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                    CONTENTS  OF  PART  I.



       Chap. I.  Chemical and Organic Forces,.....      1
              $ 1. Chemical Forces,.......      4
                  A. Determinate Value of the Forces which produce com-
                      bination. Apparent quiescence of the Forces during
                      combination,........12
                  B. Chemical Action is action at unmeasurable distances.
                      Polarity of the Molecules,.....17
                  C. The Influence of circumstances upon Chemical Forces,   24
                  D. Catalysis: Molecules in motion,   ....     28
              $2. Organic Forces.
                  A. Connection between Organic and Molecular Forces,     58
                  B. The Development of a Germ......63
                  C. Equivocal Generation,......74
                  D. Transference of Vital Force,   .      ■ .        .     76
       Chap. II. Inorganic, Organic,  and  Organized Bodies: Plants
                  and Animals,     .         .  ;......79
       Chaf. III.  The Atmosphere in its  Connection  with Organic
                  Nature,      ......    ^   .   .     89
|fV   Chaf. IV.  Water, considered in its Connection with Organic
   /              Nature, ^^.........117
      Njrf*^^.  R**t^nJ»f  tite-^jl to Q^anic Nature,   .        126
 Entered according to Act of Congress, in the year 1845,
              by B. Siluman, Jr.,
in the Clerk's Office of the District Court of Connecticut.
PRINTED I!  B .  L.  HAMLIN
    NEW  HAVXN, CONN. 
THE
              CHEMISTRY

                        OF

VEGETABLE  AND  ANIMAL


         PHYSIOLOGY.
                    CHAPTER  I.

            CHEMICAL AND  ORGANIC FORCES.

  In  the  doctrine of life, no position has been more strenu-
ously maintained, than that a peculiar force exists by which
organic substances are governed, by which they are arranged
in certain specific modes, and are enabled to assist in sustain-
ing the living system, and to  create a  chain of phenomena,
which as~ a whole are called^ phenomena of life.  This vital
force has been described as one quite peculiar, of which not
the  slightest trace is to be found, in inorganic nature.  Organic
and inorganic nature  are often indeed contrasted.   We hear
of the animate and  inanimate  forces of nature; we used to
shrink from observing any connexion between  them ; and in
particular, it was thought that the endeavor  to  explain  many
phenomena of life by  means of the so-called dead forces might
detract from the doctrine of life.                     ^j  •
  In the true study of nature  the principal  aim ouflhTto be,
not  only to make ourselves  acquainted  with  the phenomena
and  laws, which distinguish  and regulate  living  and dead
matter, but  also to arrange those phenomenaHjjd laws, and
exhibit them in  their  several relations.   The more  our know-
ledge of  these  two departments is extended, and the nearer
  Vol. I.                  1
. .«•**■ 
2                   THE CHEMISTRY OF
the several parts of the great science of nature are seen to
approximate, the more firmly must we  embrace the idea, as
necessarily conformable to truth, that the same forces govern
alike the animate and  the inanimate kingdoms.
   Those who proceed on the assumption, that no such con-
nexion exists, will  certainly not be  able to trace it; but a
search, conducted with impartiality, will be rewarded with the
discovery  of whatever exists.
   In the  natural sciences,  the  words  matter and force are
continually recurring.   We endeavor, by an effort of imagin-
ation, to separate the  one idea from the other.  Yet we can-
not conceive of matter without force,  and scarcely of any
force which does not react upon matter.  We encounter many
difficulties,  while attempting to penetrate into the  properties
of matter.   We are  perplexed, first,  with its  being divisible
either finitely or infinitely ;  secondly, with the great diversity
of substances which exist;  thirdly, with the great number of
elementary bodies now known to chemists.
   Moreover the idea  expressed by the  word atom is by no
means distinct, though the  term must frequently  occur in
treating of natural philosophy.
   In the natural sciences, we do not seek to go beyond the
knowledge which is acquired by observation and by the com-
parison of visible objects, and thus we avoid that labyrinth, in
which many of the wise and learned, both in former and later
times, have  involved themselves, by clinging to abstract ideas
borrowed  from  the visible world.   We acknowledge material
diversity because we observe it7 we acknowledge a great num-
ber of elements because  we see them ; we  do not meddle
with the term atom, but substitute for it, wherever we can, the
more comprehensive  and intelligible  expression—equivalent.
   In the natural sciences, force is used to signify an assumed
cause of  observed  phenomena; we therefore do not observe
forces, but suggest their existence to ourselves; and we do so
in  conformity  with sound principle, for the phenomena con-
straTnois to  presume that such forces  exist.   No cautious in-
quirer into nature goes farther at the present day ; we do not
introduce  forces, to which we assign properties ;  but we form
the idea of  Some particular force,  after the necessity  for its
existence  isjwemonstrated by the observation of natural phe-
nomena.  The idea  of force is therefore a concrete one, by
A 
VEGETABLE AND ANIMAL PHYSIOLOGY.          3
which every speciality in the phenomena  is embraced, and
unity is given to the whole.
   Such  are the  simple principles by  which we are, in the
present day, guided in our inquiries.  The forces of nature,
which we recognize, are in number and  kind, such as we
learn from  the phenomena they ought to be ;  and the error,
so prevalent in former times, of attributing properties to forces
without  previously proving from observation, that those pro-
perties existed, is now carefully avoided.

   Proceeding  from this point of view, we propose to make
some observations on the organic and inorganic forces of na-
ture, sometimes  called  the  living and dead forces.  These
observations will  not add any thing to the amount of our scien-
tific knowledge, but may serve  to explain  and establish the
proposition  that a  connexion exists  where hitherto it has not
been recognized.
   It is scarcely necessary to observe that the expression dead
force, when used to denote the operating causes in inorganic
nature, has  no substantial value.   Still it is understood to sig-
nify the force of dead nature, in opposition to that of living
nature, where a particular series of phenomena appears ; and
this is the meaning in  which we use the  expression.
   The chemistry of the present day, which is occupied espe-
cially with the doctrine of molecular forces, perceives  pecu-
liar causes,  operating in the small particles of matter.  Our
inquiries may not  inappropriately  be  commenced with the
investigation of this subject, the study of which is  the foun-
dation  of any knowledge  we acquire  in  regard  to organic
forces ;  for every organism is composed of materials which
are subject to the laws of those  peculiar forces that belong to
chemical substances.
   While, however, we would endeavor to show that in all or-
ganisms, living or not,  the same molecular forces  operate  as
efficient causes, we are not to be understood as holding, that
they are combined  necessarily with consciousness, or the more
elevated rational principle.
   I will not venture to raise the veil, by which the action  of
the nerves,  or the higher functions of the mind, have hitherto
been shrouded from our observation.  As man has an imma-
terial and immortal part, which is identical with his real being, 
4                  THE CHEMISTRY OF
and  of which alone he will consist, when the material frame
by which he is bound to the earth, shall  be dissolved ; and as
the inferior animals  possess, in  common  with man,  certain
powers of  perception, associated with certain appropriate or-
gans, whose functions have no connexion with consciousness ;
so do animals and plants perform  in common a great many
operations  which are distinct from both of those now mention-
ed, or which at  least  have their origin in distinct causes.
  It is only the  latter class of which I speak, and  to  which
I apply the general term  of organic life.   To that subject I
shall restrict my remarks.
  It is  well known that in animals,  such operations are per-
formed through  the agency of the nerves, and in them, there-
fore,  they  are  generally more complicated than  in plants.
The similarity of the operations themselves, however, inti-
mates the existence of a connexion between the causes from
which they respectively  arise.   But the nature of this con-
nexion, as  well as its  strength, is and ever will be an enigma,
as much as the action of the  nerves itself.  The peculiar na-
ture of organic life—the difference  between living nature and
what is called dead  nature—is, however, not determined by
the action of nerves.  The  properties which are common to
animals and plants will alone be treated of; these properties
being included in the general  idea of functions of life.   In the
first place,  we shall review in succession, the properties of the
elements, which enter into the  composition of all that exists
in nature.
  We shall be  the first to admit the force of  the objection,
with which we may be met, that it is more easy to pull down
than to  build up.   Science has not yet made such progress as
to enable us,  from a more elevated point of view, to take a
comprehensive survey ; but  this will never afford a rational
ground  for adhering to incorrrect propositions.   The sugges-
tions which follow are therefore  to be regarded as thrown out
only for consideration.  They will require to be much more
fully developed  before they can pretend to form a complete
system.

                 § 1. Chemical Forces.

  We see in all the elementary substances, without exception,
a disposition to combine with each  other, and we therefore 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.          5

 form the idea that a force exists in them, which is called the
force of affinity.  We see this combination effected ; and infer,
 that there necessarily exists in substances a cause of the pro-
 perty which  they possess, of uniting together.  There is no
 element which cannot be united with others;  there  is none,
 therefore, which is destitute of that property in a greater or less
 degree.  The power of combination is thus a property of mat-
 ter, produced by a force, to which every material thing is sub-
ject, whatever its name may be, or to whatever part of nature
 it belongs.
   We observe, however, in the elementary bodies many other
 properties besides that of uniting together.  It would not be
 a simplification of science to assign a specific force to each
 effect produced by these elementary bodies; but it is impos-
 sible to have an accurate idea of  any element, if  we think of
 it only as impenetrable  and ponderable, extended and in sub-
 stance  different from every other,  indivisible and endowed
 with a  tendency to combine  with other elements.  If we  do
 not go farther, how should we be able  to form a conception
 of  isomorphism and of  isomeric combinations—of the distinct
 character which belongs to each elementary body, as com-
 pared with others—of their dynamical differences?   We-are
 too much accustomed to confine our attention to the  sensible
 properties of matter.  We speak of copper and mercury as red
 and white, solid and fluid,  fixed and volatile, and we dwell too
 much upon these and similar physical differences.  We do not
 sufficiently inquire why the one forms combinations with  dif-
 ferent quantities of the same substances, accompanied with
 entirely different phenomena, as contrasted with those combi-
 nations which are formed by the other.  We arrange the ele-
 ments in groups, in so far as they  agree in some of their pro-
 perties ; but  we do not investigate in the first place, the cause
 why such agreement is  exhibited by some, and why the oppo-
 site is exhibited by others.  How  do we account for the great
 difference between the two metals sodium and platinum ?  The
 one cannot combine directly  with oxygen, though the other
 does, exhibiting at the same time very interesting phenomena.
 Sodium shows itself active in all  circumstances;  platinum is
 generally passive, and  incapable of producing any marked
 phenomena.   We  say  that sodium  has a greater degree of
 affinity  ; but we derive the idea of affinity from observing the
   Vol.  I.                   1* 
6                  THE  CHEMISTRY  OF
production of a combination—the final  result of the  power
which is lodged in the sodium.   When water is violently de-
composed by it, this effect ought undoubtedly  to be ascribed
to the power possessed by sodium of combining with oxygen ;
but is this combination produced  by nothing but the attraction
between  sodium and oxygen ?   We do not see any of these
phenomena  produced  by general or physical attraction, and
we  must therefore superadd something to the idea of attrac-
tion to constitute what we understand by affinity.   The ques-
tion arises,  whether the attraction by affinity operates in cer-
tain definite  and invariable proportions ?   This consideration
is necessary to an accurate notion of affinity; but it does not
comprehend all that requires  solution.   It does not explain
any thing as to the differences among bodies in regard to their
color, smell, and taste ; their  being solid, fluid, or gaseous,
fixed or volatile ; their boiling point, density, specific heat,
atomic weight;—nor any thing in regard to isomorphism, to
isomerism, or the evolution of  heat, light, and electricity  in
chemical combinations ;—nor any thing respecting the singu-
lar  quality,  which  each element possesses, of forming  1, 2,
3, and so on to the number of  7 combinations with another
element, in certain invariable proportions—combinations which
are formed  from the same two elements, under conditions,
that differ from each other only in a small degree.
  If we consider the molecular forces in elementary bodies
only as producing combinations between molecules of dissimi-
lar  kinds, the idea at which we  arrive is limited and  unpro-
ductive, and we overlook a long series of singular phenomena,
which cannot be reduced to that  principle.
  The observation and arrangement of phenomena, the inves-
tigation of the laws which  regulate them, and the ascribing
to bodies of powers which  are  in accordance with the charac-
ter  of the phenomena dependent  upon them, are all required
for  a correct knowledge of nature.  In the present condition
of  chemistry, we are obliged to  form a more distinct idea of
the forces by which the molecules of matter ere  governed,
than was sufficient in  former times;  because we know,  with
positive certainty,  that there is nothing  in common between
the quality of the matter in one  element and the quantity of
another combined with it;  and also, that the crystalline form
of  the compound is independent of the quantity also.   Sul- 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.         7
phur, selenium, chromium, and manganese, bodies ofcvery
different natures, take each three equivalents of oxygen (O3),
and yield with bases salts of the same crystalline form.   The
sulphates, seleniates, chromates, and manganates are all iso-
morphous.  And so with a great many other elementary sub-
stances.
  The conclusion which we draw, therefore, is  legitimate,—
that there are certain analogous  powers present in sulphur,
selenium, chromium, and manganese; and thus we arrive at
the idea, that the chemical relations of these  elements are
not dependent upon their matter, but upon the  analogous
forces by which  their  molecules are  governed.   Thus the
idea of the matter of sulphur is associated with somewhat  of
the idea of force, and of the same  force which operates  in
selenium also—which operates  not only in forming combina-
tions, but in contributing also to  the formation  of  the whole
character of the compound substances produced.   We observe
the effects of this force which exists in sulphur, selenium, &c.,
even  in more complicated compounds than those to which we
have  referred.  Sulphate of soda and seleniate of soda, for
instance, are both efflorescent salts, and both possess the sin-
gular property of being more easily soluble in  water of 33°
Centigrade (=91£° Fahr.) than in water of 100° Cent.
(=212° Fahr.),—a  property which is  extremely rare,  and
which does not depend here on the substance of sulphur or se-
lenium, but on the  similar molecular forces, by which  both
sulphur and selenium are governed.  Phosphorus and arsenic
are isomorphous.  Both combine with oxygen, and form acids,
whose composition  is represented by R.05.  Each of these
acids  forms with soda two analogous salts.  All the four salts
contain  one equivalent of acid, two of base, and one of basic
water;  but one phosphate and one arseniate contain  in addi-
tion 24, the other phosphate and arseniate only  14, atoms  of
water of crystallization.*
  If, in the same manner, we pass in review the whole series
of the elementary  bodies; if  we consider them  abstractly
  * The fact here stated is represented by the following general ex-
pression :—             , ■■ 
8                  THE  CHEMISTRY  OF
from their matter,  then we recognize innumerable modifica-
tions of those molecular forces, in the phenomena which each
of them exhibits.  These forces  are often exercised in the
production of chemical combinations, but this is by no means
their sole characteristic.
  The combination of two or more elements  into one whole,
is the best known effect of all the existing molecular forces.
And the  phenomena which we observe during this combina-
tion of substances,  and the results of such combination, have
enabled us to form a definite idea of a cause adequate to pro-
duce  them.   The  combination is attended with phenomena
which can be traced, and the  results of which can be meas-
ured and weighed.   We must be content with having reached
this point, and  can only  hope  that the time will yet  arrive,
when we shall  be able to form more just conceptions of the
other forces by which the molecules are governed.  We can
scarcely, as yet, give a name to the science of this subject—
a science which appears to be  actually boundless in extent.
  The effect which we call affinity, is to be ascribed to a
power of mutual chemical attraction, which dwells in the ele-
mentary bodies.  Before such a combination is completed, and
before they come into contact, they must possess a power, by
which they are  enabled to effect the combination at a fitting
time,  or  they must acquire this  power as soon as they touch
each other.   Here  it is  difficult  to choose our way;  but it
does  not seem  impossible.  So far as the idea refers to the
excitation of force, the principle is the same  as that of elec-
tricity, which is an  operating cause also present in the mole-
cules ; but though  it be  so, yet it  is not identical with the
force of  affinity.*
  If we touch a piece of wood with  a pen,  we  observe no
sign of combination ;  but when antimony and chlorine come
into  contact, they unite  immediately.   The  wood  does not
possess any power of exciting in the pen a combining force,
neither has  the pen  any power of doing so  in the wood.
The chlorine, on the other hand, has the power of exciting a
force of combination  in  the antimony; and the antimony of
  *  We cannot, of course, attempt here, however briefly, to indicate
in what respects the forces of affinity and electricity either coincide or
differ. 
VEGETABLE AND ANIMAL  PHYSIOLOGY.
9
doing so in the chlorine.   Now, it is a matter of indifference,
whether we conceive that the forces slumber in the antimony
and the chlorine, and are brought into operation by contact;
or that those forces were present in the two bodies in an active
state, previous to  the contact, but  produced  the phenomena
of combination only during the contact.   These  two ideas
may be reckoned of equal value for scientific purposes ;  be-
cause  the  power, exerted by the  chlorine,  of exciting  the
slumbering forces  in antimony, and the similar power exerted
by the antimony upon the chlorine, must undoubtedly, one or
both, pre-exist before contact; if not so, then two slumbering
forces are excited  by each other, which is absurd.   Whatever
excites action we call force.  Chlorine excites action in anti-
mony, and  antimony in  chlorine;  so  that before  contact a
power exists either  of excitation  or  of  combination,—and
that, if not  in both, at least  in one  of these  bodies.   The
mode of considering this point is almost a matter of  indiffer-
ence ; but we must always bear in mind that it is a power, a
force which is  exerted   by  the  one,  and which acts upon
the other.  This force, I  repeat, must exist in one of the bo-
dies before contact, and may be called its chemical tendency.
It manifests itself  during contact, but cannot be produced by
contact, any more than electricity or other forces.  We can-
not conceive of a force being produced by contact.   Contact
is a condition to which substances must be subjected,  in order
that some  phenomenon may be produced ;  as touching  the
ground  with the  feet is a condition required to enable us to
walk.   A condition necessary  to  any phenomenon differs
entirely from a source of action, from  the cause of the phe-
nomenon ;  and the theory of contact, therefore, seems to me
impossible  and absurd, at least  in the sense in which it has
so often been maintained.
  We are conducted by the phenomena to the recognition of
a power in substances, which can be excited under certain
circumstances, and which is capable of producing a combina-
tion.  This power necessarily exists before it is excited, and
often requires only the  contact  of substances to  allow  the
phenomena, called combination, to be produced.  According
to our view, therefore, we must suppose a power  in all  the
elements, either of exciting or of exhibiting a force which
causes a combination.   This is  what we  call  chemical ten-
dency. 
10                 THE  CHEMISTRY OF
  This power varies greatly in different  elements.   It varies
in respect, first, of quantity, and secondly, of quality.
  Those elements only which have the same atomic weight
attract an equal quantity of the same element,  while all the
other elements, with but a few exceptions, attract very differ-
ent  quantities.  There is also a very considerable variety  in
their  mode of combining with other bodies ; the phenomena
which they produce are very different, and there is especially
a great diversity in their power of combining, in one or more
proportions, with another element.  How is  this latter differ-
ence caused, if not by the difference in their combining quan-
tities, and by the special nature of their chemical tendencies ?
For (with the exception of the isomorphous bodies, and those
which have the same atomic weight)  every elementary body
has its own peculiar qualities, and its own combining quan-
tity,  showing  that the substances are  specifically  distinct.
Each element also  might be made to appear  in a specific
form, even though they were all derived from the same base,
because every one of  them is governed by specific forces;—
in other words, a different distribution  of the chemical ten-
dency in an element would  be sufficient to  make the  same
element appear specifically different.
  But, however this may be, either one and the same prin-
ciple, differing from all  others,  not  materially but  dynami-
cally, may be the base of all the elements, or there may be  as
many elements as there are groups of isomorphic substances,
or as many as are designated, in the chemistry of the present
day, elementary bodies.  This question  cannot  yet be deter-
mined.   Adhering to what we observe  and know with cer-
tainty, we conclude that every elementary body is endowed
with a great many specific properties, which,  to a large extent,
are dependent  on the same principle that causes their com-
bination, and  thus  on the proportion and character of the
chemical tendency.
  If we  adopt this idea, we have the  advantage of seeing
somewhat  of  vitality,  energy and activity  in  dead matter.
It is an idea derived  from the endless  series of phenomena
which are observed in the laboratory,  in daily occurrences,
and in nature at large.  This series of phenomena, exhibiting
the  effects  of that diversified chemical tendency in bodies,
which is  already observed in science, is  fitted to excite admi- 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.         11

ration.  Elementary works  are filled with descriptions of
substances which exist in consequence of that tendency,  and
the chemist cannot see the end of that series of new combi-
nations which are continually  formed by these substances, as
so many results of  the primitive forces.  With such  an idea,
we do not confine ourselves exclusively to the material char-
acter  of each  element; for in  this way we could not attain
to a correct, certainly not to a practical  conception of this
subject, inasmuch as this material character presents a union
of the physical properties of bodies, and not of those proper-
ties by which the elements appear capable of producing phe-
nomena.
   If the question be raised, whether  the  introduction of this
idea will produce immediate fruits, we must reply in  the neg-
ative.   Hitherto  the  subject has not been studied from  this
point  of view, and science is not yet supplied with sufficient
data to  allow of its being so  studied.  To view it, however,
in this light, may be considered as an attempt to find a bet-
ter way.
   Four of the  elements have a wholly peculiar character ; all
the others are  more or less limited in their capacity of mutual
combination, while  carbon, hydrogen, nitrogen and oxygen
are apparently unlimited in this respect.   We may modify,
in almost innumerable ways, the quantity and quality  of the
affinity found  in these  four elements.   For that reason they
deserve a prominent place in  chemistry.  Lead  and oxygen
combine in two proportions only, the protoxide PbO, and the
peroxide PbO2, and  these unite to form a third  combination,
(red lead ;)  but the combinations of carbon and hydrogen are
innumerable, and differ not only in relative but also in abso-
lute  quantities.  We have not only the series, CH,  CH2,
&c,  but also C2H2, C4H4, &c.  The combination  C5H* is
also inexhaustible,  either in the simpler form of C5H*, or as
Cl0H8,C15H12,  C20H16, &c.  We know a  combination,
C2H  ; another C4H3, another C4H5, &c.—and so with C and
N, N and H, and CNH and CNO, CHO and CHNO.   In one
word, though these four elements have a great many proper-
ties in common,  they exist as  a distinct group, endowed with
forces of affinity which are  susceptible of infinitely more
modifications  than those which  are presented by the other
elements.    We  now proceed  to examine somewhat more 
12
THE CHEMISTRY OF
closely the character of the chemical combination of elemen-
tary bodies.

A.  Determinate value of the forces  which produce  combi-
  nation.  Apparent  quiescence of the forces during com-
  bination.

   The  simple substances  differ in their power of mutual
combination.   They differ, therefore, in respect to the seve-
ral forces which cause this combination, or in the  capacity
of having those forces excited  in  peculiar  circumstances.
The substances which seem to possess this tendency at every
temperature, are potassium and sodium when combining with
oxygen, chlorine when combining with  a great many metals,
&c.   This tendency is peculiar to these substances,  and, ac-
cording to our observation,  it is correct to say, that  there
exists in potassium, independent of circumstances, a tendency
to combine with oxygen,  and in oxygen  a tendency to com-
bine with  potassium.
  This tendency is clearly characterized by its operating be-
tween molecules of different kinds at distances too  small  to
be measured, and  by its producing from these a combination
in a fixed proportion.
  If substances chemically different yield to this tendency, a
combination of two unlike bodies results,—an intimate union,
in which each new  molecule is composed of the two combined.
A mass of potassium does not possess this power  as a mass.
It is peculiar to its small particles.  The smaller even those
particles are, the more easy is their combination.
  This peculiar power in potassium of attracting oxygen, and
in oxygen of attracting potassium, thus resides  in  the most
minute particles; that is to say, in those which we can divide
no further.  The two particles now  closely approximate  to
each other, and  present  new  properties, which are chiefly
dependent on the character  of the combined substances, but
result in part also from the forces by which those substances
are governed.
  After the combination is completed, the power of uniting
still  further with  oxygen, at least under the  same circum-
stances, is lost to  the  potassium.  The two molecules have
wholly satisfied their desire  of combination, and  the two 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.         13

opposite  forces have therefore made each other quiescent,
either in part or  in whole.   If they have made each other
wholly quiescent, the  new substance cannot combine further
with any other.   But if the force  in  potassium  (K) be not
wholly counterbalanced by the force in oxygen (O), more or
less of K remains in the combination, and vice versa with O.
It seldom happens that  the two forces entirely counterbalance
each other; but,  in general,  an excess of the one or of the
other remains, which  appears externally, and impresses on
the combination  a character  conformable to that which  is
proper to the predominating element.
  The constancy of the proportions in which the elements
combine with each other, proves that  the forces are of equal
value in  determinate circumstances.   The cause  of this con-
stancy cannot be traced  to one of the combined substances
only, but it must  be present in  both,  so  as to complete the
combination,  of which the principal characteristic is a perfect
constancy of quantities.   While the combination is in pro-
gress, the sensible action of quantities of equal amount  is
apparently annihilated.  If  we suppose, for instance,  that
oxygen has a force of affinity of 3(0), and potassium of 6(K),
3(K) must necessarily remain after their combination, in cer-
tain  circumstances, whilst 3(K) and  3(0) make each other
quiescent.
  This is proved  by observation.   Potash is not inactive, but
possesses in  its turn a tendency to combine with other sub-
stances, which, though less powerful than that of potassium,
operates  in  the  same  manner; thus there is a quantity of
chemical tendency, which has not passed into a state of rest,
whilst  the metal  was combining with oxygen.  We would
call the remaining part of this force in potash 3(K).
  Sulphur and oxygen (S and O) combine with each other,
when favored by  peculiar circumstances, in the same manner
as potassium  and  oxygen combine  at  the common tempera-
ture.   It  is  thus   indispensable  to  this  union that sulphur
should have a certain quantity of force, which disposes it to
combine with oxygen and produce sulphuric  acid, and vice
versa.   By this combination the whole quantity of the oppo-
site forces is apparently lost;  but  yet a portion of the force,
either of the oxygen or of the sulphur, remains.   If we sup-
pose that the forces by which oxygen  and sulphur (O and S)
  Vol.  I.                 2 
14                 THE  CHEMISTRY OF
operate upon each other, have the proportion of 3(0) : 1(S),
we have remaining 2(0)  after the  combination of O and S
into SO3.
   Potash, therefore, retains a force of 3(K),  and sulphuric
acid of 2(0).   According  to  this view,  neither  potash  nor
sulphuric acid is neutral, but they are both still supplied with
forces of affinity opposite to each other, so that they are able
to produce a  new combination of the substances already in
composition ; that is, of the sulphuric acid and the  potash into
sulphate  of potash.  As soon as these  combine  with each
other, potassium (K) is again neutralized by oxygen (O).  If
we assume that of the  3(K) and 2(0), 2(K) are counterbal-
anced by 2(0), there remains 1(K) after sulphate of  potash
has been produced.
   In this sulphate of potash, two forces, opposite to two oth-
ers, are  thrice enveloped ; two  of  them  in  the elements of
the potash, two  in the elements of the sulphuric acid, and
two in the elements of  the sulphate of potash.  These forces
counterbalance each other;  the feebler  of them, (O), has
been  made imperceptible,  but  the stronger of them,  (K), is
able to act on other substances through the force which re-
mains active after the oxygen has been neutralized.
   In our example, 1(K),  or in other words, one  quantity of
the force originally present in potassium,  still remained after
the combination of SO3 with KO.  Sulphate of potash, there-
fore,  is also not neutral, but may combine anew with other
substances, and  especially with  those which contain oxygen
(O) once, twice,  or more times.  Supposing we  have such
a substance in sulphate of alumina, we see alum formed on
the same principles  by the combination  of the sulphate of
alumina with the sulphate of potash.  Thus it appears that
the same force originally residing in the elements, is capable
of producing all  the chemical  combinations of the first,  se-
cond,  and third orders.
   The value of  the forces which are originally involved in
the elements is still  undetermined.   In course  of  time, how-
ever,  it will be ascertained.  The quantities which we have
assumed  merely to explain our views, must therefore  not be
regarded as having a real value.  It is, however, certain that
there  must always be two forces of  opposite character where
attraction and combination are the effects. 
VEGETABLE AND ANIMAL PHYSIOLOGY.         15
   This mutual combination does not take place among all the
 elementary bodies.  Those substances which do not combine
 with each other are either destitute of both the opposite forces
 referred to, or these forces are inactive in one of them, owing
 to  the  circumstances  in which it  may  be placed.   On  the
 other hand, combination takes place every where if the forces
 (K) and (O) be different  from  each  other in a determinate
 degree.   If, for instance, there be  a  substance  containing
 20(K), and if  it come in contact with another  containing
 1(0),  the result will be a combination, and this new product
 will be able to act with a force represented by 19(K).
   We have no reason to assume the existence of other chem-
 ical forces than  those  which  we have called (K) and (O).*
 All the elementary bodies seem to possess them, though uni-
 formly in different degrees.   It results from the doctrine of
 chemical proportions (stochiometry) that the quantities of the
 several elements which combine with each other vary accord-
 ing to certain definite proportions, when the forces are excited
 in  different  degrees  by different  circumstances.    Nitrogen
 (N) combines with one, two, three,  four or five of oxygen,
 (O, O2, O3, O*, O5,)  and so with regard to the  other ele-
 ments.   We have thus solid grounds for assuming  the exist-
 ence of certain  values of  the  chemical  forces ; the relative
 proportions of which values may be  expressed   by whole
 numbers.
   Another result of experience is, that  these forces are  ex-
 hibited in ordinary circumstances by all the elementary bodies,
 but that the conditions require to be modified, either to excite
 these forces, or  to fix  them in the  substances in determinate
 quantities.   We see  oxygen  attracted  by  potassium at  the
 ordinary temperature,  and  hence  conclude that such a force
 is always possessed  by potassium.  We cannot,  however,
 produce any proof of this,  for it is  possible that  the common
 temperature causes the production of that force in potassium,
 seeing that it ceases to attract  oxygen  at a temperature of
 —150° Fahr.  It is possible  that  the ordinary temperature
 has the same effect on potassium, as a red heat has upon iron.

  *  The author employs these letters to  designate the forces more
commonly called the electro-positive and electro-negative powers of
substances.—S. 
16
THE CHEMISTRY OF
  Among the circumstances by which these forces may be
excited or  fixed in determinate quantities in  the elements,
may be reckoned a high temperature, the influence of light,
the  action of electricity, and  especially the presence of an-
other chemical substance.  We shall  here  adduce a single
example  of each,  and treat  hereafter of this subject more
fully in its proper place.
  Heat excites the forces (K) as well as (O)  in many sub-
stances ;  (K), for instance,  in the metals which are oxidized
at an elevated temperature ; (O) in chlorine, which combines
with hydrogen on the application of a taper,  producing hy-
drochloric acid.
  Light causes the sudden combination of hydrogen and chlo-
rine (H and CI), and  thus excites  (K) and (O) in these two
gases respectively.
  Hydrogen and oxygen (H and O) are at once combined by
means of an electrical spark,  which thus excites in them (K)
and (O).
  (K) and  (0) are excited by other  substances, as, for in-
stance, in the combination of hydrogen and oxygen (H and
O), which is effected suddenly by spongy platinum, and more
slowly by platinum foil.
  The peculiar forces of two substances are not lost by  their
mutual combination ; they only become quiescent, as it were,
so far as  each is counterbalanced by an equal quantity of the
opposite force.   Alum  may be decomposed into sulphate of
alumina and sulphate of potash ; each of which has its proper
character of (K) and (O),  and that in  the same degree as
before their combination.  Finally, potash and sulphuric acid
(KaO and SO3) may be decomposed in the same manner into
Ka, O, S, and O3,  each of which has the same quantity of
(K) and (O) as at first.
  This is proved by every chemical analysis, effected by the
action of  other substances upon those which  are to be decom-
posed.  The forces (K) and (O), therefore, become only qui-
escent, and are not lost while the combination of the  sub-
stances is in progress.
  We are by  no means able  to enter into this idea, if we as-
sume that the molecules of the united substances are quite
close to each other.  In this case a reciprocal  annihilation of
two opposite forces must occur.  If we suppose that the mole- 
           VEGETABLE AND ANIMAL PHYSIOLOGY.         17

cules are very near, though not in contact with each other, we
can  easily conceive  that the forces which proceed from the
molecules, having a certain  tendency towards each  other,
may seem to our senses to lose that portion of their strength
which is expended in producing the combination, and yet may
appear  again in their original quantity as soon as  the combi-
nation is dissolved.
   Substances persist, therefore, in their combinations, by the
same law in obedience to which they become chemically uni-
ted ;  they are  decomposed again  by the same law if more
powerful  forces than those which bring them together, act
upon their component  parts.   They become  combined, be-
cause two opposite  forces which either are present  in the
elements,  or are excited by circumstances  to a determinate
degree, act upon each other, and so accompany the  substances
with  which they are connected.  They persist in  their com-
bination because these forces are not annihilated, though part
of each is brought into  equilibrium with part of  the  other.
This part is thus prevented from acting  externally.   They
may be decomposed, if more powerful forces act upon one of
them, and if the decomposing forces be of the same species.
Copper, for instance, separates silver from its solution in nitric
acid ; thus withdrawing the oxygen from the silver, and itself
combining with  the  oxygen.   Suppose copper   to  contain
4(K), silver 1(K), and the oxygen of the oxide of silver 3(0);
a separation of the silver, which has but 1(K), must  neces-
sarily take place, because 3(0) may be neutralized by 3(K).
   We have, therefore,  a  direct proof that these chemical
forces are only quiescent, inasmuch as chemical  substances
are decomposed by others,  which  exercise a more powerful
influence upon  one of the combined substances than on the
other.   Hence  again we deduce  the conclusion,  that sub-
stances  are kept in combination by the same forces, in  virtue
of which they enter into combination.

B.  Chemical Action is  Action at Unmeasurable Distances.
                Polarity of the Molecules.

   It is a peculiar feature of chemical combination, that it acts
at distances too small to be measured.  To effect the combi-
nation, it is therefore indispensable that the  particles should
   Vol.  I.                   2* 
18                 THE CHEMISTRY  OF
come very near each  other.  This  is the reason  why sub-
stances, if put in mutual  contact while still in a mass,  have
for the most part either no action at all, or only an  imperfect
action upon each other, and why they act upon  each other
even at the  ordinary temperature, if they are reduced to a
very fine  powder.  This may be seen in the case of sulphur
and copper.  These substances have no effect at all on each
other when in mass ; but  when  reduced to powder they are
combined  by simple trituration,  a great  deal  of heat being
evolved in the process.  We should err, however, if we sup-
posed that minute division was the only cause of combination ;
trituration is, in the case supposed, only a powerful assistance.
We see, however,  when bodies are dissolved  in water, that
this state of division is  a principal condition of combination.
If anhydrous sulphate of  soda and  chloride  of barium  are
triturated together,  no  change will take place at all; but if
they are brought together  in a dissolved state, that is,  in  a
state of the minutest division, a perfect decomposition will
result.
   The effect of temperature,  in such cases, is not  simply to
promote the combination of substances.   Temperature facili-
tates combination in the same  way as solution in water does,
where either one or both of the acting substances can be fused.
No doubt  the  oxidation of metals in oxygen is promoted by
an  elevated temperature,  owing  either to the excitation of
peculiar forces in the metal and the oxygen, or to the increase
of these forces to a limited extent:  but fused lead or volatili-
zing zinc, for instance, has the particles very much divided
and very movable, under the  influence of an elevated  tem-
perature.   These particles, for  this reason,  are enabled to
turn to the oxygen that very side which is necessary for the
combination.   We must therefore  add this greater mobility
also to the influence of the temperature,  (as we remarked of
solutions of salts,) wholly independent of the  elevated  tem-
perature itself.  So with  pulverized lead, we find  that  if
shaken in  air and water,  it  is soon changed into hydrate of
oxide of lead ; though a  lump of lead under the same con-
ditions is but slowly acted upon.  Two gases,  if mixed with
a third of  a neutral character, combine but slowly ;  the re-
sult of their action,  however,  is  a perfect mutual attraction ;
as, for  instance, when ammonia, carbonic acid and atmoa- 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.         19

pheric air are mixed.   Thus the combination of gases is pro-
moted by the mobility of the particles.
   As it is necessary to  the  production of a  chemical combi-
nation that the particles should be movable, we infer that
the different sides of the molecules have a different power of
combining with a molecule supplied with  an opposite force.
The particles must be able to move, and it seems, therefore,
that there are determinate  sides in every  molecule which
prefer being united with molecules of an opposite force.   In
many combinations, when observed with the microscope, we
perceive  a  vehement rotation of the particles,  before they
combine with each other.*  This fact directly demonstrates a
certain property of polarization, an action  of the force  of
affinity in a  determinate  direction, influencing  an opposite
force which also operates in a determinate direction.
   That this must necessarily be the case,  will appear if we
examine somewhat* more deeply the nature of the union be-
tween two elements.  Potassium and oxygen unite by means
of a force,  which is not altogether annihilated after the com-
bination, but of which a part still remains active externally ;
the other part  is rendered  quiescent by the mutual counter-
balancing of two opposite forces.  A particle of potassium, if
it be an  indivisible one,  must be placed in juxtaposition with
an indivisible particle of oxygen in this manner:  | Ka | O  |
Their inter-penetration  is impossible, because matter does not
admit of penetration.  One substance can by no means be
closely wrapped round the other, in the form either of a ring
or of a sphere, for in that case  the enclosing sphere could
not be regarded as  an  indivisible particle.  It is impossible
that the one should be distributed in particles  round the other,
for it is one  molecule.   The only theory then which remains
for adoption,  is that of an arrangement of the opposite par-
ticles beside and near to each other.  If we suppose that each
particle of potassium and oxygen is wholly and every where
supplied  in  the same degree, with the forces (K) and (O),
the effect of these  forces will be to produce an approximation
of the molecules,  because the forces are opposite to each
other and the strongest attraction will take place  at the point
* See Harting in Bulletin de Necrlande, 1840, p. 287. 
20                   THE  CHEMISTRY  OF
of approximation ;  in other words, the attracting  forces may
be supposed  to act in the axis of two spheres.*
  Such a composite  molecule can be united with molecules
of the  same  kind, only by means  of the general  principle of
attraction.   Potash in  mass is bound  together not chemically
but physically, that is, by the universal force of attraction or
cohesion.  For  the  mass  may be divided  into  smaller parts
without disturbing the chemical equilibrium.
  * It is considered a legitimate deduction of science, that the crystals
of bodies indicate the forms of their molecules.   The perfect sym-
metry and the constancy in every angle, exhibited  not only in  the
crystal as a whole, but in the  minutest particle into  which it can be
broken,  must proceed from as perfect a symmetry and constancy of
form in the constituent molecules of the crystal.
  On these grounds it is inferred that the form of the molecule of lead
is a sphere, the crystalline form  being one of the tesseral solids, having,
like the sphere, equal axes.   The same conclusion is arrived at with
regard to the molecules of gold, silver, mercury, and many other met-
als.   In  like  manner we learn from the crystal of sulphur—a rhombic
octahedron having three unequal axes—that its molecule must be an
ellipsoid with unequal axes.  The form of tellurium being a six-sided
prism, (in which the vertical axis differs in length from the lateral,)  the
molecule is an ellipsoid of like axes with the prism.
  No aggregation of spheres could produce  the crystals of sulphur or
tellurium.  Or supposing  it possible to make  the form by means of
spheres,  the crystal would not present a difference of  lustre, cleavage,
and optical properties in the vertical and lateral directions—differences
observed in all crystals except the tesseral solids, and often extending
also to color and hardness.  These peculiarities show a dissimilarity in
the nature of the molecule in different directions,  or in other words,
indicate that  the  vertical axis is unlike the  lateral,  and  consequently
that the molecule is, as stated, an ellipsoid corresponding in its relative
dimensions with the  form of the primary.  The optical  phenomena of
crystals  as long ago as Huygens, were explained on these principles,
and to the present day they give not only a satisfactory explanation,
but the only one that accords with the facts.  In farther explanation,
we state that the axes of attraction in these ellipsoidal or spherical
molecules, correspond with their conjugate  axes or conjugate diame-
ters, and by action in their directions the various forms of crystals may
be produced.  The ellipticity of the molecule  will depend of course
on the attraction in the several directions, the length of the axes being
inversely as the strength of the attraction.t
  If the  inference with regard to  the molecules of simple elements is
correct,  it will be no less so with reference to those of compound bod-
ies, however complex their  composition.   The hexagonal prism of
phosphate of lead indicates as much that the molecule is an ellipsoid

  t This subject will be  round farther illustrated in the Treatise on Mineralogy
by J. D. Dana, to whom  we are indebted for these views: also In an article by the
same, in VoL xxx, p. 225, of the American Journal of Science. 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.         21
   If polarity really exists in the simple molecules, so must it
in the composite molecules.   We can easily imagine this, if
the substances, composed of one atom of each element, pro-
duce a binary combination, as in the case of potash ;  but it is
difficult to form a conception of the            Fi   t
nature of the combination,  when
two, three or  more  molecules  of
one element are combined with one
or two molecules of another.   How,
for instance, can we  form an idea
of  the  polarity of sulphuric acid
(SO3)  and  of phosphoric acid  (P2Os)?  It is probable that


as that of tellurium ; and the rhombic octahedron of tungstate of lime
leads to the same conclusion with that of sulphur.
  It is hence necessary in a  compound, that the molecules of the ele-
ments combined should be so united together, as to produce the results
that would proceed from spherical and ellipsoidal molecules;  or rather
they  must actually constitute molecules  of these forms,  as only thus
could the results be produced.   Axial attractions in fixed directions
are required to produce solids of perfect symmetry and unvarying con-
stancy in  the angles, and a uniformity in the texture of the molecule,
(varied only  by those unequal attractions in different directions that
occasion the ellipticity,) in order to account for the optical effects.
  In view of the above  considerations, we  may       „.
well  question whether  the  theory of juxtaposi-       *'£• *.
tion is fully satisfactory.  Take a sphere  of  lead
and an ellipsoid of sulphur, (see annexed  figure,)
and by what  process can a sphere (the molecule
of sulphuret of lead) be made from the two ? or
how can axes exist in these unequal solids, juxta-
posed, that will produce the effect of a sphere—
a cubical form of crystal, and a cubic cleavage?
The  more complex compounds in  chemistry,
would if  possible,  be  a greater puzzle  to  the
atomic philosopher.
  We are thus led to the conclusion that molecules are not atoms, indi-
visible p-a.riic\e9 ; that in forming compounds they admit of an intimate
union into spheres and  ellipsoids.  Adopting the mode of expression
of our author, the forces which constitute  molecules are capable of mu-
tual action, and they produce, as a resultant, the molecule of the com-
pound—as neat a sphere or ellipsoid as  the molecule of an  element,
similarly governed by axial attractions (at  least when entering the solid
state) on  which depend the form of the crystal,  and its optical  and
other physical characters.
  By  the  principles of dimorphism,  the  same substance  may present
two distinct forms, the one or the other being assumed according to the
temperature at which crystallization takes place.  This is true of sul-
 
