish, in comparison  with  fishes of other tribes, the
respiratory nerves are large, and their ganglia considerable.   This
fish, perhaps,  may be considered a link  between the tunny family
and the  mackerel, on  one  side, and the pelamides, on the  other;
and the respiratory nerves of one of each of these genera which I
have  dissected,  viz. of the scomber  pneumatophorus,  and the
pelamys  sarda,  have  approached  in  magnitude   those of  the
thynnus last  mentioned.   What the temperature of these  fish is,
I have not had  an  opportunity of determining  by trial; according
to the  statement of the fishermen T have consulted, they  are  cold*
blooded.   Reasoning from analogy, it may be conjectured  that they
will be found to be of somewhat higher temperature than other
fishes  less  amply supplied with respiratory nerves. 
TEMPERATURE OF SOME FISHES.
321
  As regards the rationale of the high temperature of the  species
of thynnus, there appears  to me less difficulty than in accounting
for  the electrical  power exercised by the torpedo  and gymnotus.
The peculiar function of the latter is performed by means of a par-
ticular organ, the most striking feature of which is a vast apparatus
of nerves;  but this  organization bears liltle or no  analogy to any
other natural, or to  any artificial process hitherto known by which
electricity is generated.   Not so the respiratory apparatus and
associated organs in these fish of high temperature; they are essen-
tially analogous to those of the warm-blooded  animals of the other
two classes, and hardly more different from the respiratory appara-
tus and  associated  organs of  the  mammalia, than those of the
mammalia  are  from those  of birds.  The function of respiration
in water  is commonly considered similar to that in the atmosphere;
the same change, it is supposed, takes place in the blood in both
instances;  the same change is  ascertained to  take place in the air
of the  water and of the  atmosphere; and increase of temperature
in one  case and the other is  referred to  the  conversion of carbon
into carbonic acid.  The difficulty is not as regards  the  kind of
effect, but the degree of that effect; not an augmentation of one or
two degrees above  the temperature of the  surrounding medium,
but of  many degrees.  A consideration of some of the peculiarities
of these fishes may help to diminish this difficulty, which I have
little doubt will be removed entirely, when we are better acquainted
with their  structure, and better  acquainted with all the sources of
animal heat.
   The most important peculiarities, are.  I believe, chiefly the fol-
lowing :—a large and powerful  heart; abundance of blood ; red
particles in abundance; large gills, and a very large apparatus of
branchial nerves.  These, all,  may be  considered  as concerned
either  directly or indirectly in the generation of heat.  And, the
circumstances for the preservation of heat are scarcely  less remark-
able,— as the manner in which the gills are defended by peculiarly
strong opercula, abounding in fatty matter,—and the deep situation
of  the principal blood-vessels, surrounded by thick muscles,—and
in addition, the aorta, or great  systemic arterial trunk, surround-
ed  by  the  principal abdominal viscera,  the kidneys, stomach, and
liver.
   Moreover, the habits  of these fish, may in some measure con-
tribute to their high temperature.   They are  frequently to be seen
near the surface, and seem to have a delight  in springing into the
atmosphere.  Aristotle, speaking  of the  tunny, says,  "of all  fish,
it most enjoys warmth, and on that account swims near the surface
and frequents sandy shores:"—I quote from the old Latin transla-
tion of  Theodore  Goza.    " Thuuni  omnium  maxime  piscium
gaudent tepore et ob earn rem arenatn et littora adeunt; per summa
etiam  maris iunatant quo teporis  potiantur:'"—confounding (as I
1 De Hist. Animal, lib. viii. cap. xix. 
322
davy's researches.
believe in this instance he has done) fondness for warmth, wilh the
habits connected with  its production.
   In this  enumeration of circumstances, which  may contribute to
the high  temperature of these fish, both as  regards  its generation
and preservation,  I  have intentionally been  very general;  in the
present state of our  knowledge  I apprehend  it would be useless to
be more  minute.   It is not impossible that these fish may possess
means for generating heat peculiar  to themselves, and of which at
present we have no adequate idea.  And the  situation  of the kid-
neys,  of which  a considerable  portion  is even  higher than the
stomach and  posterior to the gills, of  large size, and  abounding in
blood, and well supplied with nerves,  would  lead to the  conjecture,
that these organs,  in the function of imparting heat, may possibly
act a part.  Still, however, reflecting on  the great proportional size
of the branchial  nerves, and guided  by analogy, it  is  difficult to
resist the conclusion, that they are not principally concerned in the
performance of the function in  question, and that these nerves, as
means, are so very ample on account of the element inhabited, and
the proportionally  greater energy of function required   to produce
the same effect of elevation of temperature in the water and in the
atmosphere.   On any  other view, it seems difficult  to  account for
the branchial  nerves of these fish being  proportionally very much
larger than the  pulmonary nerves of the mammalia,   and  vastly
larger than those of birds, of all animals the warmest.1   Whether
there  is  any  immediate  relation  between   the  ganglia  and  the
branchial  nerves,  and the generation of heat in these fishes is
uncertain, and must  necessarily remain so, as long as there is any
doubt concerning the use of ganglia.   The absence  of  ganglia on
the principal  nerves of  the lungs  of man,2  and I  believe  of the

  1 The size of the pulmonary nerves of birds, and indeed of their respira-
tory nerves generally, as  far as my observations have extended, is so small
as to be truly astonishing, compared with their very  high temperature.   And,
on the  hypothesis of  nervous  influence being  essential to the production of
animal heat through the agency of respiration, the necessary  inference seems
to be, that birds require less of this influence, than  any other description of
warm-blooded animals; which may  be owing,  perhaps, to their  peculiarities
of structure, both in  relation to the diffused  aerial means  they possess of
generating heat, and  their peculiar means, in  their covering of feathers, of
preserving it; and, owing probably  further, to their less expenditure  of it,
from the peculiarities of some of their principal secretions, especially  those
of the kidneys,  skin, and lungs; their kidneys secreting'an  almost  solid
urine, their skin exhaling  little moisture, and that not in sweat, but entirely
by insensible perspiration, and their lungs though exhaling  more, from the
nature of the function they perform, yet less than might at first be supposed,
part of the aqueous vapour contained in the  air expired being, I believe,
condensed before it enters the atmosphere,  by  the trachea, mouth and  beak,
which are always comparatively cool.  And in accordance  with this view,
from the experiments of Messrs. Allen and  Pepys, it appears, at least in one
instance,—that  the  pigeon, one of the warmest of birds, consumes in relation
to its bulk, even less oxygen, or produces less carbonic  acid, than a quadru-
ped, the guinea-pig, the temperature of which is several degrees lower.
  2 Haller, speaking  of the  great sympathetic nerve, which in man  is so 
      TEMPERATURE OF THE HUMAN BODY AFTER DEATH.    323

mammalia generally, and of many birds, would lead  to the infer-
ence, that the nerves in the instance under consideration, rather
than the ganglia are chiefly  instrumental, and that the latter are in
some way subservient to the former,—but whether for giving  sen-
sation  to the branchia,  or for imparling  extraordinary  secreting
power, so as to change  the blood, or  for some other  purpose, re-
mains to be ascertained.
  In  conclusion,  I would beg to state  some  desiderata,—points,
connected with the subject  of these  warm-blooded fishes, which
may be considered as deserving of further inquiry.
  1.  The exact temperature of  different species  of the tunny
family.
  2. The temperature of the blood, coming from and  returning to
the  gills.
  3. The specific  gravity of the  blood  of these fishes; and  the
proportion of* serum, fibrin, and of red particles which it contains.
  4. The minute peculiarities of their structure.
  5. The peculiarities of their habits.
  It seems not improbable, that the investigation, if followed  up,
may not only throw light on  the function of respiration in these
fishes, and on the production of their  high degree of temperature,
but  also  that it may aid  in elucidating some obscure  parts of the
theory of respiration in general, in connection with that of animal
heat,—and especially the question, whether any oxygen is absorbed
by the blood in the lungs and carried into the circulation.
                             XXXI.

OBSERVATIONS ON THE TEMPERATURE OF THE HUMAN
                    BODY AFTER DEATH.

  It has not come to my knowledge that any precise thermome-
trical observations  have hitherto been made  on  the human  body
after death.  I was induced to pay  attention  to  the  subject,  from
having, in one  instance,  whilst engaged in  conducting  a  post

amply provided with ganglia, says, "In pectore notabiles ramos paucos edit,
neque memini me alicujus momenii truncos vidisse qui ad nervum octavi
paris accederunt, etsi ejusmodi nervi illustribus viris visi sunt."  Element.
Phys. iv. p. 260.   And, according to Sir Charles Bell's views of the nervous
system, none of the respiratory nerves are ganglionic nerves.  Sir Edward
Home (Phil. Trans, for 1825, p. 257.) has endeavoured to associate the pro-
duction of animal heat  directly with ganglia; but the instances he  has
adduced seem liable to great objection ;  and the fact, that the great sympa-
thetic nerve in birds is comparatively little developed, even less than in some
reptiles, and destitute of large central ganglia, such as  the semilunar gan-
glion in the mammalia (at least in every instance I have carefully sought for
them, I have been unsuccessful) seems fatal to  his hypothesis. 
324
davy's researches.
mortem, examination, found the deeply seated parts  of a degree of
temperature uncommonly elevated.  As the inquiry needs as much
accuracy as possible, I shall first relate the §imple facts, and after-
wards offer some reflections on them.   It will be necessary to notice
the cases in which  the  observations were made.  This I shall do
as briefly as is compatible with the objects in view.  It may be
premised, that they all occurred in Malta, in our  military  hospitals
in Valetta, during a period of six months, namely, from July 1828,
to the following January, and that they were all of soldiers belong-
ing to our regiments, serving in  that island ; and, further, that the
bodies, in every  instance,  almost  immediately after death, were
removed to a large, airy, and  comparatively  cool  room, the  old
laboratory  of the hospital of the knights, where  they were to be
examined, and where they were generally covered  merely with a
sheet, and placed on a table of wood.
   1.  Aged 23 years;  was admitted  into  hospital on the 30th of
July, 1828, labouring under symptoms (as it was supposed) of acute
rheumatism, having severe pain, first in one shoulder, then in the
other, followed by pain in  the hips, attended with much  pyrexia,
and  a very rapid pulse.  He died on the 6th of August, a few
minutes  after  seven, a. m.  As the weather at the  time  was hot,
and  dead animal matter putrefied rapidly, it was necessary to in-
spect the body as  soon  as possible.  Accordingly, it was examined
three hours and a half after death ; when the  temperature  of the
air of the room was 86°.  The appearances  most remarkable, dis-
covered on dissection, were extensive  collections of matter  in  the
right shoulder, amongst the muscles on  each  side of the spine of
the scapula, with sinuses extending  to  the  axilla, and round  the
capsule of the shoulder joint; and, a lesion of the same kind, and
as extensive, in the left hip, close to the head of the  femur, spread-
ing through the glutei  muscles;  and  marks of incipient inflamma-
tion  (as  ecchymosis) in  the  right  hip.   The  viscera were  appa-
rently sound.  The right cavities of the  heart, and the great ves-
sels, were distended with liquid blood.   The body was slender, but
not emaciated.  Its surface was warm;  and deeply seated parts
felt very  hot, imparting a disagreeable sensation, almost like that of
burning, to the hand, in contact with them.  The thorax  was first
opened, and afterwards the abdomen.  After partial exposure of
the surface of the contents of these cavities to the air for about ten
minutes,  a thermometer was procured.  Placed under the left ven-
tricle of the heart, it rose to 113°;  and, under  the liver, in contact
with the  lobulus Spigelii, to 112°.
   2. Aged 27 years; a stout robust man, died suddenly in barracks,
on the 6th of  August, at about  half-past  eleven,  a. m.  The body
was examined at five,  p. m.   There was a good deal  of reddish
fluid in the ventricles,  and at the  base of the brain.  The lungs
were distended with black liquid blood, some of which had  passed
into  the bronchia.   There was very little  blood in the cavities of
the heart.  The temperature of the air of the room was 86°.  As 
     TEMPERATURE OF THE HUMAN BODY AFTER DEATH.    325

soon as the cavities of the thorax and  abdomen were  opened, the
bulb of a thermometer was iu succession placed under the left ven-
tricle of the heart, and under the lobulus Spigelii of the liver; in
the former situation it rose to 108°; in the latter to 107°.   About a
quarter of an hour afterwards, introduced into the substance of the
right lung,  gorged with extravasated blood,  it was  105°.
  3. Aged  25 years; a large, stout, muscular  man, was admitted
into hospital on the 19th of August, with symptoms of continued
fever.  On  the night of the 22d,~he became  delirious; but only for
a short time.   On the evening of the  24th he died suddenly and
unexpectedly.   The  body was  examined  four  hours  and  a half
after death, during which time  the  temperature of the air  of the
room had been between 78° and 80°.   No organic  disease was dis-
covered on  dissection, excepting of a chronic kind, and slight, and
not explanatory of the fatal event;  indeed, the abdominal  and
thoracic viscera, and  the brain, were unusually sound.  Notwith-
standing the body was large and fat, its surface was cold : but the
deeply seated parts were warm.   A thermometer introduced under
the left side of the heart, just after the pericardium was opened,
rose to 97°, and under the liver  close  to the vena  portae, to 101°.
The brain  had been previously examined ; the cavities of the
thorax and  abdomen were opened about four hours after death.  \t
may be remarked  there was  a great deal of  blood in the cavities of
the right side of the heart, and a small quantity in the left.
  4. Aged  21  years;  rather a large  muscular man ; was admitted
into hospital on the 21st of August; and died on the llth of Sep-
tember, of  acute  dysentery.  The examination of the body was
commenced about four hours and a half after death, and  the ther-
mometrical observations  were made about half an  hour later; the
temperature of the air at the time was  about 82°.   The viscera in
general were sound, excepting the large intestines, which exhibited
the worst effects of dysentery." The trunk was warm ; the extremi-
ties cold and  rigid.   A  thermometer  placed  under the  lobulus
Spigelii of  the liver, rose to 103-5, and under the  left ventricle of
thelieart to 103°.
  5. Aged 23 years; a  stout,  muscular,  well-made  man ;  was
admitted into  hospital on the 9th of October, with symptoms of
acute rheumatism, which were followed by those of remittent fever,
but  not  very strongly  marked, attended with a  low degree of
pyrexia, rather rapid respiration, and a pulse little accelerated.  He
died rather suddenly on the  16th of October.  The body was ex-
amined fourteen hours after death;  when the limbs were rigid and
cold.   The temperature of the  air  at the time was  69°.  Some
coao-ulable  lymph was  found adhering to the back  part  of the
pleurae;  a  corresponding portion  of each  lung  was apparently
hepatized ;  and, both the liver and spleen, and also the heart, were
of a morbid degree of softness, and easily broken;  more  especially
the two former, which were nearly of  pultaceous  consistence.  A 
326
DAVY'S RESEARCHES.
thermometer placed under the lobulus Spigelii of the liver, as soon
as the cavity of the abdomen was opened, rose to 88°.
  6. Aged 24 years; a large stout man ; was admitted into hospital on
the 12th of November, 1827, with symptoms of acute rheumatism;
and died on the 4th of November, 1828, eighteen days after amputa-
tion of the thigh, on account of vast and complicated disease of the
lower part of the limb involving the bone and knee joint, and twelve
days after the  ligature of the femoral artery, on account of secon-
dary haemorrhage from the stump.  The body was not emaciated.
It was examined Ivvelve hours after death ;  when  the temperature
of the air was  6S°.  The branches of the femoral vein were  found
plugged  up with  coagulable  lymph ;  the trunk  of the vein was
lined  with coagulable  lymph, and there was pus,  or, a  puriloid
fluid,  in the iliac vein.   A thermometer  placed under the lobulus
Spigelii of the liver, rose to 9i°, and under the heart to  93°.
   7. Aged 23  years; a stout, well-made man; was  admitted into
hospital on the 9th of November; and died  on the 29th  of same
month, of acute dysentery.   The  body was  examined  three hours
after  death, when the  temperature of the air  was 66°.   A large
abscess was discovered  in the liver, of which there were no symp-
toms  during life;  and  the colon throughout exhibited, in a  high
degree, the ulceration and  disorganization  peculiar to dysentery.
A thermometer placed under the lobulus Spigelii of the liver, rose
to 96°; in the substance of the right lobe  (in which the abscess
existed) to 93°, and the same under the left ventricle of the  heart.
About five minutes after, when placed in the posterior horn of one
of the lateral ventricles of the brain, it fell to 90°.
   8.  A^ed 33  years; a tall, muscular, well-made man; was admit-
ted into  hospital  on  the  30th  November;  and died on the 1st of
December, of apoplexy,  with  hemiplegia.  The  symptoms  were
most  distinct and violent;  a large quantity of blood was abstracted,
and energetic  treatment employed.  The body was examined two
hours after death ; during which time, the temperature of the room
was between  60° and 64°.  The  cause of the symptoms was not
discovered by  careful dissection.  No blood was found extravasated
on the brain;  not more fluid than is  usual  in the ventricles; no
softening of any part of the organ;  no tumour  making  pressure
on it; and, not a greater degree of fulness of iis vessels and redness
of its membranes, than is frequently  met with  in  cases in  which
the powers of sense and intellect have remained unimpaired to the
last.  A thermometer, placed under the lobulus Spigelii of the liver,
rose to 86°, and  under the right ventricle to 88°, immediately after
the cavities were opened.
   9.  Aged 23 years;  a tall thin man ; was admitted into hospital
on the  13th  of September,  and died  on the 3d of December, of
phthisis pulmonalis, of slow progress, and mild symptoms.  During
the last month, there was no cough, no dyspnoea, no uneasy feeling,
a slight  diarrhoea, gradual  wasting,  and  loss of strength.  The
body was examined five hours after death •, during which time, the
temperature of the air varied from  59° to 64°!   The lungs abounded 
      TEMPERATURE OF THE HUMAN BODY AFTER DEATH.    327

 in  small gray firm tubercles, and in small curd-like tubercles, and
 contained  a few  vomicse ;  the principal part of their substance
 was crepitans.  The lymphatic glands of the thorax and abdomen,
 generally,  were enlarged and softened in different degrees.   There
 was an ulcer in the inner coat of the duodenum ; many ulcers on
 this coat  of  the  jejunum;  and  the  ileum  and large  intestines
 abounded in ulcers, many of them deep and large.  A thermometer
 introduced  into the substance of the liver rose to 90°: it indicated
 the same degree  of heat placed under  the  lobulus Spigelii,  and
 under the right ventricle of the heart, immediately after the thoracic
 and abdominal cavities had been opened.   The skull-cap as soon
 as possible  was  removed, and immediately the membranes  of the
 brain were  divided by a deep incision, penetrating into the  centre
 of the  cerebrum,  into which  the  thermometer  being placed,  it
 instantly fell to 82°.
   10.  Aged 28 years; rather small, but a well-made man; was
 admitted into  hospital on the 23d of December, with symptoms of
 an obscure  kind, seeming to indicate disease of the liver.  He had
 occasional  pain  in the region  of that  organ, and also of shoulder;
 a rigor now and then ; a rapid pulse; but little pyrexia, or  loss of
 appetite, or  wasting.   He died on the 31st of January.   The body
 was examined seventeen hours and a half after death, during
 which time the temperature of the room was frcm 58° to 60°.   The
 liver,  large in its dimensions,  was found  to  be  excavated in  a
 singular manner,  not  unlike a tuberculated lung, in its advanced
 stage of suppuration, abounding in  vomicae.   The excavations in
 the liver were extremely numerous  and  labyrinth-like, so irregular
 were they in form, and  communicating with each other so irregu-
 larly.   Their walls  were in  many instances columnar, and  the
 cavities intersected by  columns containing blood-vessels,  and by
 blood-vessels almost bare.   Their contents  were a viscid bilious
 purulent fluid ; and its  yellow colour was apparently derived from
 bile  discharged  from  the ulcerated ends of the  branches of the
 biliary duct, indicated by bright dark-yellow  spots on the surface
 of the excavations.  In the situation of the vena  portae, there was
 a large sinus, which was ruptured by introducing the thermometer
 under  the  lobulus Spigelii; it discharged  a  fluid  similar to that
 described above.   On  minute examination, this sinus, lined with
 ragged  coagulable lymph, and about thrice  the size of the vena
 portae,  wasVound  to  be that vein itself vastly diseased: and  the
 veins which terminate in the vena  porta? were found terminating
 in it, empty, and  their abrupt terminations in this sinus or sac closed
 with coagulable  lymph.  The hepatic artery, vein and duct (at least
 their trunks), were  not diseased.  The spleen was of usual size and
appearance, but unusually  compact  and hard.  A thermometer
introduced  into the centre of the cerebrum, so soon as the skull-cap
was removed, rose to 70°; about  half an  hour after when placed
under the right ventricle of  the  heart, it rose to 82°, and the same
under the right lobe of the liver. 
328
davy's researches.
  These examples, which I have introduced in the order, in point
of time, in which they occurred, are the only ones in which 1 tried
the  temperature of the body after death, in a warm climate.  They
will probably be considered of very  unequal  interest, comparing
those in which an  unusually high  temperature was noticed, with
the  majority in which the temperature was no  higher than  might
have been expected.
  It would be superfluous on this occasion to enter into any minute
disquisition  relative to  the  rationale of ihe very high temperature
observed in the bodies  Nos. 1 and 2, in  relation  to  the  different
degrees of temperature noticed in the other bodies.   The  question
will naturally be asked,  Was the extraordinary temperature  in one
case, of 113°, and in the other of  108°, generated during  life or
death?   I have little hesitation in coming to the conclusion, that it
was generated before death, and generated  probably in the  same
way as  the ordinary degree of animal  heat experienced in health,
or the extraordinary degree witnessed  in febrile diseases. A priori,
the  effect of the heat-generating process,  whatever it may be, can
hardly be limited.   In many birds, it raises the  temperature of the
body to  109°, when  in perfect health, and in man to 101°, at least in
the  tropics, without deranging health ;  and it is easy to conceive,
that, by increased activity or energy, it  may exalt the temperature
to the common febrile height, or to a height greatly exceeding that.
But, destitute  of life, there  does not appear to  be in the body any
source of heat, any power of generating it, that we are aware of.
Putrefaction had  not taken place in these bodies;  I believe I may
say it had hardly obscurely commenced.  Even if it had,  and had
made progress, and were it even at its greatest  height of  activity,
it is doubtful  if it would be equal to the production of the effect in
question?
  It may be matter of regret, that the temperature in the  two first
examples, was not ascertained  before  as well as  after death.   It is
only known  that the skin of No. I, the day he died,  was pungently
hot—the expression I believe  used  by Dr. White, the  zealous
medical officer under whose care he  was.  As the  weather at the
time was oppressively hot, and the sensations of those in health, as
well as of those  labouring  under disease, distressing more or less
in relation  to  heat, less  attention naturally would be paid  to the
degrees, and  there would  be the more difficulty in distinguishing
them, and saying this is natural,—that morbid.
  As the facts stand (and I  trust I may venture to call these obser-
vations  such), they may tend to put medical  inquirers  on their
guard relative to the extreme limits of  degree of animal  tempera-
ture, and especially of the blood and deeply seated parts.  If the
temperature of a body, as in No. 1, be 113°, three hours and a half
after death;  and, if generated during life, before death it must have
been  still higher.   Let  us  suppose some part  of this individual
inflamed, and  observations  made on the heat of the inflamed part;
it is easy to conceive that its temperature" might be found unusually 
     TEMPERATURE OF THE HUMAN BODY AFTER DEATH.   329

J1'?'1,—and greatly exceeding the average temperature of the body
in  health, or in ordinary disease.   If it were immediately concluded
that this was  an instance of the local generation of heat in  the
inflamed part,—it would be an assumption, and might be considered
an error.  And, have not observations of this kind been made and
published, and adduced as arguments in reasoning on animal heat,
as regards its theory ?
  Relative  to the majority of the examples in which the tempera-
ture of the dead body was ascertained, I shall avoid making many
reflections at present: I shall be  well pleased if they induce others
to continue an inquiry which may lead  to interesting results, both
as concerns physiology, and  perhaps pathology.
   The  temperature of a part, perhaps, may prove a safe  criterion,
ceteris paribus, of the quantity of blood which  passes  through it
in a given  time.  According to  this test, it may be inferred, that
the supply  of blood to the brain, in the  ordinary estimates of it, is
over-rated.
   May not the temperature  of the deeply seated  parts, after death,
give some insight into the manner  in which death has occurred, or
help to elucidate its cause?  In example No. 9, the  temperature of
the heart and  liver was  low.  Was  this connected with the  state
and function  of the lungs,  during the  latter period of life, when
much organic  disease existed in them;  when their functional action
appeared to be feeble, and the quantity of heat generated small?

Additional observations  on the temperature  of ihe  body after
                            death.

   The subject discloses, besides what have already been  adverted
to, other openings  for curious  and  perhaps useful  inquiry,  espe-
cially in medical jurisprudence.
   It may often be a question, how long a body has been dead.   By
attention to its temperature, particularly of the deep-seated parts,
taking into consideration the circumstances affecting temperature,
probably, in most instances, an answer may be given, approximating
to the  truth, and which may prove of considerable use in evidence.
   As the preceding observations were  all made in a comparatively
warm  climate,—it appeared to me desirable to extend them in this
country,—particularly in relation to the application  above  men-
tioned.  I shall now'detail  such additional  ones as I have had an
oppoitunity of collecting, all of  which have been made during  the
year 1838, in  the General Hospital, at Fort  Pitt, Chatham, on "sub-
jects similar to those on which the trials were instituted at Malta—
being  all soldiers.   It may further be premised, that immediately
after" decease, the bodies were removed from the wards, and were
kept in a room, covered merely with a sheet, in which the tempera-
ture was seldom more than  4° or 5° above that of the open air.
   I.—Aged 26; died of pulmonary consumption on the 17th Jan-
uary,  at 8 a.  m.  and  was examined twenty-eight hours  after. 
330
davy's researches.
 Emaciation  was not great.  The lungs were extremely diseased,
 presenting cavities,  numerous  tubercles, induration and  cedema,
 complicated  with ulceration of  trachea and large  intestines.   The
 quantity  of  blood generally was  small.  The temperature of the
 parts was trit-d in the order in which they are specified.
   Between the hemispheres of the brain in contact with the corpus
     callosum, immediately on removing the calvaria   -     46°
   Under  the left ventricle of heart (about an  ounce of fluid in
     pericardium)       -                                  52°
   In the cavity  of the right ventricle which contained a good deal
     of dark blood       ....      -     50i°
   In that of left ventricle which was nearly empty     -     51°
   Under lobulus Spigelii -----     50°
   In substance of liver  -----     50°
   In thigh, close to femoral artery, just before  it dips under the
     sartorius muscle    -----     42°
   Beneath the integuments of sole of foot      -      -     39°
   The thermometer  during the whole time in the open air was  at
 or below 30°; and in the morning early was as low as  13°.
   2.—Aged  19 ; died of  pericarditis on the 20th January, at 8 p. m.
 and was  examined  sixteen hours after.  The pericardium  was
 distended with 20 ounces of turbid serum, from which pus subsided
 on rest.   There was much  wasting;  little blood;  18 ounces of
 serum in the right pleura; 32 in the peritoneal cavity ;  cedema of
 limbs.
   Longitudinal sinus, containing fluid blood     -       -     30°
   Between the hemispheresin contact with the corpus callosum 51°
   In lateral ventricle    -----     51°
   At base, under pons varolii, the  brain in situ -       -     57°
   In  spinal canal, in which, and in  ventricle, pretty  much
     fluid        -      -      -       -              -     57°
   In serum of right pleura     -                           63°
   In fluid of pericardium      -                           65°
   Under the  left ventricle      -                           67°
   In fluid of  abdomen   -----     63°
   Under oedematous  integuments  of thigh, near the  artery as
    before      ......     470
   Near the artery in  calf  of leg  -       -      -       -     34°
   Under integuments of dorsum of foot -      -       -     32°
                    of sole of  foot    -      -       -     31°
   The atmospheric temperature  during the whole time was low. at
night below 20°, by day, never above  30°; the temperature of the
room where the body was placed, was 30°; when examined, it was
about 40°.
   3.—Aged 29;  died of pulmonary consumption on  the 26th Jan-
uary, and  was examined  eighteen hours  after.  There was great
emaciation ;  little blood;  there  were  the  ordinary lesions  in  the
lungs, with empyema of left pleura, and ulceration  of ileum and
caecum. 
   TEMPERATURE OF THE HUMAN BODY AFTER DEATH.     331

  In longitudinal sinus (calvaria unusually thin)       -     55°
  In lateral ventricle    -----     55°
  In upper part of spinal canal  -                          55°
  Under integuments of sole of foot    -       -       -     43°
                    of dorsum of foot -                   44°
                    of thigh close to artery    -       -     52°
  In purulent fluid of left pleura (46 oz.)        -       -     64°
  In right  ventricle, moderately distended with blood,  partly
    liquid, which afterwards  coagulated        -            63°
  In left ventricle, empty       -                          64°
  In central substance of right lobe of liver     -       -     65°
  The observations  were made in succession, without interruption.
in the space of five minutes.   The  temperature of the room the
greater part of the time was about 40°.
  4.—Aged 18 ; died of pulmonary consumption, on the 9th Feb-
ruary ; and was examined  twenty-nine hours after.  There was
great  emaciation ;  the lungs were  very extensively diseased,—
tuberculated, containing cavities, partially  cedematous, partially
hepatized ;  and the larynx, ileum and coecum were  ulcerated.
  In third ventricle of brain     -                          50°
  Under medulla oblongata     -                          50°
  In spinal canal, at its upper part      -       -       -     49°
  Under lobulus Spigelii        ...       -     56°
  In fluid of pericardium (about two ounces)   -       -     57°
  In right ventricle, which contained much blood      -     57°
  In left, nearly empty  -----     57°
  Under integuments  of  thigh, close to femoral artery  -     49°
  Under integuments  of  sole  of foot     -       -       -     47°
  The temperature  of the room, during the time, was between 38°
and 48°.
  5.—Aged 17  years ;  died  the 20th  of February, of peripneu-
monia ; and was examined  twelve hours and  half after.  The
right lung was greatly condensed, and weighed three pounds and
half;  there was sub-emaciation and cedema  of the lower extre-
mities.
  Between the hemispheres, on  corpus callosum       -     57°
  In lateral ventricles   -----     57°
  In upper part of spinal canal  -       -       -       -     59°
  Under the heart       -       -       -       -       -     67J
  Right ventricle, moderately distended fluid with blood, which
     afterwards coagulated       ...      -     64°
  Left ventricle, empty   -----     68°
  6.—Aged 24 years;  greatly emaciated;  died on the 30th  of
March, of peritoneal inflammation, with  ascites, variously compli-
cated, and was examined fourteen hours after.
  In longitudinal sinus  -----    62°
  In substance of right hemisphere     -              -    66°
  In  lateral ventricles   ....      -    64°
  In  upper part of spinal canal  -                          64° 
332
DAVY'S RESEARCHES.
   In the fluid in the abdomen (seven pounds)   -       -     73°
   Li right ventricle of heart     ...       -     73°
   In  vena cava ascendens under liver, which weighed five
     pounds     -       -       -              -       -77°
   7.—Aged 35 years; died 17th August, of malignant tumour in
 face, with  great destruction of the surrounding parts, including a
 considerable portion of each jaw-bone.  The body was  extremely
 emaciated, and contained very little blood.  It was examined  five
 hours after death ;  the temperature of the air of the room at the
 time was 68°.
   Between the hemispheres of cerebrum on corpus callosum  86°
   In  fluid of lateral ventricles, which was in  rather  large
     quantity    -       -              -       -        -     87°
   In cavity of pelvis     -----     90°
   Under lobulus Spigelii of liver       -       -       -     90°
   Under heart, within the pericardium -       -        -     94°
   Close to femoral artery, midway between hip and knee     77°
   Under integuments of  sole of foot     -       -       -     67°
   8.—Aged 40 years; died 18th August, of chronic dysentery, just
 after his return from the  West Indies.  The body was  sub-emaci-
 ated ; it contained pretty  much blood, and especially the abdominal
 viscera.   The examination was  made four  hours and  half after
 death.   The  temperature of the  air at the time was 68°.
   Between the hemispheres on corpus callosum         -    85°
   In lateral ventricle, which contained but little fluid    -    86°
   In upper part of spinal canal  -                          87°
   Under lobulus Spigelii of liver      -      -        -    97°
   In cavity of pelvis     -                                 97°
   Under left ventricle    -                                 93°
   In right ventricle, in which a good deal of frothy blood    92°
   In left ventricle, empty       -                          95°
   In middle of thigh, close to great vessels      -        -    82°
   Under integuments  of sole of foot    -                   69°
   9.—Aged 22 years; died I9(h August, (nineteen days after  the
amputation of his fore-arm, on account of  disease of the bone), of
complicated and severe organic disease,—chiefly latent,—as tuber-
cles and vomicae in the lungs,—abscess under the  scapula, commu-
nicating  with the shoulder joint, &c.  The body  was  greatly
emaciated,  and contained very little blood.   The examination was
made eighteen hours after death ; the temperature of the air at the
time 68°.
   Between the hemispheres of the brain on the corpus  callo-
    sum        -.-...    gg3
   In lateral ventricle    -      -      -      -       -    68°
   At base of brain, where there was a good deal of fluid, and
    in the  upper part  of spinal canal   -      -       -    68°
   Under liver   ------    ji°
   Under heart, within the pericardium -      -       -    72°
   In left ventricle, which was empty    -      -       -    73° 
            OBSERVATIONS ON THE ABSORPTION OF AIR.    333

  In right, in which was some blood    -       -       -     71°
  In thigh, mid-way between  knee and  hip, close to femoral
    artery      ------     G5°
  Under integuments of sole of foot    -       -       -     64°
  19.—Aged  26 years; died 19ih August, of pulmonary consump-
tion.  The body was sub-emaciated, and contained pretty  much
blood, which  was not coagulated.  The examination was sixteen
hours after death ;  the temperature of the room was 72°.
  Thermometer on corpus callosum    -       -       -     67°
  Under liver   ------     81°
  Under heart   ---.._     81°
  Under left ventricle   -                                 80°
  In right ventricle     -                                 80°
  In thigh, close to femoral artery      -       -       -     72°
  Under integuments of sole  of foot    -       -       -     66°

  These observations require little comment.  Their application to
the  use of medical jurisprudence, in  connection with the question
referred to, is obvious.  Although limited in number, (and it would
be tedious to extend them,) they may enable the inquirer, instituting
similar thermometrical  trials, and reasoning analogically, to arrive
at a tolerably  positive conclusion, in doubtful cases of death, as to
the time which  may have elapsed, between the fatal event and the
post mortem examination.
  Much  judgment, however,  and  nice discrimination  may be re-
quisite on the part of the medical man, in appreciating the circum-
stances  likely to modify temperature, so as to enable him, when
called on for  his opinion, to give one which will be satisfactory to
the legal officers, and to himself, on reflection.
                            XXIV.

AN ACCOUNT OF TWO CASES  OF PNEUMATHORAX WITH
  EXPERIMENTS AND OBSERVATIONS ON THE ABSORP-
  TION OF AIR, BY SEROUS AND MUCOUS MEMBRANES.