22
THE CHEMISTRY OF
the molecules of oxygen, being here the more numerous, are
arranged round the molecules of sulphur and phosphorus (S
and P),  and  that  the force  (K) of the latter element is neu-
tralized by a part  of the (O) of the  former.   But we cannot
conceive how by any probable means (K) can be distributed
in S and P, or what may remain of (O),  capable  of acting
and manifesting itself externally.
   In  every case,  we  may deem it  probable  that the simple
and the  compound molecules  are combined  together in de-
terminate directions, and that their character is fixed by the

phur, one of the elements, as well as of some compounds.   Thus the
molecule of an element even, is not constant  in its figure.  The form
produced at a high temperature, often changes in the cold to the other
form, every particle altering its character throughout the solid crystal.
We can easily understand dimorphism if we suppose it a simple change
in the molecular axes, depending on  temperature.  In carbonate of
lime (one of the dimorphous substances) some theorists would say that
there is a  different arrangement of the juxtaposed atoms; but how is it
with sulphur, where there is but one molecule concerned ?  And with
carbonate of lime there would be some difficulty in arranging the atoms
of carbon, oxygen, and calcium, to make either one form or the other.
   In isomorphism the substitution of one element for another, without
a change of form, accords well with  these views.  The principles of
isomerism also seem to find here  their  only explanation.   The  com-
pound represented by the formula CH,  results from the union of a
molecule of each carbon and hydrogen into a simple  molecule.  In
C2H2, two molecules of each are united into a simple molecule, con-
densed probably in a different  degree from that of CH ; so also with
C*H*, C8H8, and other cases similar.   Juxtaposition gives no satis-
factory explanation  of these singular compounds.
   These views also elucidate the condition of gases absorbed by spongy
platina,  and many other analogous  phenomena.  According  to the
principles here illustrated, we  have the obvious explanation, that this
and similar cases are instances of simple cohesive  attraction, without
that intimate combination of molecules which takes place in forming a
chemical  compound. The surface action  theory of Liebig may there-
fore be less objectionable  than is urged by our author.
   The controversy  among some chemical writers  as to whether the
molecules in a compound have one mode of arrangement  or  another
—whether sulphate of lime  consists of a compound  molecule of sul-
phuric acid alongside of a molecule of lime, or  whether it is made up
of a molecule of calcium  united to a molecule of quadroxyd  of sulphur,
as Graham  suggests—appears to be of  little  value to science, if the
views here stated be correct.   It seems important to the chemist, only
to distinguish what are the  constituents between which the affinities
were exerted that gave origin to the chemical compound, carbonate of
lime ; and this action of affinities it is well to express in the name and
in the manner generally adopted.—S. 
            VEGETABLE  AND ANIMAL PHYSIOLOGY.        23

 form which the compound molecules assume.  We see, then,
 a determinate relation between the arrangement of molecules
 and isomorphism, between the number of atoms and the form
 of the crystals.  For if the atoms of sulphuric acid and selenic
 acid are arranged in the same manner,  we can conceive that
 when these acids combine with the same  base to form salts,
 the same form of crystals may be produced, although we can-
 not, a priori, determine from that arrangement of the mole-
 cules what the form of  the crystals may be.
   The difficulty we have noticed, as to the combination of
 several molecules into one whole, is  greatly increased, if we
 endeavor to form  an idea of that state of polarization which
 exists in every compound organic molecule.  We cannot ex-
 plain how the atoms of  sugar are combined together; and so
 with every other organic compound.   It is,  however, certain
 that here also polarization exists; because in crystallized sugar,
 C»2]-jlion, two  equivalents of water are coytained,  for
 which two equivalents of oxide of lead (PbO) may be substi-
 tuted.  Hence it is  evident that a constant  proportion exists
 between the 2 of oxygen in  2HO and 2PbO, and the 9 of
 oxygen inC12H909.
   It thus appears that the oxygen of the sugar, after combin-
 ing with carbon and hydrogen, and after having several times
 neutralized their forces  (K), has forces (O) still remaining to
 oppose to water or to oxide of lead,  these in their turn pos-
 sessing (K), by which they are enabled to combine with the
 sugar.  The other elements of the sugar leave to the 9 atoms
 of oxygen, after subtraction of the quantity applied to the neu-
 tralization of the carbon and hydrogen, as much force as en-
 ables it to combine with the same quantity of oxide of lead
 as can be  attracted by two of sulphuric acid (2S03), thus:—
                C12H509, require 2PbO.
                    2S03,   "    2PbO.
 If, then, we assume a state of  polarization in the elements of
 sulphuric acid and oxide  of lead, and if we imagine, that result-
 ants of all the forces which reside respectively in oxygen and
 lead,  and  in oxygen and sulphur, are developed—resultants
 which influence each other, though co-operating as a whole—
 we cannot form any other idea,  than that a similar resultant
 proceeds from the elements of sugar, directly the opposite of
that which proceeds from the atoms of the oxide of lead. 
24                  THE CHEMISTRY OF
We  cannot, however, determine, with any probability, how
this resultant may be obtained.
  There is, however, a class of organic substances, in which
this division into groups is obvious, namely, those substances of
which we know the radicals, acetyl, formyl, sethyl, methyl, &c.
We attempt in vain to form an idea of the various substances,
of which the  radicals  are still unknown;  as,  for instance,
sugar.  If a simple substance can combine, with but one atom
of another, such a substance is probably unipolar, if with two,
bipolar, &c.   And so with more compound substances.  It is
therefore likely that the molecules of bi, tri, quadri, quinti-
               basic acids are just as much polaric ; and that
               in  a tribasic acid,  for  instance, the  three
               atoms of  base are arranged round the acid
               in the form either of 3 of oxide or of water
               (3RO or  3HO),* or 2 of  oxide and one  of
               water (2RO-f-HO),  or one of oxide and 2 of
               water (RO+2HO).

  C.  The Influence of Circumstances upon Chemical Forces.

   We  may  employ the quantities of  different substances,
which can combine with the same element, to express  the
measures of the chemical forces which reside in them.  Whe-
ther one substance can separate another from its combinations,
may be ascertained by experiment.   Now, experiment informs
us that in the  same circumstances different bodies possess dif-
ferent quantities of chemical force.  For instance, sulphuretted
hydrogen is decomposed  by iodine, and sulphur separated;
hydriodic acid by bromine ; hydrobromic  acid by chlorine.
These simple substances, therefore, stand  to  each other in
this  order of  affinity,  chlorine, bromine,  iodine,  sulphur.
So with  the metals,  silver, mercury,  copper, lead and zinc.
Each is precipitated from its solution by that which follows
it in this order of succession.  There is thus more force  of
affinity in each of the subsequent, than in each of the prece-
ding metals.   In alkalies  the affinity  for sulphuric acid di-
minishes in this order—baryta, strontia, potash, soda,  lime,
magnesia, ammonia.
* R is used in chemical formulas as a general expression for the bases.
 
VEGETABLE AND ANIMAL PHYSIOLOGY.         25
  The chemical forces, however, emanating from bodies, are
modified by so many particular circumstances, that it is as
yet impossible to lay down determinate principles.
  1. If,  for instance,  any substance is volatile,  it is easily
liberated from  its combinations.  Carbonic acid,  therefore,
passes off very quickly; and even hydrochloric acid, though
much more powerful, does so, because it is volatile.   Phos-
phoric acid expels even sulphuric acid, because it is unaf-
fected  by fire.   Silicic  acid, though  possessed of but  little
power, expels many other acids when heat is applied, because
it is not volatile.
  2. If any substance has a tendency to produce an insoluble
combination, then its force of affinity is considerably increased.
Of  this we have a striking  example  in carbonate and  acetate
of potash.  If  carbonate of potash is dissolved in water, the
carbonic acid is expelled by acetic acid ;  but  acetate  of pot-
ash, if dissolved in alcohol, is decomposed by a stream of car-
bonic acid, because carbonate of potash is insoluble in alcohol.
If a double decomposition take place, the bases and acids are
always arranged and combined together in  that  order, in which
the least soluble salts are produced.
  3. It is a remarkable peculiarity in the modification of affin-
ity by the influence of circumstances, that  many combinations
are much more easily effected, if some other substances  must
first be separated, than if the substances are brought into mu-
tual contact in an uncombined state.  Lime, if  quite dry, does
not absorb carbonic acid, though hydrate of lime does so very
easily.   Oxide  of ethyl does not combine directly with acids ;
but it does combine if the acid be made  first to separate water
(HO)  from alcohol,  and thus to form the ethyl with which it
is to combine.   If a metal is dissolved in hydrochloric acid,
the metal (M) is substituted for the hydrogen (H) of the acid,
for  MCl-f-H is produced by M-f-ClH.  In this case CI and M
are easily combined, because M is substituted for H, though it
is often very difficult to unite M directly to CI.   It is probable
that the  double decomposition is very much promoted by the
double substitution which then  takes place.*   In Graham's
opinion, the power which the hydrates of silica and alumina
have of forming combinations,  ought also to  be  ascribed to
                      * Graham.
Vol. I.                   3 
26                 THE CHEMISTRY OF
substitution, since the same substances, after being subjected
to a red heat, scarcely combine with other bodies at all.
  4. Mutual decomposition of two salts takes place, not only
when one or both of them become insoluble, but also when one
of the  two  new products, or both, are less soluble than those
which were originally employed.  Such is the case when solu-
tions of sulphate of soda and nitrate of potash are mixed to-
gether.  If sulphate of copper be mixed with chloride of so-
dium,  the  blue color is changed to green, which  proves the
formation of chloride of copper.   It is possible, however, that
this may result from mere affinity, because sulphate of copper
can be decomposed by hydrochloric acid, and chloride of so-
dium by sulphuric acid.
  5. Pressure is another circumstance which influences chem-
ical  forces.  If it be very great, no hydrogen is  disengaged
from diluted sulphuric acid and zinc.  If the vessel be closed,
the evolution of gas is diminished and finally stopped ; but it
begins again whenever the vessel is opened.
  6. If carbonate of lime is heated in a close vessel, none of
the carbonic acid is disengaged ;  but it is otherwise when car-
bonate of  lime is heated in the air,  at least in  the uppermost
layers of heated air.  But if atmospheric  air or steam be con-
veyed  through a tube, which contains carbonate of lime, then
all the carbonic acid passes off.   If hydrogen pass over red-
hot oxide of iron, water and iron are produced ; and  if steam
pass over red-hot iron, hydrogen and oxide of iron result.  In
this case the affinity is modified by the atmospheric air which
surrounds the substance ; and this phenomenon is thus related
to the diffusion of gases.
   It appears, then, that  a considerable part of what we see
as to the inclination of substances to combine or to  separate
is to be ascribed to the influence of circumstances.  To effect
a combination,  it is necessary that the chemical forces inclu-
ded in the  substance should be either excited or elevated to a
determinate degree.  It  is only thus that we can conceive
how a molecule can acquire  the power to combine with 1, 2,
3, 4, &c.  molecules of another substance, so as to produce
well-defined chemical compounds.  The  quantities of chemi-
cal forces  are thus graduated, as it were, and  substances are
combined  in proportions, which  depend on  the quantity of
those forces; such combinations, however, do not occur until 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.         27

two opposite forces are excited to a certain degree by the in-
fluence of determinate circumstances.  If, for instance,  iron
be slightly heated in the air, the protoxide (FeO) is produced ;
if it be heated to a greater degree, the peroxide (Fe203).
Why do the same iron and oxygen combine together in two
different proportions by means of the same agent, heat ?
   If we suppose, that at the ordinary temperature iron has a
tendency to combine with oxygen, and vice versa,  but  that
there exists no proportion at all between the quantities of the
forces (K) and  (O) which reside in them respectively, then
the iron would not enter into combination.  This is  what we
observe in dry air.  If the iron be heated, its force (K) is
excited, and so is the  force (O) in the oxygen, when in con-
tact  with  the  heated  iron.  A combination of the  opposite
forces, and  consequently a combination of the iron and the
oxygen, (Fe and O,) occurs only in the case where both forces
increase to such  a  degree that they both reach an equally
high maximum, with reference to the circumstances in  which
they exist.   A dull red heat makes these forces increase  to a
limited maximum only.   If we heat FeO and O to a  still
greater degree, these forces get a new increase, and Fe203 is
formed only when the  forces of Fe and O have attained a new
maximum.
   As to the production of some other compounds,  we must
adopt a different principle.  If,  for instance, sulphur is to be
oxidized  into SO2 and SO3—sulphurous  and  sulphuric acid
—then the sulphur must in each case be  placed in  peculiar
circumstances.   When sulphur is burned in the air,  the  ele-
vated temperature affects S with (K), and oxygen with (O);
in other words, the forces resident in  sulphur and  oxygen,
must be excited  in such a manner that S is  combined with
02.   The oxidation into sulphuric acid (SO3)  is effected in
a different way.   Sulphurous acid (SO2) is brought into con-
tact with a substance possessing energy, and which is known
lo have the power of exciting action in other substances,  and
even of itself giving off 1 equiv. of oxygen,  namely, with
hyponitrous  acid  (NO3).   SO2 is thus predisposed to take
up O again; NO3 excites  new  forces in SO2, and the com-
bination of  O with SO2 is effected in  the same manner, as
that of gold with chlorine, by the contact of  the gold with
chloronitrous acid (aqua regia).   This  result is attained be- 
28
THE CHEMISTRY OF
cause 1 equiv. of oxygen very easily escapes from the hypo-
nitrous  acid  NO3, which it contains,  and this oxygen, being
in the nascent state,  retains that force by which it was  pre-
viously kept in combination with NO2.  As regards the gold,
it is NO3 also which  excites  the  force in this metal,  produ-
cing its combination  with CI,  or with a substance which pos-
sesses the (O) force.
   Phosphorus may be combined with O3 at the ordinary tem-
perature, and the product is phosphorous acid.  To form PO5,
phosphoric acid, however, a more elevated temperature than
that necessary for combustion is required.
   The  predisposition either of simple or of compound  sub-
stances to form  new combinations,  the excitation of the for-
ces resident in them,  and which were neutralized so as to be
wholly or partly imperceptible externally, is produced some-
times by one, sometimes by another circumstance, often  by
the influence either of a different substance or of a certain
temperature, or of light, or  of electricity.   We learn  from
experiment that  the excitation of forces takes place in such a
manner, that determinate and constant combinations are pro-
duced.   It is, therefore, necessary that  the  measure of the
opposite forces,  which are excited,  should  be a constant one
also ;  at least a maximum of both the opposite forces must be
produced, before any combination can result, though the for-
ces may increase with the increasing influence of circumstan-
ces.  This maximum may be superseded again by other cir-
cumstances, producing a new combination of the elements.

           D.  Catalysis:  Molecules  in Motion.

  Berzelius has directed our attention to a power, which some
substances possess of exciting chemical action by their pres-
ence, though they themselves are exempt from the effects of
such action.   This power he calls Catalysis*  It  is distin-
guished from ordinary chemical force,  in so far as the latter,
while it is exerted  by one substance upon another, yet gener-
ally reacts upon both.   If sulphuric acid acts  upon  soda,  an
action is effected by both, which reacts upon both.  If oxygen
come in contact with  phosphorus, at an elevated temperature,
* Jahrbuch ftlr 1836, von Schumacher, p. 88. 
VEGETABLE AND  ANIMAL PHYSIOLOGY.        29
 then they are mutually combined.   Though the action might
 have proceeded from the oxygen to the phosphorus, the oxy-
 gen nevertheless is drawn within the circle of action.
   The  effect of catalyzing  substances is entirely different.
 Spongy platinum condenses hydrogen ; and so soon as oxygen
 comes in contact with it, water is produced, while  the spongy
 platinum undergoes no change.  Hundreds of pounds of hy-
 drogen and oxygen may be combined together  by  means of a
 small piece  of  spongy platinum.  Thus  the  platinum pro-
 duces a  force, which influences at  once the  hydrogen and
 the oxygen,  and causes an action,  from which the  platinum
 itself is exempted.   Such is the force which Berzelius calls
 catalysis.
   The greater part of the substances, which excite chemical
 action  in other  bodies,  and are  themselves involved  in the
 reaction, are  undoubtedly affected by this catalysis.  Possibly
 catalysis may always be present among chemical  causes, so
 that, if SO3 and NaO—sulphuric acid and soda—for instance,
 are combined together, a force proceeds both from  SO3 and
 from NaO, each of which is similar to that proceeding  from
 platinum, when in contact with certain gases. Catalysis might
 be defined  as the exciting cause  of chemical action, and this
 excitation may take  place whether the exciting substance bo
 contained in  the circle of action or  not.   We reckon,  how-
 ever,  as pure catalytic  phenomena,  only those in which the
 substances  provoking the combination do  not enter into that
 circle.   Those bodies thus possess the power of exciting, but
 have not the  property of sharing in the combination which is
 the result of their action.
   This force  is possessed, not only by spongy platinum, but
 by platinum in substance; for if a piece of platinum foil  be
 placed in a mixture  of hydrogen and oxygen, the  gases as
 they pass along its surface, form small quantities of water, so
 that in  a few hours  all the gas  has disappeared,  and water
 has taken its  place.
  Nor is platinum the only metal  which  has  this property.
 Every substance which is porous,  is  possessed  of it  in a
 greater or less degree.  Thenard and Dulong have detailed a
 great many experiments on the subject, and have demonstra-
ted, that this property belongs even to glass when pulverized,
but only at a somewhat elevated  temperature—namely, at
  Vol. I.                 3* 
30                 THE CHEMISTRY OF
572° F., and to gold and silver at a  lower temperature.  It
had  previously been discovered  by Sir Humphry Davy, that
platinum, if placed in the vapor either of alcohol or of ether,
began to glow, and caused a combination between the vapor
and  the oxygen of the air.  Spongy platinum was afterwards
discovered by Edmund Davy, who observed that it possessed
this  property in so  high a  degree, that if the platinum was
moistened with  alcohol, acetic  acid was produced from the
alcohol while the platinum was glowing.  Before the discov-
ery  of Thenard and Dulong, it had been remarked by Dobe-
reiner that hydrogen and oxygen could be combined together
by means of spongy platinum.   This  discovery was extended
by the two former to several other substances.
   The effect of deutoxide of hydrogen, (HO2),  when in con-
 tact with various substances,  has been classed  by Berzelius
 with the same series of phenomena.   It explodes, if brought
 in contact with platinum, silver, peroxide of manganese, and
 even with organic substances, such as fibrin.  Oxygen is dis-
 engaged,  and water (HO)  remains.*   In every case, where
 the  solid  substance can combine with the whole quantity of
 oxygen, there is of course only an ordinary chemical action;
 but  if this combination does not take  place, and if the action
 occurs on contact  simply, the phenomenon is that which
 Berzelius calls catalysis.
   This term  ought further to  be  used with reference to the
 change of alcohol into ether, by means of acids. Hydrate of
sulphuric  acid—the common oil of vitriol of the shops—into
 which  alcohol  is  dropped at an elevated temperature, is not
diluted by the water produced,  but a mixture of oxide of ethyl
and water distills off'.   Sulphuric acid, therefore, catalyzes at
that  temperature the elements of alcohol into oxide of ethyl
and  water, without itself combining  with either.  The same
effect is produced by other acids, especially if they are power-
ful.   To the same  class  we refer the changes, produced on
starch by sulphuric  acid, transforming it either  into dextrine
or into sugar—the  changes which are produced by acids on
starch, gum, sugar, forming humic acid, ulmic acid, and for-
  * It is now known that at the same time part of the oxygen is com-
bined with the fibrin, and oxy-protein produced.   (Scheikundige On-
derzoekingen, by Mulder, D. 1.) 
VEGETABLE AND ANIMAL PHYSIOLOGY.
31
mic acid—and also the action of emulsine upon  amygdaline.
Several other phenomena, besides, are referred by Berzelius to
the same class—phenomena ascribed to organic chemistry—
as for instance, the transformation of starch into gum and su*
gar by diastase, the transformation of sugar into carbonic acid
and alcohol by yeast, and also the changes which take place in
the bodies of animals and plants.  Transformation by diastase
ought doubtless to  be classed with these phenomena.  An ex-
ceedingly small quantity of this substance changes a large
quantity of starch  into gum and sugar;  but  it is also possible
that the diastase itself  is at the same time  acted upon,  and
that  thus we have in  this  instance, no pure catalysis.   This
is the case especially with yeast, which, during fermentation,
changes sugar into carbonic acid and alcohol, and probably it
is much more so in the animal secretions.
   In  view  of these  considerations,  Liebig  has been  led to
reject catalysis entirely,* and to give a totally different  expla-
nation of facts.   He has assumed,  that chemical forces are
in action in those substances, which, according to the supposi-
tion of Berzelius,  are capable of exciting action, though with-
out taking part in  that action ; and he thinks that by such
chemical action, another may be excited in other substances.
He adopts the principle, indicated by Laplace and Berthollet,
that  a  molecule,  being  put in motion, can communicate its
motion to others, if in contact with them.   He applies this
principle to  yeast especially.  The opinion of Berzelius  is
that sugar is changed into carbonic acid and alcohol  by this
substance, just in the same manner as alcohol is  changed into
ether and water by sulphuric acid;  and as  water is produced
from  hydrogen and oxygen by platinum.  Liebig,  however,
assumes that yeast is continually in a state of decomposition ;
that it thus undergoes a change in its own elements, and that
if put in contact with sugar and water, it disturbs the  chemi-
cal forces, by which the elements  of sugar are  combined to-
gether, and so produces alcohol and carbonic acid ;—this dis-
turbance being caused by the change in the  elements  of the
yeast, which follows the disturbance of its chemical equilibrium.
   Though it  seems to  be proved that yeast is really changed
during  the alcoholic fermentation,  and cannot therefore be
" Chimie Organique, Introduction. 
32                 THE CHEMISTRY OF
said to act by catalysis, yet this series of chemical phenomena
is not reducible to any class of ordinary phenomena, and we
are consequently obliged to assume three different  forms of
chemical action.
   1.  That which is effected by a  substance, without any re-
action, but which is transferred to other substances, (catalysis.)
   2.  That which is effected by  certain substances and trans-
ferred' to others; the primary substances being at the same
time  decomposed, though they do not communicate any of
their elements to the  new products, (fermentation.)
   3.  That which is effected by certain bodies, but which pro-
 duces a complete reaction upon the  bodies themselves, so
 that common products result from both the active or influen-
 cing substances,  and those which are acted upon, (ordinary
 chemical action.)
   We have already treated sufficiently of the  third cause of
 action;  we must dwell, however, more particularly on the first
 and  second.
    Catalysis.—In our opinion it is not to be denied that a par-
 ticular  action must  proceed  from spongy platinum, or from
 platinum in mass, when hydrogen and  oxygen combine to
 form water—from sulphuric Or any other acid, when oxide of
 ethyl is produced—in the transformation of starch  into gum
 and  sugar by sulphuric acid—in the  change  of sugar into
 humin  by diluted acids.  This  action differs  in character
 from ordinary chemical action.  In the latter case the sub-
 stance,  from  which the action proceeds, is always itself com-
 prised within the  circle of effects, and generally enters into
 new combinations.  There are, however, a great many similar
 actions, which are erroneously referred to ordinary  chemical
 action.   If,  for instance, gold  or platinum be  dissolved in
 aqua-regia, hyponitrous acid (NO3) takes no part in the com-
 bination.  Either  NO3 or some other  powerfully acting sub-
 stance,  however, is  indispensably necessary to  produce the
 combination of chlorine with  gold or platinum.   A still more
 striking example is  afforded in what has already been men-
 tioned, namely, that the presence of a third substance is often
 required for  the  production  of a combination, though it be
 separated after the combination has taken place—as in lime,
 water, and carbonic acid, (see above, p. 25.)   The water in
 this case, is required for effecting the union between carbonic 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.        33
acid and lime, and will, notwithstanding, soon be  separated.
It does not enter into the combination which results.
   Whatever#ame we may give  to this acting cause, it can-
not be denied, that there are a great many substances which
predispose others to combination, enabling the latter thus to
enter into combinations, which without their agency could not
take place.   The action which Berzelius has distinguished by
the name  of catalysis, is thus a peculiar mode of exciting a
chemical action.
   What conception ought  we to  form of this catalyzing ac-
tion ?
   Some molecular forces are  hidden in the elements.   One
of these forces we know to possess the great power of pro-
ducing combinations between dissimilar substances.   Such
forces generally proceed  from the very substances on which
they react.   Catalysis is precisely the same force, without the
reaction, however, on the substances, whence it proceeds.
   If we transmit a small electric spark through a  mixture of
hydrogen and oxygen, in a gaseous state, the whole is imme-
diately combined.   Two molecules—one of each—first com-
bine, and from these the action is  communicated to the whole.
They have been called by Laplace and Berthollet, molecules in
motion.  We perceive, however, in this example, an action
proceeding from two molecules of hydrogen and oxygen, and
transferring itself to thousands of molecules of the same ele-
ments ; but the particles originally affected by the electrical
spark are  not involved in the subsequent action.
   Something of a similar kind we observe in catalysis.  Spongy
platinum does not enter into the combination of hydrogen and
oxygen.  We see, however, this difference between the case in
which combination is effected by means of platinum, and that
in which it is effected by an electrical spark—the  particles of
platinum are in the state of moving molecules, no influence
apparently being exercised by external  causes.
   It would be an  interesting  experiment, to expose spongy
platinum to a mixture of hydrogen and oxygen, reduced to a
very low temperature, with the view, of ascertaining whether
platinum would then possess the same power.  It is probable
that the metal would not   retain  this property at every tem-
perature.   Nay, it is certain that pulverized glass produces the
combination of  these elements, but not  below 572° F.—thus 
34
THE CHEMISTRY  OF
acquiring  at this temperature,  the  same power which plati-
num possesses at the ordinary temperatures.   A neutral sub-
stance may therefore  be made equal to planum,  by an
elevation of temperature.   It is further known, that a deter-
minate temperature is required  to convert alcohol into oxide
of ethyl and water, by  means of sulphuric acid ; that humin
is  formed from sugar by means of an acid, but not  at every
temperature ; that the power which sulphuric acid possesses,
of converting starch into gum and sugar,  is not unlimited, but
that a determinate temperature  is  required for that purpose.
   If in this manner, we go over the series of catalytic phe-
nomena, we observe that the influence of temperature is almost
always indispensable.
   Now it is known, from abundant  experience, that heat has
the power, greatly to modify the chemical forces, resident in
substances.  This is very clearly shown by the innumerable
products,  obtained  by dry distillation at different  tempera-
tures."  If then, the influence of heat on the substances, said
to be catalyzed, be communicated to them by the catalyzing
substance, (if the heat, for instance, which causes oxide of
ethyl and water to be produced from alcohol, be communi-
cated to the elements of alcohol by means of an acid—should
the heat in this case prefer such a medium,) the idea of cata-
lysis contains nothing repugnant to acknowledged principles.
   However this may be, it cannot  be  denied that there are
many  cases in  which  chemical action proceeds from a sub-
stance, which  is not itself comprehended within the circle of
such  action.  Although  this  be a  deviation from  ordinary
chemical  action, the idea  seems  not  to  be opposed  to any
sound  principle, and creates no greater difficulty than occurs
in the  case where all the substances, which excite any action,
enter into the combination.
   The peculiar property of spongy platinum has been called
by some philosophers,  surface  action.   To this action  they
have ascribed every phenomenon, similar to that produced by
the peculiar influence of spongy platinum.  I must confess,
that I understand the meaning of surface action as little as
I do that  of contact action.  A surface cannot produce an
action ; that must necessarily be effected by matter—by the
forces imparted to matter, which manifest themselves under
certain circumstances, especially when  the matter is  minutely 
           VEGETABLE AND ANIMAL PHYSIOLOGY.        35

 divided,—though under other conditions, the same forces are
 quiescent.   We should,  I think,  approach nearer the truth,
 by inverting our conception of the subject, and assuming, not
 that substances obtain a  new power  by minute division, but
 on the contrary, that by their accumulation into masses they
 become powerless,—that  the  forces  present in molecules
 are prevented from acting, being reduced to a  state of quies-
 cence.   When iron is in mass, it shows but a slight tendency
 to  oxidation;  but  when  minutely  divided, it cannot possibly
 be brought even in contact with  atmospheric air, at a low
 temperature, without becoming red hot, and at the same time
 becoming converted into an oxide.  Cobalt, nickel, and ura-
 nium, possess the  same  property.*  It is  true that in these
 spongy bodies, obtained by reducing their oxides by means of
 hydrogen at the lowest possible  temperature, the  oxygen
 from the atmosphere is apt quickly to condense ; but is this
 condensation an effect,  produced by the iron  in the metallic
 state, or by something else—by a power dwelling  in the mat-
 ter, (the iron,) or  by a  power which  is  without ?  If it be
 absurd  to suppose that this power is present in any thing but
 the iron, then the  power coincides with chemical attraction.
 It verifies the  proverb, corpora non agunt nisi soluta, but in
 a more  definite form, corpora non agunt nisi divisa.   Chem-
 ical action operates  by molecules, not by masses.   In the
 masses  the chemical forces are rendered powerless and quies-
 cent.  If we could isolate the molecules of all the elements,
 these forces would show  their potency.
   1 see no reason  why, with regard  to spongy platinum, that
 is, platinum so minutely divided as to approach the molecular
 state, 1 should assume that any thing else takes place, than with
 regard to iron, cobalt, nickel and uranium in the same spongy
state.   On the contrary, spongy  platinum  wants  something,
 which the others possess.   Their molecules condense gases
around themselves, and if the gas be oxygen,  this condensa-
tion is  almost  contemporaneous  with the oxidation  of  the
 metal.  Thus one molecular action is succeeded by another,
and so  determinate quantities  of the two substances become
and remain united.   This power is not exercised by platinum,
and thus it possesses one power less than iron.   This mani-
* Magnus. 
36                 THE CHEMISTRY OF

festation of molecular forces, without the intervention of ex-
ternal circumstances, may be observed in every element, pro-
vided it can be minutely enough divided.  There is a whole
series of metals which, if pulverized, burn away in chlorine
at the common temperature.   The  power  of  exciting a  red
heat, and of combining chemically, exist both in the chlorine
and in the metal; they only  need to be placed in proximity,
and  forthwith  this  power is exhibited.  If tartrate of lead
be heated to a proper degree, it yields lead, in a state of
very minute division, (C4H20^+PbO=C*04+H202+Pb.)
Lead in this state is an exceedingly good phosphoric substance ;
when it comes in  contact with the atmosphere, it is instanta-
neously oxidized, even though previously saturated, either
with carbonic acid or with nitrogen.
  From the whole series of  pyrophoric substances,  we learn
still more clearly, that all the elements manifest their prop-
erties energetically, if,  when in  a  state of minute division,
they are only brought into contact.   Phosphorus and liquid
bromine cannot be brought into contact, without  entering ve-
hemently into  combination.   If a solution  of  phosphorus in
bisulphuret of carbon, be poured upon  paper, and exposed
to the air, the  sulphuret evaporates, and the phosphorus re-
mains in a state of minute division.  Whenever this  opera-
tion is completed, the phosphorus absorbs  oxygen  from  the
atmosphere, evolves heat, produces phosphoric acid, (PO5),
and the paper  burns.
  In all these  phenomena, nothing  is visible  but molecular
action, which,  however, has  been called chemical.   This ac-
tion  cannot proceed  from masses,  because the molecules,
placed  in close  juxtaposition, counterbalance  each other.
Chemical bodies,  therefore,  in a chemical point  of  view, are
entirely different from what they appear to be when  in mass.
  There is another  substance, also, which deserves particular
notice, to wit, finely powdered charcoal.   Its  well  known
power of condensing gases and retaining metallic salts, color-
ing matter, &c, is  ascribed  to a surface  action.   There are,
however, in regard  to this substance, so many cases in which
we  perceive a real chemical action, that  we can  have  no
doubt of the proper cause.   Thus, we find  that when a mass
of charcoal, recently made  red hot, and allowed to cool in
vacuo, is exposed to the air,  it takes fire ; so when sulphuret- 
VEGETABLE AND  ANIMAL PHYSIOLOGY.
37
ted hydrogen and oxygen are absorbed together by charcoal,
water is produced, and sulphur separated ;  and when a solu-
tion of acetate of lead  is  filtered through charcoal,  metallic
lead, combined with the charcoal, remains behind.
   We may therefore assume, that these well known properties
of charcoal correspond with the chemical tendencies of the
molecules of carbon in the porous charcoal,  the molecules
not being rendered inefficient by aggregation.
   Platinum possesses chemical tendency in a high degree, but
it is of such a kind,  that it does not react upon the platinum.
When in mass, the metal is no more devoid of that tendency
than the iron in  a similar state is, of the power of attracting
and combining with oxygen.
   Hence it may be inferred, that we have  good  reason for
distinguishing by a peculiar  name  such  actions as  proceed
from  certain  substances without  reacting upon themselves;
and  we  have to acknowledge  that  to the  introduction, by
Berzelius, of the peculiar term catalysis, we are indebted for
a more correct  idea of the  nature of ordinary chemical ac-
tion.
   What is called the nascent state of substances, is that con-
dition of the elements in which they exhibit both analytic and
catalytic phenomena ; in which, being free and unconstrained,
not rendered  powerless, either  by being agglomerated into
masses, or  by combination into compounds,  they show them-
selves in their proper chemical condition—that is, an active
one, in which they can operate upon others, excite a slumber-
ing energy, and cause  combinations and decompositions,  in
which they themselves may either participate or not.
   This nascent is the  real chemical state of bodies.  In that
state both the elements and the compounds exhibit themselves
in their true character.  In the organic kingdom the greater
number of  substances  are actually in that condition ; and  to
this nascent state we ought to ascribe the numerous peculiar
phenomena apparent in organic substances.
  It seems  to  me that we ought to take what has been called
by Liebig motion of molecules, in a sense corresponding with
the view now stated.  Activity, in a chemical sense,  indeed,
cannot be excited by mere motion ; but one chemical energy
is awakened  by another; the chemical  equilibrium is dis-
turbed, the  influence of cohesion is broken,  and the elements
  Vol. I.                  4 
38
THE  CHEMISTRY  OF
are brought back lo their free and proper chemical and mole-
cular condition.                                           .
  Disturbance of chemical equilibrium.—It is  a property ot
the chemical forces, when active in any substance, to excite
analogous forces in others.  We notice this especially in or-
ganic nature, and it is no where more strikingly illustrated,
than  in  the  nutrition  of animals.   Blood, a  homogeneous
fluid, circulates through very different parts of the body.   In
the muscles it sustains  muscles,  in the  liver it  supplies the
component parts of the liver, and from it the gall is there se-
creted ; in the kidneys  it maintains their various parts, and
secretes the urine, &c.   None of these secretions appear in
the blood with their peculiar qualities; of some  of  them not
even a trace is found.  But the four organic elements of the
whole are to be found in protein and its combinations, in  the
coloring  matter of the blood, &c.  The elements of protein
might, no doubt, be transposed in the liver, &c., by means of
catalysis, and so the component parts of  the liver and gall be
produced from it   It would only be necessary, then, that the
constituent parts of the liver should be put into contact with
the component parts of the blood, and the  forces of affinity
resident  in the substance  of the liver would not require to
influence those in the  protein,  or to produce  any  chemical
alteration in its component parts.
  Other causes, however, ought undoubtedly to be considered.
For instance, a change of its component parts takes place in
the liver itself,  and, from the first, chemical forces actively
operate therein.   For the continual change of its component
parts is  a chief characteristic  of every living organic  sub-
stance.   These forces may disturb the chemical equilibrium
of other substances, and cause the formation of new products.
If the constituents of the blood—the combinations of protein,
the coloring matter, &c—enter the liver when it is  in a state
of action, and are there  put in contact with the gall during its
secretion, and with the substance of the  liver itself, which is
in a state of continual alteration,  then the result  will be, that
this change of their component parts having taken  place, the
action will be transferred to the elements of the blood, and
will maintain the secretion.  If, on the other hand, the con-
stituents  of the blood are in a state of  continual change, then
the circle of  action in  which they are involved, will  extend
to the mass of the liver; and so with every organ. 
           VEGETABLE AND ANIMAL PHYSIOLOGY.         39

   We have, however, no more knowledge of the manner in
 which this  secretion originally commences—whether it pro-
 ceeds from the blood or from the secreting organ, or whether
 each of these contributes its part—than with the manner in
 which the first germ of the whole organ, the  liver,  is pro-
 duced, or in which the germ of the animal is converted into
 an animal.   But the continuance of the  action—the duration
 of secretion—entirely corresponds with some other phenom-
 ena, which we may observe separately,  and which therefore
 throw light upon these animal actions.   This  is the case espe-
 cially with fermentation,  from which Liebig has  drawn many
 illustrations,  for the  purpose of clearly exhibiting his ideas ;
 and with the same view we shall  also avail ourselves of this
 process.
   Yeast changes sugar into carbonic acid and alcohol, and is
 at the same time changed itself.   The latter change causes
 the former, and is only transferred to the sugar.  If we substi-
 tute blood for yeast, and the liver for sugar, we may form an
 idea, more  or less distinct, of the secretion of the gall.   The
 component  parts of  the blood are  continually undergoing
 change.   This constant change of the component parts  in or-
 ganic bodies is a chief cause of the continuation of their exist-
 ence.  The liver without intermission assumes new parts and
 loses others.  This process we call nutrition.  At the  same
 time that  the parts of the blood in the substance of the liver
 are thus undergoing change, chemical forces are excited; these
 forces are transferred to the elements of the blood, and so are
 enabled to produce from  them the gall.   This takes place the
 more easily, as the blood itself is also in a state of continual
 alteration, and thus g-eadily yields to the impulse which,  in
 some way or  other,  is communicated to it.  As the impulse
 varies, so does the effect.  Hence that great  diversity in  the
 secretion of very dissimilar substances, which  are  in a state
 of alteration,  from the same fluid—that is, the blood,  which
 is itself at the same time in a state of decomposition.
   From the nutrition of  the cellular texture,  however,  which
 must be  produced from  the component parts of blood, and
 from the nutrition of all the secreting organs—which, besides
 producing the  secretion,  maintain  themselves by separating
 what they require from the constituents of blood—we  learn
that catalysis cannot be left out of consideration in  the  mere 
40                 THE  CHEMISTRY  OF

process of  nutrition.   Further,  we  must  apply the  same
principle to  all the solid parts of the body, which are com-
pounds of protein.  The muscles, for instance, have the prop-
erty of secreting protein from  blood, and  converting  it into
fibrin; on the other hand, when protein is  deficient  in  the
blood, this fibrin is taken from the  muscles and converted
into blood-protein, as in diseases of long continuance and in
emaciation.    Muscles  have thus the property  of  forming
muscle—fibrin by simple  contact, if  protein abounds  in  the
blood, and this result can be ascribed only to a cause similar
to that by which crystals gradually accumulate from solutions
of salts.   It is at least a peculiar action, different from ordi-
nary chemical  action,  which takes place when the plasma of
blood  is  transformed  into muscles, which in composition do
not essentially differ from  the plasma.  The same is the case
with the production of hair, nails, and permanent horns.
   Let us now proceed to  inquire into the influence by which
chemical forces in action excite new forces in other substan-
ces generally.
   In the inorganic part of chemistry we perceive some phe-
nomena which demand  particular notice.   For instance, pla-
tinum is not  dissolved by nitric acid, but if  previously alloyed
with silver,  it is dissolved by that acid, as well as the silver.
The oxidation of the silver  thus becomes  transferred  to  the
platinum, which,  by  itself,  could  not be brought into that
condition.*   If deutoxide of hydrogen  be  put  in contact
either  with oxide of silver or with peroxide of lead, oxygen
is lost not only by the  deutoxide of  hydrogen, but also by
the  metallic oxides.   The disturbance of the  chemical equi-
librium in the one compound transfers itself to the other; the
motion in which the molecules of the one  substance are  in-
volved, is communicated to the molecules of the other.
  Some chemical compounds have a very slight internal cohe-
sion.   Their elements are in a state of unstable equilibrium;
they are either decomposed by a slight external disturbance,
or they enter into new  compounds.   To this series  belong
oxide of chlorine, iodide of nitrogen,  the fulminates, &c.   It
is easy to conceive that  such substances, when  in contact
with others, also in  a state  of action,  must immediately
* Liebig. 
            VEGETABLE AND ANIMAL  PHYSIOLOGY.        41

 disturb the chemical equilibrium of the latter.   Deutoxide of
 hydrogen belongs also to this  series of compounds.  But the
 greater part of chemical substances do not disturb this com-
 bination—this  state of  neutrality or of equilibrium,  among
 the forces in other substances—unless  they themselves  can
 combine  with  one or more of  the  elements  of those  sub-
 stances.  Sulphuric acid readily separates oxygen  from per-
 oxide of manganese ;  but it does so only because it can com-
 bine with the protoxide.  Heat, light, electricity,  &c,  may
 put  the molecules in motion,  and cause the  production of
 combinations which are  different in kind, according as these
 agents  are  more  or less intense in  their action;  but in or-
 ganic  substances  we  perceive  that  a slight disturbance of
 chemical action  in a part of the substance extends through
 the  mass, or  passes  from the  one  to  the other.   If,  for
 instance, a single spot  of an  organic substance is put into
 a state of putrefaction, the putrefaction forthwith spreads
 through the whole mass.  If a piece of rotten wood be united
#with a sound piece, the latter will quickly become rotten also.
 Thus  the disturbed action of organic forces disturbs others
 in their turn.   What we perceive in  crystallization  and in
 the  explosion  of  gunpowder,  is connected with this princi-
 ple.  A fluid may long remain uncrystallized ;  but when  one
 crystal is formed, a great many others often succeed.  If a
 grain of gunpowder in the midst of a  large quantity is in-
 flamed, the action spreads through  the whole mass.   For the
 same  reason we  perceive in organic  digestion the  appear-
 ance of biline, as a principal substance from which a chemi-
 cal  action, affecting  the assimilation,  proceeds.   It is very
 easily transformed and  changed into  bili-fellinic  acid  and
 cholic acid.   This is very strikingly  illustrated  in every kind
 of fermentation.
   Fermentation.—A great many organic substances, if expos-
 ed in a fluid state to a determinate  temperature,  exhibit an
 internal motion,  produce bubbles  of gas, and  at the same
 time are chemically changed.   Such is the case  with all kinds
 of sap from plants,  especially those which contain sugar.
 This change is caused by organic  substances entirely differ-
 ent from  each other, but yet very complex.  In proportion as
 an organic substance consists of a more complicated group of
 other compounds, formed of variously arranged elements, all
   Vol. I.                  4* 
42                 THE  CHEMISTRY OF
combined into one whole,—the more easily are these elements
transformed, the less powerful are the uniting forces, and the
more readily are new combinations  produced.  Among such
substances are to be reckoned albumen,  fibrin, animal  gela-
tine,  vegetable albumen,  gluten, and all the  substances in
which these are contained.  When one of them is mixed with
saccharine  matter,  the  phenomena  above  mentioned  soon
manifest themselves, and what we call fermentation commen-
ces.   According to Liebig, the sugar is changed into carbonic
acid  and alcohol,  by the distribution of the  chemical  forces,
which previously kept the atoms of the sugar together.   This
disturbance  is an effect  of decomposition in one of  the said
complex substances ; which decomposition is continuous, and,
so long as it lasts,  disturbs all  the organic  chemical forces
around.  If this opinion be correct,  then either the albumen
must always be in a state of decomposition, or the fermenta-
tion does not begin until these complex substances enter into
decomposition themselves; and the decomposition of albumen
must  therefore depend  upon something else.  The  former
view is not confirmed by observation, because it is impossible
that these complex substances should be produced and decom-
posed at the same time.   They could not be formed into the
organic substance, and  exist  at the same time in a state of
decomposition.  Moreover it is also indicated by observation,
that they may be kept for  some time out of the organic sub-
stance,  which produces  them, without the   manifestation of
any phenomena of decomposition.   If, for instance, they be
dried, they may be preserved for an indefinite  time.  It is
not determined, whence the decomposition  in these complex
substances  proceeds.  The forces which keep them  united,
have a chemical character, and they cannot  be disturbed by
any other than chemical forces. Thus the enigma still remains
without a solution.   A cause still requires to be indicated, by
which the first motion of the molecules in these complex sub-
stances is originated—as, for instance, when, after being dried
or preserved  for a long  time, they  are  put into sugar and
water, and  produce a fermentation.   According to Liebig,
yeast is always in a state of decomposition,  and this decom-
position is transferred to other substances, comprehended in
the circle of action, more especially sugar ; but still the ques-
tion remains, how does yeast enter into the state of decompo- 
VEGETABLE AND  ANIMAL PHYSIOLOGY.
43
sition ?   Why does the same change among its elements take
place in  yeast, as yeast communicates to sugar ?   Is  there
still  another  substance  which causes  the  decomposition of
yeast, in the same  manner as yeast causes that of sugar ?  If
we effect the change of sugar into carbonic acid and alcohol,
by means of  gelatine,  which has for  years been preserved
unaltered and in a state of non-decomposition, then the  ques-
tion is,  how  does  the decomposition of gelatine commence,
whenever by its agency the formation of alcohol—that is, fer-
mentation—is effected ?  By what cause is it  brought into
that state ?  Here  we must pause, for we can give no sure
explanation.   We  may  however assume, with Leibig, that
very complex bodies contain atoms, loosely combined, which
are decomposed by external causes,  as easily as the fulmi-
nates.*   A determinate temperature is, no doubt, to be  reck-
oned among  these external  causes;  a  temperature which
need not exceed the average temperature of the atmosphere,
and  so  may  be what we call  a low temperature,  but which,
nevertheless, is as  capable of changing complex combinations,
as one more elevated is of transforming all the organic bodies
into  a large series of pyrochemical products, whose charac-
ters  entirely depend on the temperature.  If we observe, that
the elements of organic substances are brought into different
chemical states by different temperatures, so as to unite into
new combinations, we may ascribe a  catalytic influence to
heat.  If this be applied in reference to those plants, the  func-
tions of which are suspended in winter, and which are revived
by the warmth of spring, and if it be extended  to all the sub-
stances,  which are more or  less dependent  on the influence
of temperature, then we should seem entitled to assume heat
as the primary source of chemical' change in the component
parts of complex organic substances ;  a change which,  once
originated, may be transferred to other substances.  To heat,
then, we ascribe catalytic action; and thus the commencement
of decomposition in yeast is attributable to a determinate cat-
alyzing  temperature.
  Complex organic substances are easily transformed  by a
change of temperature, and this transformation is easily  com-
  * Scheerer has proved, that fibrin, if placed in oxygen, absorbs it, and
produces carbonic acid.  (Ann. der Chem. und Pharmacie, 1841.) 
44                 THE CHEMISTRY  OF
 municated  to  other organic substances, with which they are
 in contact.   We are entitled to hold this as positively proved.
 According to our observation, therefore, we place the primary
 source of chemical action,—proceeding from complex organic
 substances, and transferred to others,—not in those substances
 themselves, but in the temperature.  We call the temperature
 catalyzing, then, in the same sense with Berzelius, as having
 the power  of modifying the  chemical forces which are hid-
 den in the elements, and which unite them into one whole—
 strengthening those forces in some cases, and weakening them
 in others, so as to disturb the equilibrium, and  produce new
 substances,—just in the same manner as spongy platinum ex-
 cites hydrogen and oxygen to enter into combination,'as sul-
 phuric acid converts the elements of alcohol  into water and
 oxide of ethyl, and as  the same  acid converts sugar into the
 humic and formic acids.
   The chemical forces which can be excited in inorganic sub-
 stances by this decomposition of organic bodies, are sometimes
 governed by  laws, different from those which usually obtain
 in mineral substances.   If, for instance, sulphate of soda, of
 which the elements are firmly combined, be exposed to the
 influence of a putrefying  substance, carbonate of soda and
 sulphuretted hydrogen are the results.  The carbonic acid is
 produced by the fermentation of the substances  in  putrefac-
 tion, but contrary to all ordinary chemical laws, the sulphuric
 acid is decomposed ; it loses its oxygen ; and at the same time
 the water is decomposed, its hydrogen combining  with the
 sulphur.   The decomposing action  of organic substances is
 thus transferred to those which are inorganic,  and even alters
 their ordinary chemical forces.*
   If we see such a transformation taking place among strongly
combined atoms, then the atoms of organic substances, loosely
combined, may, by the same means, be still more easily trans-
formed.  This  remark applies especially to such as  are so
feebly combined as to  be immediately separated from  each
other,  and made to assume a new arrangement by the slight-
est action in  which they are involved.   This transformation
takes place  the more  easily, because  the organic chemical
forces act upon others of a similar kind.  Hence the  easy
* Treatise on the Waters of Amsterdam, 1826. 
           VEGETABLE AND ANIMAL  PHYSIOLOGY.        45

conversion of sugar into alcohol and carbonic acid, or, in other
circumstances, of  sugar  into lactic acid and into mannite, of
alcohol into acetic acid, &c.
  It appears  from the variety of changes to which  sugar
is subjected by different  agents (converting it into alcohol,
ulmic, oxalic, and  saccharic acids), that its elements are very
loosely combined—more loosely,  indeed, than the elements
of many other substances.   We perceive something similar
in oil of cinnamon.  New products are continually formed in
this oil by the influence either of the air or of different acids—
namely, hydruret  of cinnamyl, cinnamic acid, and a great
many resinous substances.   In every case,  the  elements of
sugar  persist in their combination till decomposed by some
force.   Thus in the decomposition of sugar a force must be
subdued.   In the alcoholic  fermentation, the force  by which
this is effected proceeds from the yeast, but is undoubtedly to
be ascribed originally to heal.  Heat  is the pulse of life in
the chemical  changes of bodies,  and has thus an unlimited
influence upon their chemical combination.
   Substances containing  nitrogen are most liable to that kind
of decomposition,  during which the  decomposing  action is
communicated to  others also.  Nitrogen  has a strong ten-
dency to extricate itself from combination, owing to its char-
acter of indifference.*  Explosive  bodies  contain nitrogen
—for example, the iodide  of nitrogen, and the fulminates.
It is only with hydrogen  that it  easily combines,  forming
ammonia.  The chemical equilibrium of the elements is dis-
turbed from  the  very moment that the production of am-
monia commences, and then the action may be transferred to
other substances—the fulminates, and  hence their  rapid de-
composition.   Organic substances  containing nitrogen,  if in
contact with water, produce ammonia, and in consequence of
the formation of ammonia,  the carbon  and oxygen combine
into carbonic acid.
  Thus yeast,  as  well as  other substances containing  nitro-
gen, requires water to produce fermentation—that is, first, to
produce ammonia and carbonic acid,  and afterwards to excite
thereby a new disturbance  of the  chemical  forces in  other
substances.  The decomposing forces arise from the decom-
* Liebig. 
46                 THE CHEMISTRY OF
position of water and of organic matter—from the formation
of ammonia and carbonic acid.   Liebig  gives an  interesting
proof,  that those substances which can be  wholly  changed
into ammonia and carbonic  acid, may also  be  decomposed
with great facility.  The cyanic acid belongs to that class.
When dissolved in water, it is suddenly decomposed  into car-
bonic acid and ammonia.
1 cyanic acid -|- 3 water = 1 ammonia -{-  2 carbonic acid.
   NC20    -f  3HO =    NH3    +     2C°2
  One equivalent of carbonic acid (CO2),  passes  off with
effervescence, and the water retains carbonate  of ammonia
(CO2 and NH3)  in solution.  Complex organic  substances
are decomposed  the more easily the nearer they approach to
a combination, which on decomposition can produce ammonia
and carbonic acid.  Such, according lo Liebig, should be  the
case with substances which  produce fermentation.  The  ac-
tion of alkalies upon them proves, that they either contain or
easily produce ammonia, for the alkalies all liberate ammonia
from those substances, viz. from albumen, fibrin, and  the like.
But the composition of these latter substances differs remark-
ably from that of bodies in which  the carbonic acid repre-
sents the principal part, after the ammonia is abstracted.
For instance, if from  1 equiv. of protein,    C40H31N5013
We take    .     .  5 equiv. of ammonia,     H15N5

There remains,.....C*°H16   O12
  The composition of this remainder  is very different  from
that of carbonic  acid.
  These substances, however, absorb oxygen very easily on
decomposition, a  fact which has recently been proved of fibrin
and albumen.*
  When sugar is brought into a state of fermentation by  the
influence of yeast and a moderate  temperature,  (59°—67°
Fahr.)  alcohol and carbonic acid  are always the product:
and so with many saps containing sugar ; for instance,  the
sap of fruits,  beet-root,  carrots, onions.   But if these are
made to ferment at a temperature between 97° and  104°
Fahr., other products are formed.   The albumen  and gluten
of the sap are then wholly decomposed,  so that all the nitro-
* Scheikundige Onderzoekingen, Deel I. 
VEGETABLE AND ANIMAL PHYSIOLOGY.         47
 gen remains in the liquid in the form of ammonia.  With this
 alteration in the influence,  lactic  acid, mannite,  and a gum-
 like substance are produced from the sugar, instead of alcohol
 and carbonic acid;  gases  at the same time being  evolved.
 Thus it is evident, that  the decomposition of the sugar en-
 tirely depends  upon the state of the gluten and  albumen in
 the sap of plants, which bodies  are both  changed  into the
 chief constituent of yeast during the  alcoholic fermentation.
 It is also evident that yeast, if subjected to  a decomposition
 different from the ordinary  kind, forms entirely new  products
 which  are not at all analogous to those formed by the alco-
 holic fermentation.  Hence it is clearly proved, that the gen-
 eral idea of the molecules  being put  in motion, is not suffi-
 cient to explain the formation of alcohol and carbonic acid
 from sugar.   That motion  on the contrary must be  of a pe-
 culiar nature, and such  as to affect the molecules of sugar in
 one determinate mode for  the formation of alcohol  and car-
 bonic  acid.   The alcoholic  fermentation can  be produced
 only  by the most simple  transformation of yeast.   This trans-
 formation consists in the production, first of acetic acid, then
 of carbonic acid, and probably at the same time with the lat-
 ter, of ammonia.   If  this  transformation be  checked, yeast
 has not the  power either to excite or to maintain fermentation.
 The power  of yeast is  destroyed or paralyzed, by drying it
 highly, by chloride of mercury,  nitrate of silver, sulphurous
 acid, and creosote.  Yeast is also incapable of producing, or
 at least of originating, fermentation, without the aid of the
 oxygen of the air; for if the air be completely excluded, no
 fermentation takes place.
   Very incorrect ideas  have been formed as to  the  peculiar
character  of yeast.   From several analyses which I have
recently made,  I am quite  convinced  that it is a minute cel-
lular plant consisting of isolated cells.  These little plants are
utricles of a  substance  nearly approaching  to   cellulose—
woody  fibre—in its  properties and  composition, though  in
some  respects it is different.  Its composition is C12H10010.*
* Scheikundige Onderzoekingen, Deel II.
                Found.          Atoms.        Calculated.
    C           4500             12            44-92
    H       .     611             10             611
    O   .    .    48-88             10            48-97
It contains no nitrogen. 
48
THE  CHEMISTRY  OF
It is insoluble both in cold and in boiling water ;  it is not con-
verted into  xyloidine by nitric acid,  but  is  readily changed
into  humic acid by hydrochloric acid, and  is easily soluble
by strong caustic potash at the ordinary temperature.  Its
composition cannot by any means be reduced to that of cel-
lulose.
  These utricles  contain  a protein-like  substance, which is
neither gluten, for it is insoluble in boiling alcohol; nor albu-
men,  for it is with great difficulty soluble in acetic acid.  In
boiling water it may be pretty easily obtained in such a state,
that it may be regarded as a highly oxidized protein. Thus—

SU te^ froemePeaarsat' (= 1 Protein       + 8 °Xygen + 6 Water<
 C40H37N5O26' = C40H31N5012-f   O8   +  6HO.
  The protein in these utricles, however, exists in such a state
that  its composition approaches to  that of  fibrin, albumen,
and casein ;*  that is to say,  when it was extracted by acetic
acid  and precipitated by carbonate of ammonia, its composi-
tion appeared to be analogous to that of these substances.t
  The substance approaching to cellulose,  which forms the
bag or utricle of the yeast plant, does not assist  fermentation
During that action, the  protein compound penetrates exosmo
tically through this membrane, the utricles  decrease in bulk
contract, and at last remain behind in the form  of collapsed
wrinkled globules,  much smaller than they originally were
The   protein compound when expelled,  soon undergoes de
composition, to  which at a certain temperature  it is exceed
ingly liable.  It leaves nothing behind, but  ammonia and  a

  * Scheikundige Onderzoekingen, Deel  II.
                  Found.         Atoms.         Calculated.
      C  .    .    4335            40            4365
      H  .    .     6-56            37             650
      N       .    1268    .    .     5    .    .    1264
      0  .    .    37-41            26            3712
  t Scheikundige Onderzoekingen, Deel II.
                                           Found.
           C......5435
           H......704
           N......1603
           O......2258
  The sulphur and phosphorus have not been determined. 
VEGETABLE AND ANIMAL PHYSIOLOGY.
49
quantity of extractive  matter which has not yet  been suffi-
ciently analyzed.   Thus—
    From protein,     .     .     .     O°H31N5012
    Take ammonia,   .     .     .        H15N5

    There remain,    .     .     .     C40H16   O12
  Thus it is evident, that  heat  is the  primary cause of the
phenomena of fermentation.  The protein compound in yeast,
a very complex body in common with many other substances,
such as hydrate of deutoxide of copper under water, &c, has
a temperature which  forbids its  permanence  under water,
and induces decomposition.  This decomposition is transfer-
red to the sugar, and  resolves it into carbonic acid and alco-
hol.   During this decomposition, especially at the commence-
ment, a small quantity of oxygen is absorbed.  This absorp-
tion is not the cause, but the  first effect resulting from the de-
composition of the  protein compound which exists in yeast.
Thus all that has been stated as  to the chief  constituent of
yeast, holds good also with  respect  to  yeast itself, provided
we regard the  cellular membranes of the yeast globules as
having no influence whatsoever upon  fermentation,  but as
being only  the  vessels to  contain  the protein  compound.
They are left behind insoluble when fermentation is finished.
  During the fermentation of sugar  by means  of yeast, part
of the latter is decomposed,  though its component parts con-
tribute nothing to the formation of alcohol;  neither do they
to any perceptible extent add to  the quantity of carbonic acid
produced.  For Thenard has found  that 100 parts of sugar
yield 51*27 of carbonic acid, and 52-62 of absolute alcohol,
making together 103-89.  One equivalent of water, however,
is combined with sugar when crystallized, C^H1 101 *, which
thus gives nearly the same amount.   In my experiments, 20
parts of yeast which had caused  the fermentation of 100 parts
of sugar, left behind 13*7 parts of insoluble matter, which
being again put in contact with  sugar, left behind 10 parts of
insoluble matter, which  had  no  further power of producing
fermentation.  It has been elsewhere stated,  that the yeast is
also  decomposed during fermentation.   But  a  very small
quantity of yeast cannot bring a large quantity of sugar into
fermentation; while on the other hand, the decomposition of
  Vol. I.                  5 
50
THE  CHEMISTRY  OF
 the yeast still continues after  the  transformation of a small
 quantity of sugar into alcohol and carbonic acid.*
   This power, either of yeast or animal matter, to change
 sugar into alcohol and carbonic acid, has been justly traced by
 Liebig to the same principle with many other decompositions.
 If,  for  instance, the fresh urine of the horse  be evaporated
 and saturated with an acid, hippuric acid is produced ;  but if
 the urine be kept for some days, the  product is not  hippuric,
 but benzoic acid.  If fresh human urine be saturated with ni-
 tric acid, we get nitrate of urea ; if the urine be putrescent, we
 have carbonate of ammonia.  Amygdaline is changed by yeast
 and sugar  into prussic acid.t   If mallows be macerated in
 lime-water, we get asparagine after  evaporation ; but if the
 solution  be  put in contact with yeast, we  get aspartic acid,
 combined with ammonia.
  A great many organic substances, when exposed to a fixed
 temperature and to  moisture, are decomposed into new pro-
 ducts, which also can be formed by ordinary chemical means.
 For instance,  the natural change of  woody fibre into humic
 acid and other substances, may be produced also, if sulphuric
 acid be  made to act  upon woody fibre.  It is not a real fer-
 mentation,  but a transposition of the  elements, analogous to
 that which  takes place  in yeast.  If wood undergo decay
while lying  in water  containing salts  of sulphuric  acid and
iron, sulphuret of iron is deposited upon the solid substances,
whilst the rotting wood is converted into humic  acid.  This
sulphuret of iron is  produced  from the sulphur of the sul-
 phates, and  from  the iron of the iron salts.   Some substances
very rapidly undergo the alteration, which causes the produc-
tion of  humic  acid  from woody fibre.  Tannic acid, for in-
stance,  if exposed to the air, is very quickly converted into
apotheme of tannin;  and in like manner extractive matter is
converted into apotheme, by the influence  of the oxygen of
the  air  and a more   elevated temperature.  It is a similar
 transformation to that which  takes  place in  substances con-
taining nitrogen, such as yeast, &c, but of course it is  inca-
  * Liebig.
  t We must persist in calling the action of emulsine upon amyda-
line,  catalysis, till it be ascertained  that emulsine is in a state of de-
composition, and immediately communicates that to the amygdaline 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.         51

pable of producing any ammonia if they contain no nitrogen.
During this transformation, oxygen is  always absorbed, and
sometimes  only one or two new substances are  produced ;
such as when acetic acid and water are formed from alcohol
by the agency of  the oxygen of the air.  Thus—
     1 acetic acid -f- 3 water = 1 alcohol -j- 4 oxygen.
       C*H602  +   3HO  = C*H602 -f-    O*.
  By the oxidation  either of tannin or of extractive matter,
however, carbonic  acid  is also produced, and equal in vol-
ume to that of the oxygen absorbed.*  The elements in such
substances  are very loosely combined, and tend to produce
other substances,  which  combine  more  intimately.   They
have thus a tendency to act externally, and eagerly attract all
the oxygen with which they are in contact.   This state, which
is like that  of hydrate of protoxide of iron,  hydrate  of pro-
toxide of manganese, sulphuret of potassium, and many other
inorganic substances,—we indicate by the too limited expres-
sion of tendency  to oxidation.  The greater number of or-
ganic chemical substances are transformed in consequence of
this tendency.  Such  is  the case with the solutions of vege-
table acids  in water, which, if exposed to a certain tempera-
ture, can produce a series of new substances,  such as citric
acid, tartaric acid, &c, and others even of an organic nature,
such  as  mouldy plants.   If the substances  be of a complex
character,  they are still more easily  transformed.   Such is
the case, for example, with wood, which in certain circum-
stances,  is  subject  to very rapid decay—dry rot—caused by
the albumen which it contains.  The alkalies, especially, are
capable of  promoting in some substances this conversion of
elements.  Gallic acid, for instance, when in contact with an
alkali, is rapidly changed into a brown matter; so salicylate
of potash is  changed  into Acetic and  melanic acids,  by ab-
sorbing three of oxygen  (O3).
  Fat oils and other fatty matters in this manner produce nei-
ther a mixture of different substances, nor carbonic acid, but a
fatty acid.   Almost all the volatile oils form resins, the pro-
ducts of  oxidation by  the air.  Other  examples are afforded
in the transformations of orcine, phloridzine, &c, when in
contact with air and ammonia, producing blue colors  from
* De Saussure. 
52                 THE CHEMISTRY OF
white substances.  So  in the transformation of protein with
4 of oxygen into humic acid and ammonia :
   One of protein, with four of oxy- ) Q4ojj3 iN5CM2-f-04
     gen,                         )
   Are equal to 1 of humic acid,      C40H^   015+HO
   And five of ammonia,                  H15N5
   I repeat, that all these transformations correspond to such
ordinary phenomena in inorganic chemistry, as the oxidation
of iron, potassium, &c, in the air.
   This transformation has been  compared to combustion; and
whether hydrogen only, or carbon only, or both, be combined
with oxygen, it has been called  combustion.  It does indeed
resemble  combustion.  But  there is this difference between
combustion and such a transformation of substances, that the
former is a complete conversion, effected by a more elevated
temperature,  while  the other phenomena are produced by a
mere disturbance in the equilibrium of chemical forces. These
forces are modified, while the vital functions of the animals
or plants, to which the substances belong, are in action ; they
are still present  in certain circumstances,  in which  they are
not sensible—as when the body  is dry,  and is kept  at  a  low
temperature; but they are disturbed by heat and  moisture,
especially the former, so as to make room  for other forces.
Among these new forces, the tendency of hydrogen and carbon
to oxidation then appears.  These  forces  come into opera-
tion as soon as the others are at rest.  They come into full
operation if a great disturbance is effected by powerful causes,
such as when a burning substance is  brought near the organic
one ;  they are, however, but partially brought into operation,
if a different  set of atoms of carbon,  hydrogen or oxygen
meet  each other in such a proportion as to produce a new and
intimate combination.  This is clearly illustrated by the change
of sugar into alcohol and carbonic acid.
   It must not be thought, however,  that this power of affect-
ing substances resides peculiarly in oxygen.   If our  atmo-
sphere consisted either of chlorine,  or of vapors of bromine
only,  the  power of these  substances to disturb a  chemical
equilibrium, (or to form promptly, in case of a disturbed equi-
librium, a combination with substances present,) would  be
much greater than  that which we now  perceive  in  oxygen.
All these phenomena of oxidation, either in organic or inor- 
          VEGETABLE AND ANIMAL  PHYSIOLOGY.        53

ganic substances, ought not therefore to be classed as a deter-
minate and peculiar series.   They must be  referred to ordi-
nary chemical action, dependent in a great measure on the
influence of the circumstances in which a substance is placed.
This action is always terminated by the operation of the chem-
ical tendency, the production of a state of equilibrium.
  The peculiar forces of the elements must, therefore, be
classed among the principal causes of the conversion of or-
ganic substances into others, accompanied by the attraction,
for instance, of oxygen.  This tendency to combine with oxy-
gen  is not exhibited by free  carbon and  hydrogen at  the
ordinary temperature, but  may be  excited  in both  by heat,
and  in hydrogen  also by spongy platinum.   We  see these
forces very active in  potassium and  sodium, in phosphorus
and many other substances.  Hence it appears, that such sub-
stances act in the same manner (i. e. attract  oxygen), without
the aid  of any new external circumstances, as  carbon  and
hydrogen  do when under combustion, or when accompanied
by the conversion of organic matters.  As soon,  therefore, as
carbon and hydrogen cease to be influenced by those chemical
forces which modify them in the organic kingdom, they yield
to what is  originally their most powerful  tendency ;  they com-
bine with  oxygen in the same way as  the nitrogen  of yeast
combines  with hydrogen and forms ammonia.  So far, there-
fore, as the arrangement of the organic molecules is changed,
when bodies begin to decay or undergo any similar transform-
ation, the  change depends partly on that primary tendency of
the elements, partly on  the possibility of  forming  such new
and intimate  combinations of the elements, when  otherwise
arranged,  as cannot  be again disturbed in  these  circum-
stances, but can be decomposed only by more powerful causes.
  The alteration in wood, which is called mouldering, does not
essentially differ from putrefaction.  So far, however, it is
different,  that during putrefaction, hydrogen combined with
carbon is  given off in the form of gas,  while in the former
case only  oxidation, either of carbon only,  or of carbon  and
hydrogen, takes place.  Hence it appears that, properly speak-
ing, in mouldering, the elements slowly obey their most pow-
erful tendency, yielding to the strongest forces which  they
possess; and on the  other hand, that the formation of wood
is the effect of a chemical  action in an opposite  direction.
  Vol. I.                   5* 
51                 THE CHEMISTRY  OF
   The question is, whether during decomposition the organic
 forces grow weaker of themselves, permitting the elements to
 obey their primary tendency,—or whether causes must exist
 by which these organic forces are made weaker ?   Neither is
 improbable.   Every thing which ceases to be subject to the
 vital principle, becomes incapable of being stimulated by the
 vital forces ;—it is placed in other circumstances ; and as the
 products of the vital functions are different from the products
 of inorganic nature,  in  consequence of the very difference
 of the circumstances in which the elements are placed, so
 the products of substances, deprived of vital influence, must
 also greatly vary with circumstances.  Hence it may happen,
 that the forces present in  organic substances,  when deprived
 of the  vital  influence, may disappear  of themselves.  The
 impression they  had at first received  is changed,  modified,
 obliterated, and therefore the effects can no longer be the
 same.   A substance persists in  the state into which  it was
 first put,  according to the  law of  inertia ;  but the maxim,
 sublata causa tollitur  effectus, is of equal value.   The vital
 action,  which we  express by the  collective name of circum-
 stances, confers  a certain  tendency upon  the molecules,
 which in many substances disappears whenever the molecules
 are withdrawn from its influence.
   If but a small disturbance of chemical equilibrium has oc-
 curred, that is to be regarded as a focus or centre, from which
 the action extends.  A small  piece  of  mouldy wood infects
 a whole mass, acting in the  same manner as yeast in fermen-
 tation.
   What is the cause to which this disturbance is attributable ?
 There is  proof that it is caused  by temperature ;  neither
 fermentation,  nor  putrefaction, nor chemical action, taking
 place without  a determinate  temperature.  But  though this
 temperature be present, another substance is required to ex-
 cite such actions in a certain degree.  In  every kind  of fer-
 mentation, this disturbing property, as  has been proved, is
 possessed  by oxygen.   The first phenomenon observed either
 in a fermenting or in a putrefying substance, is the absorp-
tion of oxygen.  Without oxygen no putrefaction, no fermen-
tation takes place.  This has been ascertained by Gay-Lussac.
He kept the juice of grapes for some days over mercury • it
did not ferment, but the introduction of one bubble of oxygen 
           VEGETABLE AND ANIMAL PHYSIOLOGY.         55

 was enough to originate fermentation,  which then proceeded
 spontaneously.  A single bubble is thus required  to  bring a
 force to the juice of grapes, capable of disturbing in a small
 part of it the organic forces, excited by a certain temperature.
 In the other parts, disturbance is effected by the new products
 in their turn, and is transferred  through the whole mass, so
 that a decomposition  of  sugar and water into alcohol  and
 carbonic acid takes place.
   Upon this  principle the preservation of meat, vegetables,
 &c., in vessels exhausted  of air—generally by ebullition—is
 founded; so is the  method introduced  by Appert, of boiling
 vegetable saps in bottles, well corked, for the purpose of ta-
 king away the oxygen of the small quantity of air left behind,
 and of uniting it with part of the substances; and also for the
 purpose of disturbing  by the ebullition, part of the chemical
 forces, especially those in  the dissolved albumen,  which be-
 comes  coagulated  when boiled.  On  the same principle de-
 pends the sulphuration of sweet wines or of juices of fruits,
 by the application of sulphite of  potash, the sulphurous acid
 (SO2) being easily changed into  sulphuric acid (SO3).
   This auction of oxygen is very much promoted by alkalies,
 though we know not  how.   But  it  is perceived in orcine,
 phloridzine, and salicylous acid.  Alcohol, if it retain  any
 alkali in solution, produces acetic and formic acids, besides a
 brown substance, absorption of oxygen being a uniform ac-
 companiment.  A substance which  is easily decomposed, also
 readily changes alcohol into acetic acid, with absorption of
 oxygen.   Hence alcohol, when exposed to the air, is in  like
 manner changed into acetic acid by a little honey, malt beer
 or acid wine.  On this principle depends the method of prepar-
 ing vinegar by the quick process  now practiced  in Germany.
 The substances added  begin first to decompose, and when in
 that state communicate to  the elements  of alcohol the ten-
dency to transpose themselves also, and to assume a new order
 in connection with  the oxygen  of the air.*  Some organic
 substances, however, if merely present, can act here also by
 the forces which proceed from them, without being themselves
altered ;  and a real catalysis may thus  take  place.   This ap-
 pears from what occurs, when vapors of alcohol are  brought
* Liebig. 
56                 THE CHEMISTRY OF
in contact with spongy platinum, the supply of air being im-
perfect.  The spongy platinum then becomes hot;  water and
aldehyde  are produced,  with absorption  of oxygen—the
spongy  platinum,  however, taking no part in this process.
If free access be  given to the air, acetic acid and water are
produced.  Thus the same, or  some similar force, resides in
the  spongy  platinum, as in the substances  by which alcohol
may be changed into acetic acid, according to the  method of
Schuzenbach, when  these  substances are  decomposed after
being mixed with the alcohol.
  The formation of saltpetre is regarded by Liebig as an anal-
ogous process.   It is a known  fact,  that organic substances
containing nitrogen, can in certain circumstances produce ni-
tric acid, which forms a nitrate with any base that is present.
Ammonia results from the putrefaction of organic substances
containing nitrogen, and passes off in the form of a carbonate.
The nitrogen combines by  preference  with hydrogen,  and
never directly with oxygen.   It may, therefore, be a question,
how it happens that nitric acid is in this instance formed from
the  combination of nitrogen and oxygen.
  The presence of a base, especially of some alk#i, is indis-
pensable to the formation  of saltpetre.   From the nitrogen,
ammonia is first obtained by combination with hydrogen,  and
this is afterwards changed into nitric acid,—the hydrogen of
the  ammonia combining with the oxygen of the air to form
water, and the nitrogen with the oxygen to form nitric acid,
which is united with  the base  into  a nitrate.  When organic
substances are decomposed by  oxide of copper, deutoxide of
nitrogen (if the  organic  substance contain the nitrogen in
the  state of ammonia) is always formed; but if a compound
of cyanogen be burned in oxygen, the carbon only is oxidized,
and the nitrogen is liberated without the production of nitric
oxide.   Thus nitrogen, when alone, is not combined with oxy-
gen, but only when present in the state of ammonia.*  During
the nitrification,  therefore, nitric acid  is formed, because the
oxygen of the air produces water and nitric acid at the same
time from the ammonia, and  because these two substances
mutually promote the production of each other, while in the
nascent  stale.  Hence it happens, that during nitrification,
* Liebig. 
VEGETABLE AND ANIMAL  PHYSIOLOGY.        57
the animal substances  contribute but the smaller part of the
nitrogen contained in the nitric acid produced, while the greater
part is absorbed  from the  atmosphere, and  so  the organic
substances are  the chief means,  whereby the nitrogen  of
the atmosphere  is changed into ammonia, which is afterwards
decomposed  with absorption of oxygen into water and nitric
acid.  This  is fully proved by the nitrification which takes
place, without organic substances  in putrefaction.   A great
deal of nitrate of lime is found upon old walls, and in all po-
rous substances, which have been long exposed to the atmos-
phere.  In such porous substances  ammonia is not only con-
densed, but produced from the air,  and afterwards converted
into water and nitric acid.   (See Arable Soil, below.)
   On these principles, relative  to  molecules in motion, for
which we are indebted chiefly  to Liebig, several interesting
questions in science are explained.
   The primary  cause, however, of that motion may thus be
briefly described.  Every chemical molecule possesses the pro-
perty of combining with others; such combination is an  ef-
fect of molecular tendency  elevated to a determinate degree.
Tendency, producing combination, arises from various circum-
stances. The presence of a third substance, electricity, light,
heat and vital force,  give  to the combination a determinate
direction—the last producing, for the most part, complex sub-
stances, which are of a peculiar character, because it is gen-
erally  difficult to obtain an artificial  imitation of those circum-
stances.  Ordinary chemical operations are almost uniformly
more simple.  The substances  produced, differ because the
circumstances differ.  Temperature is a powerful exciting
cause  of the chemical  tendency, which effects combination.
To that tendency, we must look for  the primary and principal
cause of what may be called molecules in motion, or, in other
words, molecules in the act  of transposition, possessing a ca-
pacity  for chemical combination, both of which qualities are
indicated by the expression chemical tendency.
  By spongy platinum,—glass at a temperature of 572° Fahr.
—sulphuric acid,—any burning substance,—yeast,—a piece
of rotting wood, actions are produced in  other substances,
attended with consequences which are characterized as chem-
ical, that is, with combination or decomposition. 
58
THE  CHEMISTRY OF
  Whatever is affected by one of these substances, must be
susceptible of such influence.  This  is what we have called
chemical tendency.  The excitation of that susceptibility is
equivalent to the elevation of this tendency to a determinate
degree.
  The object of science is to determine the influence of each
circumstance.  The knowledge of this influence, in the science
under consideration, is the basis, on which all other knowledge
of the cause of combination and decomposition in substances
is founded.  The  term  circumstance  is as yet only a collec-
tive  one,  comprehending very different things.  The reduc-
tion of all these to their proper place in  science we can  ex-
pect only  from future times.

                  § 2.  Organic  Forces.