  The two following instances of Pneumathorax were communi-
cated to the Royal Society, not as medical cases, but on account of
the physiological questions connected with  them, and the  experi-
ments of the same kind which they gave rise to.   This alone could
have entitled them to a place in the Philosophical Transactions, in
which they were first published, in  the volumes for 1823 and 1824;
and  it  is this consideration  which  induces  me to include them in
the present work.
  Case I.—Abraham Iredill, a private soldier, of the 7th regiment
of foot, aged 30,  was admitted into the general military hospital, at
      12—d                                    22 dav 
334
DAVY'S RESEARCHES.
Fort Pitt, Chatham, on the 15th of January, 1823, labouring under
phthisis pulmonalis, which proved fatal on  the 11th of February.
  The disease in this its last stage exhibited some peculiarities, the
cause of which,  referrible to  pneumathorax,  was not discovered
until after death, for the case being considered  hopeless, and the
weather being very cold, the requisite examination of the chest was
intentionally  omitted.1  The body  was inspected  fourteen  hours
after death.   The right side of the chest exhibited a great  degree of
fulness;  and  it emitted, when struck, a hollow sound.   On  care-
fully opening the abdomen, the diaphragm was  found protruding
into the right hypochondrium, exhibiting a convex surface, almost
conical, instead of concave ; and it was tense and tympanitic. The
right lobe of the liver was  pressed into the epigastrium, and rented
on a portion of the stomach and duodenum, and on a part of the
transverse colon.  Owing  to the pressure of the liver, the  pyloric
portion of the stomach was  removed from  its  natural situation to
the left iliac region, where it rested on the upper part of the sigmoid
flexure of the colon ; and owing  to  the same pressure, the small
intestines generally were driven downwards and more or less dis-
placed.
  The body having been immersed in a bath, a small opening was
made with a scalpel under water, into that part of the right pleura
best adapted by situation to allow  of  the escape of air.  Air issued
out in  abundance, and with much force ;  212 cubic inches  were
collected in receivers, and  about  thirteen  cubic inches  escaped,
making altogether the enormous volume of  225 cubic inches.  The
air collected was set  aside  for analysis, and the body having  been
replaced on the  table, a portion of the ribs was removed  from the
right side to admit of the examination of the chest, the  water which
had rushed in to supply the place  of  the air  having been  carefully
taken out and preserved.
  The inner surface of the right  pleura was covered  with a thin
layer of coagulable lymph.  The  right lung was exceedingly com-
pressed ;  it adhered closely to the upper  part of the pericardium,
and  loosely to the posterior part of the  chest (about the sixth and
seventh ribs)  by a few strong bands.
  On inflating the lungs with a double  bellows through an opening
into  the trachea, the right  lung became much expanded, and air
was found to  pass freely from the  lung  into the pleura through an
ulcerated opening in the upper part of the superior lobe.
  The right lung was  carefully dissected out.  In  the upper part
of its superior lobe, a tubercular excavation or vomica was found,
of the capacity of about four ounce-measures, communicating with
the aspera arteria by a large bronchial tube, the ulcerated  end of
which  terminated in the side of the excavation opposite to the
openings by which the vomica communicated with the pleura.
  1 At this time, the stethoscope was not employed in the general hospital;
I first saw this excellent instrument the following autumn in Edinburgh,
and then commenced its use.             ''$& 
OBSERVATIONS ON THE ABSORPTION OF AIR.       335
  On examining minutely the communication between  the cavity
of the chest and the lung, a kind of valvular structure was discov-
ered,  allowing of air being pumped  into the pleura in  the  act of
inspiration ;  but not of its escape in expiration, to which no  doubt
was owing the great accumulation  of air.  Even  at the risk of
being tedious, I shall attempt to convey some idea of this structure.
Between the false  membrane of the vomica and the pleura, there
was a small irregular sinus, not exceeding an inch in diameter, the
sides of which,  though not adhering, of course were  in contact, or
very nearly so.   This sinus was the channel of communication, and
contained the valvular structure alluded to.  It opened into the
cavity of the chest by a hole in  the pleura  pulmonalis,  about the
size of a crow-quill, and into the vomica by three smaller holes in
the  substance of the lung, not  corresponding with the former, so
that a probe could not be passed from oue info the other in a straight
line;  and, consequently, when the surfaces of the sinus were  press-
ed together by the compression of the air in the pleura, in the act
of expiration, the passage through which the air entered was closed
and its exit prevented.
  A very brief notice of the other morbid appearances will suffice.
Besides the vomica described, in the right lung, this viscus contained
small  tubercles, few in  number  in  the inferior lobe, but abundant
in the superior.   The largest of them did not exceed' in size a com-
mon  pea, and the smallest were not larger than a  mustard seed.
The smallest were translucent;  the larger were of different degrees
of opacity; all of  them were solid; none  had suppurated.   The
left  lung was free from  adhesion.  Like  the right it  contained
numerous small  tubercles, which had  made very  little progress.
The bronchia were redder than natural, as was also the lower part
of the trachea.   Three ounces of serum were  contained  in the
pericardium, and a larger quantity of fluid than  usual in the ven-
tricles of the brain.  No air could be detected in the blood vessels,
or in  the cellular membrane of any part of  the body.
  To return to  the contents of  the right pleura ; the water  taken
from  this cavity (that which entered when the air was discharged)
was turbid, as if from the admixture of pus.  After resting twenty-
four hours in tall glass  jars, a white sediment formed, which, care-
fully separated by decantation, was about an ounce in quantity.  It
had the  appearance of pus, and exhibited  the properties of pus
when  examined by the most approved tests:—thus, it became viscid
with a solution  of muriate of ammonia;  it wassoluble in sulphuric
acid,  and precipitable  by dilution with  water;  and it  produced
coloured rino-s when placed between two surfaces of glass, and held
before a candle, according  to the method  recommended by Dr.
Youno-.  The decanted fluid, examined by a solution of corrosive
sublimate and by evaporation, was found to contain serum  ; and
iudgino-  from the  extract it afforded, it was about 11  ounces in
quantify, half an ounce of the decanted water having yielded, when
evaporated, 2-2 grains of dry residue. 
336
DAVY'S  RESEARCHES.
  The air collected from the pleura, had not the least  fetor, nor
indeed any smell.   It extinguished flame, and was not inflammable.
Examined  by means  of  lime-water and phosphorus, (which  was
sublimed in it without, effect,) 100 parts of  it were  found to consist
of 8 carbonic acid gas, and 92 azotic gas.
  Whence this air was derived became a question for consideration.
Reflecting on the  communication, discovered by dissection, between
the pleura and the atmosphere through the medium of the lung, it
seemed  almost demonstrated, that  the air was atmospheric  air
altered.
  The next question was, how the alteration had taken place; what
had become  of the oxygen  which had disappeared; whence the
carbonic acid gas with which the azote was mixed ?
  To endeavour to learn how the oxygen had  disappeared, the
following experiment was instituted.   The right pleura of a dog
was inflated with atmospheric  air, by means of a double bellows,
and the incision through which the air was introduced was closed
by  a suture.   At  the end of forty-eight hours, the dog was killed.
An  hour after death, the pleura was punctured under water, and
about 8 cubic inches of air were collected.  This air, examined by
means of lime-water and phosphorus,  was found to  contain slight
traces of carbonic acid gas,  and to consist of 93 parts azotic gas,
and 7 oxygen £as.  The wound in the pleura was closed by coag-
ulable lymph, and the pleura was found free from inflammation.
   The result then of this experiment seems to show that the oxygen
was absorbed in  greater proportion than the azote, and  thus tends
to account for the accumulation of the latter gas in  the preceding
case.
   It may be said, that the experiment does not warrant the infer-
ence, that any azote was absorbed ;  and, consequently, that the
expression "in greater proportion," is incorrect.   The absorption of
this gas is probable, however, though not demonstrated in  the pre-
sent instance, as Sir Astley Cooper has  found, that  common air
introduced  into the cellular membrane, and into the cavity of the
 thorax  and  abdomen of dogs,  is,  after   a certain  time,  entirely
 removed  by  absorption.1
   Relative  to the  source of the carbonic acid gas, it  is easy to
 conceive that this gas was formed, or emitted in the air cells of the
 lungs, as in ordinary respiration ;  and that  mixing with  the air
 inspired, it was received into the pleura.   If thus derived, and not
 from the surface  of the pleura by secretion, it seems to follow, that
 it is less readily absorbable by the pleura, than oxygen.   To endea-
 vour to decide this point, the following experiment was  made.
    About 30 cubic inches of air, consisting of 80 parts common air,
 and 20 carbonic  acid gas, were passed from a receiver into a bladder,
 furnished at  one extremity  with a stop-cock, and at the other with

   1 Surgical and Physiological Essays, by John Aberhethy, p. 55.  London,
 J793. 
          OBSERVATIONS ON THE ABSORPTION OF AIR.      337

a small  trochar; both  air-tight.   A small  incision  having  been
made through the integuments of the  right side of the chest of a
dog, the  trochar was  passed through the intercostal  muscles into
the pleura.   The stilette was immediately drawn from the canula
into the bladder, and the air of the bladder instantly rushed into the
pleura, and, on expiration,  was in part  forced back into the bladder.
The exact quantity of air retained was not determined; it  must
have exceeded at least ten  cubic  inches.  As speedily as possible
the canula  was withdrawn,  and  the  external wound  carefully
closed by suture.  The health of the dog was very little impaired
by the operation.  Two days after, when the animal appeared to be
quite well, a  similar experiment was made  on the left side of the
chest, and a  mixture, consisting  of 75 parts common air, and  25
carbonic acid gas, was introduced into the pleura.   The operation
had very little more effect than the former.   At the end of twenty-
four hours, the dog was killed, and immediately examined. About
three cubic  inches of air only were procured from the left pleura,
whieh were found to  consist of
              183 carbonic acid  gas,
              78 3 azotic gas,
               3-4 oxygen gas;
whilst the air admitted  consisted  of
              200 carbonic acid  gas,
              63-2 azotic gas,
              16-8 oxygen gas.
   Thus apparently showing,  that during a sojourn of three days
in  the pleura, the oxygen had been absorbed in a greater degree
than the carbonic acid gas  ; and  the latter, in a greater degree than
the azote.   The result of the experiment  on the left pleura was
very similar ; it afforded ten  cubic inches of gas, consisting  of 25
carbonic acid, 70 6 azote, and 4 4  oxygen.   The appearances, on
examining  the wounds, were satisfactory:  the. cavity of the  chest
was free from inflammation, the lungs uninjured, and the cicatrix in
the pleura only just perceptible.
   The  results of these experiments seem to warrant the conclusion,
 that, in the preceding case,  the  carbonic acid gas found, was  not
derived from the surface of  the  pleura by secretion, or exhalation,
but from the respired air, through the ulcerated opening.  And, with
this remark, I shall dismiss the case of pneumathorax,—the  consi-
deration of which, as a medical  subject, would not be appropriate
 in this  place.
   The power exhibited by the pleura, in  the preceding  instances,
 of absorbing gases,  and the manner in which  it exercised that
 power, in a "greater degree, on one air  than  on another, and that in
 no ratio to their solubility in water, appeared to  me so interesting
 and novel, that I was induced to prosecute  the subject a little  fur-
 ther.   With the same apparatus,  I made similar experiments  on
 the admission of three other gases into the pleura of dogs,  viz.— 
338
DAVY'S RESEARCHES.
 hydrogen, nitrous oxide, and nitrous gas,— the results of which I
 shall briefly describe.
   About twenty cubic inches of a mixture, consisting of 575 parts
 carbonic  acid gas,  and 425 hydrogen, were admitted  into the left
 pleura of a  dog, in the manner, and  with the  precaution, already
 noticed.   The health  of the animal was not apparently affected.
 At the end of two days, about  thirty cubic inches of a mixture,
 consisting of 44-5 azote, and 555 nitrous gas,  were passed  into the
 right pleura.  Immediately the dog's  breathing became quick and
 short, but not laborious.  It  refused to  eat,  and expired in the
 evening, at the end of five hours  from  the time  that  the  air was
 introduced.   The next morning the body was examined.  About
 six cubic  inches of  air were collected  from the left pleura,  consist-
 ing apparently of 12 carbonic acid, and 88 azote. After the removal
 of the carbonic acid gas, by lime-water,  the residual gas extin-
 guished flame, and  was not itself the least inflammable; and hence
 the inference,  that it was azote, or, at least, principally azote, as the
 presence of  a  small quantity of hydrogen might be concealed, and
 escape detection.  From the right pleura, about 5  cubic  inches of
 air were procured,  which  consisted of 69 nitrous gas, or air ab-
 sorbable by a  solution of the green sulphate of iron, and of  93-1
 azote.  On opening the chest, the wounds in the pleura were found
 closed ; the  pleura  were of natural appearance ; the substance  of
 the left lung was redder than usual, and  that of the right was  dark
 red, and it contained a good deal of blood and serum.  The bron-
 chia  did  not exhibit decided marks of  inflammation.  The  right
 auricle and ventricle, and venas cavse, were distended with grumous
 blood ; and  the  left auricle and ventricle, and aorta, contained a
 good  deal of liquid  blood, which, as well as that of the venous sys-
 tem, had lost its peculiar tini, and had acquired a chocolate hue.
   The obvious results of these  two experiments, on the same dog.
 are,— 1st,  The absorption of the greater  part of the carbonic  acid
 gas and the  whole of the hydrogen introduced into the pleura,and
 the appearance, de novo, of a  considerable quantity  of azote  ; 2d,
 the death  of the animal, in the  space of  five hours, from the  time
 of admission of the  nitrous gas and azote into the  opposite pleura ;
 the absorption  of the greater part of the former gas, without  inflam-
 mation of the membrane  with which it was immediately in contact,
 and the production of a peculiar change in the blood
  Results so singular required to be narrowly scrutinised.   I  have
 twice repeated the experiment on the  admission of hydrogen  into
 the pleura of dogs, and in each  instance, after death, I  found  that
 the hydrogen had disappeared, and that its place was supplied  by a
 small quantity of azote.
  Did the azote  found, in these instances, exist in the pleura pre-
 vious to the experiment?
  A remark  of Dr.  Laennec would seem to countenance this no-
 tion.   Me says,—" M.  Ribes assures  me,; that he has found, on
opening the serous  cavities of dogs, a small quantity  of air  con- 
          OBSERVATIONS ON THE ABSORPTION OF AIR.       339

stantly to escape."1   On the contrary, in opposition to this, are the
experiments of Haller and other accurate observers, recorded in the
controversy which  Hambergerus gave rise  to,  by reviving and
maintaining the opinion of Galen, that air is contained between the
lungs and pleura.2
< In doubt  between these contending authorities,  with the desire of
satisfying myself on the point,  I  have made some experiments on
dogs, the results of which convince me, that, in a healthy state, no
air  is  contained in  the pleura of this animal.   When  I opened
under  water the chests of dogs  killed by drowning, not the smallest
globule of air escaped ;  but when the right side  of the chest was
opened in the atmosphere, an appearance  presented, at first favour-
able to the idea of a little air  being contained  in the left pleura, for
the mediastinum was pressed from  the left side towards the right
(the body lying  on  the left  side) evidently by air within the trans-
parent membrane.   This appearance, on examination,  proved to be
fallacious, for  the air was found to be not in the left pleura, but in
a cavity of the mediastinum communicating with the right pleura,
and containing a lobule of the  right  lung, dextri pulmonis addiia-
mentum, as Haller calls it, who  has noticed this  structure  in  the
mediastinum of the dog and many other animals, and pointed it out
as one of the  principal causes  of the erroneous  notion which he
combated.3
  Was the azote derived from  the blood as an exhalation  or secre-
tion ?
  Facts might be advanced in  favour of this idea.  An exhalation
or disengagement of azote appears to have taken place  in the experi-
ments  of Messrs. Allen and Pepys, when  oxygen, nearly pure, was
respired.4   In the inspection  of dead bodies, air has frequently been
found in the vessels and closed  cavities; which is probably azote.*
  1 A Treatise on  the Diseases of the Chest, &c. translated from the French
of R. F. H. Laennec, M. D. by John Forbes, M. D.—p. 208.
  2 Haller's Not. in Praelect. Boerh. D. C. vi.—Haller's Opuscula Anatomica
de Resp. Gott. 1751,  p. 91 and 345.—Marherr's Praelect. in  Boer. Inst. vol.
iii.  p. 391.
  s Haller's Opuscula Anat. p. 44.
  4 Philos. Trans, for 1809.
  6 Vide Morgagni de  Sed. et Caus. Morb. Ep. v.; and  Trans, of a society
for  the  improvement of Med. and  Chir.  Knowledge, vol. i. in which an in-
teresting "Case of Emphysema,  not proceeding from local injury," is given
by Dr.  Baillie.
  Notwithstanding the experiments detailed by  Sir Everard Home, in ins
Croonian Lecture, published in the Phil. Trans, for 1818, I  am induced  to
believe that the gas in question is azote, rather than carbonic  acid ;—because
the alkali in  the blood is not saturated with carbonic acid ; because the serum
of the blood is capable of absorbing carbonic acid gas, rather more even than
water, as I have ascertained by experiment; because, during the coagulation
of blood spontaneously, and the coagulation of serum by heat, I have never
observed carbonic acid  gas to be disengaged, when the experiments were pro-
perly made in vessels  to which air  could  not have access, as in tubes com-
pletely filled with blood or serum,  and inverted  in blood or  mercury; and
lastly because  I have  not been able to procure carbonic  acid  gas from blood 
340
DAVY'S RESEARCHES.
   It has been asserted lately, that air thus  found is, in every in-
stance, the consequence of putrefaction.   But surely the accurate
Morgagni was not  so  egregiously deceived.  Many  times, I have
noticed air in the vessels of the pia mater, in bodies only a few hours
dead; and very  lately  I detected some in  the internal jugular vein
of a body that had  been dead only 18 hours, and free from every
mark of incipient putrefaction ; and I lay  the  more stress  on this
observation, because it was very carefully made, before any large
vessel was divided through which air could gain admission.  Fur-
ther, air seems to pass pretty readily from the air-cells of the lungs
into the pleura.  Is not this proved  by an experiment of Hales?1
And an experiment which I have  made, and which I may briefly
notice, seems to  afford some proof of it.   Immediately after death,
before the muscles had lost their irritability, I inflated the lung of a
dog under water, by means of a double bellows, through the trachea.
Air, in exceedingly minute bubbles, escaped  from the surface of the
pleura covering one of the inferior lobes; and, on making gentle
pressure with the  fingers  on any part of the  inflated  viscus, the
same appearance presented itself.
   These circumstances, which  I have ventured to bring forward as
somewhat favourable to the idea of the secretion or exhalation  of
azote, are still far from conclusive.  After having given the subject
all the attention  in my power, I do not venture to draw a positive
conclusion.   I have thought it  right to state  what 1 have observed
relative to a topic  so interesting and  obscure, and to notice such
facts as seemed to bear more immediately on the question, in hope of
exciting further  inquiry, by which alone the true source of the azote
apparently evolved  in  the preceding instance can be ascertained.
   The effect of  nitrous gas introduced into the pleura now requires
consideration.   I have made  several trials  farther with this gas.
When  admitted  nearly pure into the pleura, it produced very serious
symptoms; but did  not prove fatal, provided the lung on the oppo-
site side was free to act.   The  distressing symptoms usually sub-
sided in about twelve hours, and then, on killing the animal, the
greater part of the nitrous gas was found to be absorbed ; the pleura
was free from inflammation, the substance of the lungs very slightly
inflamed, and the blood exhibited a brownish hue.  From these cir-
cumstances  it may  be conjectured  that nitrous  gas produces its de-
leterious effects,  after it has been absorbed, eiiher by acting on the
blood immediately,  or  on the  air-cells of  the  lungs and the blood
just drawn from the vessels, and still warm, when placed under a receiver
and completely exhausted of air.  I may here remark, that I have made two
experiments on blood in vacuo, and in  both with the same negative results.
In one instance the arterial blood of an ox was employed; in the other  the
blood of a man in  health.  In the former, eight  ounces were used ; in the lat-
ter, one ounce.  In both  instances, the blood remained perfectly tranquil
when the vacuum  was as complete as could be made with a good air-pump,
and of course did not  exhibit the slightest traces of  the  disengagement of
any air.
  1 Vide Stat, Essays, i. 252. 
           OBSERVATIONS ON THE ABSORPTION OF AIR.       341

 conjointly, when converted into nitrous acid in the course of the
 pulmonary circulation.
   On the admission of nitrous oxide into the pleura, I  have made
 one experiment only.   About 30 cubic inches of this gas, contami-
 nated with 25 per cent, common air, were passed into the pleura of
 a dog.  The animal exhibited no uneasy feeling, and immediately
 after appeared  to be rather exhilarated.   It continued apparently in
 good health  for 24 hours, when it was killed.   Five cubic inches of
 air were procured from the pleura, which consisted of 10 per cent.
 oxygen, and 90 azote, being quite deprived of nitrous oxide.  The
 pleura and lung exhibited no unusual appearances which could be
 referred to the gas absorbed.
   Mr. Abernethy, in his ingenious Essay on the Functions of the
 Skin, has proved that that texture is possessed of a power of absorb-
 ing and exhaling certain gases, which  it exercises according to laws
 peculiar to the animal economy.1   The preceding experiments seem
 to show that the  pleura is possessed of a similar power in respect to
 absorption, and that in exerting this power, like the skin, it acts with
 greater energy and  effect on one  gas  than  on  another.   Whether
 the analogy  will  hold good as regards exhalation also, must be  de-
 cided by future inquiry.2
   Reflecting on  the preceding experiments  on the absorption of
 different kinds of air introduced  into the pleura, it appeared probable
 that mucous membrane, like serous membrane and  the skin, may
 possess  the power of absorbing  air.   In relation to this view,  I
 thought it worth  while to examine the air contained in the antrum
 maxillare, and  in the frontal sinus.  I chose for the experiment  the
 head of the sheep, in which these cavities are large, the openings by
 which they communicate with the atmosphere small, and the mem-
 brane by which  they  are covered an active  secreting surface.   I
 collected the air by perforating  the  cavities under water, about
 fifteen minutes after the death of the animal.   In two different  in-
 stances, the results of the examination of the air were the following:
 the air from the antrum maxillare in one instance consisted of
                        4-3 carbonic  acid,
                       130 oxygen,
                       82-7 azote.
   From the frontal sinus, of
                       135 oxygen,
                       86-5 azote,
  1 Surgical and  Physiological Essays, Part 2, by John Abernethy.
  2 When the experiments were made, which are detailed  in the preceding
pages, I was not acquainted with the ingenious and elaborate researches of
M. Nysten on the injection of different kinds of gas into the blood-vessels
and into the pleura, as described in his excellent work,  "Recherches de Phy-
siologic et de Chimie Pathologiques," published in 1817.  The results I have
obtained in most respects agree with his.  Had he examined the residual  air,
and ascertained its  composition, after the death of the animal experimented
upon, the value of his researches, great as  it  is already, would have been
much enhanced. 
342
DAVY'S RESEARCHES.
without any carbonic acid gas, the absence of which may have been
owing to there being a good deal of mucus in the cavity ;  the mucus
might have absorbed it.
  In another instance the air from the antrum  maxillare consisted
of
                        4-2 carbonic acid,
                       13-8 oxygen,
                       820 azote.
  From the frontal sinus, of
                        45 carbonic acid,
                        9-5 oxygen,
                       860 azote.
  On  the supposition that the  air.  previous to its entering these
cavities, had undergone a partial change  from  respiration, the re-
sults described seem to indicate an absorption of oxygen.
  Other facts  might be adduced, which, like the preceding, though
not conclusive, tend to support the idea, that mucous membranes
are capable of  absorbing air.   Of this kind, I conceive, are the results
of the experiments of MM. Magendie and  Chevreul, on the compo-
sition of the air contained in the human stomach and intestines;1
and very recently I have met with a fact,  the bearing of which ap-
pears to me similar.   In examining the body of a soldier, who had
died of complicated disease, I found the coecum exceedingly distend-
ed with air, and of a bright red colour, as if highly inflamed,  whilst
the ascending colon was unusually contracted.   The air collected
under water amounted to thirty-six cubic  inches, and consisted of
11 carbonic acid, or air absorbable by lime-water, and of 89 chiefly
azote, judging from its extinguishing flame,  and not being itself in-
flammable.  I had not the means  of ascertaining if any traces of
carburetted hydrogen were present.
  The question, whether mucous membranes are capable of absorb-
ing gases, I need not say, is one of great importance in relation to
the theory of respiration, and on that account deserving of particular
attention.   The theory which in 1823 was most generally adopted,
is recommended by its simplicity, but is not  well supported  by the
analogies and  facts of physiology, which seem to favour the doctrine
of the absorption of oxygen into  the blood, and the evolution of car-
bonic acid; and that perhaps, not in  the air-cells of the lungs alone,
but likewise along the  whole tract of the primae viae, and over the
whole of the external surface of the body.2

  1 Ann. de Chim. et Phys. ii. 292.
  2 Many facts  which, since  the above  was written,  have been brought  to
light, especially by the researches of Dr. Edwards, might be adduced in cor-
roboration of the remark in the text.   In the winter of 1838, I examined the
series of cells, filled with air, which occur in that beautiful osseous structure,
the vertebral column of the wild swan. The contained air, I found  composed of
                          83-3 azote,      ■ .%
                          167 oxygen, >■ 
          OBSERVATIONS ON THE ABSORPTION OF AIR.      343

  Case  II.—Patrick Calnon, of the 50th regiment, was admitted
into the General Hospital at Fort Pitt, on the 9th of May, 1823, on
his  return from Jamaica, from whence he was sent home invalided
on account of hasmoptysis, attributed to a severe fall on the left side
of the chest  eighteen months previously.  Before  the accident, his
health had been uninterruptedly good.
  Until the  13th of May, his complaint exhibited nothing peculiar.
Early on the morning of that day, after a violent fit of coughing,
the  symptoms of pneumathorax began to appear ; and they continu-
ed to increase until the 21st.   The most prominent symptoms were,
a feeling of extreme tightness about the chest and abdomen;  rapid
and difficult respiration, between  30  and 40 in  a minute ;  great
anxiety of countenance and  agitation of mind, accompanied with a
small  pulse of 130, cold sweat on the face and neck, and much pros-
tration of strength.  On examining the chest, the left side was found
more  protuberant, and in all its dimensions larger than the right.  It
was tense, and on percussion sounded  remarkably hollow and tym-
panitic.  The heart was felt beating on the right side, even under
the inamilla.
  Satisfied that the distention, and the  distressing symptoms ac-
companying it, resulted from air in the pleura,—reflecting on  the
suddenness of the  attack, the tolerable  health the patient was in pre-
viously,  and the now imminent danger of life,—I  proposed in  con-
sultation the operation  of paracentesis,—which  was approved  of,
and, with the ready assent of the suffering patient, immediately per-
formed.
  With a small trochar, attached to a flaccid bladder, I carefully
perforated the left side of the  chest,  between the 8th and 9th rib,
having  previously divided the integuments  with a scalpel.   On
withdrawing the stilette, a little air rushed out and was collected in
the bladder, but not in the quantity that I expected;  it did not ex-
ceed 5 cubic inches.   On examination it was  found to consist of
azote, and a little carbonic acid.
  Conceiving that the operation had  failed  in  consequence of ad-
hesions in the part of the pleura punctured,  and encouraged by the
composition  of the air collected, and the slight  relief which  the
patient experienced, a repetition of the  operation was decided on,
and performed  the next day.
  The chest now  was perforated, just below the  left papilla.   On
withdrawing the stilette into the  bladder, a large quantity of air
rushed out and distended the bladder ; and on separating the bladder
from the canula (by cutting  it off, after  having secured the air in
the former by a  tight ligature) air from the chest, for several seconds

  The examination was made two days after the bird had been shot: pro-
bably during life, the proportion of azote is  greater.  Probably, wherever air
penetrates in  birds, whether into  the abdominal air-cavit:es, or ihe osseous
ones, there is a continued absorption of oxygen going on, giving rise to seve-
ral effects connected with the economy of this class of animals, as buoyancy,
high aeration of blood, and high animal temperature. 
344
DAVY'S RESEARCHES.
continued to rush out with violence.  When the rush ot air  had
ceased, and it was found that air began to pass  in on  inspiration.
the canula was withdrawn, and the  wound was closed by adhesive
plaster.
  The patient experienced sudden and great relief, exceeding his
power to express.1
  For about a month after the operation, the patient continued  pro-
gressively to improve.  On the 17th of  June, he was as well as
when first admitted into hospital.   His appetite was good, and his
cough little troublesome.   He could lie on the  left  side, which he
was unable to  do many months prior to the operation. Both wounds
were healed.   The left side of the chest was  diminished consider-
ably in  volume, and was  much less tense and  tympanitic.  The
heart, however, was still felt pulsating on the right side, and a fluc-
tuation  of fluid in  air could be heard in the left side, on shaking, or
suddenly  moving the body.
  The following week the symptoms were less favourable, and those
of hydrothorax especially were more severe.  When the patient at-
tempted to lie on the right side, he was instantly seized with a fit of
coughing; and when the body was shaken, the sound of fluid fluc-
tuating  in air  in the left pleura was distinctly audible even at the
distance of several  yards.
   As the  patient's health was pretty good, it was deemed advisable
to repeat the operation of paracentesis and draw off the fluid, before
the case became desperate.
   Having, in cases of empyema, found some inconveniences attend-
ing the  puncturing of die pleura, between an intercostal space, I was
induced, in this instance, to follow the method described by Hippo-
crates, of perforating one of the ribs.2  The fifth rib was selected ;
and having cut down upon if with a scalpel, just below the papilla
of the breast, I bored through its substance with a carpenter's auger,
and punctured the pleura  with a small trochar,*as nearly as possible
of the same size as the auger.   On  withdrawing the stilette, it was
followed by a  stream of transparent fluid, fourteen ounces of which
were allowed to escape; and, then, leaving the  canula in the per-
foration, it was closed with a  cork, and secured by proper dressings.
   Daily, during six weeks, more or less fluid was discharged through
the opening in the rib, amounting,  altogether, to more than twenty
pints.   At first, the fluid was transparent, of specific gravity 1021:
it coagulated when heated, and contained some alkali in the state of
sub-carbonate.   In a few days pus appeared in it,and gradually in-
creased in quantity until the  15th of July, when the discharge was
almost entirely purulent;  after which time,  the proportion of pus
and serum varied considerably,—one  sometimes predominating,—

   1 The air collected in the bladder amounted  to 25 cubic inches.   Examin-
ed by means of lime-waterand phosphorus, it was found to consist of 93 azote,
and 7 carbonic acid; it had no offensive odoui, or odour of any kind.
   2 Hippocrat. de intern, adfect. cap. xxiii. 
          OBSERVATIONS ON THE ABSORPTION OF AIR.      ?A5

sometimes the other.  It may be deserving of notice, that at no time
was I able to detect free carbonic  acid in the fluid discharged.
  Although, from the sound of fluctuation in the chest, air was evi-
dently contained in  the pleura, yet none escaped with the fluid
during the first fortnight;—afterwards a considerable quantity was
daily expelled.  By means of the perforation in the rib, and using
a flaccid bladder, furnished with a trochar, I could, at any time, col-
lect this air for examination, with perfect ease.
  The first portion collected  (about twenty  cubic inches) was  on
the 15th of July ;— examined by means of lime-water and phospho-
rus, it was found to consist of
                       7-5 carbonic acid,
                       2-5 oxygen,
                      900 azote.
  The second portion collected  (about thirty-five cubic inches) was
on the 20th July;  it consisted of
                       60 carbonic acid,
                       5-5 oxygen,
                      885 azote.
  The last portion  collected (about forty cubic inches) was on the
29th of the same month ; it consisted of
                       80 carbonic acid,
                       40 oxygen,
                      880 azote.
  For some days  after the operation of paracentesis, the health of
the  patient  deteriorated;  his  appetite  diminished; and he had
feverish symptoms, but unattended with rigors. At the time, judg-
ing from the  increasing proportion of pus which appeared  in the
fluid discharged, the pleura was probably undergoing inflammation,
though the side affected was quite free from pain.  Gradually these
symptoms subsided;  and, on the 15th July, he felt  better than
before the operation ; he  had  less difficulty of  breathing,—very
little cough,  and  he could lie  on either side.  His  improvement
was progressive until the 23d July;—afterwards  his health again
became worse, his appetite impaired and his spirits low; he had
slight pyrexia, and a feeble pulse, varying in frequency from 90 to
120.  This  unfavourable change was  attended with the emission
of a large quantity of air from the pleura, and with  an alteration
in the character of the fluid discharged,—which had  become more
purulent,  of a greenish  hue,  and of an offensive  odour.   The
patient expired suddenly on the 29th July.
   The body  was examined twelve hours after death.   The  cavity
of the abdomen having  been laid open, the diaphragm was found
slightly protruding into the left hypochondrium, without displace-
ment of any of the abdominal viscera.
   The body  having been immersed in  a bath,—on puncturing the
left  pleura, between the first and second rib, air to the amount of 
346                  davy's researches.
 one hundred and seventy cubic inches-issued out. and was collected:
 it consisted of
                       160 carbonic acid,
                        1-5 oxygen,
                       825 azote.
   The left pleura  contained  besides about six ounces of pus,—so
 much having subsided  from  the water, which entered the chest to
 supply the place of the  air.
   The right pleura was quite free from disease.  The right lung
 appeared  to  be healthy,—but, on  minute examination, numerous
 granular translucent tubercles were detected, disseminated through
 its substance, and two small vomicae were found in the upper part
 of its superior lobe.  The heart was displaced :  it was situated on
 the spine, inclining a little to the right side, and the position  of the
 greater  part of the oesophagus was similar.  The pericardium was
 firmly attached  to  the  middle  lobe  of the  right lung by  a firm
 adventitious  band.   On  exposing to view the  left  cavity of the
 chest, the  inside of the pleura exhibited  a surface  of milk-white
 granular coagulable lymph, about two lines thick, equally diffused
 on the  costal and  the  pulmonic side.  Excepting  the  cicatrices
 externally in the skin, no traces could be  detected of the first two
 operations, nor was there any mark of the last operation,  exclusive
 of the small opening that had been  carefully kept open, just large
 enough  to admit the trochar, which  had been daily introduced to
 draw off the fluid  and  allow the air to escape.   On  maceration of
 the rib, it may be remarked, a very narrow ring of bone was found
 exfoliating from the perforated part.  The left lung was very much
 condensed, and so  firmly confined  by its thickened pleura, that it
 did not  dilate when  air was  driven  into it with some force-by a
 double  bellows  attached  to  the  trachea.  This experiment was
 made  with the lung  under water, for the  purpose of ascertaining,
 if any,  and  what kind, of  communication,  existed between  the
 lung and the pleura, with a view to discover the origin of the air
 accumulated  in  this  cavity.  Two communications were  thus
 detected; one in the inferior, the other  in the superior  lobe:  the
 former was so exceedingly small  that it could not be traced.  The
 latter  opening was sufficiently large to admit a surgeon's probe,—
 and its course was easily followed.  It was found to  communicate
 obliquely with a ruptured opening in the side of a large bronchial
 tube, situated immediately under the pleura.   No cavity could  be
detected there.   The adjoining pulmonary substance appeared  to
 be condensed from compression : the substance of the lung gener-
ally was  in the same state;  it contained  a few minute tubercles;
 and no other traces of disease.
   In the fatal case of Iredill, before  described, pneumathorax took
place  in consequence  of ulceration  effecting a communication
between the  cavity of the pleura and a vomica in  the  lung.   In
this instance, the disease originated without the  intervention of a 
          OBSERVATIONS ON THE ABSORPTION OF AIR.       347

vomica,—but, whether without ulceration, connected with the soft-
ening of a minute tubercle, is doubtful.   When I first considered
the case, I was disposed  to attribute the communication to the rup-
ture of a superficial  bronchial tube, and to express surprise that
accidents of this kind are not more common, taking into account
the large number  qf.  bronchial tubes which  lie immediately under
the pleural covering  of the lung,—the delicacy of the membrane,
and the facility with which  it and the bronchia are ruptured.   The
accuracy of this view appears to  mo now very questionable, inas-
much, as the  delicate pleura has, in  its  healthy state, always the
support of the parietes of the chest, and being constantly in contact
with the costal pleura, the  risk of its rupture may be supposed  to
be exceedingly small.
  In a professional point of view, it might be an interesting though
not an easy task, to trace the different steps of the disease, of which
I have given a brief history, from  its commencement to its termina-
tion, and connect  the symptoms with the organic changes which
occurred.   As  more  appropriate  to this place, I shall confine the
few remarks I have farther to make, to the air  procured  from the
pleura.  The following table exhibits, at one view, the composition
of the air collected from  the chest at different times.
When Collected.	COMPOSITION.		
	Carbonic Acid.	Oxygen.	Azote.
May 21 July 15 „' 20 „ 29 „ 30	7 7-5 6 8 16	2-5 5-5 4 1-5	93 93 88-5 88 82-5
   To what were these variations in composition, which the table
exhibits, owing?   I cannot conceive that they depended entirely
on the  admission of variable quantities of atmospheric air  by the
external opening; because exceedingly little atmospheric air could
enter through that channel,  both from the great care taken to ex-
clude it, and from the valvular nature of the passage.1  I believe
we must look chiefly to the source of the air, and  the absorbent
power of the pleura for the explanation in question.
   In this case, as in IredilPs. there is reason to suppose that the air
accumulated in the chest was common air, more or less vitiated by
respiration previously,  and  more or less altered by the process of
absorption  after  entering the cavity of the pleura.   Taking this
view of the subject, ihe composition of the air, each time it wa

  1 The  perforation being slightly oblique,  the pleura costalis  lined  with
coagulable lymph, closed the external aperture in the rib on expiration, and
prevented completely the  egress of air,  even when the dressings were re-
moved and the external aperture uncovered.  When the trochar was intro-
duced,, the stilette was withdrawn during expiration, and the finger was ap-
plied to the  mouth of the canula during each inspiration. 
318
davy's researches.
examined,  is easily accounted  for,  excepting in the  last instance,
when the proportion of carbonic acid gas was found to be so large,
after death.  On what  this depended  it is  not easy to say; it is
matter for conjecture, and  seems to require further  investigation.
Messrs. Allen and  Pepys,  after a forced expiration, found air from
the lungs to contain  as much as 9-5 per cent.^arbonic acid gas;1
and  in the different instances that  I have examined  the air con-
tained in the lungs a  few hours after death,  I  have found the pro-
portion of carbonic acid gas to vary from eight to twelve per cent.;
thus, in a fatal case of empyema, the air procured  from one lung,
which was sound,  consisted of
                       8-3 carbonic acid,
                       50 oxygen,
                       86-7 azote:
that from the other lung, which was in  part condensed, and as it
were hepatised, of
                       12-5 carbonic acid,
                       20 oxygen,
                      855 azote:
whilst, in  another  case, in which one  lung was sound, and the
otfier abounded  in minute cavities full of pus—air from the sound
lung consisted of
                       12-2 carbonic acid,
                       3-0 oxygen,
                       84-8 azote.
  Had the proportion  of carbonic acid gas, in  the  instance under
consideration, been within these limits, the explanation would have
been attended with little difficulty; but, exceeding these limits, one
is almost, disposed  to  refer  it to exhalation  or  secretion  from the
pleura.  And if, at the same  time, we suppose, that a similar ex-
halation took place into  the bronchia, it might account for the sud-
den death.
  In support of this idea of the secretion or  exhalation of air into
closed cavities, in addition to  what has been  already stated,  I may
notice the two following instances,  which have since come under
my observation.
  On the 23d of May, 1823, on examining the body  of a soldier,
who had died of chronic dysentery, complicated with an ulcer in
the larynx, the cellular  membrane  in both  mediastina was  found
vesicular and distended  with  air.  The vesicles were burst under
water, and  a half cubic inch of air was collected, which was found
to consist of
                       7 oxygen,
                       4 carbonic acid,
                       89 azote.
1 Phil. Trans, for 1808. 
          OBSERVATIONS ON THE ABSORPTION OF AIR.       349

  The surrounding parts were carefully examined ; particularly the
trachea, lungs and oesophagus, but  no passage could  be detected
through which air could have entered the mediastina: nor could
any air be forced into them by distending the lungs by means of a
double bellows.  It may  be, that the  oxygen found in  the mixed
airs was extraneous, and derived partly from common  air adhering
to the surface of the cellular membrane, and partly from air of the
atmosphere penetrating through  the delicate  vesicles during the
preparatory dissection,  when they were exposed to  its influence, for
half an hour at least.
  On the 2d of June of the same  year, in examining  the body of
a soldier, aged 36,  who had died of tubercular consumption, I found
air-vesicles on the  surface of the  lungs, similar to those described
by Dr. Baillie in his Morbid Anatomy ;J and considered  by  him as
resulting from the  secretion of air, and not from the extravasation of
air under the pleura, agreeably to the opinion advanced  by Laennec.2
The air contained in the  vesicles  in this instance, consisted  of 5
parts of azote, and 1 part of carbonic  acid.   The  quantity of air
collected and examined, did not exceed l-20th of  a cubic inch ; I
could not detect in it any traces of oxygen.   In neither case, it may
be remarked, were there any signs of  incipient putrefaction ; the
weather was cool.; and the examination was made a few  hours after
death.
                            XXV.

  ON  THE EFFECTS OF THE SUN'S RAYS ON  THE SKIN.
  It is known to every one, that exposure to the sun's rays renders
the skin brown ; but I am not aware that this well known effect has
hitherto been investigated  with any minuteness, if at all, either in
relation to the manner in which it is produced, or the part of the
skin in which it takes place, or  its exact cause, or its consequences.
  The following observations were made with the desire of eluci-
dating these points: they were collected whilst I was stationed in
the Ionian  Islands in 1826-27, and were originally published in the
3d vol. of the Transactions of the Medico-Chirurgical Society of
Edinburgh.
1. Of the  changes connected with the  discolouring effect of the
                          Sun's rays.
  For the purpose of ascertaining these changes, a  portion of the
back of the fore-arm,  which had  never before  felt the sun's action,

           « Fifth Edition, p. 80.
           * Treatise on Diseases of the Chest, &c. p. 89.
       12__e                                     23 dav 
350
davy's researches.
was exposed to bright sunshine,  in  Corfu, during an  hour and a
half, on the 29th July, 1826, in  the middle of the day, when the
thermometer was at 78° in the shade.  At the end of that time the
skin was slightly painful,  red, and  hot.  On the 1st  August the
erythema was nearly in the same state; during the night the redness
of the skin had been heightened, and the sensation of pain increas-
ed.   On the 2d, there was  very little alteration ; a thermometer ap-
plied to the inflamed part rose to  96°, or  1° higher than when ap-
plied to the adjoining skin.  On the 3d, desquamation had  com-
menced at the circumference ; there, where the cuticle had separated,
the part was brownish-red, and not painful.   In the middle, where
the cuticle firmly adhered, the colour continued to be rose-red, and
the pain continued, though in a less degree.   This middle part,  it
may be remarked, in which the erythema was most durable,  was
most inflamed, the sun's  rays having struck  on it perpendicularly ;
whilst, on the  circumference, from Ihe rotundity of  the arm, they
impinged on it obliquely.  On the 5th, desquamation was making
progress ; pain had ceased ; the part was reddish-brown  at the edges,
but still red at  the centre ; the temperature of the part  was not above
that of the adjoining skin.  On the 8th, the part was uniformly  of
a reddish-brown ;  desquamation  was  still taking place, the new
cuticleseparating almost as fast as  it formed, not in continuous pieces,
as in the first instance, when the  old was detached, but in small
scales.  On the 18th, the part was  of  a light brown, with a very
slight admixture of red, and its tendency to desquamation was very-
little greater than natural ; in brief, it was in that state in which the
skin is commonly said to be when tanned by the sun.