   A.  Connection between Organic and Molecular Forces.

  All vegetable and animal substances are composed of those
bodies, which in  chemistry are called elements, and which
combine with each other in very different ways.   The ques-
tion  now to be considered  is, whether  the  organic  forces,
which operate  in the organic kingdom, depend either in whole
or in part on the molecular  forces of  the elements.  This is
indeed a question difficult of solution.   We shall see how far
science in its present state, enables us to  reach a satisfactory
result.
  If we assume, that an organic whole is governed by a gen-
eral  force called vital force, then we  ascribe  to that whole
something which is not learned from  observation.   We per-
ceive an aggregation of  phenomena,  which we comprehend
in a  general idea, expressed by the term  life, but that idea is
a concrete.  It consists of a multitude of parts.   The func-
tion of every organ, though a function of life, has an individ-
ual existence,  in some  respects separate  from the aggrega-
tion,  in others not.  The  function of  the liver is not depen-
dent, and yet it is dependent, on  that of the kidneys;—not
dependent, because the liver has within  itself the power of
secreting the bile, with the requisite organs ;—dependent, be-
cause any great disturbance of the function of the kidneys, 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.        59
 influences,  and may even prevent the  secretion of the bile.
 The idea of health implies, as the principal condition, an un-
 disturbed function of each organ and of the whole.   The idea
 of life implies, as the principal  condition, the  exhibition of
 the  chief phenomena,  the  subsistence of the chief actions,
 proper to this whole.
   The entire organism, and  consequently each  organ, each
 part of any organ,  consists of elementary substances, which
 not only are individually supplied with  indestructible forces,
 but  may possess  these under  very different modifications.
 Oxygen, hydrogen, carbon, nitrogen, iron, sulphur,  phospho-
 rus, and iodine, are the substances which by mutual combina-
 tion produce organic  bodies; but to these are added a great
 many  other substances, which are  seldom wanting in living
 organic bodies.  A  great many acids,  bases,  and salts,  are
 there present, which are just  as indispensable to the existence
 of organic substances, as the  eight elements above mentioned.
 Albumen, for instance,  is an albuminate of soda; casein  is a
 combination of protein with sulphur and phosphate of lime ;—
 in a word,  the intermixture of  substances in the organs,  and
 so in the organism, is not a simple but a complex one.
   All  these elements and compounds are severally accom-
 panied by forces of their own.   Their materiality is by no
 means to be called their chief characteristic, but that by which
 matter is governed, i. e. its peculiar force.   They all manifest
 themselves as adapted for mutual combination,  and appear
 after such combination as new substances,  of which the forces
 are again modified,  and applied  by the chemist to produce
 new combinations.
   If we  pass in review the substances present in the organic
 kingdom, we perceive an endless  series of combinations from
 either two or three or four elements only.   This is enough to
 show that there is an unlimited capacity  for modification in
 the primary forces which operate in the elements.  The influ-
 ence of one element  upon another is thus unlimited also.  A
 slight difference in the state of an  element  is sufficient to give
 it the appearance of a new and entirely peculiar substance,
as compared with the other elements.   Let us take, for exam-
 ple, starch, gum, sugar, acetic acid, glucic acid, inuline.   All
these are composed of the same elements, taken in the same
proportions.  Thus they consist severally in equivalents of 
60
THE  CHEMISTRY OF
                   Carbon.  Hydrogen.  Oxygen.     Water.
    Starch,   .    .    12         9        9    +    HO
    Gum,    .    .    12         9        9    +    HO
    Sugar,   .    .    12         9        9
    Acetic acid,  £ X 12         9        9
    Glucic acid,  £ X 12         9        9    —  l*HO
    Inuline,   .2X12         9        9    +   2HO
  The carbon of one of these substances is no doubt equal to
the carbon of any of the others, in so far  as  it exhibits the
same properties if separated from its combination.  But it is
incorrect to  suppose that the carbon, hydrogen,  and oxygen
in sugar, are identical with those in  acetic acid ; for there is
a great difference  between sugar and  acetic acid, and we
cannot attribute this difference to any thing but to the differ-
ence of the forces by which the same substance is governed.
Thus the  carbon, hydrogen,  or oxygen, is  not in any two
cases supplied with the same  properties.  They assume in
each substance a peculiar form.   The general  idea, compre-
hending carbon, hydrogen, or oxygen,  in  sugar and acetic
acid, must therefore be modified, because the forces peculiar
to matter must  necessarily be modified, as matter  is  itself
unalterable.
  This will  appear clearly, if we consider the  combinations
of carbon with hydrogen.   If we supposed  the carbon and
the hydrogen  in C5H*,  C10H8, C15H13, C20H16,  to be
always the same, we should be constrained to assume the
identity of the substances,  and any distinction  would be im-
possible.*   Among the elements we  know a  considerable

  * The term impossible here used, appears to me to be too strong. It
restricts more than is necessary the powers of the elementary bodies to
form compounds possessed of different properties.   If into the  simple
combination CH, one  of the  elements, say C, enters in  two several
ailotropic states, C and C  we can readily understand that C H and
CH would or might be different substances, the  peculiar properties
of which arose from the peculiar state in which the C existed in each.
This is Mulder's view, generalized from the very interesting facts con-
tained in Berzelius' paper upon the combinations of sulphur with phos-
phorus, to which he subsequently refers.  The idea is very simple and
very beautiful, and throws a new light upon the  combinations of the
organic kingdom.
  But how do the ailotropic states of the elementary bodies themselves
arise?  It  is the effect of circumstances, which are  special for each 
             VEGETABLE  AND  ANIMAL PHYSIOLOGY.          61


 number which, without entering into  any combination, pre-
 sent an entirely different  appearance  in  consequence of but
 a slight  difference in the circumstances under  which they
 are placed.   For  example,  phosphorus becomes black when
 heated and then suddenly cooled ;  and  by means of  a red
 heat merely,  silica is  so modified, that the substance after
 and before the application of such heat,  might be taken for
 two different substances if we looked  to  its properties only.
 The interesting experiments  recently made by Berzelius as
 to the ailotropic character of phosphorus, have opened a new
 path for  scientific  investigations.   If the simple  substances
 can assume the permanent appearance of unlike bodies with-

 state, upon the forces of cohesion which  reside within the similar mole-
 cules.  Of course, we cannot describe the way  in which different cir-
 cumstances act upon the molecules  so as  to produce these different
 states.  It  may be, that under certain conditions the forces become
 stronger in a given direction, and cause the molecules to unite  in that
 direction rather than in another.  And that such  an arrangement, by
 different sides or at different distances, does  sometimes take  place
 among the  elementary molecules, is shown, I think, by the fact,  that
 in their several ailotropic states,  carbon and sulphur crystallize in dif-
 ferent forms.
   Now, if a new and different arrangement of  the molecules cause or
 accompany a new ailotropic state in the elementary body, may it not
 be so also in the compound body ?  If C H  and CH be different sub-
 stances, because in each the  elementary molecules of C are in a differ-
 ent state of arrangement, may not  CsH5 and  C5I15  be different re-
                                 a         b
 spectively from  CaH  and C  II, because" of  (or in connection with) a
 new arrangement of the equivalents of which they severally consist ?
   VVe thus recognize two causes of diversity among isomeric and poly-
 meric bodies.
   1. The different ailotropic states of  the  elementary bodies, these
 being probably caused by a change in the  relative positions or dis-
 tances of their molecules.
  2. A new arrangement, in distance or position, among the equiva-
 lents, whether of simple or compound  bodies,  the ailotropic states of
 the elements remaining the same.                         ,
  3.  Both of these causes may operate together. Some of the equiva-
 lents of C or H  may be in  one state, some  in another,  and they may
 arrange themselves in many different ways, so as, in a complex body
 like protein, to produce numberless diversities or  modifications in ap-
 pearance and properties,  the  ultimate chemical composition remaining
 the same.
  In other words, we may have an allotrope of the elementary mole-
 cules, an allotrope of the compound  equivalents, or a combination of
the two.—J.
   Vol. I.                     6 
62
THE  CHEMISTRY OF
out forming  any combination, their compounds can do  so
much more.  And such  an assumption of other characters
must take place in all cases, in which no other mode remains
of explaining the diversity  of the  compounds,  than in the
supposition of a real difference in  the component  elements
themselves.
  If we apply these  principles to the  known compounds, a
field of boundless extent  is  opened to  our view.  What we
call  protein in animal chemistry,  is a substance which we
know is composed of C40H31N5O12,  which  is insoluble in
water, alcohol,  or ether, but soluble in alkalies, whence  it
can be precipitated by acids ;  and which produces  ammonia
by means of  powerful bases, &c.    But what  meaning do we
attach to all this ? What conception do we form from these
considerations of the  substance itself ?   We have a mere idea
of distinction  in comparison with other substances which have
another atomic composition, and are soluble in water, alcohol,
or ether, which  in other words, possess different properties.
But as little ground have we for supposing, that protein is the
same in  the  very different modifications to which  it is sub-
jected in the  body of animals, as we have for saying that the
carbon in sugar  and  in  acetic acid is governed  by the same
forces.   The carbon  in these two substances cannot therefore
be comprehended under the same idea.
   It is said in physiology, that in the embryo of the  egg there
is nothing but a shapeless mass, which  by decomposition pro-
duces  always the same substance—that  is,  a compound of
protein.   From  this  embryo,  however, is gradually evolved,
during the growth of the egg, a  series of germs of organs,
which are soon developed as entire organs, together compo-
sing the chicken.  A general  force is  assumed—influencing
that shapeless  mass, the embryo, originally existing  as a
whole—and  represented as the same with  that which the
complete animal  possesses.   Muller says :  " The simple em-
bryo, which  consists of a granular  and shapeless substance,
is to be regarded as  the potential whole of the future animal,
supplied  with the essential and  specific  force of the  future
animal itself."*

  * So muss man  die einfache, aus kornigem formlosen Stoff beste-
hende Keimscheibe, als das  potentielle ganze des Spatern Thieres be-
trachten,  begabt mit der wesentlichen und specifischen  Kraft dee Spa-
tern Thieres.  (Physiologie, I, p. 23.) 
VEGETABLE AND ANIMAL PHYSIOLOGY.
63
   No idea can be less distinct than this.  According to Miil-
 ler,  the forces which  will afterwards govern  the  organs  of
 the chicken, should be present before the existence of those
 organs  themselves—before the  production of an  organism
 from the granular and shapeless substance of the embryo.
   If we recur to what we have stated as to the idea of force,
 then we see that Miiller has deviated far from the true method
 of physical investigation.  In physiology, the existence of a sim-
 ilar  general force governing the whole, is assumed in the fully
 formed organism.   Respiration,  the circulation of  the blood,
 the function  of the nerves, &c,  are effected by one force,
 which is called vital force.   This vital force causes respira-
 tion here,  digestion there, the secretion of the saliva  and  of
 the pancreatic juice in other parts of the body.  It maintains
 at once the substance of the  bones,  of the muscles, and  of
 the brain.  It is  supposed that  this  same force  is modified
jvith reference to  the  different  organs which it  influences.
This idea is also inconsistent with a sound  method.   What
 would remain of the primary  idea of force, if we  saw force
 here causing  motion,  there effecting  a chemical  alteration,
 elsewhere producing feelings or sensations ?  It seems to me,
 that in its ordinary signification, vital force expresses an idea
 as incorrect  as if we  supposed that one single force,  differ-
 ently modified, operated  in a battle  fought by thousands—a
 force which acted so as to fire cannons and muskets, cut with
 swords, transfix with lances, sound trumpets, and keep  men
 and horses in constant agitation.  The army appears as a
 substantial whole, and  produces phenomena.   The  organism,
composed of the most different organs, also appears as a sub-
 stantial whole, and produces phenomena.  If we assume for
 the latter a  single  force,  differently modified  as the organs
 vary—a single vital force by  which the whole is  animated—
 then, to be consistent, we  should assume a fighting force in a
 battle.  The existence of such a vital force has by  some wri-
 ters  been maintained, by way of distinguishing animate from
 inanimate nature; for  in a stone  there is no appearance of a
 general force capable of assuming new powers depending on
 the nature  of the  organ.   A  prejudice in favor of  living na-
ture, as peculiarly directed  and sustained by the Almighty
hand, has  caused  every  opinion  which conceived of these
 forces as residing in the molecules themselves, to be looked 
61                  THE CHEMISTRY OF
 upon as savoring of materialism.  It  was not borne in mind,
 that, in adhering  to an  intricate  and obscure  idea of vital
 force, we do not at all approach to an acquaintance with the
 manner in which the organic world  is maintained  by that
 Almighty Being, who with unlimited wisdom created and still
 sustains every  animate and inanimate  substance.   Let us
 then proceed to inquire, what forces we must regard as exist-
 ing in organic substances, and where we must commence in
 order to arrive at a sound conclusion.
   Let us  ascend  from the simple to the complex.  It has
 been ascertained from observed  facts,  especially from the
 application of them by Liebig, that some  plants* will  grow,
 when supplied with carbonic acid, ammonia, and water, pro-
 vided the bases and acids (that is, the salts) be added to these,
 which are necessary to every kind of plant.  Now,  it must
 be supposed, either that the plants  are nourished by carbonic
 acid, water,  and ammonia; that with new materials the plants
 receive new  forces from those bodies; or that the plants can
 themselves communicate forces to  the elements of carbonic
 acid, water, and ammonia.   The  idea of  communication of
forces is  unsound ;  it is only what is substantial that we can
 communicate.   Forces may be excited, they cannot be com.
 municated.
   This is fully explained by the phenomena produced by the
 magnet.  A  piece of steel possesses magnetic forces,  though
 not magnetized.   These forces are slumbering, that is, such
 an equilibrium exists between them, that they cannot be exter-
 nally perceived.  They nevertheless exist.   They reside in
 the molecules of the iron.   Three elementary substances are
 known, to which they are peculiar: iron, nickel, and cobalt.
 Every particle of these  metals is possessed of the same forces,
 and these forces can produce that series of magnetic phenom-
 ena which science has observed.   But these forces  cannot
 be communicated to tin,  lead,  or  silver.    When we appear
 to communicate them to a  piece of steel,  we merely excite
 what previously was  hidden in it—we  separate  what was
  * By saying, that some plants will grow, it is not implied that plants
in general do not extract soluble organic substances from the soil, viz.
humaie of ammonia, crenic acid, apocrenic acid, &c.  It has, however,
been ascertained, that many plants can produce organic compounds from
carbonic acid, water, and ammonia. (See infra, Arable Sail.) 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.
65
united.   In the same way, plants excite forces in the elements
of carbonic acid, water,  and ammonia, whenever  these are
absorbed, and their elements are combined in different modes,
so as to form acids,  bases, neutral  compounds,  resins,  fats,
volatile substances, and the like. If there be only excitation
from the plants, then the forces originally existed in the ele-
ments of carbonic acid, water, and ammonia : that is, though
slumbering, they are present.   Hence it results, that every
transformation in plants is effected by the molecular  forces of
carbon, hydrogen, oxygen, and nitrogen,—the elements of
carbonic acid, water, and ammonia,—the forces being excited
in these elements by the  plants themselves.
   By the  plants themselves ?  What does this mean ?  Does
the entire plant  excite  slumbering forces in carbonic acid at
the very moment the acid enters the plant ?   Or is such exci-
tation produced by some  one part of the plant ?   It is produ-
ced by the part of the  plant,  with which the carbonic acid is
in contact, at the moment it becomes changed, producing new
and indeed organic substances by the assistance of water,  or
of water and ammonia.  Let  us take starch as an example.
It is not  the entire  plant which  produces a grain of starch
from carbonic acid and water, with separation of oxygen, but
a small organ of the plant.  By this  organ a force is exer-
cised, exciting forces which slumbered in the carbon, oxygen,
and  hydrogen,  or  rather  modifying  the  forces existing  in
these,  so  that 12 equiv.  of carbon  (C12)  combine with 10
equiv. of hydrogen (H10), and lOof oxygen (O10), and from
12 equiv.  of carbonic acid (12C02)  and 10 of water (10HO)
starch is produced—24 of oxygen (O24) passing off.f  Any
one who imagines that  there is any thing else in action than
a molecular force,  than  a  chemical  force, sees more than
exists.  Such a  phenomenon is common,  and it  is one  of a
chemical  nature, produced as new combinations are in the
inorganic kingdom.  It is only the circumstances which differ.
  Are those small organs, however, necessary to the mani-
festation of such forces ? and  are those forces to  be found
only in plants ?   Certainly the different organs, which produce
different substances in plants, exert peculiar forces ; yet these
  * We do not mean that starch is formed directly from COS and HO;
we have merely taken an example from a familiar substance.
  Vol. I.                  6* 
66
THE CHEMISTRY  OF
are not  entirely peculiar to those  organs.   Gum and  sugar
can be formed without the  intervention of the plant, as well
as in its interior; and the same is the case with the benzoic,
the cinnamic, and the valerianic acids.  The  chemical forces,
therefore, which proceed  either from the minute organs of
plants, when they form new compounds out of carbonic acid,
water and ammonia,  or from  these substances  themselves,
after they are combined in some manner, may be excited in
a common chemical way also; and so far as this cannot be
effected, an accidental, not a  real  difference is the cause.
Every compound substance requires peculiar circumstances
for its formation; that is,  the forces in the elements of the
compound must be excited by the influence of peculiar cir-
cumstances.  Starch and cellulose have not as yet been pro-
duced, except in the living vegetable, and may never be so;
but neither is sulphuric acid produced in  plants from sulphu-
rous acid and oxygen, nor hyper-manganic acid,  nor chloride
of iron, nor deutoxide  of hydrogen, nor peroxide of potassium.
The forces excited  in the elements vary with the influence
which  certain  agents—temperature,  moisture, light, &c.—
exert.   By the  aid of crucibles and  retorts,  therefore, com-
pounds can be  formed which differ from those produced by
the organs of plants; while from carbonic  acid  and  water
plants can produce cellulose and oxygen, a result which can-
not yet be attained by art.
   Of what do  these small organs,  producing cellulose and
starch in  plants,  consist ?  They have originally been pro-
duced in a similar way  with the  grains of starch itself, that
is, from carbonic acid, water and ammonia,  by the operation
of organs previously existing.   On their  production they re-
ceived peculiar forces, as the grain of starch does.  The dif-
ference between the organ producing starch, and the grain of
starch produced, is not that the former can alone excite  force,
and that the latter is passive ;—both are active in  their turn.
If starch  be put in contact with nitric acid or sulphuric acid,
the acid is powerfully decomposed by the starch,  which itself
at the same time is altered.  Though starch be formed from
carbon, hydrogen, and oxygen,  it still exhibits, under different
circumstances,  a great  variety of chemical  tendency in  its
elements, inducing the production of new compounds.  Starch
yields  gum and sugar by means of diastase; sugar may be 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.
67
changed  into carbonic acid and  alcohol by means of yeast.
Alcohol is changed into oxide of ethyl be means of acids, and
into haloid compounds of ethyl by means of hydracids ; when
brought  into contact with the air, and either an organic sub-
stance or spongy platinum,  it produces acetic acid ;  with a
more elevated temperature, it produces aldehyde;  by means
of chlorine, chloral;  and lastly, by combustion in the air, car-
bonic acid and water.  At this point the primary elements of
starch reassume the same form in which they were origin-
ally presented to the plants, part of the carbonic acid, howev-
er, being separated during fermentation.  By  the combustion
all the elements  become fitted again for  nourishing plants,
and a small organ, similar to that which  produced the grain
of starch, may again produce starch from this carbonic acid
and water.
  To  express briefly what we have now endeavored to ex-
plain—no excitation of the forces of carbonic  acid and water
could be effected in the plant by its organs, unless those forces
already existed,  any more  than chloral could be  produced
without alcohol and chlorine.
   To whatever organ of plants we  direct our attention,  all,
without exception, are  formed in the same  manner  as the
grain of starch, and all have received peculiar molecular for-
ces at the moment they were formed from chemical molecules.
The  notion that  heterogeneous forces can  excite each other,
is opposed to the primary idea of force.  The force of gravi-
tation cannot excite the  magnetic force.  It is only homoge-
neous forces that can set each other in action.  Every decom-
position, every formation of new compounds,  the products of
molecular forces, can therefore be effected by molecular for-
ces alone; in other  words,  the  small organs, which form a
new  compound from substances supplied to them, and which
disturb the  existing  chemical equilibrium, can  do so only
through chemical  forces  possessed by them—through  the
chemical tendency possessed  by their elements.  This is the
source of every excitation of new forces giving rise to a new
combination.   Further, these exciting forces proceed not from
masses, but from molecules ; they are  molecular forces, and
have therefore nothing in common with what proceeds from
the whole individual.  Starch is not formed by the  plant, but
by the molecules of the organ in which it is produced, because
those molecules modify the chemical equilibrium. 
68
THE  CHEMISTRY  OF
   This may be explained by an example.  During the trans-
 formation of starch into  gum  by sulphuric acid,  each mole-
 cule of the acid influences each molecule of starch, the latter
 thereby becoming gum;—the mode in which the elements of
 starch are combined  is changed  by the sulphuric acid, the
 alteration proceeding from molecule to  molecule.  The pro-
 duction of gum from starch in the  organs of plants is similarly
 effected.
   Wherever forces  are  found  in organic  nature, there are
 substances which are all  supplied with  molecular chemical
 forces.   Even those singular structures,  the nerves, consist of
 the same elements as the ordinary substances of the organic
 kingdom.  It  is thus undeniable, that the  molecular forces
 act a chief part in the organism,  so far as a change of sub-
 stances takes  place therein; and that  no  general,  no vital
 force, should  be assumed  as the source of those molecular
 forces.   Such a  vital  force  is irreconcilable with  the true
 principles of science, which  require that nothing should be
 assumed as existing, but that every thing should be sought for
 in nature;  which teach us to ascend  only from an  unpreju-
 diced consideration of the phenomena to their causes, and to
 assign those causes only as we deduce them from the observ-
 ed phenomena.

             B.  The Development of a  Germ.

  If we review  the phenomena of life,  caused by change of
 materials, we must go back to the original formation of organs
—to the growth of an individual from a  germ.   We perceive
no  greater trace  of the future oak  in the acorn, than of the
chicken in the embryo of the egg.  Should we say  that the
acorn is governed by  an  oak-forming force, the embryo by a
chicken-forming  force ?   Does there exist  a general force,
which governs in particular all the molecules of tannic acid,
starch, cellulose, &c, in the acorn, and all the particles of
protein in the embryo of  the egg?  A particular or peculiar
force is the active cause of peculiar effects ; a general force is
the active  cause  of general effects.   Nobody can form any
other idea  of the terms.   Though it cannot be denied, that
 in the embryo the  rudiments of the future organs  of the
chicken are not  to be found ; yet we do find the materials 
VEGETABLE AND ANIMAL  PHYSIOLOGY.
69
 from which the first rudiments of organs will be produced,
 that is, we find rudiments of rudiments.  The forces which
 are inseparable from matter, their molecular forces, are pre-
 sent as  well  as the materials.  If in  these molecules there
 exists  no capacity of becoming the germ of organs, and if
 in  the germ of organs there exists no capacity of ultimately
 becoming organs, no chicken at all is produced.  The  capa-
 city,  this predisposition,  must be  present in the molecules,
 otherwise  the  heat  necessary  for  hatching would be insuffi-
 cient to produce germs of organs in the  first place, and organs
 afterwards.  This is the only reason why  the embryo of the
 egg will not produce an oak, nor an acorn a chicken.
   As the materials differ, so do their forces.  Some who con-
 cur in this conclusion are of opinion, that the granular shape-
 less mass, which they suppose exists in a passive state,  is
 acted upon  by  a power that can only be described as a chick-
 en-forming force in the embryo.   This  mass is, according to
 Miiller, " possessed of the  real and specific force of the future
 animal."*   This animal, however, does not as  yet exist, and
 not even a single organ, nor the  germ of a  single organ;
 and are we to suppose that in that shapeless mass the pectdiar
forces  of the animal exist, though that animal  itself does not
 yet exist ?   1 must acknowledge  that I  can scarcely imagine
 a gall-secreting force in the perfect liver; and  I  believe that
 no  human being can  possibly conceive of a  gall-secreting
 force in the embryo of the egg, which does not yet possess
 even the rudiment of a  liver.   This idea is also unphysical.
 In the science  of nature, we infer that forces exist whenever
 phenomena  are observed ; but  if  the  non-existence  of the
 organs, by which they are produced, render such phenomena
 impossible, no question can arise as to such forces.  No forces
 peculiar  to  the future  animal,  therefore,  can exist  in the
embryo.
  Let us  take  an example from the inorganic kingdom.  If
we  evaporate a solution of sulphate of  soda in water, we get
prisms.   In what form must we suppose that the sulphate of
soda exists in the solution ?  In that of  minute prisms ?   By
no means.   In  that of molecules  supplied with a prism-form-
ing force ?   We must reject this supposition too.   There ex-
  " Begabt  mit der wesentlichen und specifischen Kraft des snatern
Thieres."                                           v 
70                  THE  CHEMISTRY OF
ists only a force of molecular attraction in a determinate direc-
tion, the formation  of the  prism being the last result.  Be-
tween  the  first attraction of  the molecules in a determinate
direction, and that last result, a great  variety  of states of the
particles intervenes,—a great many forces come into action,
which  are  present,  and excited only  when the  molecules, by
the position they  have already obtained, cause them so to be
excited in and  by each other.  According to the doctrine of
isomorphism, the arrangement of the molecules causes the
formation of the prism; for  every  substance composed, for
instance, of  MO  and RO3, assumes forms,  among which a
crystallographic connection exists.*  But as we have no reason
for imagining a prism-forming force in each of these isomor-
phic substances, in sulphates, seleniates, &c.; so have we
none for holding, that this primary force, dependent on the
position of the chemical molecules,  is the only cause of all
the phenomena,  perceptible during  the  formation of prisms.
   Let us apply this to the substances present in the embryo.
Whoever perceives in them  nothing but protein and certain
salts, examines that shapeless mass in  a very cursory manner.
Our object should be  to mark what we see evolved from it,
namely, compounds,  which, in chemical composition, differ
either slightly, or not at all, from protein; but which, never-
theless, do differ from it.
   The shapeless mass begins to exhibit, here and there, very
small  points,  which are arranged particles.   These are pro-
duced from  the existing materials—their forces being excited
by the increase  of temperature.  Without elevation of tem-
perature, such new arrangement of particles cannot be effect-
ed ; but at the same time the molecules must possess a capa-
bility  of being arranged, just as those of the sulphate of soda.
The first  crystals of this salt cannot be formed  without the
evaporation of the water, &c, and  without a power in the
molecules of attracting each other  in a determinate direction.
  * MO denotes the protoxide of any metal M, or a combination of one
equivalent of oxygen (O), with one of metal.  R03 represents an acid
composed of one equivalent of any radical R—such as sulphur or sele-
nium—with 3 equivalents of oxygen (03).   All compound sulphates,
seleniates, &c., represented by (M0+R03), in which M may be any
one of several metals, and R any one of several radicals, crystallize in
forms, which are either identical,or are closely related to each other.—J. 
VEGETABLE AND ANIMAL  PHYSIOLOGY.        71
In the embryo,  this arrangement  of the particles increases
more  and more, so as  to produce a greater  complication.
This does not result from the primary molecular forces, till
after they are modified by those other forces, which the sub-
stances received on their first arrangement. That first arrange-
ment  of the particles in the embryo, as well as the subsequent,
must, of course, differ from that of sulphate of soda, because
protein differs from sulphate  of soda.  But neither is the pro-
tein, in each  of its particles, the same protein in a chemical
sense, that is to say, yielding on analysis no other results than
C40H31N5012 ; the protein, therefore, does not  always pos-
sess the  same  primary arranging forces.   A minute differ-
ence of condition causes the  deposition of  sulphate of soda
in very  different forms, either with 10  equiv. of water  of
crystallization, or without any;  the Jformer are produced at a
temperature  below, the latter at  a  temperature above, 91°
Fahr.  The molecules of the substances which occur in  the
organic kingdom—those of  carbon,  hodrogen, oxygen, and
nitrogen—seem  to possess an unlimited power of forming mu-
tual combinations.   The number of compounds which they
form, indeed, is incalculably great.  That power is inherent
in  these elements; neither  in the animal,  nor in the vege-
table kingdom do they  acquire it; it is only excited therein.
The  diversities  of form which  the  elements of sulphate of
soda  may give rise to, are  very limited;  but, on the other
hand, the elements of protein, by their unlimited power of
chemical arrangement, can  originate endless diversities  of
combination. If subjected to chemical examination, each par-
ticle  of  the embryo in the  egg would appear to be protein;
but by  such examination we could not discover  the peculiar
condition which  makes one particle differ from another.  We
can no more explain this than we  can the real difference be-
tween the transparent and the milky arsenious acid, between
the yellow and the red biniodide of  mercury.   We perceive
the differences,  however, and therefore admit their existence ;
and so when  we perceive them in reference to albumen, fibrin,
casein, we are equally constrained to admit them.
   Undoubtedly the differences which exist between the par-
ticles of the same organic substances are not chemical, in the
ordinary gross  signification,  but  are of the nature of those
which are connected with polymorphism.  The chemist gives 
72                 THE  CHEMISTRY  OF
us but a rude  result—the  composition  in  a hundred parts,
frequently not affording us any insight into either the real
characters of substances, or into their real differences.  When-
ever such dissimilar particles come together, a compound must
be produced, possessing peculiar forces, which, though depen-
dent upon the molecular forces of the elements, are yet not de-
termined by these alone.  The new arrangement causes a mo-
dification of those primary  forces.  Whenever it takes place,
they appear modified, and  therefore indicate  their presence
by producing new effects.   In sulphate of soda, the whole
collected  forces  of  its  constituent  molecules—those  of sul-
phur, sodium and oxygen—are still  existent; and upon these
alone depend its qualities, composition, and crystalline form.
Sulphate of soda cannot possess  other qualities—cannot be-
come other in property—than what  results from its elements-,
and exclusively originates in these.
  Thus, then, we suppose that the  molecules of the substances
in the embryo are arranged, in the first place, simply, and after-
wards more complexly.  Not a trace of any organ is as yet per-
ceptible,  however ; nor of any force, therefore, by which these
organs will  be  governed.   By  the  new arrangement of the
particles, the molecular forces are modified anew, and this
process is continuous.   Although the  primary forces, once
united with the  materials, remain  the source of every  action,
of every  manifestation of phenomena, of every chemical and
organic, that is, physical, combination ; they must, neverthe-
less, produce different effects,  as the combinations become
more complex.   Each existing particle is the germ of a sub-
sequent one, which is more complex ; and, while the tempera-
ture  necessary for hatching keeps the primary forces always
excited, there is  originated in the  new arrangement of the
particles, and also in the forces proceeding from the  groups
recently formed, a modification of  these primary forces, which
is constantly on the increase.
  The whole material of the embryo in the egg is gradually
brought in this manner within the  circle of action.  Then the
circle is  still more extended, and in its action are compre-
hended the elements of the yolk, and also of the albumen.
These are  erroneously called  the food of the newly formed
chicken, or its rudiments.  In these elements there are forces
also  conjoined with the materials—chemical forces, analogous 
VEGETABLE AND ANIMAL PHYSIOLOGY.
73
 to those which exist in  the  embryo,  and contributing to the
 production  of the  whole.  These forces differ from those
 found in the embryo,  not in nature, but only in direction, or
 in the mode of manifestation.
   Thus we do not at all suppose that the molecules  of  the
 heart in the complete  chicken existed  in the germ as heart
 molecules,  or the  molecules of the intestinal canal as intes-
 tinal molecules.  A series of successive transformations pro-
 ceeds in the  embryo—the  production of the  heart, of the
 intestines, of the whole chicken, being the final result.  Nei-
 ther do we suppose,  therefore, either a heart or intestine-
 forming force in  the germ,  but a gradual evolution of new
 series of forces, resulting from the same primary forces of the
 molecules of carbon,  hydrogen,  oxygen and nitrogen,  and
 which are to be  considered as so many exhibitions  of new
 groups,  produced in their  turn by the causes  previously in
 operation.
   In this way, therefore, neither does a gall-secreting force
 exist previously to  the production  of  a liver, nor the force
 which effects the circulation of the blood  previously to  the
 production of the heart and blood-vessels.
   It is an  impenetrable mystery how the  particles  of sub-
 stances, both organic and inorganic, mutually combine in  dif-
 ferent modes ; and after they have so  combined, again form
 new compounds.  This mystery, as regards organic substances,
 is not, however, greater than that which surrounds the inor-
 ganic.  If any one fancies that it is more easy to conceive of
 the production of a  crystal,  than of a texture composed of
 fibres, globules and cells, in other words,  any animal or  ve-
 getable organ;—of the origin of a precipitate, than of a pri-
 mary fibre;—of the state in which crystallized sugar exists
 in solution,  than of the first rudiments  of organs in the em-
 bryo,—he greatly errs.  To penetrate  into either  is  not  as
 yet permitted to man.
  To express our idea in a  few words,—the elements of  the
organic kingdom, carbon, hydrogen,  oxygen, and  nitrogen,
are  susceptible of  endless  modifications  of their primary
forces.  For that reason  they can form, with minute changes,
a great diversity  of products;  and, by the  operation  of the
same primary forces, they stand towards each other in en-
tirely different relations from those assumed by all  the other
  Vol. I.                   7 
74
THE  CHEMISTRY  OF
elements; so that they can produce a peculiar series of bodies,
which are called organic substances.

                C.  Equivocal Generation.

   Upon the principles which have been  stated above,  no
room is left for the dispute as to equivocal generation  and
epigenesis.  The doctrine of epigenesis has originated in the
idea, that  every living thing is  produced from  ova alone;
because in these only can all the forces and germs of organs
exist, which are found in the future plants or animals.  The
dictum of Harvey, Omne vivus ex ovo, has been strongly de-
fended, and has  still many supporters.  On a sound view of
organic nature, and of the essence of organic beings, this doc-
trine appears to be perfectly reconcilable with that of equivo-
cal generation.  If we consider an ovum as an organic mole-
cule, or an organic body, made up of the four organic elements,
combined in various groups, then the conclusion of Harvey  is
no doubt true.  It is still true, if by an ovum we mean a mole-
cule of a determinate kind ; for this is also proved by obser-
vation.  The mites of cheese are peculiar to cheese ; and from
certain  parts of plants—fruits, for instance—peculiar fungi
are produced also.   It is a general rule,  that from organic
molecules of a given  and determinate kind, only specific com-
pounds—specific or peculiar forms, can be produced.
  The term ovum, however, has been taken in a limited sense,
to signify the  germ  of an individual, produced  by peculiar
organs only;—a  germ in which every thing belonging to the
future animal  is concentrated.  Such ova,  we have seen, do
not exist.   There is a development, an ascension from the sim-
ple to the complex.   According to the supporters of epige-
nesis, an  egg is such a germ as,  in favorable circumstances,
always  produces the same species.  And in reality, the sup-
porters of equivocal generation do not entertain any different
idea.  In their opinion, there exist certain organic substances,
—organic  molecules,—which are  capable  of  evolving  and
forming something new, whence individual plants or animals
may also finally proceed.   Why may not cheese be an agglo-
meration of ova, that  is, of molecules,  from which an indi-
vidual being may be produced, as from the ovum of an insect?
It cannot be denied that the  existence of the spermatic  ani- 
                 I
           VEGETABLE AND ANIMAL PHYSIOLOGY.         75

malcules proves, that animals, or at least their germs, gradu-
ally growing, by merely floating in a fluid, may be secreted.
What we know of the Acarus Scabiei, the Filaria aracuncu-
lus, the Echino-cocci, and a great many other entozoa, shows
that they may be  produced from ordinary organic molecules
in the animal body, as every small  organic globule of mucus,
for instance,  or of milk, or of pus,  &c, is formed.   As the
germs of the spermatic animalcules are secreted animal germs,
so may the molecules of casein also be the ova of mites, though
these remain" molecules of casein.  The  one idea is not ex-
cluded by the  other:—an egg consists of the white and the
yolk; both, however, constitute the germ of a chicken.  In
the very same manner the ergot of rye  (Secale cornutum)  is
produced.  From  the top of this same fruit, under different
circumstances,  a different plant arises—a fungus instead of a
grass.
   The idea of an  ovum, therefore,  coincides exactly with that
of an organic molecule;  that is, of such a molecule as consists
of elements which may exhibit themselves under a change of
circumstances in infinite modifications, may form new combi-
nations, attract other elements, incorporate  them,  unite into
definite compounds, and thus  separate from other bodies with
which  they were  originally combined.   Among  species of
this nature, formed  from organic  molecules, are  the  mites
in cheese,  and  the mould upon rotting fruits,—resulting from
the molecular forces of  the elements, like the spermatic ani-
malcules.
   Finally,  the  ordinary ova of plants and animals consist of
nothing but organic molecules, such as those  of which all
organic substances are composed.  They are products of or-
ganic bodies, and therefore differ neither in composition nor
in character from  the germs  of those  substances which are
said to originate through equivocal  generation.  Nay, it is a
peculiarity of organic molecules that  they  produce organic
molecules.   As regards this leading characteristic,  ova and
organic molecules resemble each other.   Of this the vegetable
kingdom exhibits an endless variety  of striking examples.
The stem of  a  tree produces  not leaves, but branches;  these
branches produce not leaves, but petioles, and the leaves grow
from the extremities  of these.   From  the end of the foot-
stalk, a flower grows, in the same manner as a stem fiom the 
76
THE  CHEMISTRY  OF
seed deposited in the soil.  No other part can  produce a
flower.  And in the flower itself every separate portion derives
its nutriment from the spot to which it adheres.  The extreme
cells found there, are the feeding cells of entirely peculiar
parts, which  no other kind of cells can produce.
   Each cell, therefore,  is, as it were, the ovum of peculiar
parts of plants ;  as, for  instance,  the cells at the very extre-
mity of the petiole are the ova of the evolving leaf; the cells
at the very extremity of the foot-stalk are the ova of the beau-
tifully  shaped  flower, with  all  its parts.  This  is proved in
the clearest manner by grafting.
   The idea of an ovum is thus reduced, in truth, to that of an
organic molecule ; and the dispute  as to equivocal generation
and epigenesis is at an end.   In the same way, however,  the
general vital force is reduced to molecular forces.  The  ef-
fects of the vital force are effects produced by the cells, which
are so very diversified, and which exhibit phenomena that vary
with their own differences.  We must in a single plant divide
this one vital force into  thousands,—into as  many forces as
there are series of cells,  producing different  substances.   In
other words, we  must reduce them to what is effected by the
cells themselves; and thus we find that the idea of vital force
coincides with that of molecular force.

             D.   Transference of Vital Force.

   The idea of transferring vital force is opposed to the idea
of force.   A slumbering force is awakened,  a weak force is
strengthened ; but it is impossible to imagine the transfer of
a  force from one material  mass to another.   We must first
refer to this point in pausing to consider the manner in which
we must conceive of the  transition,  into a new organic whole,
of life originating in another.  If animals impart vital forces
to their offspring, then such  forces  must, no doubt, be lost by
themselves.  We do not perceive, however,  that  this takes
place ; on the contrary,  they retain their strength, sometimes
for many years,  after having produced  new beings, com-
pletely formed, of the same species.   The tree which, for a
great  many years,  produces fruit, and the  seeds of which
have,  in great numbers, become full-grown trees around  the
parent stem, nevertheless lives as at first.   A single poppy 
           VEGETABLE AND ANIMAL PHYSIOLOGY.        77

plant produces thousands of small seeds, each of which grows
up to a poppy plant  equally perfect.  Hence we are not en-
titled to admit the idea of transference of vital  force, even
where it is not opposed to the idea of  force itself.  With our
own  eyes we perceive the evolution of that force from its
phenomena.
   What part then bears the germ of that  vital  force which
is afterwards  to be developed ?  and at what point  does the
development commence ?  It is the poppy seed which bears
the germ,—a  small  quantity of  organic molecules,  different
in nature from all others,—some carbon, hydrogen, nitrogen
and oxygen,  combined in a certain manner into substances,
which are peculiar  in respect of their composition  and ar-
rangement.   The peculiar quality,  which distinguishes these
substances from  amorphous  precipitates and crystals, they
owe to their  origin.   Their  elements were brought into a
state of peculiar  tendency by the forces  residing  in the or-
ganic molecules of the plant, whose influence had previously
governed them.   They do not possess  more than they exhibit,
and they exhibit nothing but a change of their chemical com-
position.  The seed  changes its starch  into gum and sugar,
and so chemical forces forthwith  appear, which seem to be
intimately connected with the  development of new  forms.
Another phenomenon soon succeeds, namely, the absorption
of substances from  without.  These  bring something with
them : they are not merely substances, but the residence  also
of peculiar active forces to which they owe their composition.
Of these forces, some portions combine with those which  are
derived from the seed itself.  And now, the  previously exist-
ing molecule, and that which is formed from external matter,
both live—the former through what it received  from the  pa-
rent plant, the latter through its having  assumed the form of
the  other.  This conformity arises from matter, and from the
property which matter possesses, of  obeying the  action of
forces,  proceeding  from the first molecule; in other words,
the second molecule  must necessarily be endowed  with  the
capacity of becoming similar to the first, through  the influ-
ence of the first.   Thus, the second molecule did not receive
its peculiarities, but  these were excited  in it;  and so this
molecule also lives as well as the first, and in its turn  can
take up new substances from without,  and entirely assimilate 
78
THE  CHEMISTRY  OF
them.  So again, the third lives also,  and thus is life gradu-
ally extended.  The molecules, after being once  arranged in
a certain  manner,  give  birth to new  arrangements, to new
forces, as we endeavored before to explain.
  From what has been stated, it will sufficiently appear, that
the oak, when losing its acorns, loses none of its vital force;
that an animal  loses none by  generation;  but that, in  both
cases, the generating substances leave only certain quantities
of matter, endowed with the  power,  first of somewhat in-
creasing, then of taking  up other  substances, and with these
just so much of life as  they afterwards manifest.  Organic
substances, whether called germs or food, possess properties
of a peculiar  kind, existing in the four elements of which
they are all constituted. 
VEGETABLE AND ANIMAL PHYSIOLOGY.         79
                    CHAPTER  II.

  INORGANIC, ORGANIC,  AND ORGANIZED  BODIES: PLANTS
                      AND  ANIMALS.

   All bodies divide themselves naturally into two principal
 classes, namely, those possessed of peculiar organs, by means
 of which certain acts are performed, and those which are des-
 titute of such organs.  The former are called organized, the
 latter unorganized.  Those substances, which are either them-
 selves organized,  or which are derived from  such as are so,
 are called organic substances; those which contribute to the
 composition of unorganized bodies, are called inorganic sub-
 stances.
   It is not difficult to indicate the organs of an organized be-
 ing, if it have them either in great number, or very much de-
 veloped.   Such organs, in the classes of the so called higher
 animals, are the  eye, the stomach,  the liver.   It needs no
 lengthened demonstration  to show what is meant by such or-
 gans as these.   There is no room for doubt, indeed, as to the
 application of the  term, in even the least developed condition
 of organized beings ;  for, in general, an organ signifies an in-
 strument  by which a  certain  act  is performed; it may be
 either  a very complicated, or a very simple one.  A  mere
 cell, therefore,  is  such  an organ ;  the  only function neces-
 sary to constitute it such,  being the capability of producing
 cells similar to itself.
   This power of forming new substances is peculiar to a cer-
 tain class  of natural  products.  Such  as  are endowed with
 the requisite instruments are called-organized.  Each organ
 has its peculiar office  assigned to it.   But  all the  organs
 are, besides,  united into one whole : they  act in combination
 to maintain the whole, to give it a substantive existence,  to
 make  it perform  certain  actions;—in  a word, they form by
 their union what we call  living beings.   Living beings, there-
.fore, are organized.  Organized beings and substances either
 have  lived, or are still  living.  In every thing  that either
   Vol. I.                    8 
80
THE  CHEMISTRY  OF
has not lived or does not live, we miss those organs, which
are destined either to produce new substances, or to perform
certain actions; and, from the absence of those organs, their
actions also are wanting in such as are unorganized.
   This is  the  case with all  minerals.  Their composition,
however regular,  as regards their form and the proportions
of their elements, is such that, without the  intervention  of
forces acting from without, the mass persists in the state in
which it has once been placed.  The whole  is composed,  in
a regular manner, of parts, which are quiescent till their forces
are excited by external causes.  But  all plants and animals
have  an exactly opposite character.  Every thing  belonging
to them is in a  state of continual motion, till causes come into
operation,  which convert that motion into rest.  This motion
is accompanied by a constant change in the substance of their
parts, which  continues even  when the mutual harmony  of
these parts is  disturbed,—the substantive existence  of the
individual  destroyed.  The animal and  vegetable worlds are
made up of an  endless multitude of structures, which are in a
state  of almost uninterrupted activity;—an activity, the  first
indication of which  is a change in their constituents, while
its farther manifestations are characterized by a great variety
of phenomena, all  of which  we  include under the general
name, phenomena of life.   The regular recurrence of these
phenomena, we call health; their disturbance, sickness; their
entire suspension,  death; their  harmonious  co-operation for
a common end, that is, primarily, for the maintenance of the
whole, we  designate life.
   The  minutest portions of an organized being consist, for
the most part, of very small organs, which unite in vast num-
bers to constitute a substantive whole, which we call an instru-
ment or organ.   Such is the  liver or  the  spleen.  Thus  as
an organized individual consists of organs, so a larger organ
consists of smaller ones; and as the actions of an individual
result from the combined actions of all its  organs, so again
the actions of any larger organ are nothing but the combined
actions of the smaller organs, by which  the larger is made to
appear  as a substantive  whole.  So also in most organs, the
function of the whole is made up  of all the functions of all
its parts combined.   Thus, the  simplest form of a lung,  is
an air-cell, covered with a vascular net of arteries and veins ; 
VEGETABLE AND ANIMAL PHYSIOLOGY.         81
 the  smallest form  of a submaxillary gland, is a small grain,
 into which, on one side, arterial blood enters, while the secre-
 ted saliva flows from it on another.  In the same manner, the
 simplest form of a  plant is a cell, because, if numbers of
 these are taken  and placed together, in various orders, they
 produce a plant.
   The  size  of the  organs,  then,  by no means determines
 whether natural products  are either organized at all, or more
 or less organized.  The very smallest  of them are  still or-
 gans—manifesting themselves by certain actions, and origin-
 ating phenomena, not wholly, but partly dependent on exter-
 nal conditions.   Any substance, however, which possesses a
 greater variety  of these  organs—each  of which,  by them-
 selves,  or with their  respective groups,  perform several  ac-
 tions—is  properly  said to be more organized.   There exists
 in nature an astonishing variety  of such substances.   Some
 are of exceeding simplicity, as in the lower orders of plants.
 Others  are of a very complicated structure, possessing a  va-
 riety of smaller organs, united either singly or in groups ;  afid
 thus acting in a variety  of ways.  These latter  aboundin
 the higher classes of animals.
   It need scarcely  be remarked, that each organ,  or  each of
 its constituent organs, differs in substance from such as act or
 manifest themselves differently from them.  And this differ-
 ence appears not only in their  substance, but also  in their
 form—the component parts of each being arranged  in con-
 formity with the functions  they are intended to perform in dif-
 ferent  classes of individuals.   Hence an infinite diversity of
 products.   They  can present a new arrangement to the sub-
 stances supplied to the  individual  from  without; and  hence
 their products are innumerable.   The  substances, thus pro-
 duced by the organs, are  called  organic.   They are  called
 organized, if they  are either  organs themselves, or  if they
 contain organs; but generally organic  if they are the pro-
 ducts of organs..   Organized substances, therefore, are organic
substances; but organic are not always  organized.
  Organic unorganized substances do not at all differ from
 inorganic, as to the nature  of the substances themselves.  But
they materially differ as to the arrangement of their constitu-
ents.  The elements of the organic  kingdom are to be met
with in substances  which are not organic, but wherever  we 
82                 THE  CHEMISTRY  0T
find them, they are the same, and exhibit the same properties.
If, however, these elements are placed in certain circumstan-
ces, they form combinations dependent  on these  circumstan-
ces.   This tendency to combination, which exists in the ele-
ments, and which is to be looked for within, and not without
__being  dependent on nothing  but  the  elementary forces,
concealed, as it were, in the molecules of carbon, hydrogen,
nitrogen, and oxygen,—this tendency being excited to a de-
terminate degree under certain conditions, produces new sub-
stances.   This  general  law, of which chemistry gives innu-
merable examples, is obvious in organic nature.  Slight dif-
ferences of temperature are quite sufficient to produce, in the
chemical laboratory, entirely different combinations  from the
same elements.  In common chemical experiments, numerous
minute  circumstances  influence the nature of  the  product
which results from the combination of two or more elements.
  Looking at the subject in this general point of view, new
combinations, entirely different from each other, must be pro-
duped by different organs  from the  same materials, supplied
from without.  And if we add  to the endless  multitude of
different organs in plants and animals  the diversity of mate-
rials  afforded   from  without, then we shall understand, how
that endless series of new combinations must necessarily arise,
which is formed in plants  and animals, out of two, three, or
four elements,  and which chemistry makes known to us.  In
a word, every  change of  materials in  the organic kingdom,
as in the inorganic, is the result of  the primary forces of the
elements, and cannot be ascribed to any other source.
  By the nature of those products,  therefore,  the nature of
the actions of  the said organs  is more or less determined.
But there are several  other effects  of  these peculiar instru-
ments,  which go far beyond a simple change  of materials.
A great  many  living creatures are endowed with the power
of changing their position at will, and  possess for this  pur-
pose  peculiar organs,  in  which  the change of materials is
limited to their own  support exclusively—such  are  the mus-
cles.   They have a complete  system of organs, by which
they are enabled to absorb  substances from without, to retain
them for some  time, to expend  them gradually, and to em-
ploy them in the formation of new organic substances—such
are the organs of digestion.   They have peculiar instruments, 
            VEGETABLE AND  ANIMAL  PHYSIOLOGY.         83

 the organs of sensation, by  which certain  impressions from
 the external world may be conveyed to a spiritual being, en-
 dowed with a power of observation, will, and even conscious-
 ness ;—a being which chooses according to  fixed rules, forms
 judgments,  and draws conclusions ; remembers former situa-
 tions in which it has been placed ;  imagines new situations as
 if they really existed ;—a being  which is  itself conscious,
 why,  what,  and for  what purpose it exists;—a being which
 can investigate more or less, and admire  the  Cause of the
 universe ; -which recognizes  in  itself a  faint image of the
 Divinity who governs both worlds and atoms;—a being which
 may acquire moral worth, and  has a clear idea of the dis-
 tinction between good and evil;—a being conscious  that it
 was created for immortality.
   How surpassingly beautiful is  the visible world !   At one
 extreme of  organic nature spiritual man is  placed,  dwelling
 for a season in a godlike  house, formed by a  Master-hand,
 suited  to  his moral elevation, making him  familiar with all
 nature, and  with  many of its beauties :—at the other extreme,
 the minute fungus, scarcely visible, as simple in composition
 as it is humble in appearance—as  ill furnished with  organs
 as the  human body is rich in  them.
   It is easy to distinguish between these extremes in the series
 of organized beings—their difference, indeed, being  so ob-
 vious  that we  can scarcely  perceive  any conformity.  But
 whether we descend from the one  extreme,  or  ascend from
 the other—it is exceedingly difficult to draw the line of de-
 markation between animals and plants.  The result of all the
 endeavors to determine this line of  separation  has been, that
 the structures of the individuals which constitute the  transi-
 tion class between animals  and plants, and which partake in
 an equal degree of the nature of both, do  not  enable us to
 reduce them to either class.   They may with equal propriety
 be called either plants  or animals.
  There exists a mutual approach  between the materials of
which  animals and plants consist, in certain determinate con-
ditions—an approach which  is really remarkable.   Miguel*
has described an epizootical fungus,  the Isaria cycadee ; and
Vireyt has made us acquainted with a minute  moss upon the

  * Bulletin, 1838, p. 85.     t Journal de Pharraacie, 1838, p. 83.
  Vol.  I.                  9 
84                  THE CHEMISTRY  OF
silk-worm.  He has  lately*  recorded further observations,
by which the Tinea lupinosa of Guy de Chanliac is reduced
to a kind of Mucor of the genus Mycodermata.  The sporules
of these kinds  of plants find a fertile soil  in  the scales with
which the hairy part of the head of children, &c. is covered:
they penetrate  into  the epidermis, and  in this  way sustain
and feed themselves.  To these plants also belong the  bran-
like  moulds, mucors, &c, which have  been placed  in  the
order of the Coniomycetes, of Nees von Esenbeck.  A great
many dartrous  pimples belong to the class  of  the fungus-like
mosses.   The warts of the human body are classed with the
gynosporanges ?  by  Meynier of Ornans.   It is difficult to
make out, if the tubercle of the lungs be really a Cycoperdon,
and the cancer a Uredo caries.
  Though there is  no  uncertainty as to the  characteristics
proper to oaks  and lions, each of them respectively producing
a complete impression on the mind, so as to afford a standard
whereby  plants  and animals  may be examined and  deter-
mined ;  nature has, nevertheless, established forms of  transi-
tion which do not admit of a fixed classification.
  The  attempt will, therefore, be always  made in vain to
draw a distinct line  of demarkation  between  animals and
plants.   Dumas is one of the last who has tried to do so.t
He thinks that  the  following table of  distinctive properties
establishes a new system, and gives a clear idea of the differ-
ence, which we have more than once stated :—
         PLANTS
Produce  indifferent substances
         containing nitrogen;
   "    fats;
   "    several varieties of su-
         gar, starch, and gum.
Decompose carbonic acid ;
   "      water;
   "      ammoniacal salts.
Give off oxygen.
Absorb warmth ;
   "  electricity.
Are apparatus of reduction.
Are immovable.
          ANIMALS
Consume  indifferent  substances
          containing nitrogen;
   "     fats;
   "     sugar, starch, and gum.

Produce carbonic acid;
   "   water;
   "   ammoniacal salts.
Absorb oxygen.
Produce warmth ;
   "   electricity.
Are apparatus of oxidation.
Change their place.
* Journal de Pharmacie, 1841, p. 703.
t Comptes Rendus, Nov. 28,1842. 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.         85

 He to whom this detail is new,  or  appears to embody  the
 truth, is unacquainted with the actual state of science.   It is
 universally known,  and will  appear from what follows, that
 not one of these so-called distinctive characteristics will stand
 the test of examination.
   As we are not able to draw a clear and just line of demark-
 ation between plants and  animals,  neither can we between
 unorganized  and organized substances.   As soon as the func-
 tions of  the organs have reached a  minimum,  we approach
 the limits of those series of substances,  the most complicated
 of which may easily be distinguished from mineral matter-
 but of which the least complicated opens  the way to  the
 knowledge of  another series of substances,  which, being
 wholly dependent on circumstances,  do not possess the power
 to represent  any  thing but the  usual properties  which  are
 inseparable from matter.
   1.  The general characteristics of organized and living  be-
 ings are,  increase and growth, generation and death.  Besides
 these properties,  common to animals and plants,  the former
 are endowed with the power of perceiving external  impres-
 sions and of moving themselves at  will.  Schleiden* justly
 characterizes animals as having a tendency in their organism,
 to develope their life to the utmost degree of individual sep-
 aration, and thus to conceal internally their principal organs ;
 that which is shown externally being as much as possible a
 uniform surface.   The plant,  on  the contrary, bears its chief
 organs without, increases  very much externally,  and shows
 its beauties all on the surface.
   2.  If any substance is deprived of the properties common
 to animals and plants, then it is either an inorganic or a dead
 organic substance.   The latter are characterized by the ab-
 sence of the effects of organs, which are  themselves present;
 the former by the total want of any organs, which  either can
 now,  or formerly could, perform any action  in any circum-
 stance whatsoever.
  From  the  articulations  of the Gallionella ferruginea of
 Ehrenbergt being made up almost wholly of oxide of iron, it
appears that  the  transition  from organic to  inorganic  sub-
* Schleiden, Grundztlge Wisstntschafl: Botanik I, p. 29
i Ibid, p. 34.                                V 
86
THE  CHEMISTRY OF
stances is  almost as imperceptible as  that from animals to
plants.*
  3. Binary and ternary combinations.—It has been thought
that a clear line of  distinction might be drawn between or-
ganic and inorganic substances, by stating  that, among the
former, ternary and  quaternary combinations  occur,  but  in
the latter, only binary ones.   This limit being quite arbitrary,
is  at the same  time entirely  unchemical.   Every one but
partially acquainted with the  chemistry  of organic nature, is
aware that a great  number of radicals have  already been dis-
covered, and that the  terms ternary and quaternary, as applied
to combination, were of no use after the first radical was indi-
cated.   Ether does not consist of C4H50, but of C*H5-|-0.
The oxygen can be separated from it,  and sulphur, chlorine,
bromine,  iodine, or  cyanogen substituted.   Thus  we  have
ethyl (C4H5),  a binary combination.   This unites with oxy-
gen, sulphur, &c, and forms  another  binary combination.t
All organic substances are no doubt built up in  a similar way,
but the radicals of  many of them are not yet known.  A few
years ago not one was known.  Science is  gradually discov-
ering more of  them, and encourages the hope,  that in pro-
cess of time every organic substance will  be  reduced to its
own radical.
  4. If any distinction is to be made between  organized and
unorganized chemical substances, it should be  stated thus :—
that in the  former,  compound radicals exist; and in the lat-
ter,  elementary ones.   But  is  this distinction  founded  upon
their belonging to no different provinces of nature, or upon a
  * The following work may be consulted  on  the difference between
 Slants and animals:—Kutorga, Naturgeschichte der Infusiores-thiere,
 t. Petersburg und Karlsruhe, 1839 and 1841, S. 30.
  t The meaning of this passage is, that ether consists of 4 equivalents
of carbon, 5 of hydrogen, and 1 of oxygen; but the three elements are
not united together all at once, as is represented by the juxtaposition
of the several symbols in this  way, C4H50, forming  a ternary com-
pound, from which no part can be taken away without breaking the
whole up.  But first, the carbon and hydrogen  are united together to
form a binary compound, represented by C4H5, to which the name of
ethyl is given.   1 his afterwards  combines with oxygen and forms
ether, which is rationally expressed, therefore, by C*H5-}-0.  And
the proof of this is, that the oxygen can be separated from it, and chlo-
rine (CI) made to take ils place, forming CHU-f-Cl, and so on. 
VEGETABLE AND ANIMAL PHYSIOLOGY.
87
peculiarity in the nature of the carbon, hydrogen, and nitro-
gen, of which organized substances consist?  The answer is
obvious, for the  organic kingdom is built up out of  the  four
elements—the elements themselves being wholly independent
of organic nature.   It is, moreover, doubtful, whether all or-
ganic substances contain compound radicals.  On the contrary,
it is probable  that cellulose, starch, gum, sugar, &c, consist
of carbon and water.  The transformation of tannic  into gal-
lic acid (see Tannic Acid) affords strong grounds, for adopt-
ing this supposition.
  5. Juxtaposition.—Another  real difference is assumed as
to the way, in which organized and unorganized substances
are  formed.   In the latter,  a  juxtaposition is supposed; in
the former, a growth,  an  increase of solid  matter  in some
of its parts.  First, this distinction is not quite accurate ;  for
horns, nails, and hair, which are all  produced from protein
compounds, are  formed by  juxtaposition.   Of hair, this 13
proved by Dr. Van Laer beyond dispute.
  But let us consider  this juxtaposition in the unorganized
kingdom.  When burned  gypsum after being mixed  with wa-
ter  changes into a solid mass, we look in vain  for any juxta-
position.  Does any thing else happen  in the deposition of the
materials of bone, within the cells of  the bones ?   Does not
the bony matter of the skull  extend itself from a centre in the
form of  rays ?   Let us take an example from the vegetable
kingdom.  How does the formation of wood take place ?  Is
it not a real superposition, when  layers of woody  fibre are
deposited against the walls of a cell ?   But the  very same
happens  also in  the ordinary growth  of an organ.   Matter
does not penetrate into matter.  If the germ of an organ, pro-
duced  by simple juxtaposition, once exist, then the organ can-
not increase in bulk without one  particle  placing  itself next
to another, and so shifting its place—and this is a real juxta-
position.   This is fully confirmed by the way in which cells
are  produced—a subject with which, of late, we have become
somewhat better acquainted.*  There  exists, however, a dif-
ference between crystals and many organic substances.  The
  * See Schwann, Microscopische Untersuchungen uberdie Ueberein-
gtimmung in der Structur und dem Wachsthum der Thiere und Pflan-
zen.  Berlin, 1839, S. 191.
  Vol. I.                  9* 
88
THE  CHEMISTRY OF
cellular and fibrous  primary forms which are present in tho
latter,  are wanting in the former;  while the  symmetrical
forms of the crystal are not  found in organic  nature.   Tho
latter is just as averse to symmetrical forms, as inorganic na-
ture is to cells and fibres.  We seldom find crystallized com-
pounds in the bodies, either  of plants or animals; and the
substances contained  in them, which are susceptible of regu-
lar crystallization, exist there  usually in a state  of very fine
division, or of solution.   In regard to theine, which is so beau-
tifully  crystallizable, we do not find a trace of it crystallized
either in coffee or in tea.*
   If we add to this, that many organic substances, provided
they are placed in favorable conditions, assume  juxtaposition
—for instance, tartaric acid,  citric acid, &c. ; morphine, nar-
cotine, many resins, camphor,  &c.  which are all organic sub-
stances,—then the  positive distinction  between  organic and
inorganic  nature, grounded  on this  peculiarity, disappears.
We may,  however, state, as distinctions between organized
and unorganized  substances, that, generally, the former are
in a cellular, the latter in a crystalline state ; that the one class
performs a function of which the other is not capable.
   After what has  been  said, we  must necessarily conclude
that the causes  of this diversity are  reducible to  the forces
which  primarily  exist in the organic  molecules, carbon, hy-
drogen, nitrogen, and oxygen,  and  in  those of all the  other
elements.   The four organic elements have the  peculiarities,
which  are indicated  in organic nature by their almost  innu-
merable mutual reactions and  combinations.   To  these ele-
ments  a peculiar  potency is  imparted, if such an  expression
ought to be retained in science.
   6. Finally, between plants  and animals, which are both
characterized by  the cellular form  of the component organs,
there is this  real  difference,  that cellulose, (C24H21021),
forms  the principal part of the cellular mass in plants; while
in animals the primary material  is gelatine (C13H10N205),
or the  matter which  produces glue after  ebullition; and to
this rule no exception has yet been discovered, either among
animals or plants.
  * For an important paper on the substances found naturally crystal-
lized in plants, by Prof. Bailey, see American Journal of Science, Vol.
XLvm, p. 17.—S. 
VEGETABLE AND  ANIMAL PHYSIOLOGY.
                  CHAPTER III.

 THE ATMOSPHERE, IN ITS CONNECTION WITH ORGANIC
                        NATURE.

  Throughout all nature we perceive an intimate connection
existing between different actions, one being disturbed as an-
other is annihilated.   Phenomena are united together by  a
chain,  from which not a link can be taken without throw-
ing the whole  into disorder.   If water were to lose its pro-
perty of being converted into  vapor, every living being on
the earth would die;  if the composition  of the atmosphere
were suddenly changed, thousands of living beings would
instantly  perish  from the earth.  In some instances, many
causes  cooperate  to bring  forth  one phenomenon,—to pro-
duce one substance; in others, the  destruction  of one sub-
stance  is the condition on which another exists.
   On a cursory view, nothing is more  surprising than the
change of forms—the alteration of appearance—to which the
same substance is subjected.  On penetrating farther and far-
ther into this law of nature, nothing excites greater astonish-
ment, than the fact that the form alone  perishes; that matter
changes its appearance, but is itself imperishable.   We think,
observe, feel, speak to each other, by means of organs com-
posed of a mass of elements, consisting of nitrogen, carbon,
hydrogen, oxygen, phosphorus, sulphur, lime, magnesia, iron,
chlorine, soda, potash, and many others, but the unchanged
existence of these  organs is of  short duration.    At every
respiration they lose  something, and they appropriate some-
thing again.   This change is  also promoted by perspiration,
and by all kinds of secretion ; and  thus  we shall not be the
same to-morrow as we are to-day.  Our body is no longer the
same even after the lapse of a few moments.
   The organic mass,  which is called the  human  body—the
animal body of man—is a texture of substances  which are
introduced into it  by  certain apertures.   What now forms
part of the human body,  some days ago belonged to the body 
90                 THE CHEMISTRY OF
of an animal; and, again, some weeks ago it was a constitu-
ent of plants.  Whatever our human body may be to-day, it
will be changed into vegetable matter possibly after an inter-
val of but a few months.
  This body derives its origin,  partly from  the atmosphere,
and  partly  from  the earth's surface.   From the  latter it is
separated but for a short space, soon to  return to it again.
Both plants and animals are then fed from our material part;
and every man, doubtless, derives  support  from the  dust of
his ancestors.
  Thus, by means of a small portion of matter, once endowed
with certain forces, the Divinity, the Author  of these forces,
attains, in  the  course of ages,  an infinite variety of ends,
with which it is the endeavor  of the  natural philosopher to
make himself acquainted.
   1. It is a known fact, that nature, with singular economy,
has  formed the  whole organic  kingdom chiefly  from four
elements.  Carbon, hydrogen, nitrogen, and oxygen, are the
constituents  of every  thing that either  has  lived, or is still
living.  Besides these, there are some, so called,  inorganic
substances, which  complete the  organic whole;  but  it is of
these four elements, that the greater part  of organic matter
has been formed by nature.   It is of importance, therefore, to
consider  what alterations occur in the  combinations of these
four elements, after they have  constituted, at  one time, some
part of a plant;  at another, some part of an  animal.
  2. Further, it is known that animals are nourished by plants,
and thus, that plants serve to connect animals with the earth's
surface.  Taking this point of view, the  living substances by
which the mere dead earth is invested with color  and  the  air
filled with  odors,  become of the  very  highest importance.
Those which are employed as food by man, constitute,  indeed,
but a very small portion of the whole.  Man makes use of
scarce the  hundredth part  of the produce of the earth, and
not one  out of a thousand of the forms of vegetable  life
which grow upon it.  It  is, however, an indisputable truth,
that  without plants  no animals, except the infusoria, could
exist.
   3. In the  third place, it is known, that  what we usually call
putrefaction is nothing but a change of form.  A substance,
which has  formed  part  of a  living being,  is endowed with 
            VEGETABLE AND ANIMAL PHYSIOLOGY.         91