2. Of the part of the Skin in which the discoloration takes place.

  Dr. Bostock, in his "Elements of Physiology," remarks,  "It has
not been ascertained upon which part of the  integuments the sun
acts, whether upon the epidermis, the corpus mucosum, or the cutis;"
and he immediately adds,  "but it is  probably  upon the epidermis,
because we are informed that the tan of the  skin is removed by
blisters."
  Were it a fact that the skin is rendered fair by blisters, the  argu-
ment  would be plausible,—I  had  almost said  conclusive ; but, as it
is well known that blisters themselves  render  the skin  brown, this
argument can  hardly be received.
  From the observations which I have  made, and from analogical
reasoning, I am disposed to believe that the discoloration takes place
beneath the cuticle, and that the seat of it principally is the surface
of the cutis.
  1st. As the  sun's rays bleach hair, and as there is a considerable
analogy between the hair and the epidermis, its effect on the latter,
it might be expected, would be similar.1

  1 It is worthy  of remark that the effect of the sun's action on the human 
            effects of the sun's rays on the skin.       351

   2dly. I have carefully examined the cuticle detached in conse-
 quence of inflammation  from insolation, and  I  have  not found  it
 tanned in the slightest degree.
   3dly. Are not the phenomena described in the preceding section,
 relative to the immediate effects  and consequences of exposure to
 the sun's rays, almost sufficient to  convince one that the cutis is the
 true seat of the discoloration 1   Were the epidermis the seat of it,  it
 ought to be immediately discoloured by the sun's rays, which it is
 not; and when the epidermis  separates, the skin should be fair ; but
 the reverse of this is the case,—not till it separates does the skin lose
 its bright rose-red hue; and not till after several successive desqua-
 mations is the tan of the skin well impressed  and  established, and
 many months elapse before it disappears.1
   ^thly.  I have examined, with  some  attention, the cuticle of the
 negro, of people  of colour, and of Europeans  who  have become
 dark-brown  from exposure to  the sun's rays within  the tropics.  In
 each instance, when detached, it has appeared much less coloured
 than the skin; and, when minutely inspected,  it has been found to
 owe its colour to colouring matter  attached to  it, detached from the
 cutis.
   Lastly, I  have preferred assigning the surface of the cutis as the
 seat of the discoloration, (supposing it to be proved that the cuticle
 is not,) rather than the rete mucosum or corpus mucosum of authors,
 as the very existence of such a texture is problematical.   From the
 experiments which I have made  on moles, and the coloured areola
 of the  mamilla of fair persons, and  on the skin of the negro, I am
 disposed  to  believe that the colour, in all these instances, is owing
 to a colouring matter deposited in minute particles, or filaments, on
 the surface of the cutis, as a secretion  analogous, in  its chemical
 properties, to the pigmentum nigrum of the eye.8   In the skin of the

 hair is quite different from its effect on the skin,—bleaching the one, as much
 as it darkens the other; tending to bring both to a state, as regards hue, best
 adapted, probably, for defence,'such as occur in the Arabian horse, the finest
 breed of which have a white coat on a black ground,  they are  in  fact negro
 horses with white hair.  Every observant traveller must have witnessed in-
 stances in illustration, of what has just been observed.   The most striking
 example of the kind which I recollect, is afforded by  the female inhabitants
 of the border  town  of  Itri,  on the confines of the Neapolitan and Roman
 states, where the  women are in the habit of exposing themselves, their heads
 uncovered in the open air; and in consequence there is  a striking contrast
 between the dark sun-burnt countenances, and their comparatively light hair,
 which,  variously discolored  by the action of the  sun's rays, and generally
 much neglected, imparts to them an appearance of extreme wildness.
  1 The discoloration produced in August, by  exposure of the skin for an
 hour and a half, at the expiration of seventeen months, was just visible.  I
may add  that I have found  it to  continue much  longer on  a part always
covered,'as the arm, than on the back of the hand, which  has been covered
only in the open air.
  2 I find that the colouring  matter of the skin of the  negro, and the pigmen-
tum nigrum of the eye, are acted on very similarly by the three mineral acids,
and a solution of potash, when heated, and by the sulphurous acid.  By the 
352
davy's researches.
white, even in the parts discoloured, as in the areola already men-
tioned, I have not been able to discover any traces of a corpus mu-
cosum, when the cuticle has been separated by means of immersion
in the sulphurous acid.   I  have found the brown  colouring matter,
as before noticed, impregnating the surface of the cutis, and  to be
separated with difficulty by scraping it.   In  the case of the negro,
the colouring matter is deposited more thickly, and more in the form
of a membrane; yet I have not  been able to detach it as a  mem-
brane ; and only in very minute portions, and that by scraping  when
the cuticle has been raised  and separated with as little inflammation
as possible.   The evidence in favour of the  existence of  a corpus
mucosum, obtained either by maceration of the integuments, or by
the application of blisters, appears to be very doubtful.  By the first
process, a gelatinous or mucus-like surface may be formed: by  the
second, a false membrane may be produced  by the effusion of coa-
gulable lymph, exactly resembling a  corpus  mucosum.   I do  not
make these remarks hypothetically, but from experience,—from ob-
serving the effects of blistecs  on  parts of the skin  in  which there
have been moles ; on the areola of the mammilla ; and on the skin of
the negro.   In all  these examples, the  effects generally  are very
similar.  If the blister is mild, the cuticle is  simply raised ; in the
instance of the negro, with a very little  colouring matter  adhering
to it.   When severe and  long continued, not only is the cuticle rais-
ed by serum effused, but also by coagulable lymph, to which is at-
tached colouring matter, and  which may easily be  mistaken  for  a
coloured rete mucosum, and which is easily separated as a continu-
ous membrane.  When severe inflammation and suppuration is ex-
cited, the colouring matter either comes away spontaneously, or is
most easily detached.1  It appears to be most firmly connected with
the cutis in the instance of moles, next in that of the brown areola
of the nipple, and least in that of the black skin of the negro.  The
part, in healing, when covered with the first formed cuticle, is red;
it soon becomes brownish,  but a considerable time elapses before it
acquires its former intensity of colour.  In the instance of the  negro,
in which I have watched  its  progress,  the secretion  of colouring
matter began at the edges,  and spread towards the centre ;  and then,
after a few days, spots of black appeared in  the middle, which en-
larged till the whole area was coloured. When a part not discolour-
ed  is blistered, in  healing, it passes from red to brown; and it is
often a long time before the part regains its healthy hue; generally,
I believe, the fairer the skin, the less it is made brown by a blister,

former  both are dissolved ; by  the sulphurous acid, they are  rendered of a
light brown colour.  They are not dissolved by these acids, or by the alkali,
when cold; nor is their colour  changed by a solution of  chlorine in water,—
contrary to what is commonly asserted of the colouring matter of the skin of
the negro.  Both bear a high degree of temperature,  apparently without
change, viz. that nearly of a dull red heat.
   1 Thus it may be obtained in large pieces, very  much resembling a mem-
brane;  but the connecting medium, I suspect, is coagulable lymph. 
          effects of the sun's rays on the skin.       353

and the sooner it recovers its original whiteness ;  and I believe the
hotter the climate and season, so much the more slowly it regains it.


3-—Of the  cause of the change of colour, and of the manner in
                       which it operates.

  My experiments  relative to  the cause of the change of colour
produced  in the skin by the sun's rays, are not so satisfactory as I
could wish.   They tend, however, rather to prove that the effect is
produced  solely by the undecompounded rays.  I have exposed,
for more than two hours, and  that  repeatedly, the delicate skin of
the under part of the  fore-arm to the solar  spectrum;  and  I  have
concentrated  the differently  coloured  rays of the spectrum,  by
means of a  lens, on the skin, but without occasioning either ery-
thema or discoloration.
  Relative to the manner in which the effect is produced, is it im-
mediate and direct, or mediate and indirect?   In other words, is it
the simple  effect of the sun's  rays  impinging on the skin, or the
effect of the  inflammation which  they  occasion;  or  do the  sun's
rays act in  both ways 1
  That they  act powerfully indirectly in  producing discoloration,
by exciting  inflammation,  the  facts already mentioned  are,  it  ap-
pears  to  me, sufficient proof.  Indeed, whatever cause  excites
inflammation  or irritation  of the skin, seems to have an analogous
effect, and to  discolour it.   Erysipelas, erythema, most of the  exan-
themata, burns, ulcers, excoriations, all occasion this effect, (and I
believe cold even  is not  an exception,1) in different  degrees, and
very much  in proportion  to the intensity of the preceding inflam-
mation, but whether exactly in that ratio it  is difficult to determine.
And we witness something of the same kind in mucous membranes;
at least, I  have observed  that the cicatrices of old  ulcers of the in-
testines are always discoloured, and either  gray, blue, or almost
black,  apparently according to the  degree  of severity of the local
disease which preceded them.
   I have just said  it is  difficult  to determine if the effect of dis-
coloration  be exactly  proportioned  to  the  inflammatory  effect.
 There are circumstances  in favour of its  not being so.  The ery-
thema  produced by strong acetic acid, and the vesication occasion-
 ed  by the  leaf  of  the common walnut tree, are followed by disco-
 loration unusually dark and durable.  Nor are there  facts  wanting

   1 Is not the  dark colour of the inhabitants of  the arctic regions as much
 owin°- to the inflammatory or irritating effect of  the extreme cold  of winter
 as tolhe scorching influence  of the continued sunshine of summer?
  Milton's highly poetical expression, the burning "frore," which he uses
 in his description of the damned regions, is in accordance with accurate ob-
 servation of the agency of intense cold, in many respects so analogous to
 that of great heat:
                              "The parching air
            Burns frore, and cold performs the  effect of fire." 
354
davy's researches.
   which indicate that the change  of colour may take place without
   inflammation, and go on increasing in intensity gradually, from
   continued exposure to the sun, or even too bright light, without in-
.   flammation  having been once produced.   I remember an instance
   demonstrative of this, in the person of an  excellent and most ami-
   able young officer (now  no more),  a case of tubercular phthisis,
   complicated with other organic disease, who, in  hope  of deriving
   benefit from sailing,  and sea air, was taken from his room, where
   he had been confined  many months, and conveyed on board ship,
   where he was placed under a convenient covering constructed on
   deck, sheltered always from the direct rays of the sun, but exposed
   to the bright light of the summer sky of the  Mediterranean.  In a
   short time, thus  situated,  he lost the pallid hue of the sick-chamber,
   and became almost as deeply tanned as a native of southern Europe;
   and I was particular in ascertaining that the change had not been
   preceded by the slightest erythema, or any sensible desquamation.
   I  may mention,  in confirmation, the result of exposing, a second
   time, to the sun's rays,  the  part tanned, as in the experiment first
   related.
     On the  18th August, the part first acted on was exposed for two
   hours,  between 10 and 12 o'clock, when  the sky was  unclouded,
   and the temperature, in the shade, about 80°.  Immediately after
   this exposure, the tanned  part was browner than before, and the
   adjoining white  part, now exposed for the first time, was  slightly
   red. On the 19th, the tanned part was distinctly brown and  redder,
   a very little warmer than  natural, and very slightly tender.  The
   adjoining  part was florid  red, slightly painful, and hot.   On the
   23d, the tanned part was merely brown, a shade darker than before,
   while the adjoining part was undergoing desquamation, and  begin-
   ning to lose its vivid inflammatory hue.  And, farther, in confirma-
   tion, I may relate, that I  have  been at some pains  to learn from
   natives of the Ionian Islands, especially of the lower classes, who
   are very much in the open air, what effect they have experienced
   from the fern's action.   The result of my inquiry is.  that very few
   of them have ever experienced the blistering or scorching effect of
   the sun ;  and when they have experienced it, it has commonly been
   on a part of the  body not accustomed to be exposed to light; and
   on  some  occasion of unusual exposure, as that of bathing in the
  open sea.   From all which, may it not be inferred, that the sun
  acts both  indirectly, by the medium of inflammation, in changing
   the colour of the skin, and directly, without the intervention cf in-
   flammation,  in producing the same effect, or in heightening it when
   produced?

     Lastly,— Of the consequences of the discoloration of the skin.

    Sir Everard Home, in an interesting paper published  in the Phi-
  losophical Transactions for 1821, has proved that, when the skin
  is painted black, it is defended frqm the scorching effect of the sun's 
           effects of the sun's rays on the skin.       355

rays;  and, he thence infers, that the dark rete mucosum of the negro
possesses the same protecting power.
  I have made experiments similar to those of Sir Everard Home,
and have  modified  them,  and all  of them with the same results.
All the opaque colours of which I made trial, applied to the skin,
whether red, orange, blue, or green, have  afforded protection from
the scorching influence of  the sun's rays, equal to that afforded by
black.1
  But though I have  confirmed the  experimental results of Sir
Everard  Home, it  appeared to me, when reflecting on the subject,
that his inference was not  so well established as at first view might
be conceived.   It is founded  on analogy, and  that analogy not
perfect; there being this difference between the skin of a  white per-
son painted,  and of a negro with a black skin, that, in the one in-
stance, the black  surface  is laid on the semi-transparent cuticle,
whilst, in the other, it is situated under the cuticle, and on the sur-
face of the cutis.  In the one instance, the extinguishing medium
is external to the  insensible covering of the body; in the other,  it
is in contact with the  sensitive surface, and may be considered as
a part of it.   Circumstances,  too, relative to the very great  pene-
trating power of the sun's  rays, have had rather a similar tendency
to augment my doubts of the strict  accuracy of this analogical con-
clusion.   As  the facts which I now allude to appear to me to be
new and curious,  I shall mention some of them.   When the sun's
rays  are  concentrated by a lens,  they penetrate, I  find, through
bone, as a portion  of the cranium,2 through  nine folds of black
crape; and, what  is more extraordinary, through rolled platinum.
It was easy to ascertain their penetrating  through the former sub-
stances,  by a luminous point appearing on a surface beneath; but
through the opaque platinum no light passed, yet the rays of heat
passed, which was best indicated  by the sensation produced when
the metal was placed on the sensitive skin, the only part of which
affected was that corresponding to  the focus  of  the lens, the metal
itself not becoming sensibly warmer.3 Taking, then, into considera-
tion the difference  between the  painted cuticle and  the dark rete
 mucosum, and this  very remarkable penetrating power of the sun's
 rays, it appeared to me that more direct experiments than those of
 Sir Everard Home were requisite,  to ascertain, beyond all doubt, if
 the function  of the colouring matter  of the skin of the  negro is
 really such as it has  been inferred to be.  With a view to this, I
 have subjected the skin  of the negro to the direct rays of the
 sun,  and  I  have made a similar  trial on a mole on a fair skin.

   1 Considering the effect mentioned above, the  usage of the ancient Britons
 in paintin^ their bodies may  be referred to a purpose of utility as well as of
 barbarous'ornament,—the paint with which they bedaubed themselves must
 have  answered, in part, in place of clothing.                         .
   * This circumstance may help to explain the effect of the sun on the brain
 in producing the malady commonly called coup de soleil.
   3 No effect was produced through the platinum on moist chloride ot  silver. 
356
davy's researches.
 After two hours' exposure to the  sun, its  rays  moderately concen-
 trated  by a lens, (for the experiment was made in winter when the
 temperature was between 50° and 60°,) the part acted on, in which
 a dark brown mole was  situated, became slightly red;  the follow-
 ing day it was red, and  just perceptibly painful; and about the
 fourth or fifth day, desquamation  of the part commenced.   The
 desquamation took  place over the mole as well  as the adjoining fair
 part, and the mole was evidently  rendered of a  darker colour.   On
 the 27lh December, when the sky was clear, and Fahrenheit's  ther-
 mometer in the shade at  56°, a similar experiment was made on the
 fore-arm of a negro, and continued the same time.  The skin acted
 on was a little hotter than the rest,  just perceptibly darker, and it
 felt, he said, slightly sore.  On the following day, the part appeared
 to be very little darker, and he said that it was  slightly painful and
 swollen, but  this last mentioned effect was  not perceptible to my
 eye.   On the  31st December, the pain had ceased ;  there was not
 the slightest appearance of desquamation, and it was only just per-
 ceptibly darker than the adjoining skin.
  From these results, I am disposed to infer that the colouring matter
 of the skin of the negro affords some protection from the scorching
 effects of the sun's rays, but not complete protection, and that were his
 skin as much disposed to  inflame from the action of the sun's rays as
 the skin of the fairest European, this colouring matter would not pre-
 vent occasional vesication.  Some of the facts already mentioned
 tend to support this opinion, especially the circumstance  that ex-
 emption from the scorching effect of the sun is not confined to the
 African negro, but is possessed equally by all the various races of
 men—the inhabitants of hot climates, who are much in the open
air, and exposed to bright light, whether the colour be almost black,
like that of the lower classes of Singalese, or of a dull straw colour,
like that of the Bojesman of southern Africa, or of a ruddy brown, as
in the instance of the Albanian shepherd of the mountains of Greece.
  Nature, then, it may be remarked, is very provident, adapting the
skin, impressed  by the sun's rays, to bear them afterwards  without
inconvenience, or at least without painful suffering, the impression
having apparently a protecting effect from farther annoyance,  like
the first attack of many of  the infectious exanthemata; but  with
this difference, that the susceptibility to a renewal of the action is
 not long suspended, unless the cause is in constant activity. How
 long it  is suspended  it is difficult  to determine:  it is suspended
in different degrees, probably in  persons of different complexions
and temperaments,  least in the fair,1 more in the brown European

  1 Very fair persons,  as regards complexion, are least affected by climate,
 and exposure to the bright  light of a tropical sky;—in this respect resem-
bling the albino. Unusual exposure to  the sun's rays is painfully felt by
them; they experience the sun-burn;  but, after the erythema  or superficial
inflammation has subsided, and  desquamation has taken place,  the fairness
of the skin is but little impaired,—and its liability but little diminished to
suffer in the same manner from farther exposure. 
effects of the sun's rays on the skin.       357
races, and most  of all  in the deeply coloured Asiatic and African
tribes.
  Besides the foregoing,  there are other means which nature em-
ploys to counteract the influence of the sun's rays on the human
body, and to keep down animal  heat within the bounds of health,
in situations where otherwise it would be most apt to be in excess,
and  mount  to a feverish height.   These means seem to be of two
kinds, one external, the other internal.
  Perspiration, both sensible and insensible, constitutes one of the
first.  It not only cools the surface in  connection with evaporation,
but also, when in the form of sweat,  by dispersing the sun's rays,
prevents or diminishes their scorching agency, as is  easily shown
by comparing the effect of the sun's  rays, concentrated by  a lens,
on a dry and a wet skin.   The internal means are not so obvious;
but that they do exist, and act beneficially, seems undoubted.  There
is reason  to infer, that  the greater the atmospheric temperature is,
the less oxygen is consumed in respiration—that the  blood  is  less
aerated, and there is less heat in consequence produced.   Some
facts bearing on this curious point have already been mentioned,
when treating of animal  temperature in summer and winter; and
further  on, some other facts tending to illustrate it will be brought
forward,  in an account of observations on the  blood,  in connection
with respiration.  Besides this,  probably the principal balancing
circumstance, others  in addition may  be pointed out by which na-
ture fits man to  bear with impunity,  and with comparatively little
inconvenience, the heat of the hottest  regions of the globe of which
he is a native.   In a hot climate, especially within the tropics, the
cuticle appears to be  thinner than in a cold climate, so as to confine
the animal heat less.1  Moreover, I believe that the exhalants of the
skin, and indeed the whole  apparatus  peculiar to this texture, is
either more developed  or more active, or both, under the influence
of a high than of a low or moderate degree of temperature.   And
the condition of the  blood seems to  accord,  as cold appears to in-
crease its viscidity, heat its fluidity; consequently, ceteris paribus,
in a hot climate, it will be less viscid than in a cold, more fluid and
flow more freely through the cutaneous and subcutaneous vessels.
Thus, by promoting perspiration, it will contribute to the cooling
of  the  surface;  and, being cooled itself, it will contribute  again,
when it flows back to the heart, to the reduction of the temperature
of the internal parts.2
  1 The cuticle of the sole of the foot and of the palm of the hand is, under
certain circumstances,  an exception, as when exposed unprotected to the
action of a hot surface, or subjected to much pressure.  I have seen a negro
sleeping with his  feet so close to a  fire, that the outer exposed surface was
almost'scalding to the hand applied to it, and yet, owing to the thickness of
the part to the individual it transmitted merely an agreeable warmth.
  21 deduce this opinion of the blood being more liquid at a comparatively
high temperature, as 88° or 98°, than at a low one, as 38° or 48°, from ex-
periments on the  blood,  showing that a certain degree of cold thickens the
 blood and that a certain degree of heat renders it more liquid, so that in one 
358
davy's researches.
  Lastly, peculiarity of constitution appears  to be  intimately con-
nected with climate, and the  tolerance of different degrees of tem-
perature with impunity.  The African enjoys the best health, is in
the highest spirits, and is capable of the greatest exertions  in hot,
moist regions, where the temperature is seldom below 80°; and is
almost entirely exempt  from those fevers of the intermittent and
remittent type, which have been, and  probably always will be, the
scourge  and destruction of Europeans in hot climates.1  But, re-
verse the situation,  and  place the African negro where the  Euro-
pean recovers his lost energy, shakes off the languor of  the tropics,
and is restored to health and strengh,—there  the former commonly
droops, becomes  languid, feeble, and diseased, and soon sinks into
the grave.2  And thus it is, no doubt, that each  race is  propagated
and multiplied in the situation most  suitable to  the developement
of its faculties and powers.
                            XXVI.

ON A PECULIARITY OF STRUCTURE OCCASIONALLY OC-
       CURRING  IN THE BASILAR ARTERY OF MAN.

  Besides those peculiarities of structure of the basilar artery which
are well known, there is one of not uncommon occurrence, which,
to the best of my knowledge, has not hitherto been noticed by any
anatomist.  It is a band in the interior of the vessel, attached to its
sides, and consequently intersecting it.  It varies both in its dimen-
sions and situation.  I have most frequently found it near the junc-
tion of the vertebral  arteries; very seldom near the commencement
of the circle of Willis.  Sometimes the band perfectly intersects the
vessel;  at other times only partially.  Sometimes  I have seen it not
more than a line thick; occasionally two or three lines.  Its appear-
ance, as regards its  nature, has always been similar and most ana-
logous to a fibrous structure. In every instance, I  apprehend, it may
be considered as congenital, and not the effect of disease.  This is in-

state it is better fitted for torpid hibernating animals,  and those of a cold
climate, and in the other, for animals in whom the functions of life are per-
formed with energy, and that constantly, as in a warm climate.
  1 In regions more unwholesome to Europeans than the Maremma of Italy,
as (to state from my own experience) in some parts of the interior of Cey-
lon, where not one European in a hundred escaped fever, and the majority
of those attacked died ; an instance of intermittent or of remittent fever was
of extremely  rare occurrence amongst the black troops,  who were employed
in common with  our soldiers; of which most ample proof was  afforded dur-
ing the rebellion  of the native population.of the interior of that island,  be-
tween 1817 and 1819.
  1 In Ceylon, during the period just mentioned, whilst our soldiers were
recovering their health in the cool hill forts of the mountainous parts of the
island, the negroes there were dying of pulmonary consumption. 
        peculiarity in the basilar artery of man.     359

 ferred after careful examination to endeavour to detect the effects of
 diseased action.  In no instance were there any indications of such
 action observed;  the lining membrane contiguous was smooth, and
 there was no thickening where the ends of the band were inserted.
   The basilar artery, in the manner in which it is formed, and the
 thinness of its coats, may be considered as approximating to a vein.
 The similarity is increased by the peculiarity in question.  Bands
 of the same kind are not uncommon in the longitudinal sinus, and
 more delicate bands and fibres are frequently met with in the heart
 in the right auricle, especially about  the fossa ovalis, and in con-
 nection with the eustachian valve.
   Whether this peculiarity of structure has a decided  use, I am not
 prepared to say.  In each instance  in which a band or fibre pre-
 sents itself, support  is  afforded—additional strength is imparted.
 The band I have described as occasionally occurring in the basilar
 artery must necessarily have this effect.
  It was in the month of June, 1837, that my attention was first
 attracted to the subject.  Since that time, during a period of about
 sixteen months, I have taken every opportunity that has offered to
 examine the basilar artery.  In ninety-eight post mortem examina-
 tions at which I have been present, made in the General Hospital,
 at Fort Pitt, in  the time specified, I have met with it in seventeen
 instances.   In nine,  death was owing to pulmonary consumption;
 in two, to  malignant tumour;  in the remainder, in each instance,
 to a different disease.   The ages of the individuals  varied from 19
 to 59; two were 25,  two 35; in point of age there was no  other
accordance amongst them.
  I shall give the results in a tabular form, and also the the pro-
portional frequency of marked difference of size  of  the vertebral
arteries to  which my attention was at the same time directed.
Table I.
Period.	Number of bodies	Instances of band in	Instances of left verte-	Instances of right
	examined.	basilar artery.	bral larger than right	larger than left.
1837.				
June	5	3	4	1
July	16	6	9	1
August	13	2	—	1
September	9	1	2	3
October	5	1	1	—
November	8	1	—	1
December	5	—	2	—
1838.				
January	6	1	2	—
February	3	—	—	—
March	1	—	—	—
April	1	—	1	—
May	8	1	1	—
June	4	—	1	—
July	5	—	1	—
August	9	1	2	1
	98	17	26	8
 
360
davy's  researches.
  In one instance of the total seventeen, a short filament proceeded
from the intersecting band, its end floating loosely.
  In two cases out of ninety-eight, there was another peculiarity,
which I am not aware has ever been noticed, viz.—an opening or
foramen  between the tvvo vertebral arteries, in the  septum formed
by their juxtaposition posterior to the  basilar artery.   In each in-
stance it  was sufficiently large to admit a surgeon's  probe.
  In three  instances amongst the total  number, each vertebral was
as large as  the basilar artery,—which was of the usual size of this
artery; and the vertebrals did not appear to be diseased.
  The proportion in which the left vertebral  artery was  found
larger than the right is so great, viz. in the ratio of 2(3 to 8, that it
can hardly be considered accidental.  But  on  what the circum-
stance depends,  I  am entirely ignorant.  At one time, I supposed
that it might be connected with the difference of origin of the right
and left subclavian;  but  the notion was not supported by facts.   In
two instances (the only ones observed) in which the left vertebral
took its origin immediately from the aorta, between  the carotid and
subclavian, it was smaller than the right vertebral, taking its origin
from the subclavian of that side,—and that  subclavian, as usual,
from the  arteria innominata.
  In the  table I have given  the results of my observations monthly,
for a particular reason,  namely, for the.  purpose of showing how
much  more  frequently  the peculiarities  of  structure referred  to
occurred in the  bodies which died in one month than in another.
The greater frequency of rare occurrences at one time than another
is a circumstance  extremely curious and mysterious,  and I have
often  been  impressed by it, as, I believe, others have been, both in
hospital practice, and engaged in anatomical researches.  I shall
mention a few instances,  from memory,  as examples of such  im-
pressions.
  1. An  oblique opening in the fossa ovalis of the heart, occasion-
ally of such  frequent occurrence as to give  the idea of its being
normal.
  2. The eustachian valve oflarge dimensions in the adult, nearly
as large in proportion as  in the fcetal heart.
  3. A fibrous filamentous connection between the eustachian valve
and the auricular septum.
  4. The mouth of the coronary vein destitute of a  valve.
  5. Delicate tendinous  filaments or threads, bordering  the semi-
lunar valves, especially of the aorta, giving the idea  of an  atrophied
state.
  6. The ligamentous cord, the remains of the ductus arteriosus,
ossified.
  7. Fibrinous  concretions containing  a  purulent-like  matter,
formed during life, in the iliac  and femoral veins, and also in the
ventricles of the heart, most frequently in cases of phthisis.
  8. Varicose lacteals, also in phthisis.
  9. Softening of the brain, especially of the fornix, in this disease. 
        Peculiarity in the basilar artery of man.    3G1

  10. Ulceration of the larynx, also in this disease.
  11. Pneumathorax from perforation of the pleura in connection
with a tubercular excavation.
  12. Peritonitis, from perforation of intestine, in connection with
very limited local ulceration.
  13. Ulceration and  perforation of the  appendicula  vermiformis
and consequent peritoneal inflammation.
  14. Softening and wasting of  the articular cartilages, especially
of the patella?.
  The list might be very much extended.  It may perhaps be said,
that there is deception  in this matter ;  and that the asserted greater
frequency of occurrence of any  peculiarity of structure, or lesion,
independent of obvious causes, is more apparent than real, and that
were  the same  attention constantly given  in  search, the  irregu-
larity of their .occurrence would cease.   This  may hold good in
some instances;  but I  cannot admit that it is applicable in those I
have enumerated, and  more especially in  the peculiarity of struc-
ture of the band in the basilar artery, which  led to the remark.  In
each case, the artery was carefully examined, and the result noted
down at the  time, and that  specially.  And, moreover, in relation
to the subjects of observation, what could  be  less  favourable for
uniformity of result 1  The individuals were not of any particular
family or race ; they  were men of different regiments, English,
Irish, Scotch, brought to the general hospital, the invaliding station
of the army, from  different parts of the globe, in a  manner ap-
proaching to the accidental as  nearly as possible.
  I am disposed to believe, that  were  the pathological anatomist
engaged in extensive and minute research, to institute a new series
of observations on organic changes, analogous to that which Syden-
ham conducted  on  ordinary maladies, he might arrive at the con-
clusion, that there are organic constitutions  prevalent at times, not
less than atmospheric, and which (however  produced) may be as
much concerned in  the origin  of chronic  disease, as the atmo-
spheric influences are in the acute.
   I shall give in a tubular form some of the results of my experi-
ence  bearing on this subject, drawn from my notes of the various
post-mortem examinations which I have attended, during a period
of nearly eighteen years,  namely, from  May, 1821, when I com-
menced the practice of making a note of every  fatal case, in which
there was an examination of the body after death.   My experience
has been chiefly confined to our military hospitals,  indeed at home
it has been entirely so restricted ; on foreign stations, it extended
to the native population, especially in  Malta, where the civil hos-
pital offers an ample field for research. 
davy's researches.
Table  II.
■		en 1 i		«-	*- a\ '		1 ,	a
		CD 1 Q> ,A		o	o o ! a		CJ	
		odi tub ings		.2 *3	.2=12		1-2	CD
		-Q t_ 3			•= o ! S		in	3 .
Stations.	Years.	ber of ined. nces oi n the 1			2-=i § a> .— 1 OJ		a >	apert ovalis
		a Q 1 cl ■"					.«« co o rt O —• i ^ in 1	
		3 2!» D		. s-	i >- 1 . ^		i re	i ">
				rt	ca ' cs		' o	,c
				1 --■				1 e*H
England,								
Fort Pitt,	1821	29	11	-	—	1	—	1
_	1822	61	33	19	—	—	6	10
—	1S23	40	20	7	—	1	—	2
—	1824	10	5	2	1	—	—	—
Ionian								
Islands.	1824	18	2	—	1	—	—	2
—	1825	36	5	2	—	—	—	1
—	1826	9	3	—	—	—	—	—
—	1827	33	8	1	—	—	—	3
—	1828	6						—
Malta.	1828	32	5	1	—	—	1	5
—	1829	19	4	1	—•	—	—	3
—	1830	41	5	1	1	—	—	9
—	1831	54	19	3	—	i	2	8
—	1832	55	8	1	_	3	—	7
—	1833	49	7	9	_	1	—	5
—	1834	57	15	5	—	3	1	5
—	1835	10	4	1	—	—	—	—
England,								
Fort Pitt.	1835	31	20	2	—	2	—	1
—	1836	72	49	18	—	1	—	8
—	1837	81	50	15	1	5	•—	8
—	1838	43	45	11	—	1	—	3
Total,	18	786	318	99	4	19	10	82
  On the results contained in this table, I shall restrict myself to a
few remarks.
  The very large proportional number of cases in which tubercles
were found in the lungs, viz. 40 per cent, of the whole, may excite
surprise.  I must confess  it had  that effect on my mind, and the
more so, as no doubtful instances were admitted: I rigorously re-
jected every example not  coming under the  denomination of the
consumptive tubercle—that is, a  tubercle, albuminous in composi-
tion, admitting of induration by  boiling, as  pointed out by  Dr.
Abercrombie, and of softening in the progress of disease, giving rise
to vomicae and excavations in the lungs.  The melanotic tubercle
was excluded, and also certain concretions more or less resembling
tubercles, whether consisting principally of phosphate of lime and
the other materials of bone, or of a nature approaching to cartilage.
I may also  remark, that no cases were  admitted  as supposed in- 
        peculiarity in the basilar artery of man.    363

stances  of tubercles, from  the presence merely  of cavities in the
lungs.  Cavities existing unaccompanied by tubercles were inferred
to be examples of pulmonary abscess, of which  several instances
occurred.
  No doubt, the astounding frequency of tubercles recorded in the
table, is partly owing to the description of cases sent to the general
hospital, at Fort Pitt, where a considerable proportion of the whole
mortality under observation occurred.  But, making the most am-
ple allowance, on this account, I apprehend  the conclusion is una-
voidable, that the existence of tubercle is far more frequent than is
commonly supposed, and the reported deaths from phthisis would
indicate.
 » Of the four instances of ulceration of the larynx unaccompanied
by tubercles, the first was  complicated with empyema and puru-
lent effusion into the pericardium to the extent of three pounds and
a half;  the second was  associated with  melanotic tubercles in the
lungs ;  and the third and fourth  were connected  with small-pox.
  All the instances of pneumathorax, with  the  exception of one,
occurred in cases of tubercular  phthisis, and originated in a com-
munication of a valvular kind being established between the pleura,
and a bronchial tube by ulceration, commonly  through the medium
of a cavity.   In the one exception, a similar  communication was
detected, the  consequence of  a partial destruction of lung, from an
abscess  in the liver penetrating and bursting into the lung through
the diaphragm.
  Of the large number of examples of aperture in the fossa ovalis,
all were oblique, with the  exception of three.  Of the three direct,
one was sufficiently large to admit the fore-finger, and two  to admit
the end of the little finger.   In  neither  instance was  there  the
slightest appearance of the morbus caeruleus.  The subject of the
first  mentioned  and most remarkable example was an old soldier,
who for many years enjoyed excellent health.  In these cases, it
appears inevitable  that  there  must have been an  admixture of
venous  and arterial blood  in the auricles.   In  the examples of the
oblique passage, the probability  is, that  no blood flowed from one
auricle  into the other.  In one instance, in which the oblique aper-
ture was sufficiently large to receive the end of the little  finger, the
right cavities of the heart were found distended with coagulated
blood, and the left empty.
                           XXVII.

OBSERVATIONS  ON  THE FLUID IN THE VESICUL^E SEMI-
                      NALES OF MAN.