 forces modified in a peculiar  manner, which have been ex-
 cited during life, but must necessarily become again quiescent
 so soon as the life of the being ceases.
   According to a general chemical law, those substances have
 been  arranged and  influenced in a peculiar manner by the
 peculiar circumstances in  which  they  have  been  placed.
 Whenever, therefore, they  are withdrawn from the influence
 of those circumstances, a great many gaseous, liquid and solid
 substances appear, which  takeu together represent just  as
 many  substances, and those the very same, as were formerly
 contained in  the living part.   This is a new effect of the forces
 by which the organic world is maintained.   Its destruction is
 its very source of life  ; its life, again, the cause of its destruc-
 tion.  When we perceive in an organic whole, that the com-
 ponent parts  cease to Cooperate for a common object, its ex-
 istence as a  whole—its life is at an end ; a  new  life  begins
 immediately  to appear.  It may  be that the new products
 appear to us  disgusting.  Those revolting substances, however,
 contain the germ of the most  beautiful  combinations.   The
 most splendid plant has  been produced  only from such sub-
 stances, and  can derive its support only from what has  been
 such.
   4. We  may  regard a fourth  peculiarity  as also  known,
 namely, the  value of that black layer of soil  which surrounds
 the  globe we inhabit, in many  places to  a thickness of seve-
 ral feet.   If  this black crust were taken off our planet, much
 of what lives upon it would  be  destroyed or prepared  for de-
 struction.  Where this covering exists, plants readily spring
 up;  where it is wanting, many of them are  either not found
 at all, or are  found in an unhealthy condition.  It is the stand-
 ing place of the  organic beings which are bound to the earth.
 How far it is their source of nourishment, we shall presently
 endeavor to explain.
   5. Besides these four points, I must advert to a fifth,  now
 sufficiently ascertained—the value,  namely, of "the gaseous
 veil of the earth, which is extended to a considerable distance
 from the  globe;  of that air-ocean  which, in its fury, turns
 palaces into ruins, and crumbles rocks to dust in  its calmest
 moments ;—which is constantly achieving the destruction of
every dead substance on the  earth's surface ;  but, at the same
tune, maintains every thing that lives upon it.  Every living 
92
THE  CHEMISTRY  OF
being requires  the  support of that  mobile  fluid.   It affords
nourishment to  animals and plants ; it not only supplies sub-
stances, but carries force  into organic  beings; it  is a real
source of life to every living thing on our planet.
   One of the  most  beautiful contrivances  of the material
world, is that which  is exhibited in  the innumerable changes
undergone by the same substances,  which, among their  vari-
ous forms, at one time constitute parts either of the atmos-
phere, or of the black soil—at another, the  component parts
of living plants and of animals.
   We have acknowledged, as a general law, that the same
elements may assume thousands of forms, and produce new
combinations, though they  cannot change their essential char-
acter; and that by means  of the same substances, in various
instances, nature  attains  entirely different ends.  The  sub-
stances,  which, in an organized  form, adorn  the earth, will,
ere long, be decomposed.  Their constituents, combined in a
different manner, will soon assume a new shape, but will pre-
sent themselves  in the  interval as  component  parts of the
black soil and of the atmosphere.   Thus the  same substances,
at one time float in the atmosphere which envelopes the earth,
and  at another are  component  parts of plants and animals.
   For these purposes, nature employs a small  portion of mat-
ter only, compared with the large mass of the earth.  Though
apparently so  very liberal in maintaining life, she  is at the
same time  economical in applying the material  means by
which that object is effected.  The number of  animals and
plants, which may  at any time have existed on the earth,
could scarcely  be greater than it is now, because there would
be a want of materials requisite for  sustaining  their existence.
With the increase of the  number of animals, that  of plants
must diminish,  because the former are composed of parts of
the latter.  In the thin, black layer  of soil, the constituents of
animals and plants, and a little  intermixture  of the  atmos-
phere, we have the whole store,  which exists on  the earth, of
the materials necessary  for the existence and  support of liv-
ing,  of organized beings.
  Let us now consider the  atmosphere in its connection  with
organized nature.  Unknown in ancient times, it is at present
acknowledged to be a main source of life to every living be-
ing upon the earth. 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.        93
   Accordingly we must bear in mind what the atmosphere is
 composed of; what influence it now exerts on the life of plants
 and animals; what influence is exercised  by these  in  their
 turn  upon the atmosphere ;  what its probable state has been
 in former times, and what  influence it  then exerted;—and
 finally, we shall  have to consider what causes actually exist,
 having power to modify the nature of the atmosphere ; and to
 inquire what is  likely to be its future state, so that we may
 form some idea of its influence on what will hereafter be living.
   The atmosphere, we know, is an invisible, very mobile veil
 of our planet, extended upwards to a great distance, and tend-
 ing to occupy every  space not occupied by other substances.
 Being kept in continual motion  by general and special causes,
 it forms a uniform mixture of a few principal  ingredients;
 at the same  time, it  is  the  receptacle  of all the volatile
 particles,  of all the  vapors  from  the earth's surface.   The
 causes, which produce its motion, are among the most beau-
 tiful which investigation  has  observed in nature.  Without
 that motion, every disturbance  of the composition of the  at-
 mosphere would necessarily be pernicious to the  life of plants
 and  animals ; every organized  substance would become sur-
 rounded by an atmosphere of its own, expending what is use-
 ful, and leaving what is useless, so as soon to be deprived of
 every thing not belonging to that by which it is  immediately
 encompassed.  Were the atmosphere a motionless  mass—
 from which something is taken, and into which something is
 discharged, and in a different way by every organized being__
 then all things now alive on the  earth's surface would in a few
 days be destroyed.   It is, therefore, a wise and most excellent
 contrivance,  that thousands  of causes are at work,  to keep
 the atmosphere in ceaseless motion.  What may be pernicious
 to one organism, is  indispensable to another;—what is left
 from the abundance of one, is usefully applied by another;__
 what in one place is  copiously  produced,  and might be de-
 trimental,  is  rendered innoxious by being widely diffused
 through the ever-moving  atmosphere.
  1 have purposely drawn attention, in the first place, to the
 continual motion maintained in the atmosphere, by the action
of varying temperature and other causes ;  because in this lies
the chief argument m favor of  the opinion, that the  atmos-
phere—however it may  be composed,  and whatsoever may 
94
THE  CHEMISTRY OF
be either discharged into it or taken  from it—must be a uni-
form mixture ;  and that every where, over the whole earth's
surface, and at every height, it must contain the same con-
stituents.   As a direct consequence  of this  beautiful contri-
vance of nature, all the organized beings on the  earth's sur-
face, wherever they may be, are, as  regards the atmosphere,
exposed to the  same influences.
  The chief constituents of the atmosphere are four  in num-
ber—oxygen,  nitrogen,  carbonic acid,  and aqueous vapor.
The proportions  of the two  latter  vary with many  circum-
stances, in a way which  we  can detect  by observation—the
way in which  the  proportions  of the two former vary  has
hitherto escaped  us.   The received proportions of oxygen and
nitrogen are, 21 of the former, and 79 of the latter, by volume
—the carbonic acid averages nearly half a thousandth part,
the quantity of watery vapor is very variable.
  To these principal constituents of the atmosphere thousands
of others are added.  Volatile exhalations from the organized
matter of the soil,—products of the  volcanoes on the earth's
surface, and of the artificial burning of fuel,—gaseous fluids
escaping from  mines,—vapors of volatile solid substances,—
hundreds of volatile  oils from odoriferous  plants,—putrid
volatile products of animal and vegetable decomposition,—
the muriatic acid arising from salt water in shallow lakes and
lagoons,*—exhalations of men and animals,—an innumerable
multitude  of substances ascending  in vapor from manufac-
tures and chemical processes,—and finally, the volatile  pro-
ducts of animal excrements;—all these are sources of pollu-
tion to the atmosphere, which thereby undergoes innumerable
alterations in its  composition.
  The  accumulation  of these  multifarious substances in the
atmosphere is prevented  by one single cause, which is among
the most remarkable we know;—a cause, which  is the same
for the whole earth, which originates in the same source, and
acts for the same purpose ;—a cause as sublime in its effects,
as it is simple  in its nature;—a cause only to be brought into
  * Muider found free muriatic acid in the rain-water of Amsterdam,
which he ascribes to the decomposition of the chloride of magnesium,
contained in the waters of the Lake of Haarlem, by the action of the
sun's rays.—J. 
VEGETABLE AND  ANIMAL PHYSIOLOGY.        95
 operation by the Supreme Wisdom, which can attain innume-
 rable ends by one means.   It is  the rain,  which, in falling,
 carries with it every thing that floats in the  atmosphere,  and
 which is not essential to its constitution; which brings back
 to the earth, what came from the earth; and which, whilst it
 thus purifies the atmosphere from noxious immixtures, carries
 the  thousands of volatile substances into the soil, in  which
 they have abundant opportunities of forming innoxious com-
 binations with the substances which the soil  contains.
   The atmosphere, thus purified  by means of rains from  all
 heterogeneous mixtures, and kept in constant motion by cur-
 rents of air, is a mixture of four substances.  Let us briefly
 consider, how we may accurately investigate them.
   1. To determine the  composition of the atmospheric air, it
 is necessary to ascertain accurately  the amount  of nitrogen
 and oxygen, its  two chief constituents,  and  also  that of the
 carbonic acid and aqueous vapor.
   The first experiments for determining the amount of oxygen
 and nitrogen are comparatively recent; for it is not long since
 weights and measures began to be employed in the science of
 chemistry.   Lavoisier  was  the first who used the balance,
 and he but  rarely.   When in the latter part of the last cen-
 tury, the kilogramme was introduced, it was noticed as a sin-
 gular circumstance by the committee, assembled at Paris for
 the  purpose of considering the subject, that the mechanician,
 Fortin, had made a balance, which  sensibly indicated one
 millegramme.   The whole science of measuring  and weigh-
 ing is scarcely sixty years  old.  The just  determination of
 the composition of the atmosphere cannot, therefore, be older.
   Besides some  older experiments by Scheele, Priestley, Ca-
 vendish, and Horace Benedict de Saussure, those of Volta,
 De Marti, Spallanzani, Berger,Configliachi,Dalton, Humphrey
 and  Edmund Davy, Biot, Gay Lussac, von Humboldt, Brun-
 ner,  Theodore de  Saussure,  Verver and Dumas, have been
 mainly  useful, in  determining the composition  of the at-
 mosphere.
  At first this composition was thought to be variable.   In-
struments  were invented to determine the amount of oxygen
in the air.  According as the proportion of oxygen was large,
the air was thought better adapted  for respiration.  Hence
these instruments were called eudiometers, that is, measures
   Vol.  I.                   10 
96                 THE CHEMISTRY OF
of the degree of the  air's  adaptation for that specific pur-
pose.
  The invariableness  of the mixture  was first stated in the
year 1804, by von Humboldt  and Gay Lussac, who, during
the months of November and December, in dry as well as in
moist or rainy weather, and during various states of the wind,
collected the  air of Paris, above the Seine,  and  subjected it
to eudiometrical examination.   In 29 experiments, made  on
29 different days, the  largest  quantity of oxygen they found
was 21-2, the smallest 20*9.   The difference between these
two  numbers  lies  within the limits of the ordinary errors of
experiment.
   Since a constant composition, namely, 21 of oxygen to 79
of nitrogen, was thus assigned to the  atmosphere by men of
so high reputation as  von  Humboldt and Gay Lussac, it has
scarcely  ever been questioned.  Their results have been con-
firmed by those of most succeeding  experimenters.
   Thirty years later,  the air round  and within Geneva was
examined in an entirely different way  by  Theodore de Saus-
sure.   For this purpose he  employed finely divided lead,
which diffused through water, he agitated with the air under
examination ;  a method which was followed in London, a few
years ago, for manufacturing  white  lead.
   By thus  agitating air with moistened  lead, de Saussure com-
bined its oxygen with the metal, and thus nitrogen  only  re-
mained.   From his experiments made with air, collected oyer
the Lake of Geneva, and at Chambeisy, it appears, that during
very various  winds and states of the weather, the minimum
of oxygen was 20-98, and the maximum 2T15—the average
of a great  many experiments being 21-05.
   The same  results were obtained by Gay  Lussac, who, on
his ascent in  a balloon, brought with him air from a height of
21,430 feet; by von Humboldt, who analyzed air  from the
Antisana,  a mountain  of 16,640 feet high;  by  Gay Lussac
and von  Humboldt, with air from Mont Cenis, at a height of
6,170 feet; and by Coofigliachi, from the  Legnone, a moun-
tain 8,130 feet high.   Finally, Dumas has recently found the
same results  confirmed, when air is  passed over red-hot cop-
per, and the nitrogen is collected.
   Not only pure, but impure air also, has been found to give,
after the foreign ingredients were separated and subtracted, 
VEGETABLE AND ANIMAL PHYSIOLOGY.
97
21 to 79 as the proportions of the two gases, in the remain-
ing mixture of oxygen and nitrogen.  For  example, Config-
liachi examined the air  collected over  rice fields,—Seguin,
Gay Lussac, and von Humboldt, that which was collected in
a theatre at Paris,  filled  with  people,—E. Davy, that  from
hospitals,—Theodore de Saussure, that from a bed-room in
the morning.  All these specimens of air showed no variation
whatever in the amount of oxygen and  nitrogen, provided the
foreign mixtures  were previously separated.
  But, according to Levy, this composition  is not invariable.
He found, for instance, in the air of Guadaloupe, collected by
Deville  from  different places,  the  following per  centage of
oxygen by  weight:—
   November 28, 1842,   .     .     .     22-68 oxygen.
23,
29,
20,
27,
21,
23,
22-85
2300
2303
2304
2305
2314
  The air at Copenhagen gave, from  the 17th of November
to the 22d of December, 1841, 23 per cent, of oxygen  by
weight.  At Elsineur, close to the sea, he found, in February,
1842,23037.
  During a journey from Havre to Copenhagen, he collected
air,  which, on the  2d, 3d, and 4th of August, gave 226 of
oxygen.
  Levy ascribes this difference to oxygen, given off by Infu-
soria, which are occasionally found in sea-water, (see below.)
But it may be asked, if that difference ought not to be ascribed
rather to error in his experiments ?*  It  is safer, therefore, at
  * See Journal de Chemie et de Pliarmacie, May, 1844, p. 212.—Mor-
ren, however, has lately, to a certain extent,  confirmed the results of
Levy.  He found that air, collected  on the immediate surface of large
ponds of sea-water covering many sea-weeds, in the middle of a clear
and very calm, sunny day in April, contained 23 per cent, of its bulk
of oxygen.  This excess of oxygen he attributes to the rapid escape of
bubbles of oxygen gas from the surface of the  water, and of the green
plains beneath it under the influence of the sun's rays.  Of course
this gas will soon mix with the surrounding air,  and at  a  very small
distance from, or height above, the water, all sensible difference in the
per centage of oxygen should disappear.  See Annates de Chein. et de
Phyg., xu, p. 34.—J. 
98                  THE CHEMISTRY  OF
present to consider the composition of the atmosphere to be
constant in so far as regards the relative proportions of the
oxygen and nitrogen.
  Yet we ought not to conclude positively, that the propor-
tion of oxygen and nitrogen never changes.  All we are war-
ranted to infer is, that the existing variation  lies  beyond  the
reach of observation ;  that the causes of disturbance are not
greater than those by which the  difference  is made  up; that
in walled rooms the disturbed  equilibrium is much too quickly
restored by the draught of air, to admit of its being observed ;
that in open air the winds quickly supply whatever portion of
the oxygen may, by various circumstances, be abstracted.
  The quantity  of  this oxygen is indeed astonishing.  If we
assume the height of the atmosphere to be a  geographical mile,
that is, 22,843 feet;—if we bear in  mind, that  the  radius of
the  earth  is  860  of these  miles, then  the bulk of the air
amounts to 9,307,500 cubic miles, that is, a cube of which the
side is 210 miles; so that, there being 21 per cent, of oxygen,
the earth is surrounded by a quantity of this gas, equal to a
cube of which the side is 125 miles ;*—an astonishing  quantity,
indeed, in  which  small disturbing  causes must necessarily
escape our observation.t
  2. The amount  of carbonic acid in the air is  pretty con-
stant.  It has  been determined in various ways.   Dalton agi-
tated a known volume  of air with lime  water,  and  weighed
the quantity of carbonate of lime he got.   Thenard employed
baryta water for the same  purpose.  Theodore de  Saussure
took a small bottle  containing baryta water, and suspended
it in a balloon filled with air.   Brunner transmitted air, by
means of an aspirator, through sulphuric acid, moistened lime,
and again through sulphuric acid, and weighed the two latter
substances, contained in a proper apparatus.
  In 1827  and 1829,  de Saussure made 225 experiments, to
determine  the proportion of carbonic acid  in the air.   He
found, by  104 experiments with  the air of Chambeisy, a small
village near Geneva, that the quantity of carbonic acid in
  * Of the miles here  spoken of, there are 16 to u degree;  each is
equal nearly to 4J English miles.—J.  [The side of the cube  of oxy-
gen in English statute miles, will be 540£ miles.—S.j
  t Poggendorff, in Handworterbuch,  I, S. 562. 
VEGETABLE AND ANIMAL PHYSIOLOGY.         99
10,000 parts of air was, on the average, 4*15, the  minimum
being 3*15, the maximum 5-74.  This difference is too great
to be ascribed to errors of observation.   De Saussure further
found, that during the day the air contained less carbonic acid,
than during the night.  He found,  during the day, an average
of 3-38, during the night, of 4-32; the maximum during the
day  was 5"4, during the night, 5*74.  With slight winds at
mid-day he found a smaller quantity of carbonic acid than
when the wind  was violent;—in the former case, 3*76, in  the
latter, 3#98.  The quantity of carbonic acid  was diminished
less  by violent showers, than by continued gentle rains.  The
quantity was greater  over cultivated  grounds, than over  the
Lake of Geneva ; at Chambeisy, he  found 4*60, when  the
air above the Lake of Geneva gave him 4-39.   In 30  obser-
vations, which he  made simultaneously at  Chambeisy, and in
a street of Geneva, he found the proportion in the air in  the
neighborhood of Geneva, 4*37 ; in that  of the town  itself,
4-68, showing a larger quantity of  carbonic acid in the latter
place.  Finally, he found that on mountains the air contained
somewhat  more  carbonic  acid, than  in the lower regions of
the atmosphere; the difference, however, was very  small.
  The same experiments were repeated by Verver, after  the
method of Brunner, and his results confirmed  those  of  De
Saussure.*
  3.  We must  here advert to the quantity of ammonia in  the
atmosphere, which is considered by Liebigf of such great im-
portance to  the growth of plants.   It frequently happens, that
traces of ammonia are  found in rain-water; but its quantity
is so very small, that Liebig himself could obtain only a trace
from many  hundreds of pounds of rain-water.  In another
  * Verver's  results,  obtained at Groningen, give 4*2 parts in 10,000,
his maximum being 51, and his minimum 3*5.  Since these were pub-
lished, an elaborate series of observations has been published by Bous-
singault. The mean for nine months, according to his observations made
in Paris, was 4 parts in 10,000, the minimum being 2-2, and the maxi-
mum 6-7.  A series of 16 experiments, made on the same successive
days in September and October, 1843, and at the same hours, by Bous-
singault in Paris, and Levy at Andilly, near Montmorency, gave for the
carbonic acid in the air of the city 3 19, and in that of the country,
2!>89.  This is in accordance with the result of de Saussure.—Ann.
de Chem. et de Phys., x, 66,462, and 472.—J.
  t Organic Chemistry applied to Agriculture.
   Vol.  I.                  10* 
100                 THE CHEMISTRY OF
work* 1 have shown it to be impossible that plants should ob-
tain their nitrogen from that source—that the quantity of am-
monia in the atmosphere is exceedingly  small—and that, in
fact, it should  not take any higher  rank as regards organic
nature, than the many other substances accidentally mixed in
minute quantity with the atmosphere, and which are really
innumerable.   I shall recur to this point, however, in treating
of arable soil.  For the present, it may be enough to remark,
that the atmosphere contains a quantity of ammonia which as
yet it has not been found possible  to weigh ; and  which  to
organized nature, is  but of secondary importance.
  4.  The quantity of water in the atmosphere varies consider-
ably, at different times and in different places.   It is, besides,
dependent on the temperature of the air,  and  of the  water
evaporating from the earth's surface.  The air being in contact
in one place with  large collections of water, which are con-
tinually evaporating, and  in another with dry,  arid ground,
this variation must be considerable.   The continual rising of
currents of air, causes the vapors which are diffused through
the atmosphere,  to  form clouds, that is, utricular vapors,
which float in the atmosphere  at a height of from 5,000 to
20,000 feet, according to the latitude of the  place.   By the
ascent of  these, the  lower parts of the atmosphere are de-
prived of their aqueous vapor,  the  quantity of  which is thus
dependent on the source and  temperature of  the evaporating
fluid, on the temperature of the air, the velocity of the wind,
and many other causes.   Atmospheric air is never quite dry,
as it is never quite free from  carbonic acid.  To some sub-
stances this moisture  obstinately adheres; others absorb it
gradually and become liquid ; while others again are changed
in their nature through its influence.   For instance, the rust-
ing of metals is a combined effect of the moisture of the at-
mosphere, of its carbonic acid, and of its oxygen.  In a word,
an  acquaintance with the quantity of aqueous vapor in the
atmosphere  is of the greatest importance to a right knowledge
of its peculiar properties.
  The proportion of aqueous vapor  has  been determined by
Verver for the Netherlands.   In 1,000 volumes of air he found
the minimum 5*8; the maximum 10-18;  the former  on the
* Scheikundige Onderzoekingen, Deel II, p. 78. 
VEGETABLE AND ANIMAL PHYSIOLOGY.        101
 24th of August at 10 o'clock, a. m. ;  the latter on the 4th of
 May, at 11£ a. m.  The average of 50  observations, during
 May, August, and September, was 8*47.   From an early hour
 in the morning to 10 o'clock, a. m., it was 7-97—from 10 to 2
 o'clock, p. m., 8-58—and from 2 o'clock till the evening, 8*85.*
   5. Finally, Boussingault, Verver, and  others, have shown
 the  presence in the aimosphere of other substances, which
 contain hydrogen and carbon.  Boussingault and Verver pass-
 ed  atmospheric air, freed from  carbonic acid, over red-hot
 copper,  and obtained small quantities of water and carbonic
 acid.  By means of the oxygen of the air, the hydrogen and
 the carbon—no matter in what state they  existed in it—would
 be changed into water  and  carbonic acid, while passing to-
 gether over red-hot copper.
   We cannot determine in what state this hydrogen and car-
 bon  are contained in the atmosphere; they may be so, in the
 form of hydrogen  gas,  carburetted hydrogen, and carbonic
 oxide, or possibly in that of  volatile organic substances.  As
 to this point, nothing has yet been ascertained, nor can it be
 determined by such experiments as these.   It is certain,  how-
 ever, that, before the constituents of organized bodies are re-
 duced to their most intimate  combinations, they can assume
 a great many intermediate states—supplying the atmosphere
 with either solid, liquid or gaseous products.  Thus, in every
 kind of putrefaction, peculiar volatile substances are diffused
 through the air, which may contain the four organic elements
 combined in various ways. Further, in a great many diseases
 —such, for example, as  cause eruptions on the skin—volatile
 compounds escape from  the patients, and are diffused through
the atmosphere.t   Many substances,  also, which,  both  at
ordinary and at more elevated temperatures, are regarded as
fixed and not volatile, are  constantly emitting  particles  in a
state of vapor, and diffusing them  through the atmostphere
  "Bulletin, 1840, p. 191.
  t See on this subject the elaborate treatise of Dr. J. Van Geuns  Na-
tuur-en Geneeskundige Beschouwingen van moerassen en moeras'ziek-
ten.  Amsterdam, 1839.   (Physical and Medical Considerations on
Marshes and Marsh Diseases.  Amsterdam, 1839.) Mulder's Verhan-
deling over de Wateren en de Lucht van Amsterdam, (Treatise on the
Waters and the Air of Amsterdam,) p. 163, may also be consulted on
this subject. 
102                THE CHEMISTRY OF
—such for instance are potash,  soda,  and even  iron, when
smelted in blast furnaces.  Thus, the  atmosphere must con-
tain not only  substances  consisting of  carbon,  hydrogen,
nitrogen, and oxygen, but a great many others besides, which
it would really be of importance to investigate, but on which
it is unnecessary for our present purpose to dwell.
  We are therefore entitled to state,, as a general result of
this brief  enumeration of the component  parts of the atmos-
phere, that besides a countless number of accidental ingre-
dients which are continually carried down again to the earth
by  the rain,  the chief constituents of the atmosphere are a
mixture—nearly constant, so far as we are able to observe—
of  21 parts of oxygen and 79 of nitrogen by volume, a va-
riable proportion of aqueous  vapor and a  quantity of car-
bonic acid,  which amounts on an  average to something less
than half  a thousandth part.
  Two great  causes  of disturbance are continually at work
to diminish the quantity of oxygen in the atmosphere, namely,
the respiration of  animals and  combustion.   By these pro-
cesses,  vast  quantities of oxygen  are consumed and com-
bined with carbon  into carbonic acid.  We  shall afterwards
inquire, how  far these causes may tend to change the com-
position of the atmosphere ;  at  present we only remark, that
those two disturbing causes are  opposed by a third, which,
if the equilibrium be disturbed, may restore it again, namely,
the decomposition of the carbonic acid  by plants, and the sep-
aration of oxygen by their green parts.   This decomposition
is one of  great importance.   While the larger  animals by
their  respiration continually extract oxygen  from the atmos-
phere and  give off carbonic acid,  plants on the other hand
absorb carbonic acid  and give off oxygen ;  this  evolution of
oxygen being  their action during  the  transformation of the
nutritive substances which they have  absorbed,  and among
which carbonic acid is one of  the most important—into other
compounds, either containing little oxygen, or altogether desti-
tute of it.   In relation to the atmosphere, therefore, the larger
animals and plants are directly opposed to each other, and we
shall afterwards treat of their several functions in this respect.
  To this generally acting cause, tending to restore the equi-
librium previously disturbed by respiration  and combustion,
a second remains to be added  which is of no  less  importance, 
VEGETABLE AND ANIMAL PHYSI«.0GY.        103
though of less extensive  influence  than  the green parts of
plants.  I refer to the very remarkable observation made by
Morren,* that  not only plants but also some kinds of animals,
very simple in their structure, give off oxygen when exposed
to the rays of  the sun.  After a great many analyses of the
air contained  in different kinds  of  water from wells, from
stagnant pools, and  from  marshes, it appeared to him,  that
such of the latter as  contained  a greenish minutely divided
substance, gave off a considerable portion of oxygen—so that,
according  to his calculation,  from a  bulk of water of 8,000
cubic feet  in favorable circumstances, 128 cubic  feet of oxy-
gen  were given off into  the  atmosphere  in a  single day.
This production of oxygen was dependent on the sunshine,
and reached its maximum on a clear summer's day, about
four or five o'clock in the afternoon.  The quantity of gas,
during its  strongest evolution, was  considerably diminished
by the interposition of a piece of black cloth.  He found the
largest proportion of oxygen in  100 parts of air from the
water, to be 61 ;  the  smallest, 16 to 17.t  The green sub-
stance to  which this disengagement of oxygen was to be as-
cribed, he found, when observed through the microscope, to
consist for the most part, of the Enchelis monadina virescens
sulesphaenea of Bory de St. Vincent, occasionally mixed with
the Enchelis pulviscula viridis of Miiller, the Monas bicolor
of  Ehrenberg, &c, which are small monads—animalcules
therefore  performing  the  same functions which  are  usually
performed by plants.
   From  the  smaller proportion of oxygen obtained during
the night than during the day, a deviation which always de-
pended on the  quantity of these green animalcules in  the
water, Morren drew the conclusion that they decompose the
carbonic acid contained in  the water,  retaining and living on
the carbon in the same manner as plants do;  whence it is to
  * Annales de Chemie et de  Physique, Avril, 1841, and Biblioth.
Univers. Novemb. 1841, p. 386.
  t Morren states the very interesting fact, that when, in June, 1835,
the air in the waters of the river Marne, a  slow flowing river, con-
tained only 18 per cent, of oxygen, great numbers of particular kinds
of fish perished.  How beautifully does this  prove the wise purpose
for which the air, in our rivers and seas, has been made to contain so
large a proportion of oxygen !—J. 
104            %    THE CHEMISTRY OF
be  presumed  that their chemical constitution  may nearly
resemble that of plants.
  Morren obtained the same  result from other microscopical
animalcules, which were not green, but red ;  the proportion
however which  they  gave off,  reached a maximum 47 per
cent. only.   These animalcules were the Tracholomonas vol-
vocina of Ehrenberg, of a beautiful  red purple color.  The
green color of the former, therefore, has no relation whatso-
ever to the quantity of oxygen evolved.  The difference be-
tween the  quantities  of oxygen, produced  by both kinds of
animalcules, may be ascribed to accidental causes.
   Wohler has made the same observation.   In the salt-water
springs of Kur-Hesse, a green mucilaginous matter is formed
during  the  summer's heat,  in which  great  numbers of air-
bubbles appear.   These bubbles contain 51 per cent, of oxy-
gen, and 49 of  nitrogen.   The green matter consists almost
entirely of species of Navicula and  Gallionella, mixed with
fibres of Conferva?—in a word, for the most part, of Infusoria.*
   In this, therefore, a new source of purification to the atmos-
phere has been discovered.  Not only do plants decompose
the carbonic  acid, but  the countless multitudes of Infusoria,
which are to be  found in stagnant waters, act as auxiliaries to
the plants, in decomposing  carbonic acid and extricating its
oxygen.t
   It is almost certain,  that  the  atmosphere has always con-
sisted of nearly  the same constituents as at present.  I do not
here refer to what it might  have  been in another order of
things; I allude only  to the  state  in which  it has existed
since the last great geological revolution, and especially since
the dispersion of man  over the earth's surface.   Much too
  * Annalen der Chemie und Pharmacie, 1842.
  1 Morren  has more lately found  that the  air in  sea water, which,
when the sky is obscure, contains 33 percent, of oxygen, contains more
after some hours of bright sunshine, and varies between 31 and 39 per
cent.  It  is  least in  the morning and in cloudy weather, and greatest
after mid-day, and in prolonged bright weather. The whole sea, there-
fore, may be considered as a constant purifier of the air,  removing its
carbonic acid and renewing its oxygen.  It does not appear, from Mor-
ren's researches, that visible infusorial animals are necessary to this ac-
tion on sea-water, as, in the water he examined, the microscope showed
the presence of very few Infusoria.  Is the effect produced by animals
too minute even for the microscope?—J. 
          VEGETABLE AND ANIMAL PHYSIOLOGY.        105

short a period has intervened since eudiometrical experiments
were  first made, to admit of any positive conclusion being
drawn;  but  there are other grounds  which  seem  to  war-
rant  the inference,  that  the  proportion of  oxygen to the
nitrogen of the  atmosphere, as now known, is as old as the
existing state of things, or, at least,  may at first  have but
slightly differed from what we  find it now;—it being proba-
ble, also, that previous to that time, the atmosphere was en-
tirely different from  what it is now.
  It is not to be denied, that the carbonic acid, which is dis-
charged into the air  by animals and by combustion, is decom-
posed by  plants.  They decompose the amount supplied to
them from these sources, and  disengage its oxygen.  They
cannot decompose more.   Thus vegetation, or the number of
plants, depends on the quantity of carbonic acid in the air,
and conversely upon the number of plants  depends the quan-
tity of oxygen which is liberated from  the  decomposed car-
bonic acid ;—and thus the  life of animals depends on the
number of plants.
  There are some plants which live entirely on what they re-
ceive from the atmosphere, without drawing any food from the
soil, except some inorganic salts and bases.   To these belong,
among others,  the lichens  and mosses, with which  the bare
rocks are covered,  and which grow in inaccessible places,
where no change has ever been effected by the hand of man,
and no natural deposit has  ever  been  made.  To these  fur-
ther  belong  many phanerogamic plants,  the so-called fatty
plants, (plantes grasses,)  a great many Cacti,  Euphorbias,
Sempervivum, &c, and a great many of the false parasitical
plants, which are fixed to trunks and branches of trees, by
means of their own  roots, and  do not draw  any of their food
from them.*
  It cannot be ascertained how the germs of the  lichens and
mosses have  first been produced, or originally brought to their
present place.   It is  sufficient  for us that they do exist, and
that they grow by means of the atmosphere.
  A vegetation of this kind must necessarily have preceded
the present one ; for there was a time when no soil existed,
* Miguel, Bulletin, 1838, p. 86, PI. I, fig. B. 
106
THE  CHEMISTRY OF
and  its organic  parts,  together  with those of  animals and
plants, were constituents of the atmosphere.
  The first plants which grew upon the earth, but  no longer
exist in a  living form—though they have been accurately de-
termined by geology from their remains—could have found no
humus, but must have derived their organic constituents from
the atmosphere.  Among them are found gigantic productions,
which so resemble the existing vegetation in structure,  that it
may be assumed as certain, that  the function of nourishment
has never been subjected to other laws  than  those which we
recognize  in the existing vegetation.   At that time, in the
primitive  world,  the naked rocks  must have  been  covered
with gigantic Equisetacese, Lycopodiaceae, arborescent ferns,
and pines.*
  Plants which now live on the atmosphere  require carbonic
acid, water, and nitrogen ;  the last of which, by the decompo-
sition of  water, gives rise to ammonia, under conditions of
which we shall afterwards treat.  (See Arable Soil.)  In this
manner they obtain carbonic acid, water, and ammonia,  in
which  they find  all their nourishment;  the atmosphere can-
not give them  more ; and as they live on nothing but carbonic
acid, water, and nitrogen, in the form of ammonia, they must
be able to prepare from  these substances their several peculiar
constituents.
  If we suppose such plants as  now grow upon bare rocks,
to be planted in a stony  soil within an enclosed space, and sur-
  * Bronn, Lethaea Geognostica,  1 Bd.  Brongniart, Prodrome d'une
Histoire des Vegetaux Fossiles,  Paris, 1828.
  It may reasonably, I  think, be doubted, whether observed facts in
geology bear out this opinion of Mulder in regard to the entire absence
of a vegetable  soil in those remote times when the trees referred to
flourished on the earth's surface.   The dirt-bed on the Isle of Portland,
and other localities, which lies between the marine deposits of the Oo-
lite and the fresh-water strata of the  Wealden, is an  ancient  soil in
which many trees grew, and the  clays on which nearly all our beds of
coal, without exception, rest, and in which so many roots are found, is
no doubt the  soil in which the vegetation of that epoch was fixed.
Trees are known now,  both in our own and in warmer and  drier cli-
mates,  to grow occasionally  on  naked rocks; but woods and  forests
grow only where a soil  exists.  In the absence of any facts to the  con-
trary , therefore, it is safer to believe that, in the early geological epochs,
when terrestrial vegetation prevailed, vegetable soils also were gradu-
ally produced.—J. 
           VEGETABLE AND ANIMAL PHYSIOLOGY.        107

rounded by an atmosphere of carbonic acid, aqueous vapor
and nitrogen, from which last, ammonia may be produced by
the decomposition of the water—then these plants will decom-
pose the carbonic acid, and give off the oxygen ; and from the
ammonia, the carbon, and part of the  carbonic acid left be-
hind, as well as the water, several vegetable  substances will
be produced, which will  adhere to the stony ground.   The
further the decomposition of carbonic acid and the condensa-
tion of nitrogen proceed, the better do plants grow—the greater
is the amount of  the four organic elements, which they fix to
the stony ground ; and the greater also the amount of oxygen
which is  mixed with the surrounding nitrogen, carbonic acid,
and aqueous vapor.
   If the  plants,  after the seed is matured,  die within  this
enclosed  space,  then  they putrefy, and  organic humus-like
substances are left behind.  The decomposition  of these  sub-
stances proceeds still farther, and the products are  carbonic
acid, which is diffused through the air,  and ammonia, which
remains intimately combined with the humic substances of
the soil.   In these decaying substances, the seed sprouts and
grows to a small  plant; the carbonic acid from  the  air,  and
the ammonia formed from nitrogen and  aqueous vapor, are
decomposed by the young plant; the  latter  thereby  is ad-
vanced in  its growth, gives off oxygen,  and produces  new
organic substances,  which again form  constituents of* plants.
These plants putrefy in their turn, and so  this rotation is  con-
tinually going on.  The production of  plants cannot exceed
the supply of the substances on which they live; they can
only rise  to a height proportioned to the quantities of food af-
forded them, which existed originally in the air in the state
of gas.  The nitrogen which was in the  enclosed space, along
with carbonic acid and aqueous vapor,  thus  becomes  mixed
with oxygen on the first decomposition of the carbonic  acid
by the plants; and this process is  continued, till there is no
more carbonic acid  to  be decomposed.   Then the oxygen
attains a maximum.   When the dead plants decompose, their
carbon at the same time takes  up oxygen, and thus the quan-
tity of the latter  again falls towards a minimum, which  is
attained when putrefaction is  completed, and  young plants
rise from the germinating seed.  In such  a limited space, the
largest quantity of oxygen and the  smallest of carbonic acid
   Vol. I.                  11 
108                THE CHEMISTRY OF
and nitrogen would exist, when the  plants had attained the
period of most luxuriant growth; on the contrary, the small-
est quantity of oxygen and the largest of carbonic acid and
nitrogen, would exist when the dead plants had reached the
highest degree of  putrefaction.
   If we suppose that in the enclosed space, in which the stony
ground is already  covered with a layer of humic substances,
and which contains ammonia and  oxygen in the state of gas
already mixed with  the nitrogen, aqueous  vapor,  and  car-
bonic  acid—if we suppose  that in  this  space  the seeds of
other plants are present, these  will rise and attain a luxuriant
growth, and will add to the condensation of carbon, hydro-
gen and nitrogen from the surrounding gases,  and to the  dis-
engagement of oxygen into the air.
   Suppose now that at this point we enclose certain animals
along with the plants, in the same limited space in which the
latter have  already mixed  the nitrogen with  oxygen, then
the former will inhale the oxygen,  and will substitute for  it
nearly  an equal bulk of carbonic acid.   The amount of car-
bonic acid in the enclosed space being thus increased, is again
given  to the  plants  for decomposition, which thereby grow
more luxuriantly, and restore again a large quantity of oxygen.
If these animals eat of the plants thus  enclosed with them,  a
portion of the latter will be deprived of the power to decom-
pose carbonic acid :  but these animals  soon give off their ex-
crements, which putrefy,  and produce carbonic acid and am-
monia  from  the vegetable nourishment carried through the
animal  body.  These new products are again offered  as
nourishment to the plants, which thereby grow  and may again
serve as food for other animals.
   Finally, if we kindle a fire in the enclosed space after the
oxygen is introduced, then the carbon of the burning organic
substance will be changed into  carbonic acid by the combus-
tion, and in this way also food will be prepared for the plants.
   If the supposition  above made be  applied  to the whole at-
mosphere, all  the operations described remain the same.  At
the creation of the most ancient order of things, there  might
or might not  be  oxygen in  the atmosphere.  If there were
carbonic acid, nitrogen, and aqueous vapor, then, at the very
first traces of  this  peculiar vegetation, of which so many in-
dications remain,  the plants must necessarily have absorbed 
VEGETABLE AND ANIMAL  PHYSIOLOGY.       109
carbonic acid and ammonia—formed from nitrogen and aque-
ous vapor—and so oxygen must have  been diffused through
the atmosphere.  With the increase of vegetation, the carbonic
acid and the  nitrogen would gradually lessen in the atmos-
phere.  The quantity of both would fall towards a minimum,
while that of the oxygen would  rise towards a maximum—
the constituents of the primitive  atmosphere being more and
more condensed into solid substances on the rocky earth.
   Plants may preserve their existence, without the presence
of either animals or combustion.   By the putrefaction which
one part of  them undergoes, carbonic acid and ammonia are
supplied to the other part.  Except  the Infusoria,  all animals
must  have begun to  live after  the existence of plants, for
without plants  no animals could live  upon the earth.   The
black layer of  soil must have come into existence after the
plants, for it can be produced by plants  and animals only.
Thus the substance of the organic parts of animals and plants,
and of the black layer of soil, were formerly component parts
of the atmosphere.
   Animals  must have vegetable food.  As soon,  therefore,
as animals arose on the earth, the quantity of carbonic acid
in the atmosphere, and  that of ammonia in  the black layer
of soil, began to be increased by their respiration ;  and so the
food for plants became more abundant.  Thus vegetation must
have been supported and promoted  by  the continual increase
of animals on the earth; and the food supplied to plants from
the atmosphere will still go on increasing with the increasing
numbers of  mankind.
   At the beginning of the present condition of things, also, a
very remarkable  change must have been produced in the at-
mosphere, by the formation of the black layer of soil.  The
first plants,  which  lived upon and were nourished  by car-
bonic acid and ammonia, either derived or prepared from the
atmosphere, did not restore to the atmosphere on their decay
all they received  from it, but left on  the^earth's  surface a
black solid substance.   As  that layer  increased, the atmos-
phere must  necessarily have been deprived of the elements
of carbonic  acid—and of  ammonia,  either condensed  or
formed from the atmosphere by the  decayed plants.  And in
proportion as this layer of humus increased, (as we see it at
present doing  on our moors and  mosses.) the atmosphere 
110
THE  CHEMISTRY  OF
would  become  poorer and  poorer  in carbonic acid and ni-
trogen.
  That the production of a new vegetation upon arid tracts
of land is now going on so slowly, is to be ascribed  to the re-
duction of the quantity of carbonic acid to a minimum by the
great number of plants which have existed.   Every new ve-
getation fixes carbon to the ground.  If drawn from the at-
mosphere exclusively, this carbon does not easily return, but
is chiefly applied  to the support of the plants which grow on
the spot where the layer of humus has been deposited.
  After the creation, and especially after the dispersion of
the human race,  a new source of transformation of the ele-
ments  came into existence, in addition to what animals were
already contributing to the support of vegetation.   The fires
employed for warmth, for cooking, &c, provided new nour-
ishment, through which, places  hitherto bare might become
covered with plants, and existing vegetables might increase in
growth.   The coal, for instance, which  lies concealed under
the earth's surface, being changed into carbonic acid by com-
bining  with the oxygen of the  air, continually supplies  to
plants a new portion of nourishment.  The  more coal is con-
sumed, the more new  vegetable products (viz. cellulose and
other indifferent substances not containing nitrogen) may be
produced.
  From the  nature of these  reactions,  it follows, that the
black layer of soil is a product of the decomposition of ani-
mals and vegetables, and could not have existed before these ;
that the plants which existed before its formation could  have
no other source of food but the  atmosphere ;—that this food
must necessarily have been carbonic acid and  ammonia;—
that, by the increase of plants, and of the black layer of soil,
the composition of the  atmosphere must have been  changed,
the proportion of carbonic acid and nitrogen being diminished,
while oxygen took the place of the former,—that  during this
time the proportion of oxygen in the atmosphere must there-
fore have been always increasing;—that a great quantity of
carbon and nitrogen, being condensed on the earth's surface,
having passed into plants, into the  state of humus, and into
every kind of organic substance, the  proportion of carbonic
acid present in the atmosphere must have become very minute,
and the increase and extension of plants over tracts of land, 
           VEGETABLE  AND ANIMAL PHYSIOLOGY.        Ill

 not  yet cultivated, must have been thereby materially ob-
 structed ;—that then, not only the extension of vegetation had
 attained its highest point,  but that without other and peculiar
 causes, by which carbonic acid was again returned to the at-
 mosphere, it could not have been maintained at that highest
 point;—that, by the animals which came after the  plants, the
 change in the constituents of the atmosphere has been consid-
 erably increased, a larger portion of carbonic acid and nitro-
 gen being separated  from the earth's surface,  and brought
 into a state fit for being moved and  transported over the
 earth;—that animals,  by supplying  new food  to  plants,
 namely, carbonic acid and ammonia, have again  considerably
 supported  vegetation;—and finally,  that  by the increase of
 the  number of mankind, by their respiration,  by the putre-
 faction of  their dead bodies, and above all, by their fires, this
 effect has been again powerfully promoted.
   Has the atmosphere,  since the appearance of man on the
 earth, preserved the same composition as  it had  before ?  and
 will it at all times retain the same composition—the number
 of mankind being continually increasing,  and that of forests
 diminishing ?
   It is  not to be denied,  that  the quantity of carbonic acid
 must have become  greater, and that  of oxygen  less, with the
 increase in the numbers of men,  who respire and make fires,
 and  whose dead bodies putrefy;—but,  on the other hand,  a
 great many animals, on the increase of mankind,  have been
 expelled from  the earth's surface.   By the fires,  however,
 which man has kindled,  the quantity of carbonic acid  has
 undoubtedly been increased, and that of oxygen diminished;
 but it is difficult to decide with certainty whether  that increase
 in the carbonic acid would have  ever become perceptible, even
 though  the very first  human beings had  been  able to make
 eudiometrical experiments.  It  is, however, probable, that in
 any  given bulk  of atmospheric  air, they would have found  a
 little more oxygen, and somewhat less carbonic acid, than in
 the present day, provided the method of investigation had been
 sufficiently accurate.
  It is a consequence equally undeniable,  that either the at-
 mosphere  will at last become infected by man, or that famine
will arise on the earth.  By the continual increase  of man on
the earth,  the number of forests  has been diminished.  Man
  Vol. I.                  11* 
112
THE  CHEMISTRY  OF
expels and destroys animals and plants which previously lived
undisturbed.   It is principally  by the large  forests that tho
great quantity of carbonic abid, resulting from combustion and
respiration, must be decomposed.  There must necessarily be
a proportion  between the  number of plants  and that of man
and animals on the earth.  The former must restore what the
latter have taken from the atmosphere ; the one must decom-
pose what the other has imparted to the atmosphere.   Wher-
ever the equilibrium between the number of plants and  ani-
mals is disturbed,—that is, when mankind increase and plants
diminish,—then there will at last  be no longer a  sufficient
quantity of carbonic acid decomposed, and the proportion be-
tween  the oxygen and nitrogen, which we now assume to be
invariable, will be altered.
   It is true that a large portion of the earth, susceptible of
cultivation, still remains uninhabited by man.  But if, in im-
agination, we transfer ourselves into futurity ; if we suppose
the woods  destroyed, the  earth covered with edible  plants,
which reach  but to a small height in the  atmosphere; then
we have, in imagination, reached a limit to the invariableness
of the  existing composition of the atmosphere, and at the same
time to the existence  of man  upon our planet.  The disap-
pearance of the falls of Niagara and that of the human race
belong to periods which,  it may be, are still  far distant, but
which, notwithstanding, will certainly arrive,  if nothing mean-
while  interpose.
   When will  that period arrive ?  This is a question to which
we may give  an approximate answer.   According  to the ex-
periments of Lavoisier and Davy, a man consumes 26*04 Paris
cubic feet of oxygen in 24 hours ; that is, 9,505 cubic feet a
year.   Let us suppose the number of men on the earth 1,000
millions, then these consume  9,505,000,000,000   cubic feet
of oxygen every year,  that is, nearly TVhs  of a cubic  geo-
graphical mile.   The whole amount of oxygen by which the
earth  is surrounded,  is 1,953,570 cubic geographical miles.*
  * For this calculation of Poggendorff, the height of the atmosphere
has been taken equal to one geographical mile, or 22,843 feet; the ra-
dius of the earth equal  to 860 geographical  miles, and thus the bulk of
air, consisting of 21 of oxygen and 79 of nitrogen=9,307,500 cubic ge-
ographical miles.   (See ante, p. 98, note.) 
VEGETABLE AND ANIMAL  PHYSIOLOGY.       113
So that, if the number of mankind on the earth were always
1,000 millions, they would  require 2,451,000  years  to take
away all the oxygen from the atmosphere.   If, from the pres-
ent moment, plants were to cease decomposing carbonic acid,
all the oxygen of the  atmosphere would be exhausted after
two and a half millions of years.
  By the operation of this  cause, therefore, the human race
will at some time be destroyed, if it should not happen to be
so previously from other causes.
  Whence has originated  that admirable  uniformity in the
composition of  the atmosphere,  which has been observed
wherever and  whenever it has been investigated ?   First, we
must not conceal, that  our eudiometrical  methods  are not
among  the most accurate;  so that  slight  differences in the
composition of the air  may easily escape  notice.   It must
have been owing to an error in the mode of experimenting,
for instance, that after separating the carbonic acid from the
air in the pit of a theatre, where many people were breathing,
the proportion of oxygen in the remainder was found the same
as in the air outside of the  building.*  For, whence had the
carbonic acid  come,  which  is found in such air in so large a
proportion ?   Whence could  it be  derived, except from the
oxygen consumed ?  This cannot be restored immediately by
the  opening  of doors, &c, since we should expect, that by
the same cause the carbonic acid also ought to have been par-
tially removed, though it be heavier.   In such air, however,
a great deal of carbonic acid was found, but no difference in
the proportion of oxygen.
  With the exception of these smaller errors of observation,
the composition of the atmosphere is  now every where con-
stant, or nearly so.
  The heavy rains, in the first place, carry to the earth many
of the less important vapors.   These  vapors  penetrate into
it, either to be decomposed by plants, or to be converted into
chemical compounds, in the substances of the earth's crust.
Among the latter are the sulphuretted hydrogen given off by
putrefaction, and many other substances, which combine with
the. metals of  the salt-bases  in the earth, and are gradually
changed into salts by the influence of the oxygen of the air,
* Gay Lussac and von Humboldt. 
114
THE  CHEMISTRY  OF
which is present every where.  In this manner carbonic acid
and the traces of ammonia, which exist in the air,  are also
conveyed to the small radicles of plants.  And in like manner,
after having remained in the  ground for a longer period of
time, those substances which are  given off by the bodies of
animals, &c, and are at first injurious to vegetation, must be
decomposed and changed into  new  plants.   (Ball, for  in-
stance,* having left the head of  a  Delphinus phocena to pu-
trefy in a hot-house, found, after a time, a great many ferns,
as well  as other plants, in an unhealthy condition, withered,
and  discolored; viz.  Osmunda  regalis,  Adianthum capillus
veneris, many species of  Aspidium ; also Rubus corylifolius,
Oxalis acetosella, &c.)
   But  in that  air-ocean  itself,  another,  and  a much more
powerful form of its uniform composition exists, namely, the
motion imparted to it by so many various causes, by which, in
the tropics, hot strata of air rise, direct themselves to the north
and south poles, and thence extend themselves over the earth's
surface, to supply carbonic acid to plants for decomposition,
and the oxygen, thence produced,  to man, to animals, and to
the support of combustion.  It is owing to this effect of the
winds, which depend on the temperature, and to which a great
many other  causes might be  added, that an intimate mixture
of the constituents of the air is maintained, and plants and
animals alternately receive what is indispensable to each.
  It deserves particular notice, that the two chief constituents
of the atmosphere—oxygen and  nitrogen—are not combined
chemically,  but merely mixed together.   If they were chemi-
cally combined,  the respiration  of animals would  be impos-
sible, the evolution of oxygen by plants  would not restore the
atmosphere to its proper state.  The absorption, by the blood,
of oxygen, which afterwards appears in the state of carbonic
acid  on the decomposition of the  constituents of the blood,
must be considered as a chief condition of the  respiration of
animals.  This function would have been utterly impossible—
the whole animal kingdom must  have been entirely  different
from what it is at present, if  the oxygen and nitrogen of the
air had  been chemically combined.  During respiration, new
compounds would in such a case have necessarily been formed
* Biblioth. Univ., Nov. 1841, p. 412. 
VEGETABLE AND ANIMAL PHYSIOLOGY.        115
 in the animal  organism itself, not only from the oxygen, but
 also from the  nitrogen, in consequence of its being  in the
 nascent state.   The whole of the nitrogen of the atmosphere
 would then have been included in this  action,  whereas it  is
 now almost wholly excluded.
   Further, plants which can  now restore U^ disturbed equi-
 librium  of the atmosphere by a simple sefiaration of oxygen,
 would not be  at all able to produce the necessary combina-
 tion,  were the atmosphere a  chemical  compound of oxygen
 and nitrogen.   Where the combination was to take place, the
 quantity of nitrogen required might be deficient, and  some
 other combination of oxygen and nitrogen might be produced ;
 in  other  words,  a higher degree of oxidation.   In short,  if
 the oxygen and nitrogen were chemically combined, then or-
 ganic nature would require to be very differently  constituted;
 but as it is, the operation of  the winds  is sufficient to make
 the mixture an intimate and uniform one.
   Finally,  the absolute  quantity of  oxygen  and nitrogen
 which the atmosphere now contains, depends solely  on the
 absence of substances from the earth, which either give to or
 take  from this quantity, and upon the quantity  originally ap-
 propriated to the formation of the atmosphere.  This has not
 been determined after any chemical rule or natural law.   But
 as the earth, once arid and rocky, and destitute of life, became
 covered with a peculiar vegetation—whose residue, coal, for
 instance, is astonishing—a vegetation possible only in the con-
 dition of  the  atmosphere as it then existed; so  the greater
 part also  of the present vegetation must be destroyed, when
 the constitution of the atmosphere  undergoes the requisite
 change.   Thus,*every being which now has life depends for
 its existence on the presence  of 21 per  cent, of oxygen, and
 79  per cent, of nitrogen in the atmosphere.   Whenever this
 proportion is materially altered, every being now alive on the
 earth must die, and another series of plants and animals, per-
 haps a different race of rational beings also, will appear.
  It is not known how many such successive changes of or-
 ganized  beings have already happened on the earth's surface ;
 but that  they have happened,  is established as a certainty.
 Ehrenberg continues to make us acquainted with races of
 minute  beings, which have  powerfully contributed  to the
transformation of the earth's surface, and of which the influ- 
116                THE CHEMISTRY OF
ence on the condensation of the component parts  of the for-
mer atmosphere must have been not less important than that
of the gigantic arborescent ferns,  pines, and other plants of
the primitive world, of which the remains are now buried un-
der the earth's surface, but of  which the organic parts once
belonged to the atmosphere. 
VEGETABLE AND ANIMAL PHYSIOLOGY.        117
                   CHAPTER  IV.

 WATER,  CONSIDERED  IN  ITS  CONNECTION  WITH ORGANIC
                        NATURE.

   While on the one side  a  mixture of  two gases, both in a
 state  of  constant change, are  the  chief constituents of the
 existing atmosphere—on the other,  a  chemical combination
 of two volumes of hydrogen and one of oxygen  constitutes
 water, which performs a powerful part in organic nature, and
 greatly exceeds  the  atmospheric air in quantity.  This dif-
 ference between two substances, both equally indispensable
 to life, is of much importance.   From the constituents of the
 atmosphere  not  being  chemically combined, and  from the
 elements of the water being so combined, many peculiarities
 of organic nature arise.   The elements of  the atmosphere,
 by  their  non-combination, afford plants the  opportunity of
 restoring  the quantity  of  oxygen which was changed into
 carbonic  acid by respiration  and combustion—no other phe-
 nomenon taking place than a simple separation of oxygen.
  But from the chemical  combination  of hydrogen and oxy-
 gen in water, a series of special  consequences follows in the
 organic  kingdom.   It is a known fact  that when substances
 chemically combined are  again decomposed, the  action of
 other substances also which are contained in the circle of ac-
 tion,  is  reciprocally awakened.  Wherever  in the organic
 kingdom  water  is decomposed—and this frequently happens
 —the decomposition  reacts on the substance from which the
 influence proceeded, and produces important chemical trans-
 formations of all the substances included in the circle of ac-
 tion.  This chemical action proceeds, as regards water, from
 two  elements which are  both chief constituents of organic
 bodies.
  1. The first, and a very important effect of the water upon
 organized substances, is,  that they are moistened by it.  All
the  organized  bodies of  plants  and animals need water to
keep  them alive.  That water frequently plays  a  chemical 
118                THE CHEMISTRY OF
part, forming hydrates with the organic compounds ;  but very
often also it acts merely as a liquid, either to moisten, to dis-
solve, or to keep solid substances  in suspension.  We could
not imagine vitality without water,  or  at  least without some
fluid which would be a perfect substitute  for  water.  The
elements of such a fluid, therefore, must necessarily be chem-
ically combined with  each other.
  2. This moistening water is indispensable to keep the fleshy
parts soft, to enable them to grow and be fed.   The  procrea-
tion  of individuals is  accompanied by the access of a large
quantity of water;  the germs of animals freely float in a
liquid, that they may  be able  to move themselves easily, and
by the ciliar motion at their surface, to produce from the water
a continual renovation of substances at its surface.   For the
same reason, in young plants as  well  as in young animals
whose development and growth are rapid, the  amount of wa-
ter in the solid  parts  is also  much greater.   Regarded from
this point of view, the presence of water in the atmosphere
is a most beautiful contrivance,  which has  an intimate con-
nection with life.   If the atmosphere were completely dry, the
water of organic substances would quickly pass off  by evap-
oration, many of them would be  deprived of it, and the living
being must necessarily die for want of water.
  3. It is not less indispensable  to  life as a dissolving and a
suspending fluid.   For it is only by the circulation of a fluid
through the existing parts of  an  organic  whole,  that the sup-
port  and nourishment of the whole organism can  be  effected;
and many of its actions rest entirely upon this process.  With-
out water,  it would  be impossible for the four organic ele-
ments to form  the thousands of combinations which we ob-
serve ; for by its intervention the  most  heterogeneous sub-
stances  are brought  into  mutual  contact in  the organism.
Here the circulating fluid deposits  some constituents,  there it
takes up others, making them produce  a new effect at a third
place ;—in short, the existence  of  water is  inseparable from
that of life.
  4. The service performed  by the water  in  plants and in
animals is  partly  the same  and  partly different.   It is the
same in so  far as it forms hydrates of several  compounds;—
for instance, the hydrates of  protein which appear in plants
and animals under different forms, though always in  the state 
VEGETABLE AND ANIMAL PHYSIOLOGY.       119
of hydrates, and those of mucilage, both  of plants and ani-
mals.  It is the same in so far as it keeps in suspension small
particles, which are  insoluble in water—such as the globules
of chlorophyle in plants, and of the  blood  in animals;  in so
far as it carries dissolved substances through all parts of the
organism—such as the soapy matter of Scheele in plants, the
extractive substances in animals, and in both, a series of salts
under various  forms,  and of diversified composition ;  and
finally, in so far as it supplies to both animals and plants cer-
tain substances in a state of solution or minute division, which,
being fitted to nourish, are indispensable to the existence of
the organism.
   5.  The action of water differs, however, in plants and ani-
mals, chiefly as to the way in which it disappears again from
the organic  substances ;  by which difference, these two classes
of beings are  essentially distinguished from  each other.  In
the greater part of animals, an aqueous  fluid  is circulated
through the whole  structure,  and  enters also into certain
organs, by  which a part of the substances either dissolved by
that fluid or suspended in it, are separated and expelled from
the body, so  that the latter gets rid  of these substances.  In
plants  this  process  is different.   They  are  deficient  in the
organs which  are  exclusively destined to this  service, a*id
thus  retain all the  non-volatile  substances which have  ever
entered into their composition.   Exposing  a large surface to
the air, they  lose aqueous vapors  through  their  leaves, if
the atmosphere  can take up  aqueous vapor; that is to say,
if it  be dry enough for that purpose, and if  the hygroscopic
power of the parts of the leaves  be less than  the power of the
air to contain  aqueous vapor.  Though  this be by no  means
always the  case, it is, however, a condition which often arises ;
so that plants, though not  possessed of peculiar organs, fit for
the expulsion of an aqueous fluid, yet lose, in many states of
the  atmosphere, almost  pure  water through  their leaves.
This function, therefore,  is wholly  different in plants and in
animals.   The latter, though they  also lose water through
their skin—both  by exhalation through the pores, and by
evaporation from the moist skin, covered with a thin epider-
mis—usually excrete, nevertheless,  through peculiar organs
(urine-excreting organs)  a large portion of aqueous fluid.
The  leaves of plants, being possessed of stomata, and being
   Vol. I.                    12 
120
THE  CHEMISTRY  OF
besides in a moist state, lose water  both  through their sto-
mata and over their whole surface, and impart  it to the at-
mosphere.   As  this water  can differ  but  little from  pure
water, a large part of the solid substances contained in the sap
of plants must remain where the evaporation takes place—
the growth of young leaves,  which evaporate  much,  being
thereby materially promoted.   There  is  thus a growth, an
increase of mass, in direct connection with the evaporation of
the aqueous fluid—that is, with the power of the atmosphere
to absorb water.  It is not  to be  denied, that by this evapo-
ration  of the water  through the leaves and  at the surface
of plants, the renovation of the sap in the drying parts, and
at the same time, the circulation of  the sap in plants in  gen-
eral,  is materially supported.   The evaporated liquid  must
be  restored,  and besides the portion of the solid substances
contained in the sap of plants,  which  this water leaves be-
hind, the succeeding portion of liquid supplies  a fresh quan-
tity, which, in its turn, is left behind at the place of evapo-
ration.
   Another consequence of this evaporation and  circulation is,
that the ascension of new fluids through  the whole plant  is
promoted,  and so through its whole  mass  a new change of
constituents must be produced.
   6. Pure  water is scarcely ever  to be found  at the earth's
surface.   Generally, it holds some saline substances in solu-
tion.  These are found abundantly in nature,  especially in
sea-water.   Without these  very saline substances, animals
and plants could not exist.   They are  as indispensable to life
as the four organic elements themselves.   This  connection is
undoubtedly not an accidental, but a necessary one.  It places
living nature in a peculiar  relation  to the so-called  dead na-
ture.   If we imagine the organic parts of the  serum of the
blood separated from it, then  there remains a saline solution,
which, in many respects, approaches  in composition to com-
mon water.  Such coincidences are by no  means accidental,
neither is the necessity of common salt for animal life, and its
abundance in the earth, accidental.  Besides, not only  in the
serum of the blood,  and  in common  water,  but also  in the
aqueous fluid which circulates through plants,  are contained
the chlorides of calcium and magnesium,  the  carbonates of
6oda, lime  and magnesia, and  sulphate of soda,  and in the se- 
VEGETABLE AND  ANIMAL  PHYSIOLOGY.       121
rum of the  blood, potash salts,  and phosphates also.   The
greater part of these salts,  essential to the constitution of the
serum of the blood, are found in common water, and also in
the saps of those plants which are destined for the nourish-
ment of man and animals—an arrangement which establishes
an  intimate connection  between the subdivisions of nature,
which scientific writers commonly separate too much.
   By these salts, undoubtedly, an important part is played in
the whole organic kingdom.  It  is known that the greater
part of them retard chemical changes among the elements of
organic bodies.  By common salt, and  many others of them,
for example, meat is  preserved from corruption.  Thus, the
first purpose for which  salts exist in  the organic kingdom,
is undoubtedly to limit, in a greater or  less  degree, the
change of materials, or to modify it here  and there—which
change would  undoubtedly proceed  much too rapidly in the
animal body, consisting of parts very susceptible of change,
if these salts were wanting.  Some of  them, for instance the
alkaline carbonates, serve to dissolve the compounds of pro-
tein ; others supply supports for the  soft parts,—such as the
phosphates of lime, and in grasses, silica,—and form chemical
compounds with many organic substances ;  at the same time,
from these  and from the sulphates is derived the phosphorus
and sulphur by which,  in  certain combinations, the organic
substances are accompanied.  Finally,  the oxide of iron, pres-
ent in the ash of plants,  must be dissolved in water before it
can be taken up by plants,  which convey it to animals, solely
in order that, through the  influence of  the same de-oxidizing
circumstances  in the organism of animals, it may enter as an
organic element into the coloring matter of the blood, in the
same way as phosphorus and  sulphur  do into many protein
compounds.
  All the salts, soluble in  water, which  are not fixed in the
animal body, or whose constituents  are not combined there,
are necessarily carried away in the urine.  We  cannot ima-
gine any reason why they should be retained  in the kidneys,
since they occur dissolved in  the serum, and are also soluble
in urine, which  is an aqueous liquid.  These salts must there-
fore, be continually, and  to the same amount, supplied from
without.  Except common salt, they are sufficiently abundant
either in animal or vegetable food,  or  in  common water, to 
122
THE  CHEMISTRY  OF
restore what has  been lost.  Man  requires common salt, in
addition to these, and knows, even in the most uncivilized
state, how to appropriate it, and so to satisfy this want of his
body.
  7. The light in which water exhibits itself is peculiarly strik-
ing, when we consider, that this fluid is the medium in which
a countless multitude of plants and  animals  live, find food,
die, and  putrefy; and that the substances they leave behind
serve for the  production, growth, and sustenance of new or-
ganized beings, in the same manner as the atmospheric air
and the soil together do, for plants and animals which are said
to live in  the air.
  More than two-thirds of the surface of  our planet are co-
vered with water.   In that amazingly extended mass,  multi-
tudes of  beings live.   The solid part of the earth  is besides
intersected and  diversified,  in every direction,  with  rivers
and other bodies  of water, in which various plants and  ani-
mals live. Being concealed from the eye  by the surface
of  the water, and less accessible than substances on the dry
land, they have less  attracted  the  attention  of tho natural
philosopher.   This world,  however, deserves to be accurately
known.   Who would venture to determine, whether the num-
ber of organized beings,  living in the water,  or  in the at-
mosphere, is  the greater ?
  8. By  the  mobility of  organic  substances dissolved  in
fluids, their displacement and their union are  in the highest
degree promoted.   In infusions of vegetable and animal  sub-
stances, small animalcules, which thence derive their generic
name  of Infusoria, are easily  produced.   Their  existence,
commonly, is of short duration, as they devour each other,
and disappear, while their substance serves to produce  new
individuals and  new  forms,  and is converted into infusorial
plants, which, in their turn, disappear, and  make room for
others.   In  every kind of stagnant water, in marshes and
ditches, wherever they are found on the earth's surface, simi-
lar  metamorphoses  of small organized beings  occur.  Their
production is promoted by  the stillness  of the  mass of water;
hence  they are not  so frequently found either  in rivers, or in
more extended collections of water, or in  inland seas.   The
innumerable  multitudes of small organized beings in marshy
waters, derive their birth and  existence from  organic  sub- 
VEGETABLE AND ANIMAL PHYSIOLOGY.        123
stances, present in those waters.   The organized beings there
produced, vary with the  nature  of the water  itself, the cir-
cumstances  to which  it is  exposed, and the substances with
which it is mixed.  Previous to the existence of our present
plants and animals, similar infusoria existed in innumerable
multitudes :  perhaps they have contributed  to  condense the
component parts of the former atmosphere.
  9. There subsists an intimate mutual connection between the
atmosphere  and a limited portion of water.   Wherever and
in whatever  way a small  quantity of water is prevented from
escaping into the ground, if it be exposed to the atmosphere,
such an accumulation of organic substances  takes place, that
the  shallow body of water  becomes at last wholly filled up.
The distribution of seed causes plants to spring  up within it,
which—finding abundant food in the organic substances which
have been produced from the constituents of the atmosphere,
and deposited there, altered by infusorial  animals and  plants,
putrefied, changed into humic acid, apocrenic acid, &c.—grow
there luxuriantly, raise their leaves beyond the water, drink
in carbonic acid from the atmosphere, retain the carbon, and
restore the oxygen.  Every shallow mass of water is thus gra-
dually filled  up with peaty soil.   In ponds  and ditches  this
happens every year, so that they require to be widened and
deepened, otherwise they would soon disappear.*
  We therefore observe  an intimate relation between the at-
mosphere and  the water.   All the particles  from the atmo-
sphere  which are washed down by the rains, are taken up by
the  water into which  the rains  fall.  The great variety of
substances diffused through  the  atmosphere,  being  mixed
with the  water, are gradually decomposed  in  it, and at last
substances are produced similar to those which appear in the
soil.  (See Chapter V.)
  Hence, in  every confined mass of water the same substances
are  present as in the soil, and consequently,  the plants living
there are surrounded by a diluted solution  of inorganic and
organic  salts,  which are more or less the same with those of
the  soil.  The water of ditches is colored by  apocrenates, and
from these is derived an abundant supply of organic food, to
           * Wiegmann, Entstehung des Torfs.
Vol. I.                   12* 
124
THE  CHEMISTRY  OF
be taken up by the roots  of plants, which in great numbers
are floating in the water.
  In the great ocean an immense  number  of plants grow.
Besides the sea-weeds and other water-plants with which the
shores are covered,  the  vast quantities  of  the  Sargassum
Columbi, which float on the sea like the weeds on the  surface
of our ditches, are for  this  reason remarkable.   This plant
feeds on the organic substances  of the sea-water, of which
substances  the water contains so great a quantity, that it has
always a yellowish color, and leaves behind  a colored mass
of salt after evaporation.  In those large masses of water
where gigantic animals live, where their excrements  are dif-
fused, and their dead bodies putrefy, an amazing quantity of
organic substances is accumulated, and for the greater part
dissolved, or diffused in a state of minute  division.
  It is certain, also, that by these water-plants, a relation be-
tween the  water and  the  atmosphere  is established.   When
growing, all the green plants give off oxygen, which is dif-
fused through the water, and, by its intervention, partly  through
the atmosphere.
   By the continual evaporation of almost pure water from the
ocean, by the anti-putrescent power of the salts in sea-water,
and by the continual supply of organic substances, carried by
the rivers into the ocean,—the quantity of organic substances
in the soil must necessarily be diminished, and consequently
the quantity of food for the organized beings in the ocean, and
at the same time their very number, must be increased.  Thus
we observe a tendency to enlarge  that multitude of living be-
ings in the ocean.
   We have seen, that oxygen is given off by plants  in stag-
nant waters, as  far  as  they possess green parts.  From this
fact, and from the property which the  water  possesses, of ab-
sorbing oxygen  more easily than nitrogen, we are forced to
conclude, that the proportion of oxygen in the air which is dis-
solved in water, is  greater than  in  that  of  the atmosphere.
This was first observed in the water of the Seine, by von Hum-
boldt and Gay Lussac, and it has been ascertained by others,
in reference to every kind of water, not containing an abun-
dance of organic putrefying substances.  Instead of 21 per
cent., we find 28 to 32 per cent, of oxygen in this air,  dissolv-
ed by water.  Hence the  fishes  are  supplied more   readily 
           VEGETABLE AND ANIMAL PHYSIOLOGY.        125

with oxygen,—the water thus impregnated flowing along the
ramifications of the blood-vessels in the gills, and the carbonic
acid, which at the same time is given off, being dissolved by
the water.  This carbonic acid is a food for plants, and thus in
the water almost the  same succession of  changes takes place
as in the atmosphere, namely, that oxygen is supplied to ani-
mals by plants, and carbonic acid to plants by animals.
   It is well known, that  by the  plants which live upon the
earth's surface and in the atmosphere, those organic substan-
ces are prepared, of which the bodies of animals are compos-
ed—for though some animals are  carnivorous, yet the animal
food they eat obtained its first existence from vegetable food.
Such  a process, however, does not take  place in all the ani-
mals which live in water.  First, there is an infinite number
of smaller animals,—most of the Infusoria, for instance, which
owe their  production, growth,  and increase, to organic  sub-
stances, either diffused through the water or dissolved in it,
as is the case with plants of the lowest orders, such as moulds.
It appears, besides, that some aquatic animals, of larger size,
possess other sources of nourishment than those from which
the food of the larger  land animals is derived.  For we see
that many  of them, for a considerable time, live, increase, and
grow, in a  small  enclosed  quantity of river-water, provided
only it be  gradually  renewed by fresh river-water.   It may
be that they can  be  satisfied with little  food, but whence do
they derive that small quantity ?   Whence, if  not from sub-
stances similar to those on which  plants subsist—from organic
substances in  a state either of minute division or of solution,
of which a small portion is  present  in  the river-water.  A
familiar example of this kind we have in the common leech.
   On this  point, therefore, considerable obscurity still involves
 the economy of those animals that live  in  the  water, which
 science is  as  yet unable to  clear up.   And though, among
 these animals, there are some herbivorous and others carniv-
 orous, it is more than probable that many, like  plants, can
 change organic substances, when  minutely divided, into food.
 Perhaps from these organic substances  infusoria are formed
 in the first instance ; then  the larger-sized animals  devour
 these, and so are nourished  in the same manner as land an-
 imals are, upon vegetable and animal food. 
126
THE  CHEMISTRY OF
                    CHAPTER  V.

      RELATION OF THE SOIL TO ORGANIC NATURE.

   From what has been already stated, it  is obvious that the
 black matter of the soil, with which the earth is covered—to
 the depth, in many places, of several feet, in others of a few
 inches, but which is often also entirely wanting—is the pro-
 duction of plants and animals.  In fact, we perceive the for-
 mation  of substances, similar to those of which its chief con-
 stituents are made up, from the products of the decomposition
 of organized beings, and we do not see it formed in any other
 way.  We are, therefore, sufficiently entitled to assume, that
 these substances, wherever they are present in the earth's
 crust, have always been produced by  the condensation of
 substances from the atmosphere  through  the intervention of
 animals  and plants.  There are other considerations, also,
 which lead to the same conclusion.  Thus where neither plants
 nor animals exist, this black soil is not to be found ; and  on
 the other hand, where  plants and animals  exist in abundance,
 its quantity is materially increased.   It is  thus augmented by
 the plants which grow upon our dry heaths, and which, in re-
 ality, contribute,  in a considerable degree, to the elevation of
 the ground.  The water-pools, also, of the  Old Netherlands,
 which in former times were at some periods of the year 40 or
 60 feet deep, and of which a great  part of the lower districts
 of the country  consisted,  have been  filled  up, and changed
 into habitable ground, by means of other races of plants and
 their decomposed  remains.
   The black layer of  soil, so  far as it contains organic sub-
stances, in whatever part of the earth we suppose it to exist
without  the interference of art, has therefore been produced
by substances  which were condensed from, and  at one time
formed part of, the atmosphere.  It constitutes an intermedi-
ate link between the atmosphere on  the one  hand, and  plants
and animals on the other.   Were  we to adopt the  practice
now generally followed, of calling water,  carbonic acid, am- 
           VEGETABLE AND ANIMAL  PHYSIOLOGY.        127

monia, oxygen, and nitrogen, inorganic  substances—a prac-
tice, however, which  I consider  inconsistent  with  accuracy
and propriety—then surely we  could not attribute^the forma-
tion of the black matter of the soil to any thing but the so-
called organic substances.  Its elements are combined in the
same way as cellular  fibre, starch, gum, and sugar—as every
other organic substance.   From this  point, undoubtedly,  pro-
ceeded the first and sustaining  causes of the  movements to
which the molecules  in plants  and in animals are subjected.
The change of constitution, which takes place in its elements,
is unquestionably transferred to  the plants, which require a
larger or smaller portion of it to be supplied to their roots for
their luxuriant growth ; and the  same molecular motion passes
afterwards from  plants to animals.  The soil, therefore, is, as
I have said, an intermediate substance between the atmosphere
on the one hand, and  plants and animals on the other, through
which that peculiar circle of chemical action,  usually called
organic action, is kept up.  Some plants, it is true, may grow
without soil; but it is  also true,  that almost all existing plants
require to be fixed in  the soil for  their vigorous growth ;  and
though their growth may not be in proportion to the amount of
organic substances in  the soil, still, a certain quantity of them
appears to be required for the growth of many plants,—a fact
well known to every  one at all acquainted with  horticulture.
Hencej undoubtedly, carbonate of ammonia alone is not an ad-
equate food for  plants in general, though it may be the  only
food of some, if in  certain circumstances it be supplied to
them by the soil.  The continual decomposition of the  sub-
stances in the soil is thus a principal cause of the molecules
in plants being  put in motion—a motion which is transferred
by them to animals.   Without this continual decomposition of
substances in the soil, many plants which now exist would dis-
appear from the earth. This continual decomposition, there-
fore, is a service performed by the black soil, which is  alto-
gether different from  what is called the supplying of food to
plants.
  The earth, which at first was surrounded by a mere atmo-
sphere, and had nothing but rocks and  water—and not   even
these at  the very  beginning—on its surface ; which  was  a
dead and arid mass, covered with fogs, and studded with vol-
canoes and lofty rocks, has been  exposed to a great number of 
128
THE CHEMISTRY  OF
alterations on its surface.   Soon after the water had been con-
densed, the influence of air, light, and moisture made its rocks
crumble do^yn  and  decay, the  winds dispersing their debris^
the water carrying  them away, &c, by which  processes the
angular parts of the earth's surface would necessarily become
rounded.  In this manner, the exterior crust of the earth  has
been covered with  many  pulverized or granular substances.
These must be  a mixture of the fragments of those rocks
which were most elevated above the earth's surface, and there-
fore, of silica,  of salts of lime, magnesia, soda, and  potash,
and of alumina, oxide of iron, and oxide of manganese, com-
bined with the  acids  of the same salts—with carbonic acid,
sulphuric acid,  phosphoric acid, and chlorine.   In different
parts  of the earth, this external, decayed, powdery substance
must be different,—no sufficient cause in most cases existing
to move it far from the place where it was first formed.  From
the heights, from the mountains, or  rocks  themselves, they
must  have  been carried down to  the lower districts in  the
neighborhood ;  but there they must Iuivh remained, until car-
ried forth elsewhere by powerful revolutions.  Hence the dif-
ference of the inorganic substances on the earth's surface,—a
difference dependent on the nature of the rocks, the decaying
surface of which was crumbled  down.  This decay is still go-
ing on, and the surface of the  globe, originally  angular, has
been  gradually rounded ;  the crumbled rocks are still widely
dispersed by winds and streams, and by them the depths and
valleys of the earth's surface are filled up.   The high moun-
tains,  covered with eternal  snow and ice, will  follow at the
last.  After their  bases have been worn down and undermin-
ed by the action of water, they, in their turn, being overthrown
and transported into the lower parts  of the  atmosphere, will
be subjected to  the  ordinary influences which tend to round
the earth, and will be finally broken to pieces and levelled.
  Of  these decaying rocks, some are very well known, name-
ly, those from which clay originated—that very generally dif-
fused substance, which is so valuable for the growth of plants.
This clay is produced from feldspar, albite, and porcelain spar.
  Feldspar,  .    KO, Si03+Al203, 3(Si03)
  Albite,     .   NaO, Si03-f-Al203, 3(Si03)
  Porcelain spar, NaO, SiO3-f-"Al2O3,SiO3-f3(CaO)2(Si03)
                    -f-2(Al203, SiO3) 
VEGETABLE AND ANIMAL PHYSIOLOGY.        129
From these silicates of potash, soda, lime, and alumina, while
decaying-—that is, while influenced by the action of water and
carbonic acid—part of the silica, together with the potash or
soda, is washed away by the rains, and silicate of alumina, free
silica, as well as undecomposed feldspar, albite, or porcelain
spar, mixed together as clay, in the state of a fine powder, are
carried down to the rivers or valleys, by  the rains or  melted
snows.
  It is chiefly the feldspar, so generally diffused, which is of
importance here.   Together with silicate of alumina, quartz,
mica, free silica, free alumina, a little chalk, and oxide of iron,
&c, it may be considered as mainly constituting common clay
—mixed, however, with a great many other substances, which
are met with  by the clay in its course, and while it is suspend-
ed in the  water.  The  part of  these  rocks, which, on their
crumbling down, becomes soluble in water, supplies the salts
of the common river-water.
  The inorganic constituents of the arable soil have an unlim-
ited influence upon the  organic  kingdom.  Animals obtain
their inorganic constituents  partly from the water  they con-
sume—by which they have been washed out and taken  up
from the decayed rocks,—and  partly from plants, which again
extract their  inorganic  constituents  from the  earth's crust.
Hence, we perceive an intimate connection between the or-
ganic kingdom, and the composition of the upper layers of the
earth's surface.
  We cannot here present  a complete view of the nature of
those substances ; a few remarks, therefore, must suffice.
  Every thing on the earth's surface, which is exposed to the
influence of air, water, light, and heat, loses  its cohesion, and
crumbles down more or less.   This is what we call decay.
  If the decaying rocks are destitute of  what  are more pro-
perly called metallic oxides, such as those of lead, copper, &c.;
but, on the other hand, contain  compounds of silica, alumina,
and oxide of iron, mixed  with salts of potash, lime, magnesia,
&c, they then may favor vegetation.   The growth of certain
groups of plants may be promoted by such decayed minerals
as contain what those groups require ; the growth of other
groups by the constituents of other rocks.
  It is, therefore,  of  the highest  importance  to become ac-
quainted with these decayed rocks, which exist almost every 
130
THE  CHEMISTRY OF
where on the  earth's surface.  Those pulverized substances
are but  seldom found  on the spot  where  they originated.
They are carried along with  the  water, floating down from
elevated places.  Hence, it is often very difficult to indicate
their origin with accuracy;  for  this  reason, also,  they are
generally mixtures  of various decayed rocks.
  It is clear that the products of decay must vary with the na-
ture of the minerals from which they are derived.  But when
silicates, however composed, are  acted upon  by moist air and
carbonic acid, the silica is separated, and carbonates are pro-
duced.
  This is the case, not only with the generally  diffused  feld-
spar above mentioned, but also with clay-slate, basalt, porphy-
ry, and many  other minerals of frequent occurrence.  Along
with the silicates of alumina,  potash, soda, and lime, found in
feldspar, the silicates of iron  and  manganese are also present.
When these silicates  decompose,  the bases are converted into
carbonates, and silica and alumina are separated.   This ap-
plies to all the silicates which  are soluble in water.   But even
upon those which are insoluble in water, the  same decompos-
ing action is exerted  by moist carbonic acid, and so  they fall
to a powder, which becomes  the basis of the vegetable world.
From this basis water takes what  is soluble, and in that state
supplies it to plants.
  The silica which has been separated is in part taken up by
certain salts, which are soluble in water; namely, by the al-
kaline carbonates.   Through  their means it is held in solution
by all  water, both upon and within the earth's surface, and is
thus conveyed  into  the roots of plants.
  All these mixed silicates of alumina, lime, potash, soda, and
oxide of iron,  produce fertile soils.  Not only have they the
property of absorbing and holding water, but they commonly
retain also a large quantity of alkali,—especially if the origi-
nal mineral is not entirely  decayed,—which alkali they supply
to plants.
  I will select, as examples, three specimens of clay from one
country (the Netherlands), taken from the Zuiderzee, analyz-
ed by E. H. von Baumhauer:— 
VEGETABLE AND ANIMAL PHYSIOLOGY.        131
                                      First    Second.     Third.
  Insoluble quartzose sand, with alumina "> c-j.cac    r1.7r.fi    5f.^72
    8f)u 811 ICcI •■«••   *    .  \
  Soluble silica,......2-340    2-496     2 286
  Alumina,.......1-830    2-900     2-888
  Peroxide of iron,.....9 039    10-305    11864
  Protoxide of iron,.....0350    0-563     0-200
  Protoxide of manganese,  .   .    .    0-288    0354     0284
  Lime........401)2    5096     2-480
  Magnesia,......0130    0140     0128
  Potash,.......1026    1430     J-521
  Soda........1-972    2 069     1-937
  Ammonia,......0 060    0 078     0075
  Phosphoric acid,.....0466    0 324     0478
  Sulphuric acid......0896    1104     0-576
  Carbonic acid,.....6 085    6 940     4 775
  Chlorine,......1240    1302     1418
  Humic acid,......2-798    3 991     3428
  Crenic acid,......0 771     0 731     0037
  Apocrenic acid,   ....     .    0107    0160     0152
  Hurnin, vegetable remains, and water > g.304     7-700     9-348
    chemically combined,   .        .  )
  Wax and resin,.....trace    trace     trace
  Loss,.......0-542    0 611     0-753

                                    100000   100-000   100-000

  On considering the constituents of  these  clays,  it  will be
clearly  seen,  how valuable they are for the  growth of plants,
and  how  many  substances—which  are really constituents of
plants—are contained  in them.   This clay, like all the other
species  in Holland, derives its origin from the Rhine countries,
and is thus a product of decayed rocks.
  The sulphuric acid which it contains is derived from decom-
posed sulphurets ; the phosphoric acid from apatite (phosphate
of lime), a mineral which very frequently occurs.  These two
constituents must be present in  every  fertile soil.
  Of an entirely opposite kind to  these are our sandy soils, in
which the chief part is quartzose sand.   From this substance,
water  dissolves  nothing—acids  hardly any thing.   Unless,
therefore, they are artificially mixed with the substances which
are  indispensable to the growth of plants, they are wholly unfit
for this  purpose.*

  * This is so far true ;  and yet these  quartz sands, from which water,
and  even boiling acids extract nothing, do still contain small quantities
of those  bases, lime, magnesia, potash, &c,  which  plants require.
Sepds sown in them sprout, and their roots extract from the sand a por-
  Vol.  I.                    13 
132
THE CHEMISTRY  OF
  Some of the lands, reclaimed by dykes, in the province of
Groningen, have not as yet been in want of any additional al-
kaline salts ;—while on the contrary, the barren sandy soils in
the neighboring provinces require  to be repeatedly supplied
with ash from plants, to give to new plants that of which the
old had exhausted the soil.*
   We think it fit to conclude this exposition by a brief enu-
meration of some principal rocks, whose decay has given rise
to the formation of soil.
   Quartz-rocks.—To  these  belong   rock-crystal,  common
quartz, flinty slate  (quartz, with alumina,  lime, and oxide of
iron), flintt  (quartz, with alumina,  lime, and oxide of iron),
sandstone, and sand.
   Feldspar-rocks.—To these belong granite, which contains
quartz, mica, and feldspar :$  gneiss, in which feldspar, quartz,
and mica  are contained, so  as  to make  its composition allied
to that of granite ; compact feldspar, which constitutes the chief
part  of  clinkstone,^ and feldspar-porphyry or  keratite (silica


tion of these bases, though not enough in general to enable them to grow
in a healthy manner, and to ripen their seeds.  But these first races die;
those which succeed find a portion  of the work of extraction already
performed,—they, therefore, grow  better, and their successors belter
still; and thus a thick herbage at last covers the loose, and apparently
barren ground.  This fact is encouraging to the husbandman.  It shows
the existence of a power, so to speak, in the roots of plants, which we
should not  have expected, and a latent capability in soils which we are
apt to pronounce hopelessly barren.   See WiegmannandPolslorff, Ueber
die Anorganischen Bestandtheile der Pflanzen,  p. 32.—J.
   * See further : Sprengel's Bodenkunde.
   t Flint.                                   Klaproth.
             Silica,.....9800
             Alumina,.....0-25
             Lime......0 50
             Oxide of iron,  ....    025
             Water  and volatile matter,     .    1
   Berzelius has more recently found, that flints contain  a small per
centage of potash.—J.
   t Common Feldspar.
                              Vanquelin.      Berthier.
             Silica,    ...    64         6420
             Alumina,     .        20         18 40
             Potash,  ...    14         1695
             Lime,    ...    2          000
   § In Clinkstone has been found as much as  8 per cent, of potash, 9
per cent, of soda, and 3£ per cent, of lime. 
VEGETABLE AND ANIMAL PHYSIOLOGY.       133
and alumina, combined with potash, soda, lime, magnesia, ox-
ide of iron,  and oxide of manganese.)  They contain, as oc-
casional  mixtures, sulphuret of iron, hornblende, and mica ;
trachyte* (silica, alumina, potash, and oxide of iron ;) pearl-
stonet (alumina, silica, oxide of iron, potash, and lime ;) and
pumice| (silica, alumina, soda, potash, oxide of iron, and oxide
of manganese.)
   Mica-rocks.—To these  belong mica-slate,  consisting of
quartz and mica,§ (mica is either potash, magnesia, or lithia
* According	to Berthier.		
	From Pny de Dome. From Pertuis.		
Silica	65-5		610
- Alumina, . . . 200			192
Potash, ... 91			118
Lime	22		00
Magnesia, . . . 00			16
Oxide	of iron, . . 30		42
Water, . . . 0 0			20
t Pearlstone,	from Tokay.	Rlaproth.	
	Silica, ....	. 7225	
	Alumina,	. 1200	
	Potash, .... Soda, ....	I 4-50	
	Lime, ....	. 0 50	
	Oxide of iron, .	. 160	
	Water, ....	. 4-50	
t Pumice.		Berthier.	
	Silica,	. 700	
	Alumina, .	. 160	
	Oxide of iron, .	. 06	
	Soda, Potash,	I 6-5	
	Lime,	. 25	
	Water,	. 30	
§ Mica.			
	Potash-mica.	Magnesia-mica.	Lithia-mica.
	Rose.	Klaproth.	Ginelin.
Silica,	. 4750	4250	49060
Alumina, . . . 37 20		1150	33611
Oxide o	firon, . . 3 20	2200	—
Oxide o	f manganese, 0-90	200	1 420
Potash,	960	1000	4 186
Magnesia,		900	0 408
Oxide o	flithium, . —	—	3594
Hydrofl	uoric acid, . 0-56	—	3-445
Phosphoric acid,		—	0112
Water,	263	100	4184
 
134
THE  CHEMISTRY OF
mica, and contains, in combination with one of these bases,
silica, alumina, oxide of iron, oxide of manganese, hydrofluo-
ric  and phosphoric  acids ;) chlorite-slate  (alumina, oxide of
iron, silica, lime, magnesia ;) and lime-slate.
  Hornblende-rocks.—To this class belong hornblende* (mag-
nesia, lime, silica, alumina, protoxide of iron, and manganese ;)
and greenstonet (a mixture of hornblende  and  labradorite.)
The formula of labradorite  is, according  to the analysis of
Klaproth, calculated by Berzelius :—
   (NaOSi03+Al203Si03)+3(CaO,Si03-fAl203Si02).
   Serpentine-rocks, to which  belong serpentinej (magnesia,
silica, lime, oxide of cerium, oxide of iron.)
   Augite-rocks, to which belong basalt, being an intimate mix-
ture of augite, labradorite, or feldspar, and protoxide of iron.
The whole basalt§  consists of silica,  alumina,  oxide of iron,
* Hornblende, free from alumina, consists of—
         CaO, Si03-f3MgO, 2Si03 (Tremolite).
         FeO, Si03-j-3MgO, 2Si03 (Anthophyllite).
    Or— NaO, Si03-)-3FeO, 2SiOs (Arfvedsonite).
Hornblende, with alumina, consists of—
         CaFl-r-5(CaO, Si03-r-3MgO, 2Si03).
t Greenstone.
                                       Beudant
           Silica,.....633
Alumina,			142	
Oxide of iron, .			5-8	
Lime,			25	
Magnesia,			20	
Potash,			12	
Soda,			12	
Water,			03	
| Serpentine, after Mosander ar	d Lyehncll.			
3MgO, 2H04	•2(3MgO, 2Si(		)3).	
§ Basalt, from Stettin in Hoeg	an. Gmelin.			
Part	soluble in acids.		Part insoluble in acids.	
Silica,	35741			48-500
Alumina, .	11-121			6-792
Oxide of manganese,	1-487			—
Oxide of iron, .	—			9 383
Protoxide of iron,	16015			—
Lime,	11914			17-395
Strontian, .	0112			—
Magnesia,	10434			13131
Soda,	3264			—
Potash,	1-204			—
Water,	6530			—
 