  I believe I am justified in stating, that there is  still a  difference
of opinion amongst physiologists respecting the nature of the fluid 
364
davy's researches.
of the vesiculaa seminales, especially in this country, where the au-
thority of John Hunter is necessarily high and influential.
  The difference of opinion alluded to is, whether  the fluid in
question  is secreted by the testes, or by the vesiculae ; and whether,
in consequence, the vesiculaa are to be viewed chiefly as reservoirs
or merely as glands.1
  Conceiving that some light might be thrown on  the subject by
the  examination of the fluid  in the vesiculee and in the vasa defe-
rentia, after death, in a variety of cases, I have availed myself, for
the  purpose, of such  opportunities as have offered in the general
military  hospital, at  Fort Pitt, under my superintendence.   And I
shall  now relate the results—with the belief, that they may aid in
settling the disputed question ; and, also with the hope, that they
may be  found to be not entirely devoid of interest  in connection
with an  obscure branch of pathological inquiry.
  It is necessary for  this double purpose to prefix in each instance
a slight notice of the fatal case.  I shall make no selection of cases ;
but give them nearly in the order as to time in  which  they oc-
curred.  And, I may remark,  that, as  every fatal case was sub-
jected to a post-mortem examination, according to the usage of the
hospital, these brought forward (the total deaths from the 22d Sep-
tember, 1838, to the 6th of the  ensuing December) afford a tolera-
bly correct  example of the general mortality of this hospital—the
patients  in which are chiefly invalids labouring under  chronic  dis-
eases, incapacitating them for farther military service.
  I.—Aged 30; previously  labouring  under  pulmonary  disease
and an impaired constitution, was admitted with  pneumonia, and
died on the third day.  On dissection, thirty-nine hours after death,
the inferior lobe of the right lung was found  hepatized, weighing
nearly three pounds, the superior and middle only half a  pound.
There was a tubercular excavation and numerous tubercles in the
left lung—and  small cavities  and a  pretty distinct  cicatrix of a
vomica in the upper  part of the superior lobe  of the right lung.
The body was not emaciated.
  The  vasa deferentia and vesiculas seminales were  removed six
hours after death.   About a drop of fluid was obtained from each
vas  deferens,  which accorded  in appearance  with the received

  1  Vide  Dr. Bostock's Elements of Physiology, Vol. iii. p. 7, and foot-note,
where the  question is left unsettled by the learned  author. He thus ex-
presses himself on the subject:—"Besides the testes, the vesicular semi-
nales, both from their size and their situation, have been supposed to perform
some important part in the function of generation, although it has been diffi-
cult to ascertain  the exact nature of the purpose which they serve.  The
opinion formerly  entertained was, that they are merely reservoirs, in which
the semen is deposited as it is secreted.  In consequence, however, of the
observations of Hunter, who remarked that the fluid contained in these cavi-
ties appeared to be different from that found in the testes, many of the later
anatomists have supposed that the vesiculae seminales produced a secretion
of a peculiar nature, the use of which may probably be to dilute the semen,
or to add to its bulk." 
FLUID IN THE VES1CDL.E SEMINALES OF MAN.      367
 description of the spermatic fluid.   Examined with a microscope,
 constructed by that excellent maker Mr. Ross, and using an object
 glass of one-eighth inch focal distance, it was found to contain nu-
 merous animalcules, some of them in active motion. The vesiculcc
 contained a considerable quantity of fluid.  Some of it was col-
 lected after six hours; another portion later, after forty-two hours.
 1 he former did not appear to me to differ from the fluid of the  vasa
 deferentia.  It abounded in spermatic animalcules, some of which
 were alive and active :  on standing a few hours  it separated into
 two parts,  one opaque  that  had subsided, the other transparent;
 and this was  copiously precipitated  by alcohol, and rendered of a
 consistence almost gelatinous.   The  last collected had a brownish
 tinge; it, too, abounded  in animalcules; but they were motionless
 and dead ;  warmth had no effect in  reanimating them.
   2—Aged 57 ;  a violent maniac, who died  thirteen days after ad-
 mission ;  the  disease was of about a  fortnight's duration—a third
 attack.   The  dissection was made  fifty-seven  hours  after death.
 The  body  was  much  emaciated.   The lateral ventricles of the
 brain were greatly distended with fluid ;  they communicated freely
 —the septum  lucidum having been destroyed by disease.  No other
 well-marked lesion  was discovered.
   A very minute portion of  fluid was obtained from the vasa de-
 ferentia.   It was of the  colour, and very much of the appearance
 and consistence of pus.   It contained very many spermatic  animal-
 cules—all dead.  The fluid from the vesiculae was small in quan-
 tity, browner than that  from the duct, as if slightly tinged by the
 colouring matter of the  blood.  It contained vestiges in abundance
 of spermatic animalcules, and a few of distinct form.
   3.—Aged 39 ; died of pulmonary consumption, complicated with
 pneumathorax of the right side and empyema.1  The dissection
 was made thirty-six hours after death.  The  body was much ema-
 ciated.  Besides the disease in the  lungs, the ileum in its inferior
 part was severely ulcerated, and the caecum  slightly.  There had
 been diarrhoea in  the last stage of the disease.
  The vasa deferentia, and the vesiculae seminales, were removed
 and examined six hours after death.  The contents of the latter
 were small in  quantity, and of nearly gelatinous consistence.  The
 fluid of the ducts was more liquid, and nearly of its usual  cream or
 purulent-like appearance.  In neither of them could any animal-
 cules be discovered, or even  vestiges  of them, or any distinct glo-
 bules.
  4.—Aged 20 ; died of pulmonary consumption.  Extreme  de-
bility and emaciation marked the last stage of the disease, in which
diarrhea i and  night-sweats alternated.  The  dissection was made
twelve hours  after  death.   No notable lesion was detected inde-

  1 In this case, as in  every other of pneumathorax which  I have yet ex-
amined, the air  in the pleura was derived from the atmosphere  through a
valvular ulcerated opening in the lung.
       12—f                                   24—dav 
366
davy's researches.
pendent of the pulmonary disease, which was vast and various—a
complication of tubercles and cavities, of cedema and hepatization.
The intestines were not ulcerated.
  The vesiculae and vasa deferentia were examined eleven hours
after death.  The former contained a small quantity of fluid, which
was brownish, thick, and slightly viscid—the latter an extremely
minute  portion, like thin starch.  In  both, under the microscope,
there appeared, as  it were, the  fragments of animalcules and nu-
merous globules.
  5.—Aged 32 ; died of latent pulmonary consumption, after  hav-
ing been a patient in the lunatic asylum of the establishment about
a month.  The dissection  was made fourteen  hours after death.
The' body was much emaciated.   Besides tubercles  in  different
stages, and excavations in the lungs, and partial hepatization, there
was little other organic disease.  Diarrhoea had not preceded death ;
there were, however, some  small ulcers in the colon, and marks of
old ulcers healed.
  The vesiculas and the vasa  deferentia  were examined sixteen
hours after death.   A  small drop of fluid was  obtained from the
latter, of cream or  purulent-like appearance,  which abounded  in
seminal  animalcules.  The vesiculae were moderately turgid ; the
fluid in  them was  also  opaque, white, like purulent  matter, and
abounded in animalcules.   The animalcules in each instance were
dead.  Neither  fluid changed the colour of litmus or  of turmeric
paper.
  6.—Aged 39 ; died of gangrene  of the  superior lobe of right
lung, complicated with  effusion into the pleura, and with ascites.
There were sixty-one ounces of turbid serum in the right pleura,
and seven pints of serum in the  cavity of the abdomen.  The liver,
spleen, and pancreas,  were denser than natural  ; the weight of the
liver was only two  and a half  pounds.  There was a large ulcer
in the caecum, and numerous marks of old ulcerations healed  in
the colon and rectum.   Chronic dysentery preceded the fatal dis-
ease. The dissection  was made twenty-eight hours after death.
  The right  vas deferens  was  examined  two  hours  after death,
and the vesiculae half an  hour later.  A small drop of fluid was
obtained from the  seminal duct.   It  resembled in  appearance the
purest purulent matter : it had  no distinct smell;  it rendered tur-
meric paper slightly brown.  Under the microscope it appeared to
consist chiefly of minute globules, very much smaller than those of
purulent matter, and  to be entirely destitute of animalcules.   The
vesiculas were  so shrunk and collapsed, that difficulty was experi-
enced in collecting sufficient fluid  even for microscopic examina-
tion. No animalcules could be detected  in it, and no distinct glo-
bules.  It  was colourless  and  not  viscid—more  like serum  than
mucus ;  and it was alkaline, and changed  distinctly the  colour of
turmeric paper.
  7.—Aged 42 ; of twenty years' military service ; died of pulmo-
nary consumption.   The dissection was made thirty-seven hours 
         FLUID IN THE VESICULAE SEMINALES OF MAN.      367

after death.   The body was much emaciated.  The lungs weighed
five pounds.  Besides  tubercular excavations and a vast quantity
of tubercles in different stages of progress, there  was partial cedema
of the lungs and hepatization.   There  were large ulcers in the
jejunum, ileum, and colon ; diarrhoea did not precede death.   The
prostate gland contained a sinus, which opened into the neck of the
bladder.   The testes  were adhering to the  tunicae vaginales; and
the substance of the right testis was partially indurated, as if from
the effect of common inflammation.
  The vesicula? seminales were moderately distended with fluid, of
a light brownish  hue, slightly turbid and opaque.  It  abounded in
well-formed spermatic animalcules, and  contained a few blood cor-
puscles, or particles extremely like them.  It had no effect  either
on turmeric or litmus  paper.  An extremely small portion of fluid
was obtained from one of the vasa deferentia,  which, in appear-
ance, was very like that of the vesiculae.  Under the microscope, a
few animalcules  were seen in it, many  blood corpuscles and some
smaller particles.
  8.—Aged 32;  died of bronchitis, complicated with hepatization
of the right lung, and an aneurism of the arch of the aorta pressing
on  the  trachea.  The dissection was made thirty-two hours after
death.  The body was not emaciated.   The bronchia were  nearly*
filled with muco-purulent matter.  The right lung weighed three
pounds : the greater part of it was hepatized in  different degrees,
and  it  contained a few clusters of granular tubercles.   No well
marked lesion could be discovered in the abdominal viscera.
   The  vesiculas  were moderately distended with fluid of purulent-
like  appearance, which abounded in seminal  animalcules.  The
fluid obtained from one of the vasa deferentia, extremely minute in
quantity,  was found to contain a  few animalcules, and very many
particles smaller than  those of the blood.
   9.—Aged 33 ;  died  of pulmonary consumption.  The dissection
was made fifteen hours after death.  The body  was snb-emacialed.
Besides numerous tubercles in different stages of progress, and seve-
ral large cavities in the lungs, there was partial cedema and hepa-
tization of them.  The liver  weighed six  and  a half pounds, and
contained some  fatty matter.   There were  no dropsical symptoms.
 There were numerous ulcers in  the ileum and colon.   There had
been no diarrhoea.
   A  small quantity of fluid was found -in the vesiculas, of a brown-
ish hue and semi-opaque.   It did not change the colour of turmeric
 or of litmus paper.  It abounded in spermatic animalcules.  The
 very little fluid  procured from a vas deferens was like dilute puru-
 lent  matter  in  appearance; it contained  a few animalcules, and
 very many minute globular particles.
   10.__Aged 20; died of pulmonary  consumption.  The  dissec-
 tion  was  made twenty-six  hours after death.  The body was much
 emaciated.   Both lungs abounded in tubercles,  had a  large excava-
 tion  in each superior lobe, and contained many small vomicae, and 
368
davy's researches.
the right lung in  addition was extensively hepalized.   There was
extensive  superficial ulceration of the larynx and trachea.  The
ileum and colon were deeply as well as extensively ulcerated. The
appendicula vermiformis was perforated by ulceration, and through
the medium of a sinus communicated with the colon  by an ulcer-
ated opening.   There were thirteen ounces of a mixture of puru-
lent matter and serum in the cavity of the pelvis.  Severe diarrhoea
and tormina preceded death.
   The  vesiculae  and  vasa deferentia were examined  four hours
after death.  The former afforded only a small quantify of fluid ;
what was  first pressed out  was  like thin starch in  appearance;
what was last expressed was gelatinous.  The former, under the
microscope, was found to contain many animalcules, mixed with
globular particles and small masses  of  mucus.  The  latter con-
tained very few animalcules, and  consisted chiefly of mucus.  The
fluid from the  vas deferens was  very like  that which flowed first
from the vesiculae, excepting that it was without any tint of brown
which that fluid possessed.   Under the microscope, only one ani-
malcule, perfect in form, could be detected ; fragments of others,  as
it  were, appeared, and some globules, and  a good deal  of transpa-
rent mucus in minute masses.1   The fluid of the vesiculas and  of
the vas deferens was  distinctly alkaline ; each changed the colour
of turmeric paper.
   11.—A^ed 27 ; died of pulmonary consumption.   The dissection
was made ten  hours after death.   The body was  much emaciated.
The lungs were enormously diseased ; besides containing large ca-
vities and many vomicae, and a vast quantity of tubercles in different
stages of progress,  they  were partially cedematous and hepatized.
There were a  few ulcers in the ileum, and a thickened granular and
partially ulcerated state of the rectum.  There  had been diarrhoea
in (he last stage of the disease.
   Very little fluid was  found in  the vesiculas seminales.   It was
partly thin, of a light brownish  hue ; and partly thick and gela-
tinous,—the latter from the  fundus, the  former from the anterior
portion.   Under the microscope, a few spermatic animalcules were
detected in the thin fluid, mixed with what appeared to be fragments
of them.  No animalcules  were observed in the gelatinous fluid : it
seemed to consist  principally of mucus.  Neither fluid had any
effect on turmeric paper.   From  the  vas deferens hardly sufficient
fluid could be procured,even for microscopic examination.   Il con-
tained a few minute globular particles without any animalcules.
   12.—Aged  33 ; died of diffuse cellular inflammation of the neck.
with suppuration of the cervical glands.   The dissection was made
twenty-six hours after death. A  superficial cavity was found in the
cerebrum, under the posterior part of the right parietal bone, which

   1 In this and every other instance  the vas  deferens was removed for.  ex-
 amination,  before entering the cavity of  the abdomen; the cord  was laid
 bare, the duct separated, and a ligature applied previous to dividing it. 
FLUID IN THE VESICUL^ SEMINALES OF MAN.
369
contained about a drachm and a half of fluid, which became turbid
on the addition  of nitric  acid.   There  had been  no suspicion of
cerebral disease during life.  The cellular tissue of the neck gene-
rally  was saturated with thick  purulent  matter;  and most of the
cervical glands  were diseased and contained abscesses.   The right
sterno-cleido-mastoideus muscle, on its  under side, appeared wasted
and corroded, and presented a suppurating surface.  A small mass
of fibrin, softened internally, adhered to the inner  coat of the right
internal jugular vein.   Neither the integuments, larynx, oesophagus,
or pleurae, participated in the disease. "During life it had not been
suspected.  The left femoral and the right iliac and femoral veins,
were obstructed with coagula, which in the inferior parts consisted
of crassamentum, and in the superior of fibrin.   In  the upper part of
each  vein the fibrinous concretion contained a cavity in which was
a semifluid, having a  good deal the character of purulent  matter,
and which would commonly be called purulent matter.1  The lower
extremities were cedematous, the right  more than the left,—but even
the right extremity only in a moderate degree.  There  was little
hair on the pubis, or on the chin ; the partes naturales were all small;
the larynx was small; the skin delicate. According to his comrades,
he had always shown an aversion to the sex.
   A  very minute portion of fluid only could be procured from  the
vasa  deferentia, which, under the microscope, exhibited  numerous
small particles, and a few larger globules.—but no spermatic animal-
cules.  The fluid of the vesiculas  was also .small  in quantity and
destitute of animalcules.   It  was of a  light brownish hue, slightly
 opaque, contained some globules, and  did not change the colour of
 turmeric or of litmus paper.  The fluid from their fundus was most
gelatinous, and appeared to consist  chiefly of mucus.2
 ? 13.—Aged 29 ; died of pulmonary consumption, complicated with
 peritoneal" inflammation.  The dissection was made twenty-seven
 hours after death.   The body was exceedingly emaciated ; the lungs
 were very voluminous and heavy; they contained a vast number of
 tubercles in different  stages, some small cavities, and one large one.
 This cavity  was  lined with  a false  membrane, which was even
 spread over the abrupt mouths of tvvo or three bronchial tubes, and
 it  was einptv.   Whether  it was  distended with  air,  or its sides
 pressed together, was not ascertained.   Eight pints  of serum were

   ' It sustained this character subjected to the best tesls: Thus, agitated
 with water, a white matter subsided, very little prone to putrefaction, irides-
 cent  when' held before  a light, globular under the microscope  The, differ-
 ences were rather in degree than kind,  indicating, as it were  if the expres-
 sion mayb' used, an imperfect purulent matter ; thus, it putrefied  more readily
 than purulent matter; was only just perceptibly iridescent, and its particles
  veremoreTrre^ularlvglobularaid less compact.  The mode of formai.onof
  ihUkSdoffluid, with which pathologists are  now tolerably familiar, ,s a
  curious problem, and deeply interesting in  many of its relations.
:  - * The vesicate seminales. and their  contents, in this instance, resembled
  those of such castrated animals as I have hitherto examined. 
370
davy's researches.
 collected in the cavity of the abdomen.  There were very numerous
 adhesions between the viscera.   The omentum abounded in granu-
 lar tubercles, and resembled an  elongated pancreas.   The caecum
 was misplaced, and  with the colon was confined to the left side.
 The  ileum, appendicula  vermiformis, and  colon, were  severely
 ulcerated.   The  appearances indicated a perforation of the appendi-
 cula by ulceration, afterwards closed by adhesion, and  which pro-
 bably  gave rise to  the peritoneal  infli mmation.   The abdominal
 disease was not suspected during life.
   No fluid could be obtained from  the vasa deferentia ; one was ex-
 amined three hours after death.   The testes  were of natural size,
 and not apparently diseased.  The vesiculae contained very little
 fluid.  It was thick, gelatinous, nearly  transparent and colourless,
 and did not change the colour of turmeric or litmus paper.  Under
 the microscope some globules were seen in it, but no animalcules.
   14.—Aged 27 ; died of pulmonary consumption.  The dissection
 was made thirty-two hours after death.  The body was much ema-
 ciated.  The lungs were enormously diseased; besides a  large ex-
 cavation in each superior lobe, and several smaller ones, and a vast
 quantity of tubercles in progressive change, there was partial cedema
 and hepatization, and thickening of the bronchia.  One arytenoid
 cartilage was laid bare by ulceration ; the left nervus vagus was
 partially atrophied  under the pressure of an enlarged bronchial
 gland.   There were  numerous large  granulating ulcers in  the
 cascum and ascending colcn; the vermiform appendix was severely
 ulcerated, and the lower part of the ileum in  a less degree. A short
 time before death, the bowels were regular;  previously there had
 been diarrhoea.
   The fluid obtained from the vasa deferentia, less than a drop  in
 quantity, had a healthy appearance;  it contained  a few spermatic
 animalcules, and many globules, most  of them very small,  a few-
 large.  The vesiculas  were moderately  distended with a fluid of a
just perceptible brownish hue, of the  consistence of mucilage, and
slightly viscid.  It did  not change the colour of turmeric paper.  A
 small number of spermatic animalcules  were  detected in ity and
 many  large globules,  which did not disappear on dilution with
 water.
   15.—Aged 27 ; died of the effects of inflammation of the pleurae
and lungs.   The  dissection was made thirty-six hours after death.
 The body was sub-emaciated.  There were twelve ounces of serum
in the left pleura, and sixteen ounces in the right, with a  sediment
in each of flakes of lymph.   Both  lungs  were partially adhering,
and much heavier than  natural  ; the left was cedematous  to a con-
siderable extent, and the right hepatized.  Neither contained tuber-
cles.  In the superior lobe of the right lung, there was a minute
cavity, surrounded by an indurated, dark, puckered structure, con-
veying the idea of a cicatrix of  an abscess.   The caicnm an'd'as-
cending colon were red and rather  flabby.  The spleen, pancreas,
and kidneys, were obscurely diseased.   During  life there  had been 
         FLUID IN THE VESICUL.E SEMINALES OF MAN.      371.

no supicions of thoracic disease.  Symptoms of disease of various
kinds had existed at least nine months before death ; anasarca pre-
vailed at one time, and ascites ; latterly  the  bowels were irregular,
occasionally relaxed and passing blood, occasionally constipated.
  The vasa deferentia were examined  twelve hours  after death.
The very minute portion of fluid obtained from them was destitute
of distinctly formed animalcules ; it contained globules of different
sizes, some of them very like fragments of the peculiar entozoa,—
the circular portion without the filament.  The vesiculas were ex-
amined thirty-six hours after death.   They contained  pretty much
fluid, of a just perceptible brownish hue, and of a gelatinous  con-
sistence.   Very many  well-formed animalcules appeared in it.  It
did not change the colour of turmeric paper.
  16.—Aged 33; died of complicated organic disease of the bones,
lungs, pleura,  heart,  peritoneum, &c.   The dissection was made
thirty-six hours after death.  The body was exceedingly emaciated.
The os frontis was carious, and in tvvo  places penetrated  through
by ulceration ; lymph  was deposited underneath on the dura mater.
The left  clavicle was enlarged, softened, spongy, and unusually vas-
cular.  At the base of each semilunar valve of the aorta was a small
bony con-qretion.  The  heart appeared atrophied.   The  pleurae
were studded with small, white,  firm tubercles.   The  right pleura
contained sixteen ounces of serum ;  the left four ounces.  In the
inferior lobe of right lung, there were two circumscribed masses of
coagulated blood.  The  cavity  of the  abdomen contained twelve
pints of serum.   The abdominal peritoneal lining generally was
studded with tubercles similar in character to those of the pleurae,
as was also the omentum, which, gathered  into a long mass retain-
ed by adhesion,  resembled a pancreas in its appearance.   The kid-
neys were small and obscurely diseased.  The left iliac and femoral
vein, and the right femoral, were completely obstructed by coagula,
in part consisting of fibrin, softened,  and of imperfect  purulent-like
appearance, and in   part of crassamentum little altered.  There
were no  tubercles in the lungs ; no ulcers  in  the air-passage or ali-
mentary canal.
   The vasa deferentia were examined  six hours after death, and
the vesiculas thirty-six hours after.   The very little fluid procured
from the former, contained numerous minute globules, and some of
a larger size, but no animalcules.  No animalcules either were found
in the fluid of the vesiculae, merelyglobules of different sizes.  The
fluid contained in them was  in a very small quantity, of a  light
brownish hue, and it did not change the colour of turmeric paper.
   17.—Aged 31; died of pulmonary consumption.   The dissection
was made'twenty-five hours after death.   The  body was greatly
emaciated.   Besides  tubercles, which abounded in the lungs, and
tubercular excavations, there was some cedema of these organs, and
hepatization and emphysema,—the  last to a considerable extent.1

   « Contiguous to the part where the emphysema was most remarkable, was 
372
davy's researches.
with much redness of and purulent discharge on the bronchia. The
intestines were not ulcerated.
  The  vasa deferentia  and vesiculae were examined twenty-seven
hours after death.  The vesiculae were considerably distended with
fluid, which was of a brownish tint, and did not change the colour
of turmeric paper.   It differed in consistence, according to the part
from whence taken ;  that from the fundus was  of the consistence of
thick mucilage; that from the anterior part was  more fluid; each
abounded in well-formed animalcules, and in globules of a large
size.  About a quarter of a drop only of fluid could be procured from
each vas deferens.   No  animalcules could  be  discovered in it,  but
globules of different sizes, and some  resembling fragments  of  ani-
malcules.
  18.—Aged 49 ; died after an illness of three  days, in consequence
of inflammation of the brain ; had been previously in  good health.
The dissection was made  fourteen hours after death.  The body
was stout and muscular.  A largequantity of  turbid serum with  a
sediment of purulent matter was found in the ventricles, and a con-
siderable deposit of lymph with which purulent matter was mixed,
on the base of the brain, the medulla  oblongata,  and on the upper
part of the spinal cord.   The abdominal and thoracic viscera gene-
rally were sound.
  The testes  and  vasa  deferentia were examined ten hours after
death ; the vesiculae seventeen hours after.  The fluid obtained from
the vasa deferentia abounded in animalcules, some of  which were
alive and in  languid  motion. The fluid of the vesiculaE also abound-
ed in them ; they were all dead.   This fluid had  a brownish tint,
and reddened litmus.1
  19.—Aged 30 ; died of pulmonary consumption.  The dissection
was made twenty hours after death.   The body was much emaciat-
ed.   In both lungs granular tubercles  abounded, and there was  a
large cavity in the superior lobe of each.  The liver, spleen,  kid-
neys, and supra-renal glands, were unusually firm.   The liver weigh-
ed seven pounds, and contained some fatty matter.   The spleen was
about twice  its natural size, and a portion of it dried on paper left
a faint grease-stain.  The ileum, caecum, appendicula, vermiformis,
colon, and rectum, were partially ulcerated ; and some of the ulcers
in the large  intestines had penetrated through  all  the coats, except-
ing the peritoneal, and, indeed, this coat was penetrated through in
the  appendicula, where  it happened to adhere in the right iliac fossa.

a small cavity, which communicated by an ulcerated opening with the  air-
cells of the lungs. When  the part was punctured under  water, several cubic
inches of air escaped from the emphysematous portion.   It consisted of eight
of azote by  measure,  and tvvo of carbonic acid gas.  In many other instances
in which I have examined  the air of emphysema of  the  lungs, I have found
it similar.
  1 In this case, the prostate contained a good deal of fluid, corresponding to
Meckel's description of it in its healthy  state. It was of a fawn colour,
opaque, slightly viscid ; under the  microscope it was found to abound in pear-
shaped particles, nearly equal in magnitude to blood-corpuscles. 
          FLUID IN THE VESICUL.32 SEMINALES OF MAN.      373

 There had been no dropsical  symptoms; no  peritoneal inflamma-
 tion ; diarrhoea had been troublesome in the last stage of the disease.
   The vasa deferentia  and vesicula were examined  twenty-two
 hours after death.   One vesicula contained pretty much  fluid, the
 other very liltle.  The fluid was of a just perceptible brownish hue,
 and of the consistence of mucilage ; it contained a large number of
 animalcules and some  globules, and did not change "the colour of
 turmeric or litmus paper.  An extremely minute quantity  of fluid
 was procured  from the  vasa deferentia, of  cream-like appearance;
 it contained some globules, and many minute particles, but, no ani-
 malcules.
   20.—Aged  41; died in consequence of the rupture of an aneurism
 of the thoracic aorta, not suspected during life.  The dissection was
 made thirty-three hours after death.   The  body was muscular and
 robust as in perfect health.  In the left pleura, into which the aneu-
 rism had opened, there were three and  a half pints of serum, and
 five and a half pints of soft crassamentum.   The viscera generally
 were sound.
   The vesiculae were, examined thirty-eight hours after  death, and
 the right vas deferens fifty-eight hours after.   The fluid in the for-
 mer was pretty abundant, of a grayish hue, without tint of brown,
 and of the consistence of common mucilage.   It contained  many
 animalcules ;  did not change  the colour of turmeric or of  litmus
 paper ; was coagulated by alcohol, and rendered a little more opaque
 by momentary boiling.   In the drop of opaque fluid obtained from
 the vas deferens, no animalcules could be detected ; it contained very
 many minute particles, and many particles of an irregular  form.
   In all these cases the  testes  were examined, as well as the vesi-
 culae and the vasa  deferentia.  Excepting in two  instances, viz. the
 18th and 20th, no animalcules could be seen in the fluid expressed
 from the divided substance of the gland.  The fluid, when it  could
 be  obtained in sufficient quantity for  accurate  observation, was
 transparent, generally contained globules nearly equal in  diameter
 to the blood corpuscles,  and invariably contained dense particles,
 apparently spherical, very much smaller, from twelve to fifteen times
 smaller,  and which, it  may be conjectured, were the  ova of the
 spermatic entozoa.1   In  the two instances in which spermatic ani
 malcules were  found in the fluid of the tubuli,  the quantity of the
fluid was greater than in the others.2

  1 I am disposed to consider this  as probable, partly in consequence  of the
peculiarity of appearance of the particles, differing from any particles  which
I have hitherto seen in other parts of the body.—and partly  from analogy.
MM. Prevost and Dumas, from their very extended and ingenious researches,
have adopted a different conclusion, viz. that  the spermatic entozoa are the
results of secretion, and that the testes are the secreting organs ;—a doctrine,
perhaps, equally difficult to prove or disprove.  The circumstance  of the
animalcules having been detected  in the majority of the preceding cases in
the vasa deferentia and vesiculae, when they could not be found in the  testes,
appears to me more in favour of their origin ex ova than by secretion.
  2 Probably in health, these animalcules exist invariably in the testes  of 
374
davy's researches.
  What are the inferences to be drawn from the preceding observa-
tions in relation to the question started concerning the nature of the
fluid, and the  use of the vesiculas seminales?
  The first inference that appears to me unavoidable is, that the
vesiculas are seminal reservoirs, according to  the old opinion on the
subject and that which is slill most commonly entertained  by the
continental physiologists.  And  next, that they are not merely  re-
servoirs, but are also secreting organs, furnishing mucus, and per-
haps som3 other fluid, for admixture with the semen.
  The first inference is supported  by the general  resemblance,  in
several cases,  of (he fluid of the vasa deferentia and of the  vesiculae,
and of the existence of the characteristic  spermatic animalcules in
the fluid of the vesiculae, in every  instance iti which they were de-
tected in the fluid of the vasa deferentia.1  Hunter does  not  men-
tion having used  the microscope  in his inquiry.  If he had,  he
could hardly  have failed to have arrived  at a  different conclusion.
  The second inference is supported by there being a certain dif-
ference  in almost every case between the fluid of the  vesiculae and
that of the vasa deferentia, and especially by the circumstance, that
the difference of quality is most perceptible in the fluid of the fun-
dus,—where most out. of the way of being readily mixed  with the
fluid of the testes.   What the exact difference of qualities is between
the fluid of the  vesiculae and of the vasa deferentia, and,  it  may be
added, of the vasa deferentia and of the testes, in  perfect health, re-
mains to be ascertained.  It can be determined only by careful ex-
amination and comparison  in the instances of criminals who have
been executed, or  of persons who have been  killed by accident, not
labouring under chronic disease, and in  the vigour of  life.   I am
disposed to think that the difference  will not be found  very con-
siderable, and that between the fluid of the vesiculae and of the vasa
deferentia, it will consist chieflyin  the former being more dilute and
perhaps more bland and mucous.2   Hunter was of opinion that the
fluid of the vesiculae is naturally of  a brownish hue.   As an inva-
riable quality this appears  questionable.   The sooner after  death
the fluid is examined, the less brown it is.  I have given amongst

man contained  in the tubuli.  The results of the experiments of MM. Prevost
and Dumas on  twenty-five different species of vertebrate animals, may  be
adduced in  support of this conclusion :  (Vide Ann. des Sciences  Naturelles,
vols. i. and  ii.)  and I may add, that all the comparative trials  I have yet made
are in favour of it.
  1 I may add,  lhat I have observed spermatic animalcules in the  vesiculae of
the ram and bull, precisely similar to  those found  in their testes and vasa
deferentia ; and if I recollect rightly, they have been detected in the vesiculae
of some other animals by MM. Prevost and Dumas.  Whether the vesiculae
of certain animals, however, have not a specific  use, distinct from that of
being merely reservoirs, appears to be deserving of further and special  in-
quiry.
  2 That the vesicula? are glandular, or possess mucous follicles,  seems  un-
questionable ; I have seen them with the microscope, and the mucous secre-
tion is made manifest in disease. 
         FLUID IN THE VESICULA SEMINALES OF MAN.      375

the preceding cases, instances in  which it was colourless, and those
examples in which there was reason to consider  it least altered in
consequence of disease: and Mr.  Hunter's best observations are in
accordance, viz. two instances, the  only ones given in which exami-
nation was made very soon after death.   He  says, in a man  killed
by a cannon-ball, "the fluid in the  vesiculae was  of a lighter colour
than is usually found in men who  have  been dead  a considerable
time; but it was by no means like  the semen either in  colour or
smell."   And, he adds,  "in another man who died instantaneously
in consequence of falling a considerable height, and  whose body I
inspected soon after the accident, 1 found the contents of the vesi-
culas of  a lightish  whey-colour, having  nothing of the smell of
semen, and in so fluid a state as  to run out on cutting into them."1
The colour which the fluid of the vesiculae commonly exhibits in
late post-mortem examinations is probably partly derived from  the
infiltration of some of the colouring matter of the blood after death,
and, in part, perhaps occasionally,  from  a vitiated secretion of the
follicles,  or secreting surface of the vesiculas,  and of the adjoining
vasa deferentia.2
   It would be a work of supererogation  to enter  into a detailed  ex-
amination  of the arguments brought forward  by  Hunter in support
of the views he advocated  relative  to  the vesiculas  and  their con-
tents : it  has been ably done by Meckel in  his Manual of Anatomy,
by  whom each argument has been  seriatim answered, and in most
instances, as it appears to me, in a satisfactory manner, but without
reference to microscopical  research.3
   Admitting  the fact, that the vesiculas are,  like the  gall-bladder
and bladder of urine, recipients, it  may  be viewed  as  a fortunate
circumstance  in  our economy, and admirably adapted to the con-
dition of man.  Like the bile or the urine, so  the spermatic fluid in
the healthy adult appears to be in constant process of secretion, and
to pass as  it is formed into its appropriate reservoir, from whence,
without  disturbance of the system, in a state of continence, it is
either pressed out and voided during the act of  alvine evacuation,
or it may be in pait absorbed.  Mr. Hunter, in accordance with the
opinion which he had formed of the use of the  vesiculas, did  not
admit this.  He believed that the fluid  rather accumulated in  the
testes, and gave rise there to annoyance, requiring its evacuation by
a disturbing act, a doctrine of some danger, especially to youth, in

  1  Observations on certain parts of the animal economy.  By John Hunter,
4to., London, f786,p. 28.
  2 Occasionally after death, not only is the fluid of the vesiculae found of a
brownish discoloration, but also the inner surface of the vesiculas, and  of that
portion of the vasa deferentia which is  contiguous, and of similar structure ;
indeed, I  have seen the portion of the vasa  deferentia just  mentioned more
discolo' red than the vesiculse themselves.
  3 Manuel  d'Anatomie Generate, Descriptive et Pathologique.  Par J. F.
Meckel, ti-i-d-in par A. Jour, an et G. Breschet. Paris, 1825.  Tom. iii. p.
643, et seq. 
376
davy's researches.
its consequences.  In confirmation of what is stated above, and in
opposition to the docrine of Hunter, I may farther state, that 1 have
frequently examined microscopically the fluid from the urethra fol-
lowing the alvine evacuation, and I  have always found  il, from  a
healthy person, abounding in animalcules, the majority of  which
have always been dead j1 and thus, perhaps, seeming to indicate that
the vesiculas are cloacas as well as reservoirs, and are essentially de-
signed for man, to enable him to control and to  exercise that moral
check on the passions, by which  he  should  be  distinguished from
brute animals, and without which no considerable advance can be
made in civilization, or in elevation of individual condition and cha-
racter.
  Relative to the  effects  of  disease on  the fluid  of the  vesiculas
seminales,  and  on the spermatic fluid generally,  the instances
brought forward are  too few to admit of extensive induction. They
seem to show:  1st,  that tubercular consumption, even  in  its ad-
vanced  stage, has little effect in  preventing the  secretion  of the
testes, or ihe production of those  animalcules,  on which, there is
much reason to infer, the active power of the semen depends; 2dly,
that  other wasting diseases, terminating in death, have  the  effect
of arresting the secretion;  3dry. (hat the contents of the vesiculae
and  vasa deferentia,  under the influence of disease, retain  longer
their characteristic qualities than the contents  of the tubuli;  and,
4thly, that there is least fluid  in the vesiculas and in  the vasa defe-
rentia, and that it is most altered in instances of chronic diseases of
the abdominal viscera, and especially of the intestines.
  The subject of inquiry is in  many respects curious, and some other
of its relations are  not uninteresting or unimportant.  I shall allude
to one only before concluding, and  that connected  wilh medical
jurisprudence.
  Admitting that spermatic animalcules are characteristic of and
essential  to healthy  spermatic fluid, in certain doubtful criminal
cases, probably, decisive evidence may be obtained by means of
microscopical examination. The  spermatic fluid undergoes change
rapidly when exposed to  the air, and even soon becomes putrid;
but the spermatic animalcules, I find,  resist change in a remarkable
manner.   In one instance, distinct  remains of these animalcules
were observed in putrid fluid, which had been kept ten weeks, at a
temperature varying  between  50° and 60° of Fahrenheit, and in an-
other which had been kept a  year and a half.  In another instance,
some fluid of the vesiculas was applied  to linen,  and  wrapped in
paper and put  by  in a close drawer.  It was examined  the follow-
ing day,  at  the  end  of a week, and  after eighteen days, and  each
time animalcules  were discovered  under the  microscope.   The
mode of making the trial was by  saturating a small portion of the

  1 On rest, contrary to what Hunter states, I have found this fluid separate
into two parts—a sediment containing the  animalcules and opaque, and a
clear supernatant fluid destitute of animalcules—thus  analogous also to the
spermatic fluid. 
         FLUID IN THE VESICUL.E SEMINALES OF MAN.      377

smeared  linen with a few drops of water, and gently pressing out
a drop for the experiment.   Fragments of the  animalcules  were
very distinct, and sufficiently characteristic; and on careful inspec-
tion, an entire animalcule here and there was observed.   The ap-
plication of these facts to ihe purposes of evidence does not require
any comment.
  In conclusion,  it may not be amiss to allude to the views of Sir
Everard  Home  on the subject of the  fluid under  consideration.
They occur, detailed  at great length and in a very circumstantial
manner,  in the fifth volume of his Lectures on Comparative Ana-
tomy, and are well worthy of being referred to as  a scientific curio-
sity.  The  opinion which Sir Everard Home  there  maintains is,
that spermatic animalcules have no real existence; and that all in-
quirers who luyve asserted their existence, from  the time of their
discovery by Ham, in about 1677,1 to the present  period, have been
in egregious error, having mistaken,  as  he believes, filaments  of
mucus for entozoa, and fallen thereby into wild theories.   Sir Eve-
rard Home relates particularly ihe grounds on which he came to this
conclusion, and the very great pains he took to endeavour to arrive
at the truth;—how he made a journey with his able assistant and
accomplished artist, Mr. Bauer, to Paris,  expressly for the purpose
of examining the spermatic fluid with a microscope of Chevalier, by
which the  peculiar entozoa had  been  seen by certain  French sa-
 vans;—how he procured  an excellent instrument of the same kind,
 and employed it  at home; and how, aided by Mr. Bauer, after exa-
 mining the spermatic fluid of the fallow-deer, when in heat, during
two seasons, under most  favourable circumstances,  he was unable
to discover any animalcules in it, and was confirmed in  his opinion
 of their non-existence.
   At present, this opinion  of Sir Everard Home's being unques-
 tionably erroneous, it is  not  necessary either to  criticise or contro-
 vert it.   The reflection, however, which  it gives rise to, (if I may
judge from my own feeling,) is of a painful  kind ; especially in
 relation to  his other microscopical  observations—so beautifully  re-
 presented by Mr. Bauer, and admirably engraved—in the accuracy
 of which now it seems a  matter almost of impossibility to have any
 confidence.  And this I think it  right to point out particularly,
 considering the  manner in  which Sir Everard Home prefaced the
 most remarkable of the  microscopical observations,—observations
 which, if correct, would, as he anticipated, have been of the  great-
 est importance, and which could  not fail producing a great change
 in our  physiological doctrines.  Take, as an example, his introduc-
 tory remarks to his Croonian Lecture,  for 1817, "On the Changes
 the Blood undergoes in  the act of Coagulation," in which he en-

   1 Vide  Leuwenhoeck's letter to Lord Brouncker, dated Nov.  1677,  in the
 12th volume of the Philos. Trans., in  which he mentions that the discovery
 of spermatic animalcules in man was first made by Ham, and how he con-
 firmed it, and discovered them also somewhat different in form in the semen
 of the dog, cat, and rabbit. 
378
davy's researches.
deavours to prove that the blood-channels, giving rise  to vessels,
are formed  in lymph by carbonic acid gas, in the act of passing as
it is disengaged, as he supposes, from blood in coagulating.
  "It is not a little remarkable," (he says) "that in the first lecture
of this kind,  which I laid  before the society in the year 1790, I
should have endeavoured to show that  a muscular fibre was too
minute an object to be seen by the human eye, even assisted by the
best  magnifying glasses then in use;  and that,  in this lecture, 1
shall be able, by means of the great improvements that have been
made in the use of the microscope, to show that a fibre,  not larger
in diameter than one of the globules of the blood, can be demon-
strated.
  "To the members of this society," (he continues) "who have so
lately seen  Mr. Bauer's drawings of  the glandular apparatus pecu-
liar to the Java swallow, of the internal membrane of the human
stomach, exposing structures that were not known to exist,  also of
so small an  object as the human  ovum,  in which is seen the
seat of tvvo of the most important organs of the body, (drawings
rendered beautiful  by their simplicity  and distinctness,)  it will
readily suggest itself,  that Mr. Bauer is the person to whom  I con-
sider we are indebted for those improvements.  His whole  life, I
may say, has been employed  in investigations of a similar nature:
in plants, observing first the natural appearances, and  then  mag-
nifying  them in different degrees, and comparing, with the  nicest
discrimination, what was exhibited by one magnifying power with
what was shown by that immediately above it,—and, where they
did not  correspond, employing the whole energies of his mind, with
a patient labour almost beyond  what is natural, in ascertaining  the
cause of the deception  which must in one of them have taken place.
To the  observations of such a man upon subjects of this nature, if
we are  not confidently to place a reliance, how are we to give
credit to the remarks that are made by common observers?
   "I have said thus  much," (he adds)  "as an introduction to  the
observations  that I am going to bring forward, for the public to
know, whatever opinion they may form of them,  they  have been
the results of long and unwearied research; and have been so fre-
quently repeated as to satisfy Mr. Bauer of their correctness."1
   The  reader acquainted with  the history of the  microscope, and
the powers of the best instruments which  have  been  in use from
the days of Letiwenhoeck to the present time, will smile at Sir Eve-
rard Home's mistaken views of the improvement of the instrument
as alluded to  by him, and at the test which he gives of the power
of the  microscope employed  by Mr. Bauer;—the defectiveness of
whose instrument, it must be inferred, was one of the chief sources
of error to which  those two very zealous inquirers were exposed.
I fear it must be admitted  of Sir Everard  Home, that he was too
ambitious  of being ranked  as a great discoverer, and  that he had'*' '^
1 Philos. Trans, for 1818, p. 172. 
OBSERVATIONS ON THE AO.UA BlNELLl.
379
not the power of resisting the  temptation of represenling as a dis-
covery what he  believed himself, although not clearly demonstrat-
ed.  His account of the human ovum, referred to in the preceding
quotation, may be noticed as an instance of this his disposition. It
is  now believed  by those who had the best means of correct infor-
mation  on the subject, that the supposed ovum—to which he at-
tached so much importance, and of which there are such beautiful
representations engraved in  the Philosophical  Transactions  for
1817, from Mr. Bauer's drawings—was only the egg of a large fly,
deposited  in the cavity of the uterus after it had been laid open for
examination.
   Comparative anatomy is  under great obligations to Sir Everard
Home;  but, on that account, we ought not to take his authority for
more than it is worth, and  most of all be on our guard  lest we are
misled  by one who was extremely incautious and  precipitate in
forming his philosophical views.  The Royal  Society  for the  Pro-
motion  of Natural  Knowledge has wisely always  taken  for its
motto the words
                     "nullius in verba."
XXVIII.
OBSERVATIONS ON THE " AUUA BINELLI," WITH AN AC-
  COUNT OF SOME EXPERIMENTS MADE TO ELUCIDATE
  ITS SUPPOSED  EFFECTS.

  This  water, for several years,  has had  some reputation in Italy,
under the name  of "Aqua Balsamica Arteriale,"  or the more  brief
one of "Aqua Binelli,"—the one designation derived from the pro-
perties attributed to it, the other from the individual who invented it.
  The properties attributed to it  by Binelli, and those who prepare
and  vend it at  present, are not a little  marvellous; such as the
stopping both internal and external  hemorrhages, and even of the
laro-e arteries when cut transversely—the cleansing and healing of
alUrinds of wounds—the renewal of uterine evacuations when sup-
pressed, and the moderating of them when excessive,' &c.
  My attention  was called  to  this water  first  by the late Captain
the Honourable  Sir Robert Spencer, in the summer of 1830, after a

  ' A pamphlet, descriptive  of the effects of this water, distributed with it
bv its venders, thus opens:                       .   ..,..,, j  .
  "Da eran  tempo e nota in Europa 1' Aqua Balsamica Arteriole'del dot-
tor Fedele Binelli, native del Piemonte, e versaiissimo in ogn. meditaz.one
ed esnerimento di chimica et di bottanica.  L' efficacia della medesima ad
arrestare o*ni pm minacciosa effusione di sangue, fu mai sempre s. costante
e di  tal  eiovamento alia medica arte, che non potrebbe otienersi piu univer-
sale, e piu meritata lode di quella che all' inventorc di  essa venne, da gran
tempo, relributa." 
3S0
davy's researches.
visit which he had made to  Naples,  at a time when the extraordi-
nary virtues  attributed  to it  were,  in that city, a common topic of
conversation, and when the proprietors of the secret of its prepara-
tion were selling it in large quantities.
   The specimen which I examined shortly after was part of a case
of several bottles which he had ordered to be forwarded to him. at
Malta,1  for the  purpose  of having'its qualities  fairly investigated.
It arrived after the decease of this en lightened officer, and was put
into my hands for trial  in our military hospitals, by the then go-
vernor,  the late Major-General. the Honourable Sir Frederick  Pon-
sonby.
   1 first examined into its  physical  and chemical qualities.  It
proved to be of t;;e same specific gravity nearly as distilled water.
It was neither acid, alkaline,  nor saline.   Its odour was not unlike
that of coal gas not purified, which it lost byjsoiling; the taste was
rather pungent;  not in the slightest degree astringent.   In brief, it
appeared to be merely water containing a little volatile oil or naph-
tha, and was probably prepared by the distillation of  water from
petroleum or some kind of tar.
   I next made trial of it as a styptic.   I scratched the back of the
hand  with the lancet till the blood flowed ;  the water, applied to
the scratch,  rather increased the  bleeding than stopped  it.   The
following morning the razor inflicted a slight  cut;  the Aqua Binelli
was again applied, and the result  was the same.
   These few and  simple trials were  made in January, 1831, just
after I received the water, and they, of course,  convinced me  that
the thing was an  imposition on  the  public,  and  deserving of  no
further  investigation.  About two  years after,  my attention  was
recalled to the subject by a medical practitioner of Malta, who had
studied at Naples, inviting me, with others, to witness the effects of
a preparation made in imitation of the Aqua Binelli, and which,  he
maintained, was identical with it in composition and virtues.
  The experiment  he  invited us to witness  appeared  an unobjec-
tional one, namely,  the  partial division of the  carotid  artery of a
goat,  the bleeding of which he undertook to  stop by means  of his
fluid.   He allowed us to expose the vessel and cut it across ; about
one half of the circumference of the artery  was divided, and  the
bleeding was most  profuse.   He  stood  ready with  compresses,
moistened with the fluid, which he  instantly  applied, one over the
other, and secured them by rolling a bandage about the  neck, mak-
ing moderate pressure  on the wounded  vessel; a little oozing of
blood followed, which soon ceased.  He said that in  three hours
the bandage  and compresses might be removed without any re-
newal of the  hemorrhage.2

  1 The charge for this case was aboul 8/.  The price of the water at Naples
is four carlini an ounce, or 2s. ire/.                                   <
  1 The  following matvellous result  is related in the  pamphlet already
alluded to,—witnessed, it  is asserted, by a commission composed of some
of the most respectable medical men in Naples,—whose names are <nven 
OBSERVATIONS ON THE AQUA BINELLI.         381
    Accordingly, at the end of three hours, they were removed, but,
  when the last compress was raised, the bleeding broke out as furi-
  ously as at first, and, to save the life of the auimal, the artery was
  secured by ligature.  On examining the last compress, a small coa-
  gulum of  blood  was found  adhering to it. just the size proper to
  close  the wound  in the carotid,—thus accounting for the  ceasing
  and renewal of the bleeding.
    Reflecting on this result, and considering the chemical nature of
  the fluid employed to moisten the compresses, which appeared ana-
  logous to that of  Binelli,  the conclusion I  arrived at was obvious,
  namely, that had the compresses used been moistened simply with
  common water,  the effect would have been the same,—the bleeding
  would have been stopped; and it also appeared very probable that
  had the compresses been allowed to remain undisturbed, there would
  have been no renewal of the bleeding.
    To ascertain  the truth of these  inferences, the  following experi-
  ments were made.
    On the same  day, Februrary 8,  1833, in  the presence of  several
  medical officers,  1 divided transversely the carotid artery of tvvo
  dogs; one small and feeble, the other of moderate size and  strong.
  In each instance the bleeding was  most profuse, till compresses
  dipped in common water had been applied  and secured by a band-
  age, which, as  in the case of the goat already given, completely
  stopped the hemorrhage.
    The small  dog, from the proportionally  large quantity of blood
  which it  lost,  was very feeble  immediately,  and  appeared  to  be
  dying; but it presently rallied,  and for several days seemed  to  be
  doing well.  It unexpectedly died on the 15th, seven days after the
  infliction of the wound.  The bandage during this time had not
  been touched, and no application had been made.   Now, on expos-
  ing the neck, the wound was found covered  with coagulable lymph,
  discharging pus,  and  on  dissecting out the artery and  the eighth
  nerve contiguous to it, a mass of coagulable lymph appeared lying
  over the wound in the vessel, extending about half an inch above
  and below it.   This  mass of coagulable  lymph having been  care-
  fully removed, and the artery slit'open, the vessel was found  quite
  pervious,  not in  the least contracted.  The wound in the fibro-
  cellular tissue or  external  coat was closed  by a minute portion of
  dense coagulable  lymph.   But  not  so in the middle and inner coat;
  in these there was a gaping aperture, across which, on minute in-
  spection, two fine threads, apparently of coagulable lymph, as if the

  many of them professors in the university of that city. "Il Professore D. Ni-
  cola Mancini alia  presenza della commissione, e di altri professori concorsi
  nel Teatro Anatomico del Regio Ospedale degl' Incurabili, apri trasversal-
  mente  l'arteria crurale di una pecora, vi pose sopra la filaccia bagnata nell'
gfyiqua Balsamica, ed all' istante I'emorragia cesso; dopo un niinuto fu tolta
^la: filaccia, e 1' arteria, con summa raeraviglia degli astanti, si rinvenne gia
  innestata, e  la ferita nelta come se mai da essa vi fosse sgorgato del sangue."
         12__o-                                    25 dav 
382
DAVY'S RESEARCHES.
commencement of the healing process, were observable. The cause
of the dog's death was not discovered.
  The other dog did not appear to suffer from the wound.  The
bandage  and compresses were  removed  on the 15th  February,
without the occurrence of any bleeding.   On the 20th of the same
month, the wound in the neck was nearly closed by granulations.
The artery was  now cut down on, and the portion of it that had
been wounded taken out between tvvo ligatures previously applied.
On  careful examination of this excised part,  it was found free from
coagulable lymph,—at  least  there was not the same thickening or
tumour from lymph deposited as in the former case; it was proba-
bly  absorbed.  When the external loose cellular tissue was dissected
off,  a very minute elevation, about the size of a pin's head, appeared
on  the site of the wound, the  remains of the cicatrix externally.
The artery was completely  pervious, and  not at  all contracted,
where  it had been wounded.  Slit open for internal  examination,
the wound  in the inner coat  was marked by a red line, interrupted
by  two white spots; there was no gaping, the edges adhered  to-
gether, excepting at one point, elsewhere the union was complete.
The white  spots resembled  the natural lining membrane, and had
the whole wound been similarly healed, I believe it  would  have
been impossible to  have traced it.
  These experimenls were  made in  Malta.   I shall  mention one
more, which was made after leaving that island,  and  subsequently
to the  publication of an account of them in the Edinburgh Medical
and Surgical Journal.
  On the 29th November, 1837,  at Fort Pitt, the carotid artery of
a pointer was laid  bare, and partially divided transversely.  Yery
florid blood gushed out with  great violence.  Two linen compresses
dipped in water were immediately applied, one over the other, and
secured by a roller.  It was drawn too tight by an  assistant, and
the hemorrhage was not suppressed until the pressure was relaxed;
indeed, it was necessary to  remove the bandage, and re-apply it,
not tight.  About six ounces of blood were lost during the opera-
tion.   Nothing farther was  done;  there was  no farther bleeding:
the dog's health was not  affected.   In about a fortnight,  the wound
in the integuments had completely healed ; and in about six weeks,
namely,  on the 12th of January, on examining the artery, carefully
dissected out after the death  of the animal, from the injection of pus
into its pleura, no  traces of the wound could be detected in the outer
coat of the vessel, or in the  contiguous parts, nor internallv when
slit open, excepting on narrow scrutiny, when a faint line was just
perceptible, marking the cicatrix, like the impression made by a tine
ligature on an artery not  drawn sufficiently tight to divide the inner
 and middle coats.
    The general results of these experiments, (if I may  be allowed to
 speak so of so small a number,) are not without interest in applica-
 tion to surgery.   They show how a  hemorrhage from  the wound 
OBSERVATIONS ON THE AQUA BINELLI.        383
of a large  artery, which by itself would be speedily fatal, may be
easily arrested by moderate compression, through the means merely
of several folds of linen or cotton moistened with water; and they
further show how, under this moderate compression, the wound in
the artery heals,  the vessel remains pervious, and without the for-
mation of an aneurism; and  how, after a time, the short space of
six weeks,  only just perceptible  traces of the wound are discover-
able.   Under this moderate compression, the healing of the wound-
ed artery seems to be very analogous  to that of a wounded vein,
and apparently by means of the same natural process.
   Whether similar results would be obtained were trial made of the
same means in the wounds  of arteries  in the human subject, can
only be ascertained positively by judicious experiments.  The pro-
bability is,  the results would be the same; the analogy is very com-
plete, and some facts well known in surgery accord with if, not to
mention the experience of the effects of the Aqua Binelli, as certified
by men of high respectability.1
   I  have laid  stress on the effect of the pressure, afforded by the
wet  compresses applied in the experiments  related,  believing that
the virtue of the means consists in the pressure,—of course not in
the water, excepting so far as it renders the compresses better fitted
for adaptation  to the wound, to produce the degree of resistance
requisite to counteract the heart's impulse on the vessel; and also
better  fitted to exclude atmospherical air.   T would also  lay stress
on the moderate  degree of pressure that is produced in the manner
described,  allowing the blood  to pass through the canal of the
artery, and, as before  observed, doing little more than resisting the
momentum of the blood  in  its passage from the moving source.
The importance  of this moderate degree of pressure—reducing as
much  as possible the wounded artery to the condition of a wounded
vein, is, if I do not deceive myself, very considerable. When I have
pressed with the fingers forcibly on the compresses applied  to the
wound, expecting at the moment to arrest the bleeding, I have been
disappointed—it  has continued.  It has only ceased when the com-
presses have been secured, and  not tightly, by a roller passed round
the neck of the animal.  And further, in illustration, I may  remark
that I have been  equally  disappointed in  using graduated com-
presses, ensuring considerable  pressure on  the wound.  This me-
thod has failed when general moderate pressure, effected by com-
presses about  two inches  long and one wide, succeeded.  And, on

   • It was my intention  to have given a selection of the certified cases in
favour  of the Aqua Binelli brought forward  in the pamphlet which is lur-
nished with the water; but, on reconsidering them, it appeared a superfluous
labour  as the results, (giving them credit for correctness,) however excellent
In a curative point of view, are no more than the  enlightened surgeon of the
present time may readily admit to be owing to water dressings alone, with-
out the aid of pressure; the majority of the instances adduced beingexam-
ples of gun-shot wounds, and contused  wounds  from, which there was no
profuse bleeding, and no necessity, according to the ordmary mode of surgi-
cal treatment, for securing wounded vessels. 
384
davy's researches.
reflection, the difference of result is  perhaps what  might be ex-
pected ; the severe pressure can  hardly arrest the  bleeding except
by pressing the sides of the vessel together, and closing the canal,
the accomplishment of which requires a most  nice  adaptation,  and
a force which cannot easily be applied with  steadiness except by
mechanical means, and in situations affording firm support beneath.
  Should the expectation  which I  have  ventured to form of this
method of stopping the bleeding of wounded arteries of a large size,
in man, be realised on trial, I need  not point out how very useful
it may prove in military surgery, how very available it will be in
the field  and in battle, especially in great actions,  when, however
numerous  and well  appointed the  medical staff of an army, the
number  of wounds  requiring attention  must always  exceed  the
means of affording  adequate surgical relief,  according to the plan
of treating them at present in use,  of suppressing hemorrhage by
ligature.
  I have said nothing of the  boasted efficacy of the Aqua Binelli
given internally.  I trust it is as little necessary to  make any com-
ment on  it now-a-days, as on the tar-water of Bishop Berkeley, so
very analogous in nature and reputation.  Both the one and the
other in  some cases may be serviceable, but their principal recom-
mendation  seems to be, that in doubtful cases  they are innocent.
                           XXIX.

ON A NEW  METHOD OF  PRESERVING ANATOMICAL PRE-
             PARATIONS FOR A LIMITED TIME.

  During two years and a half, namely, between 1825 and the latter
end  of  1S4.7, as leisure and opportunities permitted, I  first made
trial of a method of  preserving anatomical preparations, which I
believe to be  new, and which 1 have found to possess  advantages,
in many respects, greatly exceeding the  expectations I had formed
of it.
  Its principal advantages consist—first, in its cheapness ; secondly,
in its durability within certain  limits; and, thirdly, in the clear and
instructive  manner in which  it displays the  minute structure of
many textures and compound parts.
  The  cheapness of the method will be obvious, merely from the
mention that the substance employed is a solution of the sulphur-
ous acid gas  in water, and that it may be prepared in  a manner,
equally economical and easy, by burning sulphur over distilled or
rain water, in any appropriate glass vessel;1 agitating  the water,

  1 A tall receiver, provided with a cork, one-third full of water,  answers.
well.  The sulphur may be introduced kindled, in a small gallipot, attached 
     METHOD OP PRESERVING ANATOMICAL PREPARATIONS.  385

when  the  sulphur ceases to burn, and, when  the  water is suffi-
ciently impregnated with the acid gas, filtering the solution, to  ren-
der it transparent and clear.
  Its durability, to a certain extent,  I infer from  many circum-
stances.  In December, 1827, when I communicated an account of
the effects of the acid to  the Medico-Chirurgical  Society of Edin-
burgh, in the third volume of whose Transactions it was published,
I had preparations by me, which  had  then been made nearly three
years—nothing  further  had been done to them—no fluid  had been
added—no evaporation  had taken place, and they then  appeared
as perfect as when they were first immersed in the acid, and merely
confined in a  bottle with a glass stopper, lubricated  with a little
cerate.   Other considerations induced me  to think favourably of
its preservative  powers.  From experiments I had previously made,
the sulphurous  acid appeared to have nearly the  same  power in
preventing the putrefaction  of animal  matter, as it has of stopping
the  fermentation of vegetable juices.  I found  that serum coagu-
lated by this acid gas, and converted into a  kind of jelly, may be
kept in water several weeks,  exposed to  the air, without undergo-
ing any  change, and that the fibrin of the blood, thus  treated,  was
equally exempt from change.  Similar trials were made with many
anatomical preparations ; they were exposed to  the  air in this acid,
and were then taken out of the acid and placed  in water exposed to
the air ; and the  result showed that  after  having been well acted
on  by the  acid,  they were no longer liable  to putrefaction.  Some
of them underwent very little change, during exposure to the air,
for several weeks in water ; others became soft and gelatinous, and
were partially reduced to a  pulp, but without emitting  any offensive
odour, like that of putrid animal matter, an odour  rather like that
of decaying vegetable  matter affected  with mildew.1
   How the sulphurous acid acts in preserving animal substances it
is difficult to say.   I am not aware that it is yet ascertained how it
preserves  vegetable substances; how it prevents vinous fermenta-
tion in vegetable juices, such as  are  most prone to undergo it, as
the juice of the  grape, &c.;  how  it prevents light wines and vinous
fluids to which  atmospheric air has access, from  becoming sour or
converted  into  vinegar; or how, moreover, it  stops the  process of
ulterior  change to which unpurified vinegar, and  most, if not all, of
the  unpurified vegetable acids are liable, when exposed  to the air.

to a strong wire.  As soon as the flame expires the sulphur  should be quickly
withdrawn, the cork replaced, and  the vessel agitated, that  the water may
absorb the  acid gas formed.  After asitation  for about half a  minute, the
cork should be taken out—and fresh atmospheric  air supplied  by blowing
into the jar with  a common bellows ; the burning of  the  sulphur may then
be  repeated, and  the process so continued, until the water is  sufficiently
strongly  impregnated.  Hard  water should be avoided ;  for, if the water
contain any lime, it will render the solution turbid—a fault which  even
filtering will not perfectly correct.
 • ' These experiments were made at Corfu, and during  the hot summer
months. 
386         '       davy's researches.
It is not owing  to the mere  abstraction of oxygen, for phosphorus
has not the same effect permanently, nor nitrous gas.  It may be
conjectured, both  in  the instance of vegetable and  animal sub-
stances, that the antiseptic power of the acid depends on its effect-
ing some new arrangements of the particles of the proximate prin-
ciples which render them exempt, from the changes  alluded to ; or
on renderino- inert the vegetable and animal leaven which, under
favourable circumstances, excite  these changes.
  The last  advantage which I have  mentioned, the manner in
which the acid  displays the minute structure of many textures and
compound parts, is that which I  shall  most dwell on, as I consider
it its  chief recommendation  to notice.  It  does not, like spirits of
wine and a  solution of alum, contract what  is immersed  in it;  it
does not, like a  saturated solution of common salt, or of nitre, or of
any of the salts of chlorine  which  I have tried, after a little while,
lose its transparency  and become thick and turbid ; nor does it,
like a solution of corrosive  sublimate, when used without precau-
tion, deposit on  the inside of the  glass and on the preparation  itself,
a crust which soon  becomes  a complete  mask.  On the contrary,
it expands and  developes the parts, some more, some  less, so as to
magnify them and  make  them more distinct, effecting in structure
what the lens does in vision ;  and, at the same time, it  remains
clear, so that the lens still may be  employed to heighten the effect
and convey  still more minute information of the object.
  1 shall enter into  some details in illustration.  All the descrip-
tions  will be taken from preparations from the human subject.
  The skin  immersed in the sulphurous acid swells considerably,
and the cuticle  is either thrown off or easily detached.   The cuticle
of the sole of the foot, to  mention a particular instance, is rendered
almost transparent, and is but little thickened. When held between
the eye and the  light, its symmetrical structure is beautifully shown,
with  innumerable dotted points, as  it were, in  the  course of its
linear waving, which  probably serve the  purpose of pores.   If the
cuticle, detached by means of sulphurous  acid, is dried, it shows its
peculiar structure still  more distinctly and elegantly.
  The cutis, distended by the sulphurous acid, appears as a  tissue
of extremely minute  fibres and particles,  condensed towards the
outer surface, where in contact  with  the cuticle, and loose  inter-
nally, where it  gradually blends  itself with the adipose texture.'
  Serous  membranes, immersed in  the  acid, swell considerably,
and lose very little of their transparency.   The inner  surface of a
portion of pericardium, now before me, has an uneven surface, and
exhibits, when examined with a  common lens, a slight appearance
of pores; its section shows  as if it were composed of layers, and its
outer surface displays a loose  intertexlure of fine  fibres.   A por-

  1 In the scrotum and eye-lids—the transition is into cellular texture; she
surface of the cutis appears  as  the boundary merely of the cellular tissue a
little condensed. 
method of preserving anatomical prepa
387
   tion of pleura, (with the exception of the cut part, which is  very
   much  thinner, and not visibly in layers,)  appears very similar, but
   less distinct.                               ...        ,  ,,
«     On  the cellular structure, the sulphurous acid has much the same
   effect  as  on  the serous;—it distends it  greatly, and preserves it
   transparent.                                              „
      On  fibrous membranes the sulphurous acid has not much effect;
   they become swollen in it slightly, and  diaphanous.  The outer
   layer of the dura mater, in  a specimen before me, is considerably
   corrugated, whilst the inner has  remained smooth, which, perhaps,
   is owfng to the outer being of greater density than the inner,  (as it
   appears to the eye to be); in  consequence of which greater density,
   it is more expanded.  The sclerotic coat  of the eye is equally acted
   on throughout; and is not in the slightest degree wrinkled.  The
   outer  surface of the tunica albuginea  testis is corrugated  very
   slightly.
      It acts  more powerfully on tendons and ligaments ; and on  some
   more than on others, showing a striking difference in this respect.
   The tendons of muscles in general it expands amazingly, and ren-
   ders semi-transparent.   To  take  an example—the tendo-achillis
   thus swollen  has the appearance of an  opalescent  mass,  divided
   pretty  regularly into  cells,  the boundaries of which  are white
   opaque lines.  On  the ligamentous sheath of the  penis its expan-
   sive power is less forcibly  exerted ; the sheath is rendered nearly
   transparent; and its structure is beautifully shown, as if composed
   of a white pulp as a ground-work, intersected and  bound together
   by very fine opalescent fibres.  On the aponeurotic sheaths of mus-
   cles its effects are  very similar.  On the chordae  tendinese of the
   heart  its  effect is inconsiderable;  it expands them  but little, and
   renders them semi-transparent.   On one part of the intervertebral
   substance it  acts in the same manner as on tendon, of  which part
    the inner portion, that nearest the cavity of the abdomen, chiefly
    consists,  at least in  the lumbar  region ;  but, on the other part, its
    action is hardly perceptible.  In consequence of this difference of
    action of the acid on the component parts of the intervertebral sub-
    stance, it is well adapted to display its peculiar compound structure.
    When the acid is strong, an imperfect solution of a part of the ten-
    don or ligament takes  place, which subsides in the form of a semi-
    transparent very fine jelly.
       Cartilage  is  not  changed by the acid : neither  the dense carti-
    lages  of  the ribs, nor  the delicate ones attached to certain organs,
    as the tarsus, epiglottis, &c.  It is equally  inactive on bone.   Nor
    does it appear to have any sensible effect either on muscular fibre,
    or on the substance of the brain and spinal  chord, or of the nerves
    and ganglia.
       On mucous membranes  its  action is considerable: it does not
    appear to dissolve them  in the slightest degree,  but  it  distends
    "them: renders them firm;  and shows their  peculiar structure in a 
388
davy's researches.
striking manner.   As an example, I shall give a brief sketch of
the prima? vice.
   First, 1  may premise, that  it displays the cuticle or epithelium,
terminating abruptly in  the oesophagus, just above the entrance of
the latter into the stomach, and in  the  rectum, just within the cir-
cle of the anus, or the upper boundary of the sphincter muscle.  In
both, the terminalion is distinct, and abrupt, and unquestionable,
as it appears in a preparation now before me.'
   When the epithelium is  removed, (and it is  most easily, either
by placing it under a stream of water, or by the friction of the fin-
gers,) and the mucous coat  is  brought  distinctly into view,  in the
upper part of the  oesophagus  it appears very thin, provided with
many and  pretty large  mucous follicles on each side, and several
minute  branches of nerves.   With  a magnifying glass of ordinary
power, it seems to contain  a  most  delicate tissue of  white lines,
running chiefly longitudinally, branching off slightly and anasto-
mosing.   The  same  appearance presents  itself in the  middle and
lower part  of the oesophagus, and more distinctly.  But it is only
in the upper part that any nerves can be seen distinctly ramifying
in the semi-transparent mucous tissue.   In the middle  no follicles
are visible, and only a few near its  termination.  Where it termi-
nates, there is, in one preparation before me, quite a zone of what
appears to  be minute  follicles :  but this does not show itself in ano-
ther preparation.
   At the cardiac orifice of the stomach many minute follicles pre-
sent themselves.   Where the  gullet ends,  and the stomach com-
mences, there is a sudden change of the appearance of the mucous
texture; the linear marking suddenly ends; and, as  it were, a
dotted one  commences, and, with some variations, extends through-
out this organ.  When magnified, it has the appearance of a very
delicate  lacework, formed in  the upper part, by the close juxta-
position of circular lines; and, in  the lower, by lines in the form
nearly of the figure of 8; and, in the great arch of the stomach, by
lines irregularly tortuous.  But this, it must be confessed, is not to
be seen  in every preparation that I have examined; and, therefore,
1 would  rather limit  myself by saying, that, in the  stomach, the
mucous texture has the appearance of a very delicate  lacework'of
lines or vessels.
   At the commencemect of the duodenum, the appearance of the
texture  again distinctly  changes.   Here it appears as  if covered
with tortuous threads or  vessels twice or thrice the size  of those of
the mucous coat of the stomach; and, as the duodenum descends,

  1 It appears very questionable, that the stomach and intestines generally,
the gall-bladder and the biliary ducts, the urinary, seminal and the air pass-
ages, possess an  epithelium analogous  to cuticle and a continuation of it.
All these parts must  necessarily have a lining membrane, which seems to
be their mucous coat, in each part somewhat different.  It has been sup-
posed that the mucus secreted  by the membrane serves in lieu of cuticle
and it seems to be a probable conjecture. 
     METHOD OF PRESERVING ANATOMICAL PREPARATIONS.  389

the appearance strengthens.   In some preparations there is an ap-
pearance of follicles, and of circular depressions, but  not  in  all I
have examined ;  and, when seen, they are most distinctly seen  with
the  naked  eye.   A  longitudinal section, including the pylorus,
strikingly  and invariably shows a  layer of a  minute  glandular
structure,1 embracing and belonging  to the mucous  coat  of the
duodenum, which terminates abruptly at the pylorus, but  gradu-
ally in the contrary direction, and disappearing, or nearly so, about
an inch and a half from the pylorus.  The same section, too, shows
how very thick the muscular and cellular coats of the stomach are,
in comparison with those of the duodenum.
  The inner coat of the jejunum, viewed with the naked eye,  in
sulphurous acid, appears to be distinctly  villous, or as if studded
with innumerable projecting  capillary points; but this appearance
vanishes when it is examined with a common lens; then, in some
lights, it appears to  be covered  with convoluted threads, having a
kind of centre, round which  they are described, which, to  the un-
aided eye, seems a minute mucous gland;  and, in other lights,  as
minute projecting lamina? variously bent.
  As the jejunum passes into the ileum, and as the ileum descends,
another change takes place, and it is very strongly maiked close  to
the termination  of the latter  intestine, where the mucous coat  is
truly villous;—so it appears  to the naked eye in sulphurous acid ;
and, when examined in a favourable light with a lens, the villi ex-
hibit the appearance of tubular projections  rounded at the ends ;
and  some of them have a form  approaching  to  the conical, rather
than the cylindrical.  The sulphurous acid makes the  glandular
structure2 of the lower part of the ileum  very distinct to  the naked
eye.
  This villous structure terminates suddenly at  the valve of the
colon (where the valve begins.) and a new kind of structure  suc-
ceeds it in  the valve, and proceeds, with very little variation, of the
same kind throughout the large intestines, even to their termina-
tion,  not excepting the appendicula  vermiformis.  It  resembles
honey-comb in its appearance, more than any thing else to which I
can compare it;  but it is so very minute and delicate in every  part
of the large intestines, that  it cannot be well distinguished,  except-
ing with the aid of a magnifying glass.  The  glands, on the  con-
trary, of the large intestines, appear very distinct in the sulphurous
acid ; and their orifices are easily seen.
  Relative to the other mucous membranes,  I may briefly mention,
that this acid shows them equally as well as the prima? vise, and
enables one equally well to notice how they differ  from each other.
  I shall now proceed to some other parts.   By rendering  the fib-
rous neurilema, and the connecting cellular tissue, semi-transparent,
  1 The glands of Brunner, first  described in 1687, and called by him, not
inaptly, pancreas secundarium.
  2 Gl'andulae aggregatse; Peyer's glands, not  discovered but  minutely de-
scribed by him in 1677. 
390
DAVY'S RESEARCHES.
and  by expanding these textures, the sulphurous acid has a re-
markable effect in displaying the nerves, with the exception of the
ganglionic.   It shows,  almost without dissection, and still better
when  aided  by  dissection, which it  facilitates, the  parts of each
fasciculus of nerves and their junctions;  and, if the nerve be cut,
the proportion of the medullary matter which it contains, which be-
comes  projecting, squeezed  out, owing to  the  pressure just alluded
to.   It shows very distinctly the fibrous nature of the optic nerves
beyond their junction ; but, at their junction, and  towards their
thalami, their substance appears to be exactly similar  to the com-
mon medullary substance of the cerebrum.  It shows the papilla?
of the tongue to  be each the termination of a minute nerve, and
this  without  the  aid of a  magnifying glass.   It demonstrates how,
as the  nerves proceed from their source,  the  proportion of medul-
lary matter diminishes, and the thickness of their sheath increases;
and  this very remarkably  in the nerves  of the fingers.   On  the
ganglionic nerves, judging from the very few  trials which I have
yet  made, it  appears to have but little effect, as if their composition
were different  from that of the other nerves, as has been lately
maintained.
  It displays, too, almost without dissection, the composition of the
vessels, and, I  may add,  of the passages  and canals  of the body
generally ;  owing to its expanding, in different degrees, the several
coats of which they consist.
  The manner in which it exhibits the muscles is most distinct in
all the details of  their anatomical structure.  A transverse section
of a  long muscle, well steeped in strong sulphurous acid, is an in-
teresting anatomical  object.  With  the  naked eye its constituent
parts may be clearly seen, the blood vessels and nervous filaments,
the muscular fibres collected in bundles of different sizes, and  con-
nected by cellular tissue and ligamentous threads.
  The effect of the acid  on other compound  parts is not less in-
structive.  Were I to describe  the  appearance which the more im-
portant only  exhibit in this fluid, I should greatly exceed the limits
to which it appears desirable to confine  the  description.  In this
part of my subject I shall restrict myself to one example, which I
select, as being well adapted to illustrate the effects of the acid on
an organ variously compounded.  This example is the penis:  im-
mersed in  the  acid, it swells like a sponge when put into water,
and  very soon becomes completely distended ; then, when the cutis
has been dissected off, its  ligamentous sheath is brought beautifully
into  view, with the nerves and vessels on the dorsum penis running
superficially  through this sheath, now rendered  transparent;  and
sections, in different directions of the organ, display equally clearly
its internal structure, which, to the eye, either naked or assisted by
glasses of different  powers,  appears to  be  distinctly cellular, analo-
gous to the substance of  the lungs;  or, perhaps, still  more analo-
gous in appearance to the  structure of the common  sponge, espe-
cially the anterior part of the corpora cavernosa, where the cells 
     METHOD OF PRESERVING ANATOMICAL PREPARATIONS.  391

irregularly formed are largest,  and where, as in a cut piece of com-
mon sponge, there are large circular orifices, which seem to belong
to canals formed of ligamentous substance, which penetrate a cer-
tain way, and terminate abruptly with closed extremities.1
  From such trials as I have yet made of the effects of sulphurous
acid on the textures of other animals besides those of man, I am of
opinion that  it may be usefully employed in comparative anatomy,
especially to  aid in  the display of minute structure.   For this pur-
pose, inquirers will find it very serviceable,  in the instances of pre-
parations sent from abroad unskilfully put up, or in examining the
viscera of animals  which have  been obtained entire, preserved in
spirits.   The effect of the acid  in  dilating the contracted parts,
especially those which are  membranous and cellular, as the prima?
via?, and the air  passages and lungs, exceeds expectation.   If the
parts are delicate, I should mention, by way of precaution, that the
acid is not fitted for preserving them. When distended, they should
be transferred to dilute spirit of wine.   If allowed to  remain in the
acid,  they may become  softened, and in a  few months reduced to
the state nearly of  a pulp: this  I have witnessed in the respiratory
and alimentary passages of small birds.
   For the purposes of pathological  anatomy, I believe the sulphur-
ous acid will prove equally, if not more useful, than for those already
alluded to.   I rest  this opinion  partly on the trials  which I have
made, and partly ou the consideration, that,  whilst  its expansive
power is so great on most tissues, its solvent power is very incon-
siderable, and on coagulable lymph appears to be null, (an ingredi-
ent of the blood,  which, in  most morbid changes, acts so important
a part); and it appears to be null on mucous  membranes, the seat
of so  many diseases.   The specimens which I have by me, of diseas-
ed parts preserved  in this acid, are satisfactory beyond my expecta-
tion ;  not so  much as showing the exact diseased appearance, such
as it presented itself on dissection, as in giving a correct notion  of
the nature of the lesion, by magnifying and rendering more distinct
the effects of the disease, contrary to what happens when the mor-
bid parts are immersed in spirits of wine.2
   The sulphurous acid enables one to detect the slightest ulceration
of mucous membranes, existing even in so inconsiderable a degree,
that, without this aid,  it might escape detection.  It enables  one,
too, to detect the cicatrices of old ulcers;3 to detect coagulable lymph


   1 These, probably, are the arteria? helicina? of Professor Muller.
   2 For the purpose of pathological research, the part to be examined may,
with advantage, be immersed for a few  hours in  sulphurous acid, and then
transferred to a cylindrical bottle, of thin and very clear glass, full of water,
perfectly clear; very slight  changes in the delicate structure of the part, be-
fore obscure, or not to be distinguished,  will become apparent and distinct;
 and more particularly, very slight lesions and changes, whether recent or
 old, of the mucous membranes.
   3 These cicatrices, from the observations which I have made, seem to dif-
fer chiefly from sound mucous membrane, in containing no follicles, when 
392
davy's researches.
poured out and adhering to their surface, even in the intestines,con-
stituting a false membrane ; and to notice many other changes in
relation to the  different coats, vessels, &c. which it would be tedious
to enumerate.
   It shows equally well the effects of disease on serous membrane.
on the blood-vessels,  and on  the  viscera, especially the lungs.  1
have, in my possession, preserved in this acid, a very delicatespeci-
men of tubercles on a portion of pleura costalis, covered with a very
fine  net-work of coagulable lymph, and, after several  months, it is
as distinct as when first immersed, and more distinct than before it
was  introduced into  the acid.  A portion of hepatised  lung, thus
preserved, shows the  air-cells filled with an  albuminous deposition,
and the blood-vessels  closed with the same, and the minute branches
of the bronchia.  And a vomica, which has been kept in this acid,
displays not only the  ordinary phenomena of  a tubercular excava-
tion, but,  what is considered a very  rare  occurrence,  blood-vessels
(veins) terminating in the cavity with open mouths.1
   I apprehend  it will prove very useful  in  studying the  nature of
tubercles,  and in determining  some doubtful  points respecting them.
There are two preparations now before me,  which  I may mention
in illustration ; one, a portion of lung containing tubercles in  their
early granular stage; another containing a tubercular mass; the
former are clearly in the cellular structure of the organ ; in the latter
blood-vessels and bronchial tubes may  be detected,  clearly indicat-
ing that the tubercular  matter has been deposited on them so as to
include them,2  according to the  analogy of the deposition of lymph
in hepatised lung.
   The  morbid changes of the arteries are very easily examined and
exposed by immersion in this acid,  and  chiefly in consequence of
its rendering the  different coats so very distinct and distinguishable.
In all the specimens of aneurism which I have examined, and in
every instance of tendency to it, I have found ihe inner and middle
coat of the vessel diseased; the latter generally diminished in  thick-
ness, and  rendered brittle, and sometimes entirely absorbed in ihe
dilated part of  a  true aneurism, or in  the  part contiguous to the
orifice communicating with the  sac of the false; and the inner coat
corresponding  generally thickened,  and corrugated, and  easily
broken.   In many instances, since I have used the sulphurous acid,


the previous ulceration has been deep; and, when only superficial, in exhibit-
ing a structure more or less different from that of the part in health.
  1 This occurrence, I believe, is  much less rare than is commonly supposed.
It  may frequently  be detected in tubercular excavations, by passing fine
probes into the vessels which terminate in the cavity abruptly, marked by  a
short projecting portion, their  course having been interrupted by the ulcer-
ative process which formed the vomica. I have often found the canal of the
vessel unclosed,  its aperture,  in  a  manner,  hid  by the projecting portion,
which, in some instances,  has been so situated as  to act the part of a valve.
  8 The appearance .mentioned above, not carefully examined, might give
rise to the idea, that tubercles are vascular. 
      METHOD OF PRESERVING ANATOMICAL PREPARATIONS.  393

I have noticed a very strong tendency  in the arteries to aneurism,
with  only incipient dilatation, in which the middle coat of the vessel
has been partly reduced to the thinness of the finest paper,  and its
colour changed to yellow;  and the  inner  membrane admitting of
being easily detached, has been thickened to thrice or more its thick-
ness in its sound state.
   Lastly, in relation to the  use of sulphurous acid for anatomical
purposes, I must not conclude  without  offering some precautions
taught by experience, the neglect of which  may occasion want of
success.
   1.  It is of consequdnce that the part to be preserved should be im-
mersed in the acid, as soon  as possible ; for if in the slightest degree
putrid, it will not be well preserved, the fluid will become  turbid,
though frequently changed, and the  preparation will not keep.
   2.  If the part be putrid, as is often the case, when  taken from the
body, though  the  post-mortem examination be made a few hours
after death,  it should be immersed in a solution  of chlorine in salt
and water, till deprived of its putrid smell and tendency ; then it may
be washed clean, and put into  the acid solution, without danger of
spoiling.
   3.  Attention should  be paid to the  strength of the sulphurous
solution, to proportion  it to the  nature of the part to be preserved,
and the object in view in employing it.   If  the intention is to ex-
pand  and develope the structure of the parts, for the  purpose of de-
monstration, a strong solution answers best;  if merely topreservea
part as little changed as possible, a weak solution is most successful,
especially if cuticle, the  visible  epithelium, or tendinous parts, are
concerned, as a strong acid  separates the former, and partially dis-
solves the latter.
   When strong acid is thus used, if it be desirable to keep the part,
the structure of which has been distended, it is safest to transfer it
from  the acid to dilute  spirit of wine, as proof  spirit  diluted with
twice its  bulk of distilled water.
   4.  If the object is to preserve a part for a number of years, I would
recommend  in every instance the transferring  it from the  acid to
dilute spirit, such as that just mentioned ; especially if the prepara-
tion be scarce, and of value  in consequence.   I am induced  to offer
this suggestion from the experience  which I have had during  the
last twelve years : during this period some preparations have been
well preserved; others have undergone  change,  and  have  become
spoilt.  The uncertainty of preservative effect is sufficient ground
for caution.
   I believe,  too, that this acid is not  inapplicable to the service of
the botanist, for preserving entire plants and their parts, especially
the smaller and more delicate.  I have a bottle now  before  me in
which many kinds of vegetables are  immersed, and have keen kept
several  months, and their  forms are as distinct, as  ever,  and  in 
394
DAVY'S RESEARCHES.
excellent preservation ;  and amongst them I see the flower of the
olive and the orange trees, and many more equally delicate.1
   On the economical uses  of this  acid, and they are  many, as in
relation  to its power of preventing the fermentation to which all the
saccharine preparations of  the kitchen are so subject,—of prevent-
ing the changing of wines into vinegar, to which all the lighter and
more delicate ones are liable,—and, further, of preventing the com-
mon vegetable acids, as vinegar and  lime juice, &c. and vegetable
preparations in general, from spoiling, it would be unsuitable in this
place to  dwell.   I shall merely remark, that the efficacy of the acid
in ail these respects is great  and extraordinary, as  must be known
in part to many, and which may be learned  by the easiest trials.2
This subject, the economical uses of the sulphurous acid, is an im-
portant  one  to society, and would well reward the labours of the
inquirer who would undertake the minute investigation of it.


  1 The effect of the sulphurous acid on the colour of vegetables, and I may
add of animal substances, is much less than might be expected.  Some vege-
table colours it does not change, others but slightly, and very  few entirely:
and even  the last mentioned return, though not with their original intensity,
when the sulphurous acid is converted by the absorption of oxygen gas into
the sulphuric.  The red rose, bleached white  by the fumes of burning sul-
phur, on exposure to the ab, again becomes red.  Of  animal textures, those
which are white, it renders  delicately so ;  those which  are yellow,  as the
gall-bladder, and common gall-duct stained by bile, the liver of this  colour
owing to  disease, and  parts of the supra-renal gland, it does not alter.  It has
very little effect in altering the healthy colour of the  lungs  or liver; but.
where there is blood either effused in the parts, or  contained in its vessels,
the acid changes its colour to dark-brown,  and, by  coagulating it, fixes it for
a time; and thus it is well adapted to detect the effusion of this fluid, in parts
where it is apt to escape observation, as in the  substance of (he spleen, liver,
&c.  It is often difficult to distinguish  between the redness produced by  in-
flammation, and that which is occasioned after death  by the staining power
of the blood.   I believe  (and  not hypothetically)  that the sulphurous acid
affords a means of distinction.   If the change should  have taken place after
death, the part stained will  be rendered brown  by the acid, and in  other re-
spects appear sound ; but if, during life, owing to inflammation, by immersion
in the acid, either coagulable lymph will be detected  effused on the surface,
or under  it, or serum in the adjoining cellular  tissue, or some slight ulcera-
tion of the part affected.
  2 It is not improbable but  that it may be useful for the  preservation of
meat, especially in a hot climate.  I recollect,  when sanguine of its efficacy.
at the time I was engaged in experiments on it, keeping a chicken a week in
the acid gas in the hottest time of the  summer of the Ionian Islands, and
having it approved of at table. 
ON THE ACTION OF VINEGAR, ETC.            395
                            XXX.

  ON THE ACTION OF VINEGAR ON ANIMAL TEXTURES.

  Although vinegar, of all the acids, has been longest known, and
from time immemorial  used  as  a condiment, I am  not  acquainted
with any account hitherto published of its effects on animal matter,
minutely considered, or of its application to anatomical purposes.
With the desire of obtaining such  information, several years ago  I
instituted some experiments  on  the subject, the results of which  I
shall now record, believing that they may prove not without use or
devoid of interest.
  The vinegar I  employed in  the inquiry was distilled vinegar,
almost colourless,  of specific gravity 1005.  This kind  appeared
preferable, both as  belonging to the materia medica, and being nearly
pure and almost always of the same strength.   On the contrary, the
common kinds of  vinegar, those which have not been subjected to
the process of distillation, are extremely various in composition ; and
according to this variation,—according to the nature of the vegetable
principles which they hold in solution, they are liable to vary in the
changes which they themselves undergo, and in their effects on the
animal textures immersed in them.
  It might be expected, perhaps, that the solvent power of vinegar,
on  the textures of  the body, would be considerable ; but, experiment
proves it to be otherwise.  In 1828, whilst stationed in Malla, por-
tions of aorta, dura mater, brain, nerve, muscle, intestine, skin, liver,
and intervertebral substance, were put into this acid, in a vessel not
completely filled,  and  from which atmospheric air was not com-
pletely excluded.   This was done in the month of January; at the
end of six months, all  the parts  were in good  preservation.  The
acid retained its transparency, but  was slightly coloured, and there
was a slight sediment.  1 may  mention farther, to show how very
inconsiderable is the solvent power of this acid, that on evaporation,
it afforded only a  very minute residue, of a light brown colour, semi-
transparent, viscid and bitter: the greater part of which was  soluble
in  water.
   The colourless  acid produces very little change  of colour in any
of  the textures on which I  have tried it,—unless the parts were
goro-ed with blood ; and then the alteration  is referrible to the blood,
 the^colouring matter of which, when not  concentrated, is changed
 to  brownish green ; and, when concentrated, to almost black.
   To ascertain the degree of dilution, which the acid, of the specific
 o-ravity already mentioned,  will bear, without  being deprived of its
 antiseptic power,  I  have  used  it  diluted with  one,  two, four, and
 eight parts of water.  Portions of muscle were immersed in these
 mixtures of vinegar and waler, and air was allowed to have access.
 Examined after two months, during  which the atmospheric tem-
 perature varied between 80° and 92°, each portion  of muscle was 
396
DAVY'S RESEARCHES.
found well preserved and free fron putrid smell, excepting that in
trie most dilute,—which, in a fev  days, began  to  putrefy: the ex-
periment was made in  Malta.   In* this country I have made a few
other trials.  In November, 1830, a portion of stomach, of duode-
num, ileum, rectum, and  tongue, after having been steeped  for a
day or  two in distilled  vinegar, were transferred to weaker acid,
(distilled vinegar diluted wilh four parts of wafer.)  Three years
have now passed, and all these parts are in perfect preservation.
Each was placed in ajar apart, suspended in the fluid in the  usual
manner, and covered with bladder, &c. to exclude atmospheric air :
t.ndr with the exception of one, aftei the lapse of the time mentioned,
no air has got admission.  In the  exception,  the  bladder was at-
tacked by insects, and yet, notwithstanding the accident, and partial
evaporation and free admission of atmospheric air, the preparation
(the tongue) is in a good condition,  and displays well the peculiari-
ties of the organ.
  Vinegar, I find,  has not only the power of preventing putrefaction
from taking place,  but also of arresting it, when commenced and in
full activity.   So soon as the  putrefying part  is plunged into  the
acid, the destructive change is stopped, and the part may be pre-
served without farther change ; and thus show the effect of putre-
faction on the  texture in  the stage in which if was arrested.
  But,  although the acid stops putrefaction, it does not, like the
sulphurous acid  and corrosive sublimate, destroy the principle on
which the change  depends, or effect an elementary change, incom-
patible with its taking place.   I find that parts transferred from acid
to water, and well  washed, undergo putrefaction under  favourable
circumstances,—but much more slowly than if they had  never been
in contact with the acid : and, the changes which take place in them,
seem to be, in  some respects, different  from those resulting from
ordinary putrefaction, and are, perhaps, peculiar.
  In its action on different textures, in relation to its visible effects.
it very much resembles the sulphurous acid.  Its expansive power
is similar ; its power of increasing the transparency of cellular tissue
and  of  the diaphanous membranes is also similar.  And, in con-
sequence,  like that  acid, it is  well fitted to show the structure  of
many compound parts, and the minute structure of many organs.  1
have mentioned  preparations  of different portions of the alimentary
canai, preserved  for two years in dilute acid.  Without the aid of a
lens, the peculiar structure of  each  division may now be distinctly
seen, and the  mucous  follicles even more distinctly  than in  the
instance of sulphurous acid,—in consequence of the glands them-
selves having acquired a certain degree of opacity, and the envelop-
ing tissue a certain degree of transparency.  I have now before me
a thoracic duct,  which has been kept in distilled vinegar nine years,
and it could not be shown better were it Injected with mercury ; with
this advantage on the partof the acid,.—that, whilst by distension it
shows the form of  the vessel,  it. also, where the vessel is laid  open,
shows its valvular  structure. 
ON THE ACTION OF VINEGAR. ETC.
397
  From  my own experience, - e^que^ve I am  not  too sanguine in
expressing, confidently, my ophirn:, that both the anatomist and
pathologist,  engaged in research,  may derive very  material help
from the use of this acid, and the latter especially, as it is well fitted
to bring to light diseased structure, of such minuteness or obscurity,
as to escape detection by the senses unaided.1
  There are other uses to which  this acid is applicable, some  of
which, as connected with my present subject, I shall briefly advert
to.
  On account of its antiseptic quality, I believe distilled  vinegar
may be often usefully  employed in surgery, in washing foul ulcers,
and in  washing out abscesses deeply seated, containing offensive
and putrefying matter. In one instance, of an abscess in the liver,
which was opened  by the knife, this acid, diluted  with water, was
employed, at my recommendation, and apparently with very good
effect; for, although air got admission, putridity was prevented.
  Whether  vinegar is efficacious, as a means  of fumigation, for
which purpose it is still commonly employed, it is not easy to decide.
Its properties, on the whole, are rather unfavourable to its efficacy—
at least permanently.  However, as it ensures, by  the pungency of
its fumes thorough ventilation,—as it  is most easily applied,—has
no noxious  quality that is known ;—and its activity, when concen-
trated, is  certain and  considerable,—perhaps  it deserves the good
opinion it has gained,  and it may be right to continue the employ-
ment of it, as at present,  when  slight fumigation  only is required,
and there is no suspicion of the presence of any pestiferous fumes.
  As vinegar  dissolves tannin with  facility,"and in considerable
quantity, it  may be added, with good effect, in tanning such parts of
the body as it may be thought desirable, by this process, to convert
into dry preparations.  The addition of the acid ensures the advan-
tage of preventing putrefaction,—and the consequent destruction of
delicate organisation.   I  have by me, thus tanned,  the stomach with
part of the oesophagus, its epithelium adhering, the valve of the colon
and some other parts of the intestines.   They  display accurately,
not only the forms and  striking peculiarities of  these organs, but
 also their delicate texture.  To witness the latter, the parts should
 be saturated with  water,  by immersion  for a  few hours, and sus-
 pended in water in a cylindrical jar,  to have the aid of magnifying
 power : in this way the villi of the ileum, even when tanned, may
 be made apparent.
   Although vinegar  has  been  so long known, and so long in use,
 and so very much and so variously  employed, yet, I believe, that
 for culinary purposes it  deserves to be more known and more em-
 ployed  and, especially amongst the poorer classes, with a view to
 economy in the preservation of food.  Amongst all classes, the waste

   1 Minute ulcers in the-intestines and loss of the villous structure, I have
 several times detected and  mali6 apparent by;;immer8ion in this acid,  not
 perceptible in ordinary examination.
        lo—a 
39S
DAVY'S RESEARCHES.
of animal and vegetable food, fo Vv^ot keeping, is great,—diminish-
ing  the  quantity and enhanc.  g the price.  Now, by means of
vinegar,  it is practicable to prevent this waste,—and it is most easily
effected.  In the hottest weather, during the summer in the Medi-
terranean, when cold meat  became tainted and  unfit for  use  in
twenty-four  hours, or even in a shorter time during the prevalency
of the damp  sirocco wind, 1 have had slices of roast and boiled meat,
offish, poultry, &c. put  into  vinegar,  with  a proportion of gravy
or any plain sauce,  and they were preserved perfectly good  and  fit
for the table for weeks.  It is well known how long vegetables may
be thus kept.  Fruit may be preserved in the same way ; and many
kinds probably would be palatable and wholesome so preserved.
In Asia  Minor, and in  the  Ionian islands,  the natives, as  I have
witnessed, are in the habit of keeping ripe grapes  and ripe olives  in
vinegar,—and both are far from unpalatable ; the grape retains much
of its sweetness, though  a little disguised by the taste of the acid;
and  the oil  is  preserved in the olive, free from rancidity, and of a
very delicate flavour.
  The formation of vinegar, naturally, in fruit and their juices, and
in milk, seems as if it were intended, to insure their longer preser-
vation for the use of animals as articles of food, as much so, as the
changes beyond this, connected with decomposition and a new ar-
rangement of the  elements, appear destined to form manure  and
furnish food  for plants.
                           XXXI.

EXPERIMENTS AND OBSERVATIONS ON  THE  PROPOR-
  TIONAL QUANTITY OF ANIMAL AND CALCAREOUS MAT-
  TER IN THE BONES OF DIFFERENT ANIMALS.
  At distant intervals, my attention has been directed to the com-
parative composition of bone.  The  results which I have obtained,
I shall now bring forward.  Although they are far less numerous
than I could wish, and too few for full and  satisfactory comparison
and induction, yet, I am not without hope, that as a contribution
they may  conduce to these ends,
  The trials which I have instituted, have  been of a  simple kind,
with a view to determine principally the proportion of calcareous
and animal matter; and this has been effected by calcination, or
exposure to the action of fire  in  a  crucible until  the whole  of the
animal matter was consumed.
  For the sake of brevity, I shall give the results in the form of
tables, and I shall include in them the earliest which  I obtained so
long ago as 1811;  and  which Dr.  Monro  did me the  honour of
introducing into his " Elements of Anatomy."  Indeed these early 
PROPORTION OF CALCAREOUS MATTER, ETC.
399
experiments were made at his request, and principally on specimens
which he was so obliging as to furnish me with for the purpose.

                              Table  I.
Proportion of calcareous  and animal matter in  human bone,  of
                         different races, <y*c.
No.
24

25

26
27
28

29

30
Description of Bone.
the bone
15, recent,
Pars petrosa of the temporal bone of an adult  (Scot-
  ish?) from Dr. Monro's museum: dry: how prepared
  not known........
Temporal bone of the same, under the zygomatic pro-
  cess..........
Occipital bone of the same......
A part of the lower jaw of the same between the sym-
  physis and processes     ......
Portion  of parietal  bone of another adult (British)
  from the same museum, its history unknown .
Parietal bone of another adult
Shaft of tibia of an adult
Shaft of thigh bone of an adult
Occipital bone of an old man
Part of lower jaw of an  old person, between the sym
  physis and processes: alveoli absorbed
  brittle......
Occipital bone of a young person aet. about
  previous to drying  .
Frontal bone of the same
Parietal bone of the same
Tibia of the same
Fibula of the same
Ileum of the same
Thigh bone of the same
Molar tooth of a man set. 20, (sound)
    Ditto        ditto    23,  ditto
    Ditto        ditto    30,  ditto
    Ditto        ditto    31,  ditto
    Ditto        ditto    32,  ditto
Portion of parietal bone of J. Keefe (Irish) aet. 33:
  died of phthisis pulmonalis, complicated with pneu-
  mathorax ........
J. Spiers, Irish labourer, aet. 20: died of diabetes mel-
  litus and phthisis pulmonalis1 .    .    .    •    •
M.  Bayley, English  labourer, eet. 21: died of phthisis
  pulmonalis of very rapid progress  .    •    •
J. Haliday, Irish labourer, aet. 29:  died of phthisis   .
G  Cocking, English labourer, oet. 21: died of phthisis
T.  Godfrey, English labourer, aet. 26: died of phthisis,
  complicated with pneumathorax of each pleura   .
H.  White, English labourer, aet. 20: died of phthisis
  of rapid progress   .     •    •    ',.   ' ,  ,\. .'
E.  Bridger, English labourer, aet. 21: died of phthisis
  of very rapid progress    .    .    .    •
Calcar. Animal
Matter. Matter.
66-7
653	34-7
60-0	40-0
59-5	40-5
64-4	35-6
62-5	37-5
640	36-0
62-5	37-5
690	31-0
56-6

58-0
58-9
58 8
53.6
44-0
450
47-0
72-4
75-0
75-3
731
71-0
68-4

67-5

67-2
68-1
66-6

68-4

67-9

67-7
333
43-4

42-0
41-1
41.2
46-4
560
55-0
53-0
27-6
25-0
24-7
26-9
290
31-6

32-5

32-8
31-9
334

31-6

32-1

32-3
  1 When not specified, it is to be understood that the bone is of the same de-
nomination as the preceding, and a similar part, and dried in the same way. 
400
davy's researches.
No.
Description of Bone.
Calcar.
Matter.
31


32

33

34



35


36

37


38

39


40



41



42


43


44



 45


 46
D. Hurley, Irish labourer, aeet. 30: died of devastating
  disease  of  knee joint, complicated with  tubercles
  and small vomicae in lungs.....
G. Mullins, Irish, aet. 30: died of complicated disease
  of lungs, partial emphysema, tubercles, &c.
R.Allan,  Scotish blacksmith, aet. 20: died of phthisis,
  complicated with cynanche laryngaea
J. M'Donough, Irish labourer, aet. 31: died of compli-
  cated organic disease without tubercles:  softening
  of fornix:  marks  of  old  peritoneal inflammation:
  ascites, &c........
W.  Macpherson, Scotish  labourer,  aet.  52: died of
  complicated  disease,  connected with  an enlarge-
  ment of heart and arch of aorta: partially  ossified  .
H. Higgins, English baker, aet. 45:  died of suppura-
  tive inflammation of right elbow and ankle joint   .
R. M'Cartney, Irish, aet. 28:  cause of death obscure:
  probably syncope: it was sudden:  a false aneurism,
  not ruptured, just below  the arch of aorta
P. Kelly,  Irish, aet.  48:  died of  complicated disease:
  softened fornix:  chronic inflammation of  bronchia
J. Masterton, Irish labourer, aet. 38: died of  cedema of
  lungs, and  thickening of small intestines after in-
  flammation    ........
J.  Gray, English labourer, aet. 36: died  of  hydrotho-
  rax and cedema of lungs : (cranium subjected to coc-
  tion without lime in the water,  and  it was after-
  wards greasy)  ........
R.  Stewart,  Scotish, aet.  28: died of hepatised and
  cedematous lungs supervening on ulceration of tibiae,
  enlargement of liver (it weighed  13 lbs.  and  con-
  tained no fatty matter)......
C. Sidney, English, set. 33:  died from the bursting of
  a  softened medullary tumour of the liver into cavity
   of abdomen........
J. Shrub, English, aet. 42:  died of hepatised lung, &c.
   complicated with a large aneurismal tumour, press-
   ing on  gullet and right bronchus    .    .    .    .
J. Fairweather,  Scotish  labourer,  aet. 34:  died  of  a
   ruptured  aneurism of  the abdominal aorta (bone
   subjected to coction without lime in water; not ap-
   parently greasy)    .......
 J. Woods,  Irish labourer, aet. 40:  died shortly  after
   disembarkation debilitated by sea scurvy (bone sub-
   mitted to coction without lime, slightly greasy)
 W. Bickers,  English weaver, aet. 44: died from the
   effects of sea scurvy  (bone treated like the last)
 T. Jones, aet. 49: died  from the effects of sea scurvy1
67-8

68-0

66-9



702


68-5

66-6


67-0

68-6


68-5



65-9



69-4


67-0


63-5



68-4


 64-4

 64-4
 66.7
35-6

35-6
33-3
  ' In these three cases the fatal event was probably'owing to effusion into
the lungs;  in each there was cedema  of these organs  to a considerable ex-
tent, and besides this, no lesion in any part of the body of any consequence,
in connection with the cause of death.
  It is to be regretted that sea scurvy, which for many years was almost un-
known amongst our invalids returning from our distant colonies,  has lately
become of  not unfrequent occurrence, especially amongst old soldiers from 
PROPORTION OF CALCAREOUS MATTER, ETC.
401
No.
48

49

50

51



52

53

54

55


56


57

58

59
60
61
62
63
64
65
66
67
68
69
70
71
72


73
                  Description of Bone.

G. M'Carthjy,  Irish, aet. 31,  maniacal:  died of hepa-
  tisation and partial oedema  of the  lungs  .
J. Brennan, aet. 34, imbecile: died  of hepatisation of
  lungs.........
J. Lewis, English, aet. 41, maniacal: died of tubercu-
  lar phthisis.....
J. Green, Irish weaver, aet. 25, imbecile:  coma follow-
  ing convulsions and partial palsy preceded  death;
  blood effused under dura  mater, softening of fornix;
  partial hepatisation of lungs.....
J. Tomlinson, English, aet.  37, maniacal: died  of par-
  tial hepatisation and gangrene of lungs .
J. Hanson, Dane, aet. 61,  imbecile: died  of malignant
  disease of orbit and  liver  (tumours)
Anne Hartley, English, aet.  5 i, maniacal: died of can-
  cer of stomach (medullary  tumour)
J. Ball, English  labourer,  aet. 42, maniacal:  died of
  complicated disease with fibro-cartilaginous tumours
  of neck, compressing larynx and gullet .
Portion of frontal bone (of a very beautiful form) of a
  young Greek woman,  of Ipsara,  (it had been  ex-
  posed to the air two years).....
Portion of parietal bone, Albanian Greek, of middle
  age (how prepared not known)     ....
Portion of parietal bone of a Burmese woman, middle
  age (how prepared not known)     ....
Canadian Indian, middle age.....
Hindoo.........
Hindoo     .         .......
Hindoo.........
Hindoo1.........
Hottentot, middle age.......
Bojesman.........
Ashantee.........
Ashantee.........
Ashantee.........
A portion of parietal bone of Ashantee
Ashantee.........
Ashantee*.........
Occipital bone  of a negro (race unknown)  from  Dr.
  Monro's museum; very hard, compact, and  white;
  dry, but not dried on stove.....
Occipital bone of another adult negro, from the same
  museum, less compact  and  hard    ....
Calcar. Animal
Matter. Matter.
65-1

661

65-5
66-9	33-1
68-5	31-5
64-1	359
64-7	35-3
64-9
34-9

33-9

34-5
35-1
65-2	34-8
69-8	30-2
66-5	33-5
646	35-4
63-7	36-3
65-8	34-2
64-9	35-1
66-7	33-3
65-8	34-2
62-6	37.4
68-7	31-3
68-3	31-7
68-1	31-9
68-8	31-2
68-6	31-4
69-3	30-7
59-5	40-5
58-9	41-1
India ;  and is to be attributed mainly to due attention not being paid to the
health  and comfort of the men on these long voyages; the provisions are
often of bad or indifferent quality; lime juice is seldom supplied in sufficient
quantity, or given in a judicious manner, and there is too often a neglect of
attention to dryness and ventilation between decks.
  1 The four crania of Hindoos appeared to be of middle age; they had no
marks  of  having suffered from exposure to the weather.  They varied in
size, form, and thickness; the weights of similar  pieces cut out with the
trephine were, 234 grs. 38'9, 496, 27-6.
  2 The Ashantee crania were taken from a field of battle, on which  a
large number  of these people fell when they last  invaded  Sierra Leone; 
402                   davy's researches.
   In this first table of results,  the specimens of bones from No. 1
to 17 were  miscellaneous, from  Dr. Monro's museum;  they be-
longed, it is understood,  to  natives of Great Britain.   Some were
recent and moist;  others dry,  but not deprived of hygrometrical
moisture  before being subjected  to  trial.  They afford  proof,  at
least, that the  proportions of calcareous and of animal  matter in
different  bones  of  the same  body are, as indeed might be expected
a priori,  somewhat different.
   The specimens, the subjects of trial,  extending from No. 18 to
71, were  from the  museum at Fort Pitt.   Previous to incineration
they were thoroughly dried,  by exposure on a stove  to a tempera-
ture of about 212°, till they  ceased to  lose weight.   This is a cir-
cumstance of  some  importance  in  comparative experiments:  if
neglected, the results will be of little value for the purpose of com-
parison, whether the bones are recent, impregnated with .their pe-
culiar fluids, or dried by exposure to the air.1
   The specimens from No. 23  to 55  were from crania prepared for
the museum  by the process of boiling,  and in the majority  of in-
stances in water in which lime was  suspended.  To  ascertain the

the exact time of their exposure is not known; probably it was less than a
year.
  1 The variable proportion of the peculiar fluids of recent bones is,  I believe,
as great, if not greater,  than  of the solid contents: the recent  parietal bones
of Nos. 42 and 43 lost  by drying, the  former 18-49  per cent., the latter 23.
The  proportion of hygrometrical water is always changing  in bone, as in
other porous substances, according to the  state of atmosphere in relation to
humidity.  I have found apparently dry bone lose by the expulsion of  its
hygrometrical  water  from 4 to 7 per cent.  The power of absorbing mois-
ture by different  bones probably varies with their other qualities, as is wit-
nessed in substances  generally, and especially those used as articles of dress:
I may offer an experimental illustration, and I am the  more  disposed to do
so, as the subject  has not received  that attention which, practically consi-
dered, and  especially in relation  to health, il deserves.
  On the 11th  November, the substances which will presently be mentioned
were weighed  in  a room  in  which  was a  fire,  and  where the thermometer
stood at 60°, and  a thermometer with its bulb moistened used  as a  hygrome-
ter at 56;  the weather was very damp; they were  then taken to an alcove
in the garden,  where  the dry thermometer  was 50°, the moist 49°; after hav-
ing been left there an hour, they were weighed on the  spot;  and  next they
were dried by  the fire completely till all hygrometrical water was expelled,
and weighed warm.  The results were the following:—
Room.	Alcove.	Fire-side.	Lost percent.
Fine flannel 37-2 grs.	39-5	32-9	170
Brown merino 236	24-	205	14-6
Fine silk sarsenet 139	14-1	13-	7-8
Fine muslin 135	14-1	12 5	11-3
White kid glove 186	20-2	164	18-8
New linen 68.45	71-6	64-1	10-4
Old linen 53-	54-4	49-	9-9
  The same substances were placed next the skin over the chest, where the
thermometer was 89°, covered with  a shirt, flannel waistcoat,  &c: after
several hours they were found to weigh as follows:—Flannel 35'6, merino
2225, silk 135, muslin 1305, kid glove 175, new linen 662, old linen 50-9. 
PROPORTION OF CALCAREOUS MATTER, ETC.
effects of the process, a portion of the parietal  bone, No. 25, before
being subjected to it, immediately after the post mortem examina-
tion, was deprived of its periosteum, and thoroughly dried and then
incinerated; the  residue of calcareous  matter was  66-2  per  cent.
indicating 33-8 per cent, of animal matter, instead of 328 after the
boiling, thus showing a removal of 1 per cent, of animal  matter by
the boiling process.
  How the remaining specimens, excepting No. 56, were prepared
is  not known.   They were sent from  foreign stations,  and  were
probably previously macerated  in water, or left exposed  to the air,
like No. 56, till the soft parts had been destroyed by the action of
the elements.
  The  crania extending from No.  23 to 55, it will be seen, were
from four descriptions of patients:—1. those who had died of tuber-
cular phthisis;  2. those who had died of other diseases not connect-
ed  with tubercle; 3.  those  who  had died of sea scurvy; and 4.
insane  persons.  The majority of them were  part  of a series pre-
served  during  twelve  months, taken from every  fatal  case that
occurred, and put aside for the purpose of comparison.
   The average proportion of calcareous matter afforded in  these
four different classes, was the following per cent.—
     Phthisis      -----       67-7
     Other diseases unconnected with tubercles      -   67-6
     Sea-scurvy   -----       65-1
     Insanity         -----   67-5
   With the exception  of the instances of sea-scurvy,  these differ-
ences are so small, that  perhaps it may appear questionable that
they are owing to disease: in sea-scurvy, it has  been asserted that
the bones have  been affected,  and  that old fractures have become
disunited.  Three cases are hardly sufficient to  inspire  confidence
in  the conclusion.  In  each of the three, however,  the  proportion
of calcareous matter being below the mean of all  the others, is very
favourable  to the idea that  in this disease there is actually an ab-
sorption of the earthy matter of the bones.
    As the manner in which the crania of the  foreign  races sub-
 mitted to trial were prepared is not known,  no satisfactory infer-
 ences  can  be drawn relative to  the proportions of the  calcareous
 and animal matter in them.  The results are so very different, espe-
 cially in the African instances, that if of no other use, they are well
 adapted to prevent hasty generalisation. 
404                   davy's researches.
                           Table II.

Proportion of calcareous and animal matter in bone in early and
                        in advanced life.
Description of Bone.
Portion of margin of parietal bone of a foetus of six
  months.........
Portion of margin of parietal bone nine months old   .
Portion of the same towards the centre
Frontal bone of a child, the bregma still remaining,
  from Dr. Monro's museum.....
Parietal bone of the same......
Lower jaw of a child from Dr. Monro's museum
Milk teeth of a  girl, shed at usual time, the roots ab-
  sorbed: thoroughly dried, very brittle and  fragile
  (three front ones weighed only 594 grs.)
Hollow summits  of teeth of inferior jaw of a fetus,
  between five and six months, several years pre-
  served in spirit of wine, (they weighed only -4 gr.)
  enamel not deposited......
Under-jaw of the same,  connected  by ligament at
  symphysis, deprived of periosteum, nerve, Ac. tho-
  roughly dried, weighed only 8-5 grs.
Portion of parietal bone of a Maltese woman, aet. 98:
  very thick and heavy, abounding in stearine  .
Portion of parietal bone of a Maltese woman, act. 83:
  unusually thick: it contained very little fatty matter
The occipital bone of an old man, from Dr. Monro's
  museum.........
A part of the lower jaw of an old person, between the
  symphysis and processes; the alveoli were absorb-
  ed, the  bone brittle.......
Portion of radius from an old woman whose bones
  had been frequently broken,  and were supposed to
  be peculiarly brittle, from Mr. Liston's museum
Molar tooth of a man, aet. 61: weighed 31-9 grs.
Calcar. Animal
Matter. Matter,
50.0
62-1
63-4

54-5
54-0
57.2
79-5
75-0
56-6
66-0
73-6
500
37-9
36-6

45-5
46-0
42-8
20-5
25-0
56.0	44-0
47-6	52-4
660	34-0
69-0	31-0
43-4
34-0
26-4
  The  bones noticed in  this second  table, with the exception of
those from  Dr. Monro's museum, were thoroughly dried previous
to incineration.  Both on account of the small number of specimens
tried, and it not being known how they were all prepared, I shall
not attempt to deduce any conclusions from the results:  I  have
thought it  right to give them, with the hope that they may excite
doubt, and  lead to  further inquiry.  There being no deficiency of
calcareous  matter in the bone  No. 10, belonging to an old person
who had repeatedly suffered from the  accident of fracture of bone,
would seem to indicate (supposing the  tendency to fracture to  be in
the bone) that weakness and brittleness may arise from other cir-
cumstances than deficiency of phosphate of lime.   This is  a point
deserving of special inquiry.   Probably it will be  found  that in
regard  to strength and power of resistance, more depends  on  the
arrangement of the constituent particles, and the proportion of fluid 
PROPORTION OF CALCAREOUS MATTER,  ETC
40'
matter interposed, than on the quantity of solid contents, especially
the calcareous portion.

                              Table III.
Proportion of calcareous and  animal  matter in bone of different
                                animals.
No
Description of Bone.
Calcar.  Animal
Matter.  Matter.
10
11
12
13
14
15
16
17
18

19
20
21
22
23
24

25
26
27
28
29
30
31
32
Portion of the tympanum of a whale, the species not de-
  termined :  of specific gravity 224,  and after having
  been subjected to the air-pump, 246   ....
Pars petrosa of the temporal bone of another whale, spe-
  cies not known, from Dr. Monro' museum .
Pars petrosa of an elephant, from the same museum
Under-jaw of another elephant.....
Under-jaw of hippopotamus......
Under-jaw of dromedary     ......
Metatarsal bone of a pure-bred horse, "Lorenzo," six
  years old, (just taken from the macerating tub) of spe-
  cific gravity 1854, and after having been  subjected to
  the air-pump, 2033: it lost by thorough drying 9*5 per
  cent..........
Metacarpal bone of a troop horse, rather lower bred than
  usual, (prepared partly by macerating, partly by. boil-
  ing) of specific gravity 2010 before action of air-pump,
  and 2077 after:  it lost by thorough drying 5*45  .
Shaft of humerus of a blood-horse (the compact part) be-
  fore being  subjected to air-pump  of specific gravity
  2045: after, 2092: it lost by thorough drying 7 per cent.
Similar part of shaft of humerus  of a dray-horse,  before
  being subjected to the air-pump  of specific gravity
  2000: after, 2126: it lost by thorough drying 6 per cent
Parietal bone of Bombay buffalo, close to the horn
Horn of the same, near its base
Parietal bone of Persian  goat
    Ditto     of Bengal antelope (goral)
    Ditto     of damalis risea, Bengal  .
    Ditto     of cervus capriolus   .    .
    Ditto     of sheep of Southern Africa
 Extremity of process of parietal bone of the  same, sup
   porting the horn
 Portion of horn of the same  .
 Parietal bone of wild hog (Bengal)
 Superior portion of tusk of the same
 External table of parietal bone of another wild hog
 Parietal bone of tiger   .    .     .     •
 Cellular structure of inner table  of frontal bone  of the
   same .
 Incisor tooth of the same
 Molar tooth  of the same
 Lower jaw of common cat
 Parietal bone of dog
      Ditto      jackall .
      Ditto      wolf   .
      Ditto      hare
 Shaft of tibia of tame rabbit
81-2

72-6
70-0
70-8
67-3
68-4
65-77
65-78
69-44
70-8
60-3
 3 02
66-4
64-7
66-5
61-3
57-1

57-6
 2-7
67-3
71-9
63-7
65-4

65-6
69-5
72-1
71-5
68-2
684
70-5
61-7
65-8
18-8

27-4
30-0
29-2
32-7
31-6
34-23
34-22
30-56
29-2
39-7
96-98
33-6
35-3
33-5
38-7
42-9

42-4
97-3
32-7
28-1
36-3
34-6

34-4
30-5
27-9
28-5
31-8
31-6
29-5
38-3
34-2 
406
davy's researches.
No-
33
34
35
36
37
38
39
40
41
42

43
44
45
46
47

48

49
50
51
52
53
54
55
56

57
58
59
60
61
62

63

64
65
Description of Bone.
Shaft of femur of a young kangaroo
Ditto of mustela vulgaris, rather oily
Ditto putorius vulgaris......
Parietal bone of full-grown seal (species unknown)
   Ditto    of another seal .....
   Ditto    of another seal .....
Shaft of femur of vespeitilio vampyrus, Bengal
Ditto of vespertilio murinus, oily  ....
Ditto of vespertilio noctula, oily   ....
Ditto of radius  of  petaurus macrourus, oily and semi
  transparent    .......
Ditto of-tibia and fibula of bathyergus capensis
Ditto of pteromys petaurista, oily and semi-transparent
Ditto of tibia of a common fowl (a hen)  .
Superior portion of sternum of the same  .
Ridge  of sternum of wild swan of a delicate  cellular
  structure                     '.
Portion of sternum of ostiich,  including the delicate eel
  lular structure connecting the outer and inner tables
Parietal bone of a large species of falcon
Parietal and frontal bone  of pelican
 Ditto  of adjutant bird (ciconia argala) elegantly cellular
 Ditto  of bucercs caratus.....
Portion of lower jaw of diomedea fuliginosa .
Portion of spine of testudo graeca  ....
Sternal portion of the shell of the same  .
Portion of lower jaw of turtle of large size  (Ascension—
  chelonia midas) .......
 Ditto of gaviala tenuirostris     ....
 Ditto of trigonocephalus lanceolatus (St.  Lucia) .
Poison fang of the same1     .....
Portion of upper jaw of the same  ....
Shaft of femur of common frog     ....
     Ditto      common toad; it was more oily than the
  preceding........
Vertebrae of  cod-fish (they lost by thorough drying 32-
  per cent.)........
Portion of bony integument of ostracion quadricornis (it
  was  dry, by thorough drying lost 5-7 per cent, hygro
  metic water).......
Teeth of dog-fish (mustela laevis)  ....
Its skin yielded.......
Calcar.
Matter.
60-0
66-6
61-5
63-0
68-4
70-1
60-1
57-0
55-0

62-8
63-0
62-0
68-6
55-5

57-0

56-6
63-9
63-3
67-5
60-6
57-2
57-0
59-0

67-5
69-6
70-1
62-1
55-9
68-6

58-1

58-7
40-4
50-0
24-0
Animal
Matter.
  All the bones noticed in this third table,  excepting Nos. 2 and 3,
were thoroughly dried previous to incineration; and the majority
of them belonged to the museum at Fort Pitt.
  The difference in the  proportions of  the animal  and calcareous
matter constituting them is less strongly marked  than  might  have
been expected;  and, as it appears to me, not sufficiently great and
constant in animals of the same natural families, to admit of any
satisfactory conclusion being drawn on  the subject.   Nor is it pro-
  1 The canal in the fang of this snake was found to be in part cellular, its
middle portion;  after calcination, the part was very easily examined. 
PROPORTION OF CALCAREOUS MATTER, ETC.
407
bable that any such conclusion can be drawn, until a series of com-
parative experiments shall have been instituted,  conducted with
minute attention to accuracy, and under circumstances, especially
as regards the method of preparation, precisely similar.
   It has been asserted that there is as marked difference in the pro-
portions of the constituent parts of bone of the blood-horse and the
cart or dray-horse, as there is in their appearance and some of their
physical qualities; that the former, though stronger and more com-
pact than that of the latter, is of lower specific gravity, and contains
a less  proportional quantity of calcareous matter.  To endeavour
to satisfy myself on these points,  I have been at  some trouble to
procure for examination specimens of bone of the varieties of horse
in question; for those of the thorough-bred horse "Lorenzo," and of
a common life-guards' troop-horse, I am  indebted  to Mr. Gulliver.
The  results  they have afforded  are not  in confirmation  of the
opinion referred to; they seem rather to favour a conjecture already
proposed, that in relation to strength, more depends on the arrange-
ment of the  constituent particles than on  the proportion of calca-
reous matter; and indeed many other of the results of the compa-
rative trials contained in this table point the same way.

                           Table IV.
Proportion of calcareous and animal  matter in  exhumed and
                          fossil bones.
Description of Bone.
Portion of parietal bone of a human cranium, from an
  ancient tomb in Cerigo......
Portion of zygomatic process of the temporal bone of an
  ancient Egyptian cranium from a tomb in Thebes; in
  form like the finest Grecian    .    .
Frontal Roman bone, found at Pompeii ....
Bone found at Borrowstownness, included in sandstone,
  apparently a human tibia.....•
Bones from the banks of the Ohio, reddened by oxide ot
  iron and penetrated by extraneous earthy matter, said
  to have been found at the depth of twelve feet   .
A tooth of the mammoth......
The enamel of the same tooth    .    .         •
Portion of os humeri of a horse, found in clay near Upnor
  Castle, in Kent, twenty-four feet below the surface   .
Portion of a cylindrical bone of an elephant,  from a ca-
  vern in Corfu  .    •......
Calcar. Matter.	Animal Matter.
73-8	26-2
76-1 64-5	23-9 35-5
83-2	16-8
69-0 69-5 82-6	31-0 30-5 17-4
75-0	25-0
95-0	5-0
  For the few examples in this fourth table, I have been indebted
to Dr. Monro,  with the exception of Nos. 1, 2, 8, and 9.  No. 1
I received through the  kindness of Major  Macphail, who, I under-
stood  found it  in an ancient Greek tomb  in Cerigo, cut out of the
porous calcareous free-stone of that  island; and No. 2 was given
me by the late Mr. Henry Stodart, who, on his return from Upper
Egypt assured me he had taken it himself from a tomb m ancient 
408
DAVY'S RESEARCHES.
Thebes.  Both skulls are brittle; the former is  probably more than
2000 years old, and the latter not less than 3000.
   The  considerable proportion of animal matter which these bones
contain, all but the last, is remarkably contrasted with the total or
almost  total want of it in  bones belonging1 to the most recent rock-
formations.   In the bone  breccia of the Mediterranean—so widely
scattered—I have been able to detect a just perceptible  trace only
of animal  matter: and in the  teeth of the squali, which  occur in
the tertiary formations of  Malta and Gozo, I have not been able to
detect even a trace of it.   In an enormous tooth1 of one of these
fishes now in my possession I carefully sought for animal matter,
but in vain.  They, and the fossil bones generally, which  have  not
been exposed  to the air, owe their strength and hardness to a kind
of cement  of carbonate of lime, which they all acquire.   Judging
analogically from  the partial effect of a known period of time, what
an idea of vast antiquity  is conveyed by the circumstance  of  the
total destruction of the animal  matter of bones!  Perhaps the  in-
stance of the Borrowstownness  bone  mentioned, in which the ani-
mal  matter was only partially decomposed, may be considered as
in opposition  to  the preceding remark.   But it hardly can fairly
be so considered, taking into account that it is probably human, as
its form indicates, and that the sandstone is probably of very recent
formation, and may be even still in progress.


                            Table Y.
Proportion of calcareous and animal matter in diseased bones.
No.	Description of Bone.	Calcar. Matter	Animal Matter.
1 2	The body of a large thigh-bone of an adult affected with hyperostosis, very thick and hard, but not very The hone of a person supposed to have died of lues venerea, thick, light and spongy in a slight degree.2	76.9 70.7	23.1 29.3
  1 It is 6i inches long, 1 inch thick where of greatest thickness,  and 4|
wide where of greatest width.
  1 Death from lues venerea seems to be very problematical;  and disease of
bones, as an effect of syphilis, seems also to be problematical.  After an ex-
perience of nearly 25 years in the army, I do not recollect having witnessed
a fatal event  consequent on lues  venerea, fairly  attributable to it alone.
When such an event has occurred more or less remotely following syphilis
—tubercles or other organic disease have been developed, and have been the
principal cause of death.  And I have never met with any instance in which
in secondary syphilis the bones had  been diseased, unless mercury had been
used. In  offering  these  remarks, it is  not my  intention to  maintain that
secondary  syphilis  is  never complicated with disease of bones: it  may be
so, and any other disease-may be so complicated, accidentally, not essen-
tially—bone being liable to  morbid action  from a variety of causes  and
which may take effect during the progress of other diseases. 
PROPORTION OP CALCAREOUS MATTER,  ETC.        409
No.                    Description of Bone,

 3   Cancelli of a curved tibia......
 4   The compact body of the same bone .
 5   A portion of rickety parietal bone, about an inch thick
, 6   Another portion of the same bone    ....
 7   The body of a rickety thigh bone, very thick
 8   An exostosis........
 9   A scrofulous exostosis......
10   A spinal process of a  lumbar vertebra of the curved
       spine of a  rickety person.....
11   A rib of the  same person......
12   The tibia of a rickety  child, soft and spongy
13   A deformed  female pelvis : soft and porous, and not
       unlike horn in appearance.....
14   Portion of detached necrosed bone   ....
15   Callus of fractured femur of an  adult, supposed to be
       very old :  in appearance very dense—denser than
       the shaft  .    .     .......
16   Shaft of the  same bone,  about two  inches distant
       from  the  callus, (Fort Pitt  Museum, Loc. Div. 4,
       No. 81.)      ........
17   Callus of fractured femur of a person set. 43.
18   Shaft of the same close to the callus,  (Fort Pitt Mu-
       seum, Loc. Div. 4, No. 65.).....
19   Callus of another fractured long bone from the same
       museum,........
20   Shaft of the same bone, which was more easily inci-
       nerated than the callus,......
21   Callus of a  fractured  femur  of a  soldier, who died
       four years after the accident: very compact,
22   Shaft of the same, about an inch from callus, (F. P.
       M. Loc. Div. 4, No.  19.)     .    .    .
23   Callus  of a very old fractured  femur,  (its exact age
       not known) very compact,.....
24     Shaft of same, about 1 inch from callus, (F. P.  M.
       Loc. Div. 4, No. 20.)     .    .    .    .
25   Fractured end of bone of leg of a rabbit, difficult to
       saw, 29 days after injury (from Mr.  Gulliver.)
26   Callus uniting the fractured ends of the same bone. .
27   Healthy portion of the shaft of the  same,  .
28   Exfoliation  from  human  clavicle, presented to the
       museum by Dr. Williams,    .    .    .    .
29   Necrosed end of femur after amputation of limb,
 30   Portion of shaft of the same, near the end,
 31   Portion of the same high up,.....
 32   Necrosed shaft of femur,......
 33   New bone enveloping the  necrosed shaft, (F. P. M.
        Loc. Div. 4, No. 22.)......
 34  Portion of necrosed tibia, near  the head of the bone,
        its outer compact part,......
 35  Portion of new bone enveloping the  preceding, (P.
        P. M. Loc. Div. 1, No. 95.).....
 36  Necrosed tibia of a boy set. about 16,
 37 ) New bone  belonging to  the same limb,1 (F. P. M.
    l   Loc. Div. 1, No. 169.)   •    •   >.
Calcar.
Matter.
74.5
63.0
72.9
69.5
62.2
63.8
63.0
59.3
59.2
26.0

24.2
59.2
52.4


59.8
50.4

55.8

61.2

61.4

62.8

61.2

58.3

59.4

65.4
•54.6
65.8

58.0
65.4
63.6
60.0
60.6

57.1

63.4

43.6
60.0

53.6
1 In this instance, as is generally, if not invaiiably the case, the new bone 
410
davy's researches.
Description of Bone.
38


39

40


41


42


43


44



45
Porcelain-like deposit, (hard, compact, polished) on
  head of humerus, deprived of its  cartilage, (F. P.
  M. Loc. Div. 2, No. 49.).....
Portion of new bony matter deposited round the mar-
  gin-of the articular surface of the preceding,
Portion of  healthy shaft of the  same bone: from a
  woman, who for many years  had been  subject to
  the gout,      .........
Portion of tibia from G. Snellings, set. 17 :  whose leg
  was  amputated on account of caries with softening
  of ankle-joint, (F. P. M. Loc. Div. 2, No. 49.)
Upper part  of os humeri exhibiting osteo-sarcoma, so
  soft,  as to be easily cut (F. P. M.  Loc. Div. 2, No.
  29.).........
Tibia thickened and  softened of an adult who had
  taken large quantities of mercury, (F. P. M. Loc.
  Div.  1, No. 33.)    .......
Portion of os  calcis from a  limb amputated on ac-
  count of disease resembling elephas: by drying, it
  lost 37.5 per cent.: it  was soft, and  abounded  so
  much in oil, that it was semi-transparent,'
Molar tooth of a soldier said to. have been loose four
  years,......■
Calcar.
Matter.
54.2

48.8
58.8


38.2


39.6


60.0



15.0

68.5
Animal
Matter.
45.8

51.2


41.2


61.8


60.4


40.0



85.0

31.5
deposited to supply the place of the dead bone, showed no regularity of struc-
ture ;  after incineration, it was crushed to powder by moderate pressure.
  1 The limb was amputated by Mr. Shelly of Epsom, and by him presented
to the museum at  Fort Pitt, where it  is now deposited.  It would appear,
from the information afforded by this  gentleman—that  his patient Thomas
Grainger,  an invalided artillery man, received a  slight contusion on the
dorsum of the left foot at  the Cape of Good Hope, in 1806 ;  that after appa-
rent recovery, ulcers of a severe and intractable kind formed about the left
ankle, for which he was sent home  and  discharged the service ; that after
deriving benefit from change of climate—he had  a febrile attack in 1815, fol-
lowed, whilst he was a patient in St. Thomas's Hospital,  by swelling and
ulceration of the foot; and with which he  was discharged, the disease being
considered incurable.  In 1834,  when Mr. Shelly first saw him, the leg had
acquired an enormous size, and  was discharging  a very offensive sanies. He
then objected to  an operation.  Ulceration  continued  and  increased, the
bones of the toes, it is stated, becoming carious and gradually disappearing.
Life being in danger from the  state of the limb, and from  the  hemorrhage
which occasionally took  place from the ulcerated parts, in  the last week of
August, 1838, he submitted to the  operation of amputation, which was per-
formed above the knee.  The wound rapidly healed, excepting close  to the
ligatures; on the 21st October, nearly nine weeks  after the removal of the
limb,  one  ligature was still attached.  The  most remarkable appearances,
which presented on examining the limb on its arrival at Fort Pitt, were the
softened spongy state of the bones abounding in  oil, (the tarsal and what re-
mained of the metatarsal bones, actually floated when thrown into water;) a
conversion of the muscles more or less into fatty matter;-a condensed state
of cellular tissue, with much accumulation,of fat, and a hypertrophied state
of the cutis and cuticle.   In Ceylon many years ago, I had an opportunity of
making a  post-mortem examination of a native who died in the Leper-Hos-
pital,  of elephas, complicated with elephantiasis, (that is,  the enlarged leg
with the tubercular disease of the  skitt,v) and  the appearances of the affected 
     CONTENTS OP THE URINARY BLADDER AFTER DEATH.  411

  In comparing the results in this last Table, it appears how very
variable is the  proportion of calcareous matter in diseased bone;
and what very little agreement there is between the quality of hard-
ness and of softness of bone, and the proportions of calcareous and
animal matter ;  further confirming the conjecture  that more seems
to depend, in  relation  to these qualities, on arrangement of the in-
gredients than on their respective  proportions.  Undue softness, it
would appear, may co-exist either with animal matter  in  excess,
which is the  most  common occurrence; or in  about  the average
quantity, or even in deficiency, which is far more rare.  Perhaps
more extended research may lead to  clearer general views of the
connection of the proportions of calcareous matter  with certain dis-
eased states  and physical conditions according  to precise rules.
But on  this head there is little encouragement to be sanguine at
present: the limited experience which we possess does not point
to any such  rules.   The subject  is one of difficulty,  and of little
promise, and therefore not likely to be prosecuted with the dili-
gence and care  requisite to discover order; and  which assuredly
can only be effected by the simultaneous study of the  pathological
state of the part, and  its chemical composition, following it in its
different stages.
  In  application to particular questions,  the results contained in
this table, I would  hope, even limited as they are, may be of some
use.
                            XXXII.

 OBSERVATIONS ON THE CONTENTS OF THE URINARY
                 BLADDER AFTER DEATH.

  I have been induced to pay some attention to  this subject, from
finding, in an  instance of  diabetes complicated  with tubercular
phthisis, the urinary secretion, shortly before death, restored nearly
to its healthy condition.   The outline of the case was the follow-
ing :—
  J. Spiers, aet. 20,  three weeks after enlistment was found to labour
under diabetes.   After treatment for nearly six months in the hos-
pital of the regiment to  which  he belonged, he was sent to  the
general hospital  at Fort  Pitt, preparatory to being discharged the
service. On admission, the symptoms of diabetes were well marked

limb were  closely similar to the  preceding.   An account of the dissection
is to be found in the last chapter of my work on the Interior of Ceylon.  In
this instance, the disease extended to  the thigh:  a large quantity of oil was
found in the capsule of the knee-joint in the place of synovia.  The bones
were not examined. 
412
davy's researches.
and characteristic;  those of phthisis, less so.   The urinary secre-
tion in the twenty-four hours amounted to six quarts, it was of sp.
grav.  1040,  and  abounded  in saccharine matter.   He lived two
months longer.   Towards the termination of the disease the pec-
toral symptoms increased, the diabetic diminished ;  two  days be-
fore his death, the urine  was of  sp. grav. 1017, and a few hours
before  of 1022, and was found to abound in  urea, and to contain
very little saccharine matter.
  On inspection of the body, cavities and tubercles were detected
in both lungs ; and  no other material organic  lesion  was  discover-
able.
  The urinary bladder contained about one and a half pint of
urine, of sp. grav. 1014, clear and of a bright brown hue.  It was
found  on chemical  examination  to contain  a large  proportion of
urea, without any appreciable quantity of saccharine  matter.
  Exclusive of this case, I have notes of twenty-seven others col-
lected at Fort Pitt, in which, the inquiry, post-mortem, relative to
the urine, was  prosecuted.   I shall give the results in  a  tabular
form ;  stating the quantity of fluid found in the bladder; its appear-
ance under  the  microscope when  any wise ^.peculiar;  its specific
gravity, ascertained by a delicate  balance ;  its acidity  (when pos-
sessed  of that quality) by litmus paper; whether serous or albu-
minous, in a marked degree, or not, by the test of nitric acid ; and
the presence in it of urea,  by the  effect of the same acid  on it, when
concentrated by evaporation over boiling water, to the  consistence
of syrup.  No selection of cases was made for  the  examination ;
almost every fatal case that occurred during a period of nearly six
months was taken advantage of for the purpose ; and I shall intro-
duce  the results  obtained from  each, in the order of  time, rather
than classed according to  the nature of the fatal disease—this being
most in accordance with the experimental plan.

                            Table

  Of observations on the Urinary Bladder and urine after death.
No.	Age.	Principal organic lesions discovered by autopsia.	Hours alter death, f	Observations on the urine.
1 2 3 4	51 33 58 21	Cancer of stomach (medullary tumour softening, with ulce-ration) Tubercles and cavities in lungs, with pneumathorax from per-foration of pleura of right lung Partial gangrene of left lung: 12 pints of serum injRavity of abdomen; peritonaeum thickened and granular Tubercles and cavities in lqngs,	17 11 6 9	About 8 oz. found in the bladder : ale-ooloured : of sp. gr. 1015 : not serous: abounding in urea About 1 dram of urine in blad. der : of natural colour and appearance About 4 oz.: of natural brown-' ish hue, with slight mucous sediment: sp. gr. 1013: not serous : abounding in urea Bladder quite empty
 
CONTENTS OP THE URINARY BLADDER AFTER DEATH.  413
No.
Age.
Principal organic lesions discovered
         by Autopsia.
Hours
 after
death.
Observations on the urine.
9   40
13
14
15
29
44
39
Tubercles and cavities in lungs,
  &c.
Ditto        ditto

Partial hepatisation of lungs : a
  large aneurism  of thoracic
  aorta, not ruptured
Tubercles and cavities in lungs;
  a medullary tumour in lower
  portion of spinal canal. Ure-
  ters   and  urinary  bladder
  bloodshot, &c.

Partial oedema  of  lungs: gan-
  grenous fistula in ano

Tubercles in lungs with cavi-
  ties in left lung

Hepatisation and   cedema  of
  lungs
Ecchymosis with bloody serum
  in lungs, containing pus-like
  globules;   rima  glottidis,
  slightly cedematous:  valves
  of heart and large blood ves-
  sels  strongly stained  by co-
  louring matter of blood : pus-
  like globules in blood, and in
  softened subst. of spleen'
Cavities in left lung: tubercles
  in both
Hepatisation and cedema, with
  partial gangrene of lungs
Cavities and tubercles in lungs
31

16

12


23





22


  6


21





 12
28
28
1 dram : turbid :  serous

6 oz.:  porter-coloured :  sp. gr.
  1019 : abounding in urea
A few drops only : too little for
  trial

J oz.: turbid, purulent: of sp.
  gr. 1027 : under microscope
  pus-globules seen in it, wilh
  a few blood-corpuscles: and
  particles of a  smaller size:
  no urea detected
3 oz.:  ale-coloured:  sp.  gr.
  1011:   slightly  serous:  a-
  bounding in urea
1  oz.:  ale-coloured:  sp. gr.
  1014:  not serous: urea not
  deficient
4 oz.: porter-coloured: of offen-
  sive  cadaverous odour : con.
  tained pus-like globules, and
  many spermatic animalcules:
  sp. gr. 1020:  not  serous:
  abounding in urea
2 oz.:  ale-colonred : odour very
  offensive :  sp.  gr.   1317 :
  abounded in urea
3 oz.: porter-coloured: odour
  offensive, cadaverous : acid :
  sp.  gr. 1019 :  not serous : a
  few pus-like globules in  it,
  and many much smaller par-
  ticles
3 oz.: porter-coloured : acid :
  slightly serous : sp. gr. 1023:
  one spermatic animalcule de-
  tected : a  few pus-like glo-
  bules,  and  fine  filaments:
  abounding in urea
1 oz.: high-coloured : odour of-
  fensive : sp. gr. 1022: slight-
  ly serous:  not deficient  in
  urea
  ' This case of confluent variola which proved fatal on  the 14th day, on
post-mortem examination  afforded a  striking  example of red discoloration
or staining of lining membrane of the heart and great blood vessels, in con-
nection  with red serum  and  incipient  putrefaction ; the blood  mixed with
lime emitted an unusually strong ammoniacal odour, and the blood particles
were puckered and diminished  in  size.  At page 103, will  be found some
observations on the dependence of the staining of  the heart  and great ves-*
sels on the cause just referred, viz. putrefaction and the serum of the blood
holding in  solution colouring matter of the blood.
         13—b                                             27 dav 
414
DAVY'S RESEARCHES.
			Hours	
No.	Age.	Principal organic lesions discovered by Autopsia.	after death.	Observations on the urine.
16	33	Cavities and tubercles in lungs	20	No urine in bladder
17	33	Caries with partial necrofis of frontal and parietal bones: softening of fornix: tuber-cles and cavities in lungs	17	4 oz.: ale-coloured: sp. gr. 1006.
18	21	Cavities and tubercles in lungs	21	2 oz.: porter-coloured : not se-rous : sp. gr. 1017
19	35	Lungs partly cedematous, partly hepatised, and containing pu-riloid fluid. Puriloid matter and fibrinous concretions, ob-structing iliac veins, connect-ed with sea scurvy	28	A few drops only
20	47	Ulcers in rectum and lower portion of colon : a perfora-tion into cavity of abdomen, with gangrene and marks of peritoneal inflammation	15	3 oz.: ale-coloured : acid : slightly serous : sp. gr. 1015
21	18	70 oz. of scrum of sp. gr. 1019 in left pleura : 27 in right of the same sp. gr. 3£ oz. in pe-ricardium of sp. gr. 1014: tubercles in both lungs and cavities in the left	37	Slightly serous : acid : sp. gr. 1016; abounded in urea: contained pus-like globules and many very minute ani-malcules—thread-like—their length equal to about the di-ameter of a blood-disc, some with a vibratory, others an undulatory motion
22	30	Tubercles and cavities in lungs	33	4 oz.: straw-coloured: slight-ly turbid : not serous : con-tained spermatozoa and some pus-like globules: sp. gr. 1013: abounded in urea
23	38	Lymph extensively effused over pericranium (erysipelas): two small cavities and a few clustered tubercles in lungs (latent phthisis)	6	1J oz.: dark ale-coloured: acid: serous: sp. gr. 1021: very little urea : many globular fil-amentous particles, probably of mucus, and deriving their form from mucous follicles
.24	31	Tubercles and cavities in lungs	25	1 oz : high-coloured : acid : not serous ; sp. gr. 1019 : not de-ficient in urea: contained many minute particles : one spermatic animalcule was seen, and a globular animal-cule in motion, smaller than a blood corpuscle
25	39	Tubercles and cavities in lungs. Large intestines several ulce-rated: end of appendicula ver-miformis perforated by ulce-ration, adhering to colon, and gangrenous where adhering	13	14 oz.: light ale-coloured: slightly turbid : acid : sp. gr. 1014 : slightly serous : con-tained many spermatozoa, and very minute particles: not deficient in urea
26	33	Ulceration of pharynx and lar-	34	4.qvi^aJe ale-coloured: a mu-cous- sediment on standing:
		ynx, with cedema of margin		
		of epiglottis and glotlis^and		. iftp, grv'ft)27: acid: slightly serous: contained some urea
		partially of thq,. WPg^W^ destructiorf ©f a ftonsl^fhie	0$.	
				' -VT- ■ \>i. '".
		portion of the palate, incT^d>-.	] ■"VJ:.;jv!>>	7. •» • •'.
		ing the greater part of ttie	■■ 7'■■':.<'	
		bony plates		a->
 
CONTENTS OF THE URINARY BLADDER AFTER DEATH.   415
No.	Age	Principal organic lesions discovered by Autopsia.	Hours after death.	Observations on the urine.	
27 28	33 35	Tubercles and cavities in lungs Fracture of cranium, with la-ceration of middle menin-geal artery and extravasation of a large quantity of blood within the cranium	29 27	1 oz.: ale-coloured: sp. gr. 1020 : acid : slightly serous : contained urea 1 dram : a sediment of gelati-nous mucus, consisting (as seen under the microscope) of particles, globular and fil-amentous, like those noticed in case 23. The little super-natant fluid was acid, and re-sembled some urine, drawn off by catheter, ten hours be-fore death, of sp. gr. 1010 : and abounding in urea	
  Do not these observations seem to indicate  that the kidneys, in
the majority of cases, perform their function even in the last hours
of life; and that the secreted fluid of the moribund differs less from
healthy urine, than in  many instances of diseases, not threatening
life?   The first case, introductory to the others—that of diabetes
complicated with phthisis, is a striking example in point.   Admit-
ting the inference  to be  correct,  it is necessarily matter of  conjec-
ture how the effect takes place.   Other organs exhibit phenomena
somewhat similar.  In  phthisis, shortly before death, it  is  not un-
common  to witness a  cessation of distressing  pectoral symptoms,
and a return of comparatively easy respiration.  In insanity, com-
plicated  with  organic disease of  either  the  thoracic or  abdominal
viscera, and  especially  with tubercular disease, it  generally hap-
pens  that the  destructive malady runs its course, without appa-
rently deranging the functions of the organs  in which it is seated.
In  ail organic diseases, and most distinctly marked  in instances of
chronic  disease of the heart, there are marked periods of rest, as
well  as of exacerbation.  And during  the fits of aggravation, cer-
tain  medicines, as narcotics, timely  administered,  often have  the
effect of affording great and sudden  relief, seemingly allaying the
deranged functions and restoring the organ  to its healthy state of
actiom   Lastly, it may be remarked, that  the functions  of most
organs, even  when free from organic disease, are  liable to  irregu-
larities ;  as the sudden blush, the quickening  of the pulse, the open-
ino- of the pores and bursting forth of sweat,  the sudden change of
the urinary secretion,  becoming  at once excessive in quantity and
extremely dilute—all connected  with mental  emotion.  Now, as in
these instances  the  modifying  effect  appears to  depend  on  the
 nervous system exerting some peculiar  influence, it seems  not  im-
 probable, that, in the  la'st stage of life, a  similar influence  may be
exerted on  the kidneys, and a kind  of healthy action  temporarily
restored.  But this is  speculation—and  as such  of little  weight.
 Practically considered,  perhaps a useful  caution may be deduced,
 from the comparatively healthy  state  of the urine  in  death  ;  a 
416
davy's researches.
caution of not attaching too much importance to the condition of the
secretion during life,  and in instances  of disease,  especially on
casual observation and trial.  The natural inference seems to be,
if in  dying the urine  can resume  its healthy qualities, or an ap-
proximation to them, it is likely to do the same occasionally, under
peculiar influences, duripg the prevalericy of  active disease.   Ex-
amples  of  this kind are  probably  familiar to every experienced
practitioner, who has directed his attention to the subject.   And
the propriety of using caution in this matter seems to be enforced
by what is now and then witnessed in  the condition of the secre-
tion, in  persons apparently in perfect health—a  condition the re-
verse of that alluded to in death, viz. a change from the healthy to
a  morbid  state—as  a  sudden and  unexpected deposit  of a large
quantity of brick-red or  rose-coloured  sediment,  to the no little
alarm of the individuals,  till they find (as often happens) that such
a deposit is of as little consequence  as the  appearance of a pimple
on the forehead, or of a papular eruption on the lip in sound or ap-
parently sound health.
   Reverting to the  particular observations, it  appears, that in two
instances—cases No. 21  and 24, minute living animalcules  were
seen in the urine under microscopic  examination.   I believe they
came from  the bladder; but  it is right to  state I  am not  certain
that they did, as the vials in which the fluid was received had pre-
viously  held pump-water.   In using the microscope it is  impossible
to proceed with too  much caution, or to be  too sceptical, especially
when the results are in any wise extraordinary.
   Further, reverting to them, it appears, that in several instances,
viz. in  cases Nos. 11,  14, 22, 24, and 25, spermatic animalcules
were  detected in the urine.   Of the nature of these animalcules,
there  could be no question, their forms were so distinct.  Nor can
there  be, I  apprehend, any doubt entertained  that they had been
collected previously  in the vesiculae  seminales.   Probably in the
convulsion  ofdeath, which is  often accompanied with the discharge
of a portion of the contents of these organs, some of the fluid may
have been irregularly propelled into  the urinary bladder.
                          XXXIII.

SOME DIRECTIONS FOR MAKING AND KEEPING ANATOMI-
          CAL PREPARATIONS IN HOT^IMATES.

  It is too generally'ssupposed that the making and keeping of ana-
tomical preparations in hot climates is almost impossible, or attended
with so much difficulty as to be practically impossible, with the or-
dinary means within the reach of medical men. 
MAKING AND KEEPING ANATOMICAL PREPARATIONS.   41?
   This is  a mistaken notion, and it is for  the  interest of science
that it should be refuted.1   The changes which  animal matter un-
dergoes  at a temperature  between  80 and 90° Fahrenheit (the
average  maximum of the  highest temperature,  in the hottest sea-
sons, even in intertropical climates,) do  not differ in kind from
those  which occur  at a temperature between 45° and 55°, and a
fortiori between 55° and 70°, which may be considered about the
average  in-door temperature of the winter and  summer seasons in
Great Britain.   The difference then in the changes is chiefly in
degree: in a hot climate  they take  place more rapidly, than in a
temperate  one, twice or thrice as rapidly, according to the elevation
of temperature.   This should always be kept in mind as a  maxim
and principle; and  to ensure success in making anatomical  prepa-
rations, the rapidity of change of animal  matter must be met with
proportional quickness and energy of the conservative processes of
art opposed to the destructive ones of nature. With the same view,
and against the same tendency to change and  decompose,  besides
quickness, great neatness and cleanliness are requisite.
   Every dissection  should  be conducted in  a regular and scientific
manner, according to a certain  method, and with definite objects in
view.  The principal objects of all dissection are three: the detec-
tion of the effects of the disease, and the cause of death ; the removal
of diseased parts for preservation; and the acquisition of general
anatomical knowledge.   Neatness, and  cleanliness,  and method,
conduce equally to these  objects.   Attending to  them, obscurity,
confusion, and  error are avoided;  the  pursuit loses as  much as
possible its disgusting aspect; it gives  information of a satisfactory
kind ; excites interest powerfully ; and zealously pursued becomes
almost fascinating.   Farther, when the dissection is conducted on
these principles, it is the source of much valuable  instruction.   It
makes the hand dexterous for surgical operations; it  produces cau-
 tion  in deciding on post mortem appearances,  which are so often
deceptive; and habituates the  eye  to the nice discrimination  of
 what is sound in structure, and what is diseased.
    When any morbid appearance presents itself,  the part displaying
it should be carefully examined before it is removed ; its situation

   1 Mv attention  was  directed to the above subject in 1825, when the pre-
 sent director-general of the army medical department  was calling  on medi-
 cal officers on foreign stations  to contribute to the museum at Fort Pitt,
 then in its  infancy, and which now, owing in great measure to the assistance
 so afforded   is  become one of the most valuable  collections of pathological
 anatomy in this or in any other country.  Most of the observations contained
 in this paper  were written at that time, and privately circulated with the
 view to remove the impre^ion alluded ,tp in the  text; and were afterwards
 nubfished in the ^th Vol. ofthe Edinburgh Medical and SurgicalJournal.  I
 am induced agairrHo brinfthem forward, with such alterations as extended
 experience  has suggested, with the hopethat they may be still useful in  he
 important eause of pathological  research, and of that  museum which is the
 permanent record of such research amongst the medical officers of the army,
 by whom it has been  formed. 
418
DAVY'S RESEARCHES.
should be noticed, and its connections traced.  If it  is considered
worthy of being  preserved, with  that intention, it should be  dis-
sected  out so as  to appear to the best advantage;  to require as
little explanation  as possible ; and to be by itself as  intelligible as
possible.
  If dissected out  neatly and cleanly at once, free from extraneous,
adipose, cellular,  and  muscular substance, &c.  much subsequent
trouble will be spared, and time saved. Generally speaking, indeed,
the suggestion just given cannot be too strongly inculcated.  For
the morbid part to become a good  preparation, it should be put out
of hand at once ;  arid nothing should be left that ought and can be
removed by the knife and scissors.  Delay breeds neglect and for-
getfulness ; the nicer peculiarities of the diseased part are forgotten ;
after a time it ceases to excite interest, as a confused mass putre-
fying, or bordering on  putrefaction, it is a loathsome and worthless
object ;  and thus,  in consequence of not having been  finished at
once, it ends in being  thrown  away; and an aversion too often  is
acquired, rather than a fondness for pathological anatomy.
  The present remarks are applicable to all kinds of anatomical
preparations, but more especially those intended to be kept in spirit
of wine, which  experience has proved is better adapted for the pre-
servation of moist  preparations than any other liquid yet tried.
  The methods of proceeding in preserving preparations, must to a
certain extent be modified according  to the nature of the morbid
parts, and agreeably to the intention  of the anatomist.
  If the diseased  part is small, and it is wished  to preserve  its
colour, as a portion of inflamed, or of ulcerated stomach or  intes-
tine, it should be immersed immediately in strong spirit; and in-
stantly put.up, as  it  is intended it should remain.   After a mouth
the spirit may be  changed for fresh  spirit, and  the mouth  of the
vessel should be firmly secured.   The blood in  the part will thus
be  coagulated and preserved;  the shape will be retained without
unseemly distortions, which  when once  rigid are not  easily re-
moved ;  and the  preparation is fit  for the shelf of the  museum
without any further trouble.
  Preparations of the brain,  spinal  cord, and  nerves, should be
treated in the same manner, and so treated they are easily kept.
  Thus  also should be  managed  preparations of the eye, pleurae,
peritoneum, testes, and  their tunics,  and in fact  all such parts as
are either colourless, and therefore not requiring steeping in water,
or are  liable to be injured by that  process, and by incipient putre-
faction.
  On the contrary, parts containing  much blood, as the  liver, kid-
neys, lungs, heart; or stained and discoloured with  blood or bile,
&c. as the blood vessels and gall-bladder, <fcc.;.or, smeared with a
lubricating fluid, as  the aspera  arteria, prima? ;viae, synovial  mem-
branes, &c.  should be immediately  well washed, and if practica-
ble, in  a stream of  water.   By persevering washing in  running
water, and gently  pressing the part,  treating; it  like a sponge, in a 
      MAKING AND KEEPING ANATOMICAL PREPARATIONS.   419

short time, as  from  ten to  twenty minutes, most textures may be
deprived of the blood  which they contain,  and of any secreted
fluids peculiar  to them.   If leisure does not admit of such manipu-
lation, and  assistance is not, available  for the purpose, the  parts
may  be  suspended in  water,  and  the hotter the  weather is, the
shorter should  be the time of suspension, and the more frequently
the water should be changed.  In thus steeping, it is of importance
to use a tall large vessel, full of water—and  to have the parts im-
mersed only just below the  surface.   The rationale of this must
be  manifest to those  who reflect on the subject, and take into con-
sideration, 1st, that blood and bile, especially the colouring matter
of the former, is of greater  specific  gravity than water,  and conse-
quently has a tendency to subside rapidly and collect at the bottom;
and 2dly, that the colouring matter of both, and more particularly
of blood, in solution  in water, has the power of combining  with
animal textures, and of staining or dyeing them.  By using a tall
vessel in the manner suggested, the colouring matter in dissolving,
will rapidly quit the part immersed, and descend beneath it; and
by employing a large quantity of water, the object of separation is
more effectually attained, and  very frequent  change of  water is so
much the  less necessary.   Demonstrative proof may be easily ob-
tained of the propriety  of these directions, by reversing them, as by
allowing the part in  steeping  to sink  to the bottom, or  by using a
shallow vessel or  a small  quantity of water.  In the  former in-
stance, the part will necessarily be  immersed  in a strong solution of
the colouring  matter, and will be intensely dyed ; and in the latter,
the effect will  be very similar, presuming that the colouring matter
is diffused  through  the whole of the  water.1  I may appear  to lay
too much  stress upon  these points :  but, in reality, they are very
important,  and commonly  not sufficiently  attended to.  I   have
known them  neglected even by anatomists, not unaccomplished in
the art of making preparations for  the museum ; and  I also  know
how difficult  it is to  have them  observed by novices in the art, for
whom chiefly  these observations are intended.
   Immediately after the thorough washing,  as soon as possible, if
steeping be employed,  the  parts should be transferred from  water
to spirit.  Before immersion in the latter, unless of peculiar delicacy,
they may be pressed gently between  folds  of linen, to  remove the
excess of water.   A mixture of seventy parts of proof spirit, and
thirty of water (rain,  or distilled  water should be used2), is well

   1 Vide note,  page 104, for further  remarks on the staining agency of
 the,colouring matter of blood.  Whether dissolved in consequence of inci-
 pient putrefaction iff; serum, or merely in water previous to putrefaction even
 in an incipient-state, it's dyeing power appears to be similar.
   2 If the watei/can,tflin carbonate and sulphate of lime, which are ot com-
 mon occurrence in spring'water, they will  be precipitated by the spirits ; the
 appearance of the preparation may thus be injured, or the inside ot  the jar
 may become dull, and prevent ai-distiact view of the contents. 
420
davy's researches.
adapted,  even in  warm climates, for preserving the  majority of
moist preparations.
  For the useful  purposes of a museum, it is necessary that  the
part to be kept should be,  not  only carefully and neatly dissected
out, but  also carefully and neatly put up, and that immediately,
and as it is intended it should  appear on the shelf.   If this  be
neglected at  the moment, the season for  doing it in  perfection is
lost.  A  preparation crammed  into a bottle, just large enough to
hold it, or thrown  into spirits in a large vessel, as  is too often done,
without attention to suspending it in a natural way, that it may be
properly  seen, becomes (unless  it be some very simple structure)
misshapen, distorted, and confused.   A preparation in such a state
it is very difficult afterwards to amend : this is well known to those
who have had occasion to attempt the annoying task of endeavour-
ing  " to  make something" of a preparation,  perhaps  highly inte-
resting in itself, which has been thus neglected in  the first instance.
  It may perpaps be thought that the  measure just recommended
is not easily carried into effect; that to accomplish it much art and
skill are  requisite;  and that glass vessels in plenty, and of various
sizes, are indispensable.
  This,  fortunately, is not the case; very moderate  skill is suffi-
cient, such as every medical  man ought to possess, and must pos-
sess, if he is fond of his profession, and only tolerably zealous in  the
pursuit of it.   And instead of many  glass  vessels, one  or two  are
amply sufficient for holding all the preparations a professional man
is likely  to be  able to collect in one year in the course of his ordi-
nary practice.
  A glass vessel of the capacity of a gallon, with a large mouth
closed either with a cork enveloped in cerate-cloth, or a glass stop-
per, is very convenient for the object in question.  The preparation
neatly dissected, may be advantageously attached by a thread,  the
outer end of which should also be smeared with  cerate ;  or if the
preparation is lighter than spirit, as a portion of lung  containing
air, the same  object may  be effected  by attaching it to a piece of
glass.
  In  this way a great many preparations may be introduced into
the same vessel—indeed the vessel may be almost filled with them
without  detriment, provided each is  free, and  not pressed against
by another, which  is easily managed  by using threads of  different
lengths.  This method, it maybe added, is particularly well adapted
for  sending preparations to  England, on account of its economy,
the little space required,  and its security.  Using it, there  is  no
danger of the preparations being left dry and ruined by the capillary
action of threads sucking up the spirit, and draining the vessel,  the
cerate preventing  such action;  nor is there  any danger of atmo-
spheric air finding admission, provided the glass stopple  or  cork
with which the bottle is closed is covered with moist bladder firmly
tied down, and smeared  with  oil when dry; nor  of any  material 
      MAKING AND KEEPING ANATOMICAL PREPARATIONS.   421

loss from  evaporation.  Here  a caution may be  given, that  when
bladder is thus used, the bottles should be  placed out of the reach
of rats, mice, and cockroaches, animals greedy, of this  membrane,
and who attack it whenever it comes in their way.
   Numbers written  with a lead  pencil on slips of strong paper,
parchment, or wood, may be introduced with the preparations when
they are numerous and there is any apprehension of mistake; which
numbers  will of'course have reference to a descriptive list, that
should accompany the preparations to England.
   Relative to the making of  dry preparations in hot  climates, it
will be sufficient  to  offer a very  few observations.   The  unexpe-
rienced in these  climates  may fancy the task in question  exceed-
ingly easy, from a common and erroneous  association of the ideas
of proximity to  the  sun  and  parching heat.   They will find it,
however,  a more difficult labour than can be imagined a priori;
and for this reason, that the connection of heat and dryness just
now alluded to, is in most hot  climates of rarer occurrence  than the
association of high temperature  with a great degree of humidity.
This latter happens when the  wind sweeps on its way over a great
extent of sea, and on its passage becomes loaded with moisture, as
is the case with the S. W. monsoon along the coast of India, the
S. E. or sirocco in the Mediterranean, and the  sea  breeze in the
West  India  islands.   During the prevalence of these  winds, it is
very  difficult to dry any anatomical preparation, and impossible in-
deed, unless recourse is had to some helping circumstance, as ex-
posure to the direct rays of the sun, or the dry heat  of a charcoal
fire.   On the contrary, when the  atmospheric heat is accompanied
with  dryness, as it always is when the wind comes over an exten-
sive tract of country, such as the  land  wind in India, the N. W. in
the Ionian  Islands,  the S. E. on the  Western shore of Southern
Africa, then the making of dry preparations is very easy—exposure
to  the wind is by itself sufficient.   When dry,  in every instance,
the preparations  should be varnished  to  defend  them from the ac-
tion of the atmosphere, and from the effect of vicissitudes in point
of humidity, and then they should be carefully packed  up  in dried
paper in a box of tight construction to be sent  home  by  the first
opportunity.  As dry  preparations of morbid parts, with the excep-
tion of bones, are of comparatively  little value, nothing that is par-
ticularly interesting, capable of being kept in spirits should be pre-
served in any other wav.
   It is not considered necessary  to  give any hints respecting the
methods of making  injected preparations.   Those who have suffi-
cient zeal for anatomical pursuits to engage in this undertaking,
will have no difficulty incarrying it into effect wherever they may
be, with the knowledge Which they must have acquired previously,
and being possessed of,the same apparatus that is requisite in tem-
perate climates.         . .. >^  ^>   • f
   In concluding, it may be remarked, that, simple and  easy as are
the means described for making and preserving morbid anatomical 
422
DAVY'S  RESEARCHES.
preparations in hot  climates, they are quite adequate, and  with
ordinary care cannot fail to succeed.   On  this subject I can speak
with some confidence from experience.  During a period of eleven
years,  that I was stationed in the Mediterranean, in  the Ionian
Islands and Malta, they had a fair trial, and were found to answer
perfectly; of which,  I may add, permanent proof is afforded by the
specimens of diseased structure  thus  preserved, sent from  thence,
and  which are now in the Museum of Pathological Anatomy at
Fort Pitt.
                          XXXIV.

NOTICE OF A CASE IN WHICH THE ARTERIA INNOMINATA
  AND THE  LEFT  SUBCLAVIAN AND  CAROTID ARTERIES
  WERE CLOSED WITHOUT LOSS OF LIFE.

  Sir Astley Cooper, in the first volume of Guy's Hospital Reports,
has given a valuable  paper on the effects of tying the carotid and
vertebral arteries in  the dog and the rabbit, proving, that in the
former animal both arteries may  be suddeuly and at the same time
tied, without  destruction of life, and that in the latter they may be
successively tied with the same result—the circulation of the blood
in the  brain being continued by the admirable  conservative pro-
cess of anastomosis.
   What Sir Astley Coopor has demonstrated as practicable in these
animals,  might be inferred analogically of man, taking into account
the results of ample  experience on the ligature of all the larger ar-
teries singly in different instances for aneurism,  successful beyond
even sanguine expectation ; and a case which has come under my
observation, confirms the  justness of the conclusion, as clearly, I
apprehend, as if instituted, were it possible, experimentally for the
purpose.  As the subject is very important in its physiological re-
lations, as well as in  its  bearings on pathology, I  shall  describe this
particular instance with some minuteness, although not so much
in detail as may be desirable, owing to circumstances connected
with the individual.
   An officer  of  rank, aged about 55, distinguished for his services
in the field during the Peninsular war, and who had been severely
wounded in  the chest at Waterloo,  after good  health for  several
years, had, when absent in  England  from his command in the
Mediterranean, in the winter of 1831, an attack, which i was in-
formed was considered  rheumatic, attended with pain in the  right
shoulder, for which calomel and opium were largely prescribed. In
September of the  following  year, he had  acute catarrh, of consi-
derable  severity and duration, followed by chronic inflammation 
CASE OF CLOSURE OF ARTERIES.
423
with enlargement of the uvula and a granular state of the pharynx,
of great obstinacy, attended with  cough, and  an impaired state of
the general  health.  In the spring  of 1834, when his healih  ap-
peared to be improving, he noticed a peculiarity of alvine  evacua-
tion ; and scrutiny being made, it was found, that he voided daily
a small quantity of purulent fluid, and which  resisted treatment for
rather more than six weeks.  The summer of this year was spent
in Switzerland, where his  health improved.  During the winter of
1834-5, he was in  a valetudinary state ; subject to cough ; to  fre-
quent pain in the right shoulder;  to occasional difficulty of breath-
ing :  the pulse was small and always quick ;  rarely below 90°-—
sometimes exceeding 100° : the respiratory sound was natural;  the
heart's action (judging from its  sound and  impulse)  was rather
tumultuous : there was emaciation, loss of strength, and depression
of spirits—alarming his friends.  For several months,  his state
fluctuated—on the whole  apparently  improving.  He ceased to be
immediately under my observation in March 1835—on my leaving
the Mediterranean. In the June following, he returned to England
by way of the Continent; and  in August, about three weeks after,
he wrote to me, that he was then unusually well, but that on land-
ing, he had been ailing a  little, and had consulted Dr. Chambers ;
and this gentleman, in  a  note with which he has favoured me, in
reply to  my inquiry  relative to  the  then state of pulse, mentions
that he "never could perceive any pulse from the time he  first  saw
him."  In September, he went to  Brighton, and  was taken sud-
denly and seriously ill with tendency to  syncope and vertigo fre-
quently  recurring : then it  is certain  that no  pulse could be  per-
ceived at either wrist.   In October, when he had returned to town,
 I saw him twice, and the  second time in  consultation  with Dr.
 Chambers and  Dr. Hume.   His general health was  better than it
 had  been at Brighton ; he experienced vertigo seldom, and syncope
 never; he daily walked  to his club-house in  St. James' from an
 adjoin'incr street, and played gently at billiards under caution.  His
 disease now was clearly aneurism of the arch of the aorta, with an
 obstructed state (it might be inferred) of the great vessels arising
 from it • for no pulse could be felt any where in the course of these
 vessels'neither iu the neck, temples, axilla or wrists, and there was
 a throbbino- pulse at the  upper  part of the sternum, and a slight
 prominence of the bone there to some little  extent.   Until the au-
 tumn following, I saw him generally once a  month :  he had fewer
 uneasy sensations-felt stronger  and considered himself better  ; the
 rising of sternum was rather extending, the abnormal pulsation not
 increasino-. He then went inlo the country; he felt, I was informed,
 still better; his general  health  was decidedly better.  This  was
 indicated  by his wishao shoot—an  amusement he was extremely
 fond of, but which, whe\i applied to, of course I opposed; strongly
 uro-ino-  in  common with his ordinary medical attendant, his re-
 maining very quiet, and  in regard" to diet living below par.On
 the  11th of January, 1837,  that is, nearly a year and a half from the 
424
DAVY'S RESEARCHES.
cessation of the pulse at the wrist, he expired suddenly.   That
morning he left his friends to return to town, and felt and appeared
unusually well: he traveled about 60 miles in a close carriage be-
fore  stopping  to dine, and  where  he intended  to pass the night.
The last post or two  he  felt  some pain in  his  shoulder,  but, as I
was  informed,  spoke lightly of it.  According to his usage on quit-
ting  his carriage,  he  took in  his hand a small  writing case; and
shortly after arrival at the inn, sat down to dinner with an appe-
tite,  and the expectation of the removal of some uneasy feelings.
He took some soup, and  was in the act of taking some fish, when
suddenly his jaw was observed  to drop, and  without uttering a
word or a sound, he fell  back in the chair dead.
   A  post mortem examination was made by a very competent sur-
geon.  The pericardium  was found distended with  coagulated
blood, and a small fissure was detected  in the aorta,  near its base,
through  which the blood had penetrated.   The heart was rather
large, and its cavities  large, but without distinct hypertrophy ; its
valves natural.  The arch  of the  aorta was, as  had been inferred,
the seat of a large aneurism, about six inches high, and about four
inches wide, nearly filled with coagulum, dense, fibrous,and nearly
white,  occupying all  but the inferior  space, where  there was a
channel  open by  which the blood passed from the  heart into the
descending portion of the vessel.   Where the vessel commenced its
descent, there  it recovered  its natural dimensions; but though of
ordinary size, it was not  perfectly sound ; there were some athero-
matous deposits on it,  and a few bony scales.  All the great vessels
rising  from the  arch  were completely closed  up at their origin.
The  upper portion of the innominata was open ; the  right carotid
and  subclavian arteries  also  were open, but rather diminished in
size.  The  left carotid, subclavian  and vertebral arteries, as far as
they were examined,  namely to the extent of about  two inches,
were impervious, plugged up with  lymph.   The intercostal arte-
ries  at their origin (they were not  examined farther) were large.
The state of the cerebral vessels, in consequence of the rapid man-
ner in which the inspection  was made, was not ascertained :  the
aneurismal tumour was  preserved, and through the kindness of
the gentleman, who removed it, (Mr. Johnston,) I had an opportu-
nity  of examining it, and of satisfying  myself respecting  the most
important points.
   In this instance, probably, the aneurism  was  of slow formation,
and  was latent, as so often happens in this malady, not only many
months but even several years : the interesting part of the case, how-
ever, is the obstruction of the great arteries, arising from tlie diseas-
ed portion,  at their origin, and yet the supply of blood,' ng| |»ing
cut  off, clearly  proving  that new  channels were establMied by
anastomoses, by which a quantity of arterial blood wastf^smitted
to the head and  upper limbs, not only sufficient to.ma^fain life,
but enough to maintain it with the vigour of ordinal health.  At
no time, after the obstruction of the great arteries,  was there any 
CASE OF CLOSURE OF ARTERIES.
425
paralytic weakness of the hands, no numbness even of the fingers,
and no decided diminution  of temperature.   The intellectual organ
performed its functions unimpaired, excepting there was occasion-
ally some slight confusion of mind and a vertiginous feeling, espe-
cially in suddenly rising from the horizontal or reclining to the
erect posture.   All the senses were ordinarily unaffected ; the sight,
the hearing, the smell, and  taste, were commonly as acute as ever,
and the general functions of the system were  well performed ;  so
that, had not the aneurism burst into the cavity of the pericardium,
life might have been continued  with  ease and  enjoyment, and  no
doubt would  have been so continued,  had a channel for the passage
of the blood been formed through the fibrinous mass in the aneurism
instead  of below it.
   As the circumstances under which the  post-mortem inspection
was instituted did not admit of  minute examination, much less of
the injection  of the vessels, the  manner in  which  the circulation
was carried on above the obstructed vessels can only be conjectured.
The intercostal arteries, especially the superior, were probably the
ones chiefly concerned in  effecting a communication, either with
the pervious principal arteries springing from the innominata, and
their branches, or the probably pervious branches, given off" by the
left subclavian and carotid  arteries.
   As supplementary to this case, 1  shall  briefly notice another, in
which also there is reason  to believe, that  the  same great vessels
were permanently obstructed, as in the preceding, but  with a train
of symptoms and an event  very different.
   Hector M'Callum,  of the 42d  regiment, aged  36;  twenty-two
years a drummer in that corps ; notwithstanding intemperate habits,
had good health, until the  beginning of 1833;  when he first expe-
rienced some difficulty of breathing;  but he continued at his duty
until  the 18th of February, 1834.   He was then admitted into hos-
pital, at Malta, and I  frequently saw him in  company with the able
surgeon of the regiment, Dr.  Nicholson, (now Assistant-Inspector
of Hospitals,) to whom I am indebted for most of the particulars of
the case.   The principal symptoms at that time were palpitation
with  tumultuous action of the heart, greatly aggravated by bodily
exertion, with dyspnoea, aggravated by the same  cause, occurring
in paroxysms, during which he experienced temporary loss of vision,
and occasionally syncope.   No pulse could be felt at  either wrist,
nor in  the brachial arteries,  and  indistinctly only in the carotid
arteries, but  strong in the femoral.   The tongue was clean, the ap-
petite good, the functions generally (independent of respiration) well
perfoj^mgd ; yet he was feeble.  He gradually  became worse.  In
Mayfthe dyspnoea was continually severe, often threatening suffoca-
tion, t% face assuming a livid hue, with great  agony  of suffering.
Now, rioi^lsation could be felt iVthe left carotid  artery, and only
very indisimclily in the right, without return of the pulse in either
wrist.  He died suddenly on the 2d of June. 
426
DAVY'S RESEARCHES.
  Owing to aversion on the part of the widow to a post-mortem ex-
amination,  the inspection was very partial and hurried.
  Two pints of serum were found in the left pleura and three in the
right.  The lungs were not apparently  diseased.   The heart was
somewhat larger than natural:  its valves were pretty sound, even
the  semilunar of the aorta.  The aorta  throughout its arch was
enlarged ; but only in a moderate degree, and its coats were more or
less altered.  Its inner coat was irregularly thickened and opaque,
and the middle  coat  corresponding had become thinner, and of a
heightened yellow tint.   Thin  plates of bone were formed in, or
under the former, and atheromatous  matter here and  there in  the
latter, and in one spot matter of this  kind, of about  the bulk of a
peppercorn, soft, brownish, poultaceous, had penetrated through all
the  coats to the external loose cellular enveloping tissue.  The left
carotid and subclavian arteries were  completely obstructed,  firmly
plugged up with dense white matter,  which it may be inferred was
lymph.   No trace even of the opening of the carotid from the aorta
could be discovered,  and  a very slight trace only of the other, a little
cavity a line or two deep, resembling the vestige of the aperture of
the  ductus  arteriosus in the adult.   It is to be regretted  that in the
hurried examination, and  owing  to  interruption, the state  of the
arteria innomiuata, and of the right subclavian and carotid arteries,
was not determined.  The  descending aorta was of its  normal
dimensions.
  This second case in relation to  symptoms is remarkably contrast-
ed with the first:—in the one, a natural curative process appears to
have been set up, to  counteract the local evil; in the other, the  re-
verse of this  process  appears to have  been in progress,—probably a
closing of the larger arteries, without expansion and extension of
their branches, or of the adjoining arteries,  and consequently the
production of a permanent impediment to the circulation in the brain
and upper  limbs, and especially in the former.  If this were so, for-
tunately, it may be considered a very rare occurrence, and as it were
the exception to the  general  rule.  The common  train of events,
that which constitutes the rule, seems to be that which was witness-
ed  in the first instance, and which has been so happily illustrated
by  the experiments of Sir Astley Cooper  already referred to.
  The subject of the occlusion of arteries is one of great interest and
of more frequent occurrence, I apprehend, than is commonly sup-
posed.  I have met with  many examples of  it. after death, which
during life were never suspected,  and even in large vessels,  and in
soldiers of active habits,  who died of acute  diseases of short dura-  *
tion, totally unconnected with the local peculiarity.  I am disposed
to  believe  that  whenever the  middle  coat  of an  artery  beeves
diseased, whether from atrophy, or change of structure, or deposition
in it, of  that matter which has  been  called atheromatous, or any
 other, there is invariably an effort, as  it were, made to strengthen
 the part, by the deposition of lymph on both sides;  and that accord- 
     FATAL CASE OF RUPTURE OF THE HEART AND AORTA.  427

ing to the rate of progress of the two processes, there is either  a
closure of the vessel, or an aneurism established: if the lymph is
deposited rapidly, the former; if the atheromatous matter, the latter:
and also the latter, if the absorption or weakening of the middle coat
from diseased alteration in its texture proceed with more speed than
the deposition  of lymph.  This I admit is hypothesis; I wish it to
be considered as such ;  I  venlure to propose it, with the  hope of
calling attention to a subject, as 1 believe, of great importance, and
with the hope of exciting discussion, which is always useful.
                           XXXV.

NOTICE OF A FATAL CASE OF RUPTURE OF THE HEART
  AND  AORTA; WITH  AN  ACCOUNT OF  SOME  EXPERI-
  MENTS ON THE POWER OF RESISTANCE OF THE HEART
  AND  GREAT VESSELS.

  Thomas M;Garey, aged 42,  about to be invalided on account of
length of service and diminished activity; according to a comrade.
of" lonely habit," fond of walking by himself;  but well conducted
and sober, and previously in good health,—was found dead early in
the morning of April 14th, 1823,  in  a chalk.pit in the neighbour-
hood  of Chatham, at the foot of a precipice, between 50 and 60 feet
deep,—the  greater part of it perpendicular.   The  body was ex-
amined on the 16th, the weather was cool, and it had been kept in
a cool place.  Externally  there was no mark of violence or appear-
ance  of contusion.  The face and surface of the body  generally
were pale.   The pupils were contracted;  the  limbs rigid.  The
right inferior extremity was a little shorter than the left;  it was sup-
posed that the thigh was  fractured; and  on exposing the bone it
proved to be so, at the neck, in an oblique direction just without the
capsular ligament.  Nothing  morbid was discovered in the brain.
No ribs were fractured.   On opening the chest, a large quant ty of
blood was found in the left pleura, about six pints, and  a small
quantity in the pericardium, about an ounce.  The blood was dark,
of the colour of venous blood, and had separated into crassamentum
and serum, and the serum was tinged red.  No lesion was detected
either in the right auricle or ventricle, or in the vena cava ascendens,
or descendens, or in the pulmonary artery.  The left ventricle also
was uninjured; but not so the left auricle and aorta, each was rup-
 tured.   The true  auricle was ruptured in two places ; each opening
 was -sufficiently large to allow the passing of the finger.   The aorta
 was  ruptured just above the mouths of the  coronary arteries; and
 also at the upper part of its arch, a few lines inferior  to the origin of
 the left carotid and subclavian arteries.   The laceration at its base 
428
davy's researches.
was nearly circular, and through all the coats, and were it not for a
narrow strip, of about two or three lines which remained entire, the
vessel  had been completely toin  in two; even  the external loose
cellular membrane was divided to the extent of about half its cir-
cumference.  The rupture at the arch was oblique, also through all
the coats, and rather more than one half the circumference of the
vessel.  There  was no blood in either of the cavities of the heart.
Both ventricles were firmly contracted ; and the valves of the aorta
and pulmonary  artery were unusually large and perfect.   The aorta
was carefully examined throughout its course; excepting two  or
three opaque spots on its inner membrane, without sensible thick-
ening,  it exhibited no  signs of disease, and  appeared to be of usual
firmness.  Where the vessel was ruptured,  in each place the coats
seemed sound ;  nor did the ruptured auricle exhibit any indications
of organic disease. The lungs were free, and crepitous ; their sub-
stance  was redder than usual, and contained more blood than usual.
The trachea and bronchia were bright  red  internally, and  coated
with blood, probably owing to hemorrhage from the lungs. Nothing
abnormal was found  in the cavity of the  abdomen ;  neither the
spleen  nor liver, (of all the viscera most liable to laceration from
falls) was appreciably  injured.  Both the stomach and bladder were
found moderately distended, one with yellowish chyme, which had
no smell of spirits,—the other with pale urine.
  According to the report of those who discovered  the body, and of
those who saw it before it was moved, it lay on its  back,—the feet
nearest the precipice, in a diagonal position.   The limbs, it is said,
were rigid, and  every part of the body cold, excepting the leftside of
the chest which was pretty warm.  No part of the dress  was torn.
The ground was firm, bare chalk.
  These particulars of this very uncommon case were noted down
at the time.  Taking them all into consideration, it seems most pro-
bable that the soldier lost  his way in a lonely night-walk, and com-
ing to the brink of the precipice stepped over and fell on his feet, or
rather  perhaps  on the one (the left), the neck  of the thigh-bone  of
which  was fractured.   On this supposition  the  unbruised state  of
the integuments, the uninjured state of the clothes, and the oblique
or diagonal position of the body in relation  to the  foot of the preci-
pice, as well as  the kind of fracture, seem to be tolerably accounted
for.
  Relative to the fatal injuries, the rupture of  the left auricle, and
the double rupture of the aorta,—I apprehend, that, reasoning  a
priori, conjectures only can be offered as to the manner in which
they were produced ; and especially taking into  account a fact, which
occurred about  the same time, and of the accuracy of which" I am
well assured, viz. that a lad fell down  the same precipice and alight-
ed on his feet without sustaining the slightest injury.  But, how-
ever explained, whether on the supposition that the lacerations were
owing to muscular action,—to the violent contraction of the left
auricle and ventricle; or, to other  causes in  conjunction with such 
          EXPERIMENTS ON THE RUPTURE OF VESSELS.     429

action,—the effects  themselves seemed to demonstrate, that where
they took  place, there was a greater tendency to yield and to rup-
ture than elsewhere, at least in this particular case.
  Thinking it probable that elucidation might be obtained by experi-
ment,—I instituted at the time some trials directed to test the strength
of the parts concerned,  which I shall  now detail, with  a few ad-
ditional ones since made.

                        Experiment  1.
  Tied the descending vena cava of a sheep recently  killed, and
through an  opening in  the  ascending vena  cava, introduced the
tube of a powerful injecting syringe, and secured it firmly by ligature.
Forced water into the right side of the heart; a large quantity was
introduced ; the vein, auricle, ventricle and pulmonary  artery be-
came very much  distended, as did also  the lungs, and a watery exu-
dation took place from their surface, without any sensible breach of
continuity of surface.  Continuing the forcible injection of water,
the right side was at length ruptured ; the rupture took place in the
sinus venosus close to the auricle, and was large enough to admit
the finger.

                        Experiment  2.
  Made a similar trial on the left side of the heart of the same animal,
by injecting water through one of the pulmonary veins, close to its
termination, having previously secured by ligature the aorta,  below
the arteria innominata.   The auricle became greatly distended, the
ventricle in  a less degree, and the aorta still  less.  Rupture took
place in this instance much more readily than in the former ; the
auricle was  the  seat of it;  it  was  sufficiently large to admit the
finger.

                        Experifiient  3.
  Made a similar experiment on the  aorta.  It expanded but little ;
it was ruptured about one inch from its origin, and to the extent
nearly of  one half of its circumference.   The pipe of the syringe
was introduced just below the arteria innominata.   The semilunar
valves performed their function perfectly, and were found uninjured.

                        Experiment  4.
  Made a similar experiment on the pulmonary artery.  Introduced
the pipe of the syringe into one of its main branches, and secured
the other by ligature.  It dilated more than the aorta, and consider-
ably; its rupture took place before much force had been employed;
it was transverse, about one half the circumference of the vessel, and
throOgh all its coats, and about half an inch above the valves, which
acted* well and were uninjured.

                        Experiment  5.
  Tied the pulmonary artery, and descending vena cava, and forced
      13__c                                   28—dav 
430
DAVY'S RESEARCHES.
in water through the ascending vena  cava ; when  but little  force
had beer]  used, and when the auricle  and ventricle were  not very
much distended, a  rupture took place,  which on examination  was
found to be of the fossa ovalis ; the rent was oblique ; the membrane
was torn at its margin, with some muscular fibres  with which it
was there united.

                         Experiment 6.

   Tied the ascending vena  cava, just  before its termination in  the
heart; and, having introduced the pipe of the syringe, through a
small opening made in the vessel just  above the liver, and secured
it well  by ligature,  an  attempt was made to  burst  it. but in vain,
although  all the force of a strong man  was applied to the piston.
aided by all the pressure I could make with the hand on the dilated
vein: its dilatation was considerable, but not to the extent that might
have been expected.

                         Experiment 7.

   This and the following  experiments were made  on  the  human
subject.   About four  hours after death,  from tubercular disease of
cerebrum, with softening of  its substance, complicated  with tuber-
cles and a few small cavities in the lung, in the instance of a young
soldier, aged 26, water was  injected through one pulmonary vein,
close to its termination ;—the other pulmonary veins, and ihe arteria
innominata, and the left  carotid and subclavian arteries, as well  as
the aorta  just below, having been secured by ligature.  The left
side of the heart became greatly distended: after much force had
been applied a rupture took place—the auricle, its sinus, burst close
to the entrance of one of the pulmonary  veins.1


   1 In the above, and in many other instances noticed in this work, the post-
mortem examination was made sooner than is usual.  In all such cases means
were taken to determine previously  the reality of the fatal event—as by
making a small incision through the cutis,  and puncturing  the fibres  of the
platisma myoides (a muscle, which is probably very retentive of vital con-
tractile power, judging from the analogy of thepanniculus carnosus) and by
exposing the eye to  light.  To the pathologist, conversant with necroscopi-
cai research, such precautions  may appear superfluous ; he may say, Who
ever knew an example in hospital experience, of a body supposed to be dead,
and removed as such from the  ward  to the dead-house, either reviving, or
affording any indications  of remaining vitality?  I never witnessed an  ex-
ample of the kind, nor ever heard of  one  well authenticated, excepting in
bodies which had died of that mysterious disease, cholera, in which in a few
rare instances, it is well established, that particular muscles have acted after
the extinction of life.  Notwithstanding, although all experience supports the
foregoing conclusion, yet as apparent death—suspended animation—is'withi.n.
the limits of possibility, and keeping  in recollection what happened to  the
illustiious Vesalius, it is at least in accordance with proper feeling, and a
 satisfaction, to employ the tests alluded to; and the popular advocates of..'  .
measures to prevent what is held  up  to horror—too early burying, on  the  *v«'V.
supposition combated, that  suspended animation and apparent death is  not  "":.
uncommon, would act more consistently with their views, if, instead of pro- 
          EXPERIMENTS ON THE RUPTURE OF VESSELS.      431

                         Experiment S.
  About four hours after death from chronic dysentery, complicated
with a few tubercles in the lungs, and tvvo small  cavities, in the in-
stance of a soldier aged 28 years, after tying the aorta below its arch
and its main ascending branches, injected water  by one of the pul-
monary veins, the others being left untied. Thelelt auricle became
exceedingly  distended, and  the coronary arteries.  The  ventricle
and aorta were less distended.   The lungs were very much distend-
ed, and there was an oozing of water from their surface; when  a
portion was pressed gently "between the hands, the  water actually
dropped from it, and yet the investing pleura appeared to retain its
integrity. - After employing much  force, a rupture was with some
difficulty effected.   The water rushed out through the  trachea, in-
dicating the  bursting of a pulmonary vein in the substance  of the
lung.1

                         Experiment 9.2
   Next secured by ligature  the pulmonary veins, just  before th'eir
termination,  and the syringe being applied to  the same vein as in
the former instance, the subject being the same, and the other cir-
cumstances the same, water was injected, until a rupture occurred.
It took place opposite the fossa ovalis, in the thickest part of the
sinus, close to the auricular-ventricular passage; the rent was suf-
ficiently large to admit two fingers.  Much  force  was required  to
effect it, and it was preceded by much dilatation.

                         Experiment  10.
   From the pulmonary vein,  the pipe of the syringe was removed
to the descending aorta,  just  where  it begins  to descend, and  was
secured by ligature.   On injecting water, the  vessel gradually be-
came much dilated ; at first the semilunar valves appeared to perform
their functions well; but as the dilatation increased, water began  to

 posing that bells should be hung up within reach of the interred, or attached
 to their persons, they recommend the puncturing of some irritable part, be-
 fore the body is committed to the coffin.
   1 It was curious to see in this instance, how the lining membrane of the
 left side of the heart, and of the aorta, above the  ligature, were intensely
 stained red ; whilst the portion of the latter below it, was colourless; afford-
 ing strong proof of the dyeing power of the colouring matter of the blood
 (the left side  of the heart contained some blood) when in solution.
   2 Previous to commencing this  experiment, a small opening was made  id
 the pericardium, and the contained fluid was carefully  removed by means of
 a sponge, and then the opening was closed by a ligature.  At the end of the
 experiment, it'was re-opened and examined ; notwithstanding the distended
-state of the auricle and ventricle, and of the coronary arteries, and that nearly
 half an hour was passed in making the trial, owing to delays, not more than
 three or four  drops of water were found collected,  the result of exudation.
 This result may be adduced as a confirmation of the conclusion  arrived  at,
 heretofore, relative to the source of the fluid so frequently found in the pericar-
 dium after death. 
432
davy's researches.
 flow out through the ruptured auricle, augmenting with the disten-
 sion, till it flowed freely.

                        Experiment 11.
   Twenty-nine hours  after death, from pulmonary consumption,
 with  numerous  cavities  in the lungs, and one of vast  size, in the
 instance of a soldier aged 29, introduced the pipe of the syringe into
 the right internal jugular vein, not having tied any vessel, except-
 ing the opposite veins in the neck,—the cavity of the abdomen
 having been carefully laid open, and also of the chest  partially by
 the removal of the sternum and  of the  costal  cartilages.  After a
 certain quantity of water was injected,  it flowed out through the
 trachea, probably through ruptured vessels in  the tubercular exca-
 vations.   The lungs, the liver and spleen, were rendered tense, and
 there was an exudation of fluid during the continuance of the pres-
 sure, not only from the surface of the lungs, but apparently, gene-
 rally, in the cavity of the abdomen from  all its  contained viscera.

                        Experiment 12.
   The result was similar, when  water was injected into the aorta,
just above its divisi6n into the common iliac arteries.  As the artery
 became dilated, the semilunar valves performed their function less
 perfectly, and the flow of water through  the trachea increased.

                       Experiment 13.
   Twenty-five hours after death from peritoneal inflammation, in
 the instance of an insane soldier, aged 44; after examining the brain,
 and securing the vertebral arteries  within the cranium,  and the
 carotid arteries in the neck, previous to opening the chest,  introduced
 the pipe of the syringe into the aorta just before its division info the
common iliac arteries, and having secured itby ligature, (all the
abdominal viscera remaining undisturbed,) injected  water as before.
It  was necessary to inject a very large quantity, and to employ great
force, before a rupture was effected.   The ruptured  part was detect-
ed with some  difficulty; it proved to be the left emulgent artery,
 about a quarter of an inch  from its  origin.  Its middle coat was
 lacerated in two places, in the direction of the fibres composing it,
 and also the inner coat.  There  was  no  perceptible opening in the
outer cellular.   The course of the aorta, even through the chest,
 was distended with water, and indeed the whole of the posterior
 mediastinum was so distended, and pretty much had found its way
 into the pleurae.  The  left ventricle  and auricle were  empty, ex-
 cepting that the latter  contained a little blood, showing that the
semilunar valves had performed their function  to perfection.

                       Experiment 14.
   Thirteen  hours after death from tubercles and  cavities in the
lungs, complicated with diseased omentum, enlargement of the liver
 and severe ulceration of the large intestines, in the instance of a sol- 
          experiments on the rupture of vessels.      433

dier aged 33; after examining the brain and tying the jugular veins,
the pipe of the syringe was introduced into the right internal jugular
vein, below its ligature, and water was injected; considerable resist-
ance was almost immediately experienced, giving the idea, that the
right cavities of the heart were obstructed with coagulated blood.
After the syringe had been emptied two or three times, great force
was required to introduce more water ; the  vein towards the heart
was amazingly distended, and shortly, the pressure being continued,
it became ruptured ; the effect took place just before the entering of
the vessel  into the  anterior mediastinum.  It seemed as it were
rather  the separation of its fibres with distension, than the breaking
of them from distension.

                         Experiment 15.

   The vertebral arteries, where they enter the cranium,  having
been secured by ligature, and  the  left carotid artery in  the neck
having also been tied, the pipe of  the syringe was placed in the
right carotid artery, and water was injected,—the cavity of the chest
and abdomen remaining unopened.   Very little  resistance was ex-
perienced till a large quantity of water  had been injected, and even
when  an  enormous quantity had been introduced, the resistance
was not considerable.  The experiment was discontinued when the
flow of water from the neck, the nostrils and the inside of the  cra-
nium,  was almost equal in quantity to that which could be thrown
in.  This flow of water  seemed to  be from exudation.  The body
was amazingly distended, and exhibited a very singular appear-
ance,—the  penis turgid, the mamilloe dilated, the papillae erect, the
trunk  and limbs tense, rounded and filled out, which (with the ex-
ception of the abdomen in which some fluid was effused in connec-
tion with  the diseased omentum  and enlarged  liver,) were previ-
ously shrunk and emaciated.1

  1 Hales, in his Haemastatics, details many curious and instructive results
of experiments on the injection of water into the vessels.  In an experiment
on a dog, he states:  "If the warm water was continued thus" (in a column
9i feet  high) "flowing into the artery for half an hour, or two hours, all the
parts of the body would, during that  time, be  continually swelling bigger
and bigger, so that there would be a universal dropsy over the whole body;
both the ascites and the anasarca: the salival and other glands were greatly
swelled, and the mouth and nose filled with  mucose  slimy matter, which
flowed  from  those glands; the ubera were much distended by the filling of
their fat vesicles, as  were  also all the fatty vesicles of the body.  All the
muscles were swelled, and the interstices of their fibres  filled with water;
and some of them were by  this means washed white.  All this was effected
with a  force of water no greater than that  of arterial blood in  its natural
state."—Stat. Essay, 3d ed. vol. ii. p. 113. With these results,  the above,
and what else was observed at the same time, so accorded, that  in reading
the one, I  found described  the other, substituting perhaps for fatty vesicles
when speaking of the ubera, their erectile vascular tissue, and for the same
term generally, cellular tissue, or the subcutaneous vascular. 
434                  davy's researches.
                       Experiment 16.
  The sternum having been  removed  and the pericardium laid
open, water was again injected into  the  right carotid artery, other
circumstances remaining  the  same.  The arch of the  aorta, as
much as could be seen of it,  was greatly distended:  but the left
ventricle was not at all distended.   No force that could be  used
could rupture the aorta,—the  exudation continuing.   Laid  open
carefully the left ventricle  so as to be able to apply the  end of the
finger to the  semi-lunar valves.   Water was again injected forci-
bly, the aorta was again distended, and there was only an oozing of
water from the ventricle: the valves were  felt very tense, and, it
may be inferred, completely closed the mouth of the vessel.

                       Experiment 17.

  I shall  give  one trial more, in which—twenty-four  hours  after
death from tubercles in  the lungs, with very large cavities in the
left lung and extensive ulceration of the large intestines—the pipe
of the syringe was  introduced  into the  right carotid artery, before
the calvaria was removed, and after tying both  jugular veins, and
bolh vertebral  arteries, close to their origin,  and the left carotid in
the neck.   As water was injected, all the integuments of the neck,
face, and head  became distended, especially of the right side, and
at length,  in a very remarkable  manner,  much  surpassing the
greatest swelling [ ever  witnessed  in  the  most severe  cases of
erysipelas, or of confluent small pox.   The eye-lids, nose, lips,
were protuberant and tense; the eyes closed; the mouth opened,
from  expansion of the lips ; the tongue enlarged.   Water  exuded
from  the eyes,  the  nostrils and mouth;  and,  it  would  appear,
from their surface generally.  The  experiment was discontinued,
when the  water which flowed out from  various parts seemed to
be, nearly equal in  quantity to that which was injected.   On ex-
amination no large  vessel could be found ruptured.   On  remov-
ing  the calvaria, a strongly marked contrast was observable  be-
tween the  state of the exterior  parts and of the interior,  as, per-
haps, might,  a priori, have been  expected, considering how the
latter were encased in unyielding bony parietes.   There  was only
a very little fluid effused  in the cellular tissue of the pia mater;
merely a  moisture between the arachnoid membrane and the dura
mater, and only a moderate quantity in the lateral ventricles and
at the base of the brain: and the fluid so effused was probably
not water which  had been injected, but which  had previously ex-
isted there; this is inferred from the circumstance that  there was a
larger proportion in the left lateral ventricle than in the right, not-
withstanding that the pia  mater of the former side throughout was
red,—its vessels containing blood as usual, whilst that  of the right
was perfectly colourless,—all the blood  having been washed out of
its vessels.  It  is hardly  necessary to observe that no vessel was
found ruptu red within the cranium.
4 
          experiments on the rupture of vessels.       435

  The results of these experiments, in the  way of illustration, as
applied to the case with a view to which they were instituted, are
in no wise clear and satisfactory; but, on that account I have not
thought it right to keep them back, believing that as they have been
faithfully detailed, they may not be altogether unacceptable or with-
out use,  especially  in  connection with  the important  and obscure
subject of aneurism.
  Considering them generally, they are, perhaps, less uniform than
might have  been  expected; and  hardly favourable to any general
conclusions being deduced from them, excepting, indeed, the follow-
ing:—1st,  That the power of resistance possessed by the heart and
large vessels, independent  of any  vital properties of endurance
peculiar  to them, is enormous;1 and, 2dly, that there is much varia-
tion in point of strength in the same parts in different instances.
  I have alluded to the rareness of the  accident, which induced me
to institute these trials.  Referring to authors,  I  can find  only one
clear instance on record of a similar kind, that is, of rupture of any
part of the heart, from a force acting through the  medium of other
parts, on this organ, apparently free from disease and in its perfectly
normal healthy state.  The case is noticed by  Portal, in his Anatomie
Medicale;2 it was of a young man, over part of  whose chest, the
wheel of a cart loaded with  stones passed: death was almost imme-
diate, and the left auricle  was  found  open.  Chaussier, who ex-
mained the body, attributed the effect of the  rupture to compression
of the aorta by the wheel, and to over-distension of the auricle with
blood, the consequence of  that  obstruction.   It is true,  that very
many other  cases of rupture of the  heart are recorded,—as  acci-
dents, but they are either not sufficiently clearly  described, to be
depended  upon, or there  is reason to  suppose that the heart was
either crushed or else wounded, or that the part  ruptured  was pre-
viously diseased.   The authors I have chiefly consulted have been,
Senac, Morgagni, Haller, Portal, and Laennec.  On the  compara-
tive strength of different vessels, besides HaJe's very ingenious work
already  referred to, I have  consulted Clifton WTintringham's  "Ex-
perimental Inquiry on some parts of the Animal  Structure," pub-
lished in 1740, a few years after the Statical Essays of the former ;
but although having great pretensions to accuracy in his manner
of giving  the details of his experiments, I must confess  I  have not
been able  to place sufficient confidence in his results to use them.

   1 Vide Hale's Hsemastatics.—The results of his experiments on the above
point are very striking.   Referring to them, he says,—" We see in these in-
stances, the great strength of the coats of these vessels;  what great reason
have we, therefore, with thankful hearts to  say to our Creator, as holy Job
did, when he contemplated on  the wonderful frame and strength of his body,
Job x. 11, Thou hast not-on\y fenced me with bones and sinews, but hast also
effectually  secured the vital fluid in such strongly  wrought channels  as are
proof against its most  lively and vigorous sallies, when  either agitated by
 the different passions, or by strong and brisk actions of the body."—Op. Cit.
 vol. ii. p. 156.
   * Tom. iii. p. 97. 
436
davy's researches.
  In a previous  page, a table will  be found of the specific gra-
vities of different textures, formed from experiments conducted with
some care, and which I believe to be tolerably accurate.   It was in
comparing some of my results with his, that my faith in his correct-
ness was shaken.  According to  him (to mention  only one point),
there is a marked  difference in the specific gravity of the descend-
ing aorta and  of the vena cava corresponding, gradually diminish-
ing with age:  thus, the specific gravity of these vessels in a young
man appears from  his details to be, as  1060, and 1101,—the former
the artery, the  latter the vein ; and in an old man as 1098 and 1105.
  This difference I have not been able to discover.  Very recently
I have carefully  tried the specific gravity of each vessel,  belonging
to a man aged 30;—the artery  was 1060, the  vein  1061.   They
were similarly treated in every respect preparatory to weighing.
  Clifton Wintringham's results  are so uniformly consistent,—they
all support each  other so well, and are in  such  perfect conformity
with his conclusions, that it is rather difficult to avoid the inference
that he formed an hypothesis in the first instance and then  made
experiments to  support  it,—notwithstanding  the  passage  from
Leibnitz inserted in the title page of his book—Ex iis, quce experi-
ment's  constant, ducere  tentimus quicquid potest, antequam  in
hypotheses liberiores expatiemur.
the end. 
 

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