VEGETABLE AND ANIMAL PHYSIOLOGY.        135
 oxide of manganese, lime, and magnesia, with soda, or potash.
 The composition of dolerite  nearly approximates  to that of
 basalt.
   Alumina-rocks, to which belong  alumina-slate (silica, alu-
 mina, lime, magnesia, oxide of iron ;)  often also potash, soda,
 gypsum, and common salt.
   Lime-rocks,of which the chief constituent is carbonate of lime.
   Gypsum, or sulphate of lime.
   Iron, oxidulated iron, magnetic oxide of iron, iron-slate.
   We perceive  that the  substances above  enumerated, and
 which after their decay cover so large a portion of the earth's
 surface,  contain for the  most part, the same constituents.
 Their real difference consists either in their less important in-
 gredients,  or  in the various  proportions they contain of the
 several constituents, whose mutual combinations form the sev-
 eral minerals.   Hence it  is clear, that in different parts of the
 earth's surface, they must be very different.
   These rocks, which covered the earth in the beginning, and
 which, during the long period of  their existence, have been
 gradually crumbling down, have thus produced the  inorganic
 constituents of the soil, and are every day still doing so.
   By the  condensation  of  the  four  elements  from   the
 earth's atmosphere, carbon,  hydrogen,  nitrogen,  and  oxy-
 gen, during the  first growth of plants—by the  continual in-
 crease of this condensation in living plants—and by the pro-
 duction therefrom of the black  organic substance,  which we
 now find  in the ground,—this black  substance, must have been
 immediately mixed with the fragments of the decayed rocks.
 The final result of this process must necessarily have been
 the production of a  mixture, in which inorganic compounds,
 both alone and in combination with organic compounds, would
 be found.  On considering the chief inorganic constituents of
 the soil briefly enumerated above, we see that such of them as
 are soluble in  water, are the same  with those which we for-
 merly noticed  as being also found in common water, owing to
 the facility with which they are dissolved out of the decayed
 rocks, either by the falling rain water, or by the melted snows.
 And as these sails are also indispensable constituents of plants
 and animals, the  whole inorganic earth appears to be in inti-
 mate relation with organic nature,  and vice versa.   Finally,
the substances soluble in water are  mixed  both with the or-
   Vol. I.                  13* 
136
THE  CHEMISTRY OF
ganic constituents of the soil, and with the insoluble remains
of decayed rocks ; and so they are supplied to plants in a fine-
ly divided state.
   Supposing the products of the decomposition of plants and
of animals to be the very same, in  certain circumstances, it
is still impossible that the several  kinds of soil should be the
same in different places.   The inorganic  substances present
in the soil influence  this decomposition, and frequently mo-
dify it.   The presence of bases, acids, or salts,—all acting so
powerfully in inducing changes among the elements of or-
ganic substances,—must necessarily influence the decomposi-
tion of plants and animals, and modify the products which re-
sult from it,  influencing at the same time also the motion im-
parted by the decomposing molecules of the black crust of the
earth to the  plants which grow there.   Hence the difference
of soils which arises from a difference in their inorganic parts;
hence the difference in the new products, which spring from
the soil, according as the inorganic constituents of the earth's
crust differ; hence, in other words, the relation between the
rocks of any district, and the vegetation which grows upon
their decaying fragments.
   It is a known fact, that the flora of  our country (the Neth-
erlands), agrees with that  of the whole district on the Rhine.*
This is justly ascribed to the diffusion of seed by means of the
waters of the Rhine ; but  another cause may  be superadded,
namely, the uniformity of the inorganic parts of the soils, car-
ried down by the stream.
   In different plants, different constituents of the salts, bases,
and acids are found.  It may be true, that substances, to which
they are nearly allied, may  be substituted  for them, as potash
for soda, &c.; but every species of plant preserves a high de-
 gree of peculiarity in this respect, and often dies from want of
 its peculiar  inorganic constituents.
   Hence the reason  why certain  plants prefer certain soils—
 why they refuse lo live in some tracts of land,  though in other
 respects they are  placed in  the same circumstances: hence
 the necessity that fields,  from which plants  are continually
 reaped, should have the ash of  plants occasionally added ;
 hence, finally, the  increased fertility  of pastures irrigated by
* Miquel, Distributio Geographica Plantarum. 
VEGETABLE AND ANIMAL PHYSIOLOGY.       137
the winter floods, which restore  the  inorganic substances of
which the soil has been exhausted by its vegetable produce.
   A fertile arable soil, therefore, is an intimate mixture of in-
organic substances,  insoluble in  water,—especially fitted to
make the soil penetrable, by the roots of plants, and by water ;
or, by their hygroscopic force, to  retain the water, a property
of which clay is possessed in a very high degree—or of sub-
stances soluble in water, which can be taken up by plants,
and to which the  salts already enumerated belong.   It is a
mixture, also, of organic with inorganic substances,  with the
latter of which the former may or may not be combined.
   These organic  substances existing in the soil, would be of
an incalculable variety, if they were not, by a general cause,
reduced  to a small number.  If this general cause did not  ex-
ist, the  first  plants produced  on the  decayed rocks would,
when dying, have deposited on the earth's crust all their ma-
terials ;  to these, the succeeding  plants would  have added
 their share—and thus there would have been  formed every
where a mixture  of all sorts of vegetable substances, differing
with the nature of the materials, from which different tribes of
plants are  built up.   In nature, however, this operation pro-
ceeds in a very different way.
   Not only is the individual destroyed at its death,  but all its
 organic substances are  decomposed,  transformed, changed,
 and modified in such a manner, that,  finally, a few only  are
 produced,  whatever may have been  the plant or the animal
 whose  individuality  was destroyed.    There are,  however,
 some vegetable  as  well  as animal substances, in which  this
common change  is  not yet known; nor is  it likely to take
 place.   As to these,  the inquiry still  remains,  what becomes
 of them in the earth's crust ?   The resins, fats, vegetable ba-
 ses, and acids are of this class.   As to the chief component
parts of the organic kingdom, however, it is known into what
 they are transformed during their  decay in  the soil, that is,
 during the formation of humus.  This decay is a peculiar de-
composition  of organic bodies, not  to be confounded with pu-
 trefaction, from which it greatly differs ; owing, especially, to
 the influence of the decayed rocks, and the division of the or-
 ganic substances, effected  by this cause.  This change is re-
 markably  uniform, since, from the innumerable organic com-
 binations, which  exist in plants and animals, the same few con-
 stituents of the black layer of soil are derived. 
138
THE CHEMISTRY OF
  If we exclude the substances accidentally mixed with the
black soil, as well as those substances which have not yet un-
dergone sufficient decomposition,  its constituents are limited
to a small number of organic substances—substances existing
in it every where, and  on the decomposition of which the
growth of plants depends.
  These substances have the following properties :—Some of
them are soluble in \yater, others in alkalies,  others  again are
insoluble in both, while some dissolve more or less  readily in
alcohol and ether.   The latter are resinous  substances, and
they appear to have no share in vegetation at all.  The resins
obtained from turf  are of  an  exceedingly singular composi-
tion, which indicates that they contain combinations  of carbon
and  hydrogen,  in  different proportions—namely,  CH, and
C5H4—-either combined  or not combined with oxygen.
  In the hard Frisian turf,  4 resins exist :*—
             «. C50  H40  O9r=10(C5H4)-|-O9.
             (9. C77  H67  O9
             y. C104H94  O9
             d, C131H12109
  In the three latter, the a  resin is no doubt chemically com-
bined with carburetted hydrogen, CH, for if,  from each of
them, we subtract the a resin, we have :—
           1.  (9.  C77H6709
               «.  C50H4009
   C27H27=9 X C3H3
y,  C104H94O9
a.  C50 H4009
  C54 H54—1S xc3H3
8. C131H12109
a. C50 H40 O9
                  Csi H81=27 X C3H3
  In long Frisian turf, the composition of these resins is some-
what different:—
* Bulletin, 1839, p. 147. 
           VEGETABLE AND  ANIMAL PHYSIOLOGY.       139

           C35H29  05 = 7(C5H4)-H>
           CaoHies Q6 —6(C5H4  -f-0) 60(CH).*
  These are all the substances of this kind which,  so far as
they exist in  the  soil, have  been as yet  investigated.  But
similar substances, produced from the decomposition of or-
ganic bodies,  exist undoubtedly in all  sorts of soils, and in
other strata.  The light carburetted hydrogen, CH2, is a pro-
duct resulting from the decomposition of plants,  which have
been buried under the ground to a great   depth, and trans-
formed into coal.   There are two other carburetted  hydrogen
compounds, CH and C5H4,  which have a solid form, and
by a similar change are produced at the surface.  It is very
likely that further investigation will make us acquainted with
more of  them.t
* a Resinate of lead, hard Frisian turf.
» Found. C 5733 H 781 O 13 44 PbO 2142	Atoms. 50 40 9 1	Calculated. 57 77 755 1361 21-07
R Resin. Found. C 77.37 H 10.98 O 1165	Atoms. 77 67 5	Calculated. 7721 10-97 11 82
7 Resin. Found. C 79 12 H 1194 O 8-94	Atoms. 104 94 9	Calculated. 79 32 1179 8-98
& Resin. Found. C 80-77 H 1215 O 7 08	Atoms. 131 121 9	Calculated. 80-60 12 15 725
a Resin, long Frisian turf. Found. C 7620 H 1021 O 13-59	Atoms. 35 28 5	Calculated. 75-89 992 1419
7 Resin. Found. C 80-38 H 1252 O 710	Atoms. 90 84 6	Calculated. 80 68 12 29 703
t Johnston. 
140
THE  CHEMISTRY OF
  2. The organic substances which are soluble in water and
alkalies, are present in certain kinds of soil in considerable
quantity, in others to a very small extent.  Their characters
are analogous to those of the substances which are insoluble
in water and alkalies, with  the exception of the resins above
mentioned.  These soluble substances present themselves with
different characters in the soil, owing to their being combined
with different inorganic bodies ; the same organic  substance,
which forms a soluble compound  with potash,  forming an in-
soluble one  with oxide of iron or lime.   There are, however,
two organic constituents of the soil which do not combine with
bases, and are insoluble both in water and in alkalies.
  At present seven different organic  substances  are known
to exist in the soil.  They  are crenic  acid, apocrenic acid,
gei'c acid,  humic acid  and humin, ulmic acid  and ulmin.
Humin and  ulmin are insoluble in alkalies and in water; the
others are readily soluble in alkalies, and more or less in water
also.   In different kinds of soils  the relative proportions in
which these substances  are  present, are very different, as are
many  of their  physical and chemical properties ;  but nume-
rous experiments seem  lo show, that a  greater number can-
not at  present be admitted.*
  It is of importance to be  acquainted with these  substances.
I shall divide them into  two  groups, the crenic and the humic.
In the  latter, I include geic acid, humic acid and humin,
ulmic acid and ulmin;  in the former, crenic acid and apo-
crenic acid.
  In a good  arable  soil—that is, one  of which the organic
constituents are as far as possible decomposed—none of these
substances contains  nitrogen as a constituent element.  All
their nitrogen exists in  the  state of ammonia.   And as  five
of the constituents of the soil already enumerated are acids,
five different salts of ammonia, and also double salts of  pot-
ash, soda, lime, magnesia, and oxide of iron, may be formed
from these five acids ; which salts, being soluble in water, can
be supplied to plants in  a state of  solution.
  * In a subsequent page, T shall state the result of some researches of
my own, which show that to this number others may already be ad-
ded.—J. 
VEGETAELE AND ANIMAL PHYSIOLOGY.        141
  If the soil is exhausted by means of water, a great many
salts are extracted from it.   Three different kinds of soil gave
of salts in 100 parts :*—
                         0-424
                         2-771
                         1-540
  These salts are the chlorides of sodium, potassium, calcium,
magnesium, and ammonium, with formic, acetic,  sulphuric,
carbonic, crenic, apocrenic,  and humic acids, in combination
with the oxides of the same metals.   They form altogether
what is called humus extract.
  From the soils treated with water in the manner described,
alkaline solutions extract substances, which  may be  precipi-
tated by acids.  In different  kinds of soils the substances thus
extracted  are  sometimes different.  They all consist, how-
ever, of one or more of the following three, namely :—
              Gei'c acid,       C40Ht2014
              Humic acid,     C40H12012
              Ulmic acid,      C40H14012
  The latter is that which, in neutral vegetable substances un-
dergoing decay,  is  formed first.   From  it,  by absorption of
oxygen from the  air, humic acid is produced, and  finally, by
a further absorption, geic acid.
  Of these three substances—soluble in alkalies, and  precipi-
table by acids from their solutions—the above mentioned three
kinds of soils gave in 100 parts :t—
                         4-249
                         5-289
                         8-667
The substances which  are insoluble in alkalies,  (ulmin and
humin,) can be rendered soluble, and so converted into ulmic
and humic acids respectively, by the decomposition which is
always going on in the constituents of the soil.
  The  organic  substances  now  enumerated, which in the
mass we call humic, may thus in  part  be supplied to plants,
provided there be an  alkali at hand  to  bring them into  a
soluble  state.   This may either be  one of the fixed alkalies,
or ammonia—especially the latter, which,  in a  way I shall
* Scheikundige Onderzoekingen, Vol. II, p. 92.
t Scheikundige Onderzoekingen, II, p. 92. 
142
THE  CHEMISTRY OF
 presently describe, may be  so easily formed from the atmo-
 spheric air included in the soil.   In this way the humic sub-
 stances, in a state fit for supplying food for plants, are added
 to  the  soluble salts above enumerated—provided  ammonia
 have access to render them soluble in water—and, therefore,
 they must be taken up by the roots of plants,  along with the
 salts, unless plants  be able to select—a supposition which is
 by no means probable.*
   In the fluid, from which the humic substances have  been
 precipitated by an acid, apocrenic and crenic acids  are still
 contained, which substances may  also be collected, and their
 proportion calculated  by adding  first acetate of copper, and
 afterwards carbonate of ammonia.   By the former, apocro-
 nate of copper is thrown down, in which about 50 per cent, of
 apocrenic acid is contained ; by the latter, crenate of copper,
 which contains a variable proportion—from 40 to 70 per cent.
 —of crenic  acid.   When  treated in this  way,  the  three soils
 referred to gave respectively—
                  Apocrenate of Copper.
                           1-865
                           1-228
                           0-701
                    Crenate of Copper.
                           0-774
                           1-901
                           1-260
 These two acids, also, as they exist in the soil, can be separated
 from their insoluble combinations with lime and  oxide of iron,
 by  means of ammonia, potash, or soda, with which they form
 soluble  salts.   If ammonia, therefore, be present, the soil will
 be  found to contain  five  different compounds of this base,
 sometimes in considerable quantity,—substances which  can
 be supplied to plants in a soluble state, and which are thus of
 great importance to their growth.
  In giving a slight outline of the  production of all  these sub-
stances, and of their influence on the life of plants, we shall
  * Some of the reasons in support of the opposite view, which I am
inclined at  present to regard as the more  probable, will be found in
my published  " Lectures on Agricultural  Chemistry and Geology,"
p. 112.—J. 
VEGETABLE AND ANIMAL PHYSIOLOGY.        143
 begin  with the humic,  and treat afterwards of  the  crenic
 group.
   First, however, we must advert to the ammonia, which so
 powerfully supports the growth of plants, and deserves to be
 particularly noticed, not only as a  base, rendering the five
 acids above  mentioned soluble,  (in which  respect, like  the
 ashes of plants, so valuable as a manure, it plays an  impor-
 tant part,)  but also as a substance containing nitrogen,  the
 only one,  indeed, of this kind, which  exists in  a soil suffi-
 ciently  decomposed.
   We are, I believe, entitled  to conclude,  from  the  experi-
 ments  of Liebig himself, (page 99,) that this ammonia cannot
 be carried  down to the soil from the atmosphere, by means of
 the rain-water.  It exists in  the atmosphere in  too small a
 proportion—a proportion which has never  been  determined.
 Nay, it is so minute, that it appears not to be capable of being
 determined,—its mere presence even is difficult to be detected.
   Nitrogen, in the state of pure gas, and also atmospheric  air,
 are, however, possessed of one common  property, namely, that
 when  in contact  within an enclosed space with putrefying
 substances,—from which hydrogen is in consequence given off,
 —the nitrogen combines with the hydrogen and forms ammo-
 nia.   This property of nitrogen is known.   It is the principle
 on which saltpetre is formed ; the production of that substance,
 as has been correctly remarked by Liebig, being always prece-
 ded  by  that of ammonia.  Now,  air is contained in the soil,
 and  is  in continual contact with moist and decomposing sub-
 stances.   This air  could produce saltpetre, if  there  were
 only a sufficient abundance  of bases,  and  even  without  the
 presence of putrefying  organic  substances.  There  are in
 Ceylon  twenty two natural saltpetre grottoes, where there  are
 no organic  substances, from which nitrogen might be supplied.
 Nitrogen is derived  from the air contained  in these caverns,
 and, in favorable circumstances,  even the water is decompo-
 sed,  and ammonia at the same time produced, which after-
 wards is oxidized into nitric acid by the oxygen of the  air, in
 places where it has more  easy access ; this  acid  then com-
 bines again with the bases from the walls of the grottoes, and
 forms nitrates.
  All this would happen in the soil if organic substances were
not present to absorb the oxygen, and thus to prevent the oxi-
   Vol.  I.                  14 
144                 THE CHEMISTRY OF
dation of the nitrogen in the ammonia,  and the formation of
saltpetre.
   In a porous soil, in which moist air is contained, nitrogen
combines with  the hydrogen of the organic bodies only into
ammonia,  the oxygen from the water and the air being con-
sumed in  the higher oxidation of the organic substances them-
selves.   In this way, the first product of  the  decomposition
of organic substances,  namely, ulmic acid,  C4oH14012, is
converted into humic acid, C40H12O12, and  this  again into
gei'c acid, C40H12O14  ; the latter, again,  being then further
oxidized into apocrenic and crenic acids, which we intend to
treat of hereafter.
   It may be enough to  repeat here, that in the soil, as in the
natural caverns of Ceylon, the ammonia is produced from the
nitrogen of the atmosphere, and that the  oxygen  of the air
converts the organic substances successively into ulmic, hu-
mic, geic, apocrenic, and crenic acids, instead of forming ni-
tric acid.
   What is  said  here of the  formation of  ammonia from the
nitrogen of the atmosphere, contained in  the  moist soil, has
been treated of elsewhere at great length.*
   By all porous substances, therefore, ammonia is produced—
provided  they are moist, are  filled with atmospheric air, and
are exposed to a certain temperature.!  It is by this process,
that the porous lime in the walls of moist rooms comes to con-
tain first ammonia, and afterwards nitrate of lime,—that moist
charcoal becomes impregnated with ammonia, and forms, af-
terwards,  by oxidation, the substances resembling humus ex-
tract, which Biichner  found  in charcoal  to the amount of 2
per cent., and  in which Lucas cultivated  plants—substances
consisting chiefly of apocrenate of ammonia,  produced from
 the charcoal by oxidation.
   This formation of ammonia from the nitrogen of the atmos-
 phere has been denied by several writers, especially on the
 ground,  that at an  elevated  temperature nitrogen does not
 form any combination  with hydrogen.  But the combination
  * Scheik. Onderz. Vol II.
  t See Kuhlman upon the formation of saltpetre, in Annalen der Phar-
macie, Bd. 29, s. 272, who ascertained, in lb39, that the formation of
ammonia precedes that of saltpetre. 
           VEGETABLE AND ANIMAL PHYSIOLOGY.        145

of nitrogen with hydrogen at ordinary temperatures, in vari-
ous circumstances, is equally true with the result of the expe-
riments made upon the former point.  It has been demonstra-
ted by many experiments, that, at an elevated temperature,
nitrogen has an indifferent character,  being unable to form di-
rect combinations at a red heat', either with hydrogen or with
oxygen.   This is, however, not the case with regard to car-
bon.  Coke, when heated to redness with potash in the open
air, produces cyanuret of potassium.  There are some cir-
cumstances also in which nitrogen does combine with oxygen
at a high temperature :—for instance,  Cavendish obtained  ni-
tric acid by  passing electric sparks through moist atmospheric
air, and the  same acid is  also  produced,  when a mixture of
hydrogen and nitrogen is burned in the air.
  It is  a fact, especially  important to our present purpose,
that hydrogen, in the nascent stale, combines directly with ni-
trogen into ammonia.  When reddened litmus paper is hung
up in  a bottle,  filled with pure atmospheric air, and when pure
iron-filings, moistened with pure water, are laid at the bottom,
then the red litmus is quickly turned  blue by  the -action of
ammonia, formed from the nitrogen in the air, and the hydro-
gen of the decomposed water, the oxygen of which had com-
bined  with the  iron.
  Such a formation of ammonia continually takes place in the
soil.   There, atmospheric air is present, and consequently  ni-
trogen ; hydrogen  is continually liberated  (see below,) and
thus the conditions, necessary to the formation of ammonia,
are fulfilled  as often as cellulose, ligneous matter, starch, &c,
are changed either into humic acid, or into other constituents
of the soil.
  To  this formation  of ammonia  from the constituents of at-
mospheric air  and water, we  must look for the cause of one
of the most important  peculiarities in the growth of plants.
It is owing to this slow formation of ammonia, that the organic
substances of the soil, insoluble in water, are  rendered solu-
ble, and so can be offered to plants as organic food, even with-
out a  supply of ammoniacal  manure to  the soil.  In other
words, it is owing to this cause that  the  five acids already
mentioned can all be converted into soluble ammoniacal salts.
  The humic substances,—that is, the substances which can be
extracted  from the soil by alkalies, and precipitated from the 
146                THE CHEMISTRY OF
alkaline solution by acids—from  whatever kind of soil they
may have been prepared, have a  very great uniformity, and
are remarkably similar to those substances which, by the ac-
tion of several chemical  agents,  may be obtained from the
materials which are generally diffused through the vegetable
and animal kingdoms.   Hence, we perceive a remarkable con-
formity between putrefaction and chemical action, and also a
change of very dissimilar bodies into the same substances, by
which we are led to recognize a certain conformity in the na-
tural arrangement of  the  elements of these bodies.   While,
therefore, we see woody fibre, starch, gum, sugar, and also
protein, severally yield the same chemical substances by means
both of putrefaction and of an acid, and woody fibre by means
of putrefaction, an acid, or heat (in soot,)—we have undenia-
ble proof,  that  putrefaction, acids, and  heat, must exert on
these substances the same effect, and consequently their chem-
ical influence must be uniform.   Putrefaction  being thus a
chemical action, and at the same time a phenomenon which im-
mediately succeeds the individual vital force, we are,  in spite
of ourselves, led to draw the  conclusion, that  this individual
vital force is very much regulated by chemical action, though
it may be determined by other series of chemical actions, than
those by which putrefaction is effected.
   But we are not  less entitled to draw  the conclusion, that,
as the  same substances are produced in circumstances so very
different  (putrefaction and the  action of acids), and from so
many  different materials (woody fibre  and protein, starch and
phloridzine),*—there must exist  in all these dissimilar com-
plex  substances (viz.  protein, woody fibre, starch, gum, su-
gar, phloridzine,  and  a great many  others,)  a uniform ar-
rangement of the  molecules,  or  some unknown combination
of the elements, which occurs as  a prototype in humic acid
and humin, and which is constantly liberated from these differ-
ent substances under very different circumstances.   This pre-
sents another  generality in the arrangement  of the  organic
world, and exhibits in  a beautiful  light the simplicity of the
whole  scheme.
  3. The soil contains a humic substance, which is insoluble
  * Nitro-humic, and nitro-phloretic acid are identical ; they are both
apocrenate of ammonia. (Scheik. Onderzoek. Vol. II, p. 105.) 
VEGETABLE AND ANIMAL PHYSIOLOGY.
147
in alkalies.  A similar one is found also in the products ob-
tained by the action of acids upon sugar, <fcc.  The composi-
tion of the latter is known.  That of the former is very difficult
to ascertain, because the different insoluble products of putre-
faction remain in a state of mixture, and can scarcely be com-
pletely separated—such, for instance,  as rotten wood, which
cannot be separated from that which is  but partly rotted. We
may, however, suppose, with a certain degree of probability,
that the substance of the soil, which is insoluble in  alkalies,
will also be similar to that which can be produced from sugar,
&c, by means of acids.
  The humic substances, soluble in alkalies, are divisible into
three  classes  according to  their composition—into  those,
namely, which can be supposed to consist of carbon and the
elements of water,—those which contain  more hydrogen than
the oxygen requires to form water,—and  those which contain
an excess of oxygen.   Such are the humic, ulmic, and geic
acids.  Their composition is  as follows :*—
* Bulletin, 1840, p. 1.				
Ulmic acid from sugar, at 195° C	3 Is	(383° Fah	O	
Found.		Atoms.		Calculated.
C 68-95		40		68-98
H 4 23		14		394
O 26 82		12		26 08
Ulmin at 140° Cels. (284° Fahr.)				
Found.		Atoms.		Calculated.
C 6527		40		65 65
H 4 52		16		428
O 30 21		14		30 07
Ulmic acid from long Frisian turf, at 140° Cels.			(284°	Fahr.)
Found.		Atoms.		Calculated.
C 6185		40		62 62
II 4 79		18		4 62
O 33 36		16		3276
Humin from sugar, at 140° Cels.	(284c			
Found.		Atoms.		Calculated.
C 64 67		40		64 44
H 4 32		15		394
O 3101		15		3162
Humic acid from sugar, combined		with oxide of silver, at 100		
(212° Fahr.) Found.				
		Atoms.		Calculated.
C 49 05		40		49-36
H 3 23		15		3 02
O 24 53		15		2421
AqO 2314		1		2341
Vol. I.                  14* 
148
THE  CHEMISTRY OF
40	14	12		
40	14	12	+	2
40	14	12	+	4
40	12	12		
40	12	12	+	3
40	12	12	+	3
40	12	12	+	4
40	12	12	+	4
40	12	12	+	4
40	12	12	+	3
40	12	12	+	2
40	12	12	+	5
                                 C   H   O      HO   0
Ulmic acid from sugar by means
  of acids,
Ulmin from the same,
Ulmic acid from long Frisian turf, 40
Humic acid from sugar by means
  of acids,
Humin from the same,
Humic acid from hard turf,
Humic acid from a rotten tree,
Humic acid from an arable soil,
Humic acid from soot,
Geic acid from two kinds of soil,  40  12   12       3 + 2
Humic acid from a pasture field,
Humic acid from an arable soil,
Humic acid from protein, by means
  of muriatic acid,    .     .      40  12   12


  Humate of ammonia from hard Frisian turf, at 140° C. (284° Fahr.)
                  Found.          Atoms.         Calculated.
           C       013            40            60-28
           H       4 74            19             4 68
           N       3 61            1             3 49
           O      3155            16            31-55
           =C4oHi20i2+NH3+4HO
  Humate of ammonia from an old willow, at 140° C. (284° Fahr.)
                  Found.          Atoms.         Calculated.
           C      59 06            40            58-98
           H       496            20             482
           N       2 80            1             3 41
           O      3318            17            32 79
           =C4 0Hi2Oi2-f-NH34.5HO
  Geate of ammonia from an arable soil, at 140° C. (284° Fahr.)
                  Found.          Atoms.         Calculated.
           C      57 37            40            5800
           H       443            19             448
           N       3 25            1             3 37
           O      34-95            18            3415
           =C40Hi2Oi4-|- NH +4H03
  Humate of ammonia from an arable pasture soil (284° Fahr.)
                  Found.          Atoms.          Calculated.
           C      57 16            40            56 63
           H       5 38            23             5 32
           N       611             2             6 56
           O      31 35            17            3149
           =C4oHi20i2+2NH3+5HO 
VEGETABLE AND ANIMAL PHYSIOLOGY.        149
  Almost all these substances are combined with ammonia in
the soil, and contain different proportions of water, with which
they remain in combination, if dried at the same temperature
of 140° Cels. (=284° Fahr.)  They ought, therefore, not to be
considered  as  the same, though analogous substances; they
differ from each other in accidental, and not in essential, pro-
perties.   The varieties of the  three acids—ulmic, humic, and
geic acids—must be viewed in the same light as the different
kinds of sugar, in which it is clear, that C12 H9 O9 is contain-
ed, but from many of which the whole of the water cannot be
driven off by bases.*
   Let us now briefly consider the manner in which the above
three acids are produced.
  Ulmin and ulmic acid  are  formed from  cellulose, starch,
gum, and sugar, by the influence of acids, and at the same
time,  formic acid is produced.  The following may serve as
an example :—
J of 7 equiv. of sugar, =	C . 42	H 35	0 35
1 equiv. of ulmin, = 1 equiv. of formic acid, = 18 equiv. of water, =	. 40 . 2	16 1 18	14 3 18
	42	35	35
Humate of ammonia from a garden mould, at 284° Found. Atoms. C 57 87 40 H 4 98 21 N 352 1 0 33 53 18		Fahr. Calculated. 57 72 4.97 3 34 33 79	
          =C4oHi20i2-f-NH3-f6HO

Humate of ammonia from protein by means of muriatic acid, at 284°
  Fahr.
               Found.          Atoms.         Calculated.
         C     64 86           40            64 58
         H      4 61           16             4 22
         N      3 70            1             3 74
         O     26-83           13            2746
         =C4oHi20i2+NHs + HO
• See Scheikund. Onderz. Vol. II, p. 88. 
150                THE  CHEMISTRY  OF
  It is certain that a change similar to the above takes place
during the formation either of ulmin or  ulmic acid from cel-
lulose or other neutral substances during  decay.  In this case,
however, the formic acid either cannot be produced at all, or
cannot be so exclusively; but, in its stead, two equivalents of
carbonic acid and one of water must be produced, two of oxy-
gen being absorbed from  the air.*   In the same  manner  the
above organic substances are changed into humin nnd humic
acid, which are formed in the soil more frequently than ulmin
and ulmic acid, and consist of C40H12O12.   They are pro-
duced from sugar, by the action of acids, with access of air,
as follows:—
                                       C      H     O
   J of 7 equiv. of sugar,      .        42     35     35
1 equiv. of humin, 1 equiv. of formic acid, 22 equiv. of water,	40 2	12 1 22	12 3 22
                                      42    35    37
  Thus, two  equivalents of oxygen are taken from the atmo-
sphere, when humin is formed in this way.  In the soil, again,
during the decomposition of sugar, four  of oxygen are  ab-
sorbed, and two of carbonic acid and one of water are formed,
instead of one of formic acid.   (See preceding note.)
  The change of sugar,  therefore, either into  humin or ul-
min, or into their acids, during decay, is a simple transposition
of its elements.   Thus ulmin is formed from it, with absorp-
tion of two of oxygen, humin of four of oxygen, and geic acid
of six of oxygen, as follows :—
                                       C     H     0
   J of 7 equiv. of sugar, -f-O2,       42    35    37

   2 equiv. of carbonic acid,
  19 equiv. of water,
   1 equiv. of ulmin,

                                      42     35    37

  * These two of oxygen are required to convert the formic acid into
carbonic acid and water.  Thus :—
       Formic acid-j-2 of oxygen=2 of carbonic acid-f-water.
        C2H1O34-    20    =      2C02   -fliO
2		4
	19	19
40	16	14
 
VEGETABLE AND  ANIMAL PHYSIOLOGY.        151
 £ of 7 equiv. of sugar, -f 04,       42     35    39

 2 equiv. of carbonic acid,
23 equiv. of water,
 1 equiv. of humin,
2		4
	23	23
40	12	12
42	35	39
42	35	41
2		4
	23	23
40	12	14
   £  of 7 equiv. of sugar, -f-O6,

   2  equiv. of carbonic acid,
  23  equiv. of water,
   1  equiv. of geic acid,

                                      42     35    41
  As  to cellulose, starch,  gum, inuline, and  lichen starch,
what has been said with regard to sugar,  holds true of them
also.   Pectin,  and other  analogous substances, which are so
very much diffused through plants, do not require any  oxygen
from the air, to  be converted into  humin.  They  consist of
C12H8010 ; and thus, taking the same tabular view as for
sugar, they would give :—
                                     C     H     O
   J  of 7 equiv. of pectin,           42     28     35
2	equiv.	of	carbonic acid,	2		4
16	equiv.	of	water,		16	16
1	equiv.	of humin,		40	12	12
                                     42     28     32
  There is here, then, a remainder of three equivalents of
oxygen, so that cellulose, starch, sugar, &c, if mixed with a
certain quantity of pectin, might produce humus, and give off
a certain quantity of carbonic acid to the atmosphere, without
taking from it any oxygen.
  Of these neutral materials plants chiefly consist, and it is
highly probable  that their decomposition is  effected  in the
manner above described.   There are some organic substances,
of which the mode of conversion into humus cannot, with any
probability, be demonstrated : with many, however, it might
be; but the illustrations already presented in  regard to such 
152
THE CHEMISTRY OF
of the neutral vegetable substances as are most generally dif-
fused, may suffice for the present.
  There is one of the chief component parts, belonging both
to the bodies of animals and of vegetables, the change of which
into humus is equally simple.  This substance is protein.  By
the influence  of hydrochloric acid, and the oxygen of the air,
it is converted into humic acid, in the following manner :*—
                              C    H     N    O    CI
  1  equiv. of protein,        40    31     5     12
  4  equiv. of hydrochloric acid,      4                  4
  4  equiv. of oxygen,                            4
	40	35	5	16	4
From these are produced :	—				
	C	H	N	0	CI
1 equiv. of humin,	40	15		15	
1 equiv. of ammonia,		3	1		
1 equiv. of water,		1		1	
4. equiv. of chloride of					
ammonium,		16	4		4
                             40     35    5     16    4
  In the formation of humus from protein, again, humin and
ammonia are  produced; four equivalents of oxygen being
absorbed from the air :—
                                   C     H    N    0
  1 equiv. of protein, -f O4,         40    31     5    16
1 equiv. of humin,        .       40     15          15
1 equiv. of water,        .               1           1
5 equiv. of ammonia,     .              15     5
                                   40     31    5     16
  The other chief constituents of the animal body have not
been  investigated with reference to these transformations;
so that it is not known what kind of  changes they undergo in
the  soil, when they are converted into humus.
  Though it be true, that the products of the decomposition of
organic substances differ with circumstances, and consequently
* Bulletin, 1840, p. 74. 
VEGETABLE AND  ANIMAL PHYSIOLOGY.        153
that, in the above outline, the decomposition is stated for one
particular case only;  yet it results from what has been said,
that  the same substances, of which the black layer  of soil
chiefly consists, ore formed  from the most different products
of the vegetable and  animal kingdom, especially from their
constituents—both by the influence of chemical agents, and
by that of the formation of humus.
  The ulmic, humic, and geic acids, however prepared, have
the property of condensing ammonia and water, to the extent
of several  parts per cent.   This water cannot be separated
from them, unless they  are exposed to a very high tempera-
ture.  We have observed that from 8 to 16 percent, of water
are given off at 284° Fahr. from different kinds of humin and
ulmin.*   They can be entirely deprived of water, only by a
temperature of 383° Fahr.   By this great hygroscopic power,
the growth of plants is very materially promoted.   In the soil,
humic and  geic  acids are always  combined with ammonia.
All the ammonia produced by the decay of substances con-
taining nitrogen, (protein  from  plants and animals,   &c.;)
and all that is formed in the porous soil from the component
parts  of the atmosphere and of water,  combines with the
humic and  geic  acids,  into  humate and geate of ammonia,
which are severally present in different kinds  of soils.  We
have found, in different specimens of  soils and turfs, humates
and geates of ammonia, which, at a temperature of 284° Fahr.,
had the following composition :—
  Turf,        .       C40H12012 -f-  NH3+4HO
  Decayed tree,           idem    -f-  NH3-j-5HO
  Soil from an orchard,     idem    -j-2NH3-f-4HO-|-02
  Garden mould,          idem    -f2NH3-f-4HO-f-02
  Soil from pasture land,   idem    -j-2NH3-J-5HO
  Garden mould, planted
    with young oaks,      idem    -f-  NH3-|-5HO
  Garden mould, planted
    with currant bushes,   idem    -j-  NH3-j-6HO
  This power of condensing ammonia, possessed by the ul-
mic, humic, and geic acids, is so powerful, that the acid, pre-
pared from sugar by means  of muriatic acid, contains almost
* Bulletin, pp. 10, 47, 50. 
151
THE  CHEMISTRY OF
always ammonia, unless the air  be carefully excluded.   The
ammonia, which always either exists in the atmosphere, or is
produced from it in the manner above mentioned, (p.  143,)
(for instance, the ammonia, from which the incrustations round
the necks of bottles containing phosphoric acid, &c, and the
collections of  liquid on  the necks  of bottles containing  nitric
acid,  &c, are formed,) combines with the geic, humic and
ulmic acids, and thus geate, humate, and  ulmate of ammonia
are produced.   By this property, Hermann was, no doubt, mis-
led, when he thought that the humic acid from sugar contained
nitrogen.*   We may ascribe to it a very important function of
the soil.   It enables these acids to retain ammonia, either con-
densed from the atmosphere, or formed from its constituents,
and thus to supply nitrogen to plants—to absorb the ammo-
nia formed during the deeay of substances which contain ni-
trogen—and greatly to promote the growth of plants by means
of  nitrogenous manures.
  It is by this ammonia also, that the geic, humic, and ulmic
acids of the soil are made soluble in water, and so fitted  to be
taken up by the roots of plants,  in the same manner as so
many inorganic salts, such as the alkaline sulphates and  chlo-
rides, are taken up by them.  Thus, the ammonia is an  addi-
tional base in the soil,  and joins the  potash, magnesia,  soda,
lime,  and  the oxides of iron and manganese, to form a long
series of ulmates,  humates, and  geates,  some of which are
soluble, and others  insoluble in water.
  As the proportion of ammonia increases, more of the other
bases,—for instance, oxide of  iron and  manganese—are dis-
placed by it, and in this way geates,  humates, or  ulmates,
which are either insoluble, or soluble with difficulty,  are con-
verted  into the very soluble geate, humate, or ulmate of'am-
monia.   Thus, as substances, giving  off  ammonia, decay in
the  soil, they must produce soluble geate, humate, or ulmate
of ammonia.
  4. These remarks may suffice  in regard to the humic sub-
stances in the soil, that is, such as can be extracted from  it by
  * Journal filr Practische Chemie,  1841, Erster Band, p. 68. The
whole treatise of Hermann, in this and the following parts, 1841, Part
II, p. 375, and 1842, Part I, p. 189, proves of itself the inaccuracy of
his results. 
VEGETABLE AND ANIMAL PHYSIOLOGY.       155
alkalies, and precipitated by acids from the alkaline solution.
There are two other constituents of the soil, however, which
deserve  particular attention, viz.   the crenic  and  apocrenic
acids.  Both  of these, like the humic acids, exist in  the soil
as double salts, that is, in the state of salts of ammonia,  pot-
ash, and soda, combined with lime, magnesia, and oxide of iron ;
being also partly soluble, and partly  insoluble in water,  and
changeable into soluble salts by means of ammonia.
   The composition of these acids is the following :—
           Apocrenic acid,        C48H12024
           Crenic acid,            C24H12016
   These acids, of course, never exist  uncombined in the soil.
They unite intimately with ammonia, so as to exhibit the char-
acters of quaternary substances.  Treated with potash, how-
ever, at an elevated temperature, this  ammonia is completely
separated.  But these acids are also combined in the soil with
other  bases, in such a manner, that the ammonia forms almost
always a component part of a double apocrenate or crenate of
potash, soda,  lime, magnesia, or  oxide of iron.
  From the three soils above mentioned,  (p. 140,) as well as
from others, the following crenates and apocrenates were ob-
tained, either in the state of double apocrenates, or of  simple
crenates of ammonia and of copper, according to the mode of
preparation.   These acids, like  the ulmic, humic, and geic
acids, are extremely difficult to dry, and, when dried  at the
same temperature, they retain different proportions of  water,
which increases as the quantity of base, in combination with
the acid, decreases.  From these soils were obtained apocre-
nates  of  oxide of copper and of ammonia, the organic con-
stituents of which gave the  following formula? :—
              C48H12024-{-l£NH3-r-5Aq.
              C48H12024+  |NH3-f lOAq.*

  *  Scheik. Onderzoek. Vol. II, p. 99.
  Apocrenate of ammonia fiom two kinds of soils, at 284° Fahr.
                  Found.            Atoms.      Calculated.
              I.           II.
      C      5189        50-83        48         51-66
      H       375         416        21i         3 78
      N       3-37        4 09        \h         3 74
      O      40-99        40-92        29         4082
           =C4 8Hi2024+l^NH3+5HO
  Vol. I.                   15 
156
THE  CHEMISTRY  OF
  The apocrenic acid  is an acid which saturates five equiva-
lents, either of base or of water.  It is thus a five-basic acid,—
at least the artificial acid is so.  That which exists in the soil
may, perhaps, be able to combine with a greater number  of
equivalents of water, or of bases, as the humic class of acids
does.
  There are several modes of preparing an artificial apocre-
nic acid, two of which are of especial importance, in connec-
tion with the subject we are now considering.
Apocrenate of ammonia, from two other kinds of soils, at 284° Fahr.
                  Found.            Atoms.      Calculated.
              I.          II.
     C      4837        4818        48         49-24
     H       390         404        23£          3-94
     N       111         148          i          119
     O      4662        4630        34         45-63
          ==C4 8Hl2O24+iNH3+10HO

Apocrenate of ammonia, from humic acid prepared from sugar by ni-
    tric acid, at 230° Fahr.
                 Found.          Atoms.          Calculated.
          C      55-43             48            55 10
          H       349            17             319
          N       2 98             1             2-66
          O      3810             26            39 05
           =C4 8Hi2024-fNH3-f-2HO
Neutral apocrenate of ammonia and lead, at 230° Fahr.
                Found.           Atoms.          Calculated.
          C      28-97            48            29-98
          H       188             17             1-73
          N       1-80              1             145
          O      22 67             26            21-20
       PbO      44-68              4            45-64
           =C4 8Hi2O24-fNH3+4PbO+2H0
Anhydrous apocrenic acid.
          _,     ^A11)^           Atoms.          Calculated.
          C      59 06             48            59 00
          H       287             12             241
          O      3807             24            3859

Crenate of ammonia from an arable soil, at 284° Fahr.
                                Atoms.           Calculated.
                                 24             45 59
                                 17              5-27
                                  1              441
                                 18             4473
               =C24Hi20i6-f-NH3-f2HO
	Found.
c	45 98
H	550
N	3 88
O	45 64
 
VEGETABLE AND ANIMAL PHYSIOLOGY.        157
   When humic acid, in whatever way prepared, or  wood
charcoal, is exposed to the action of nitric acid, apocrenate of
ammonia is produced.  Thus in every case, where humic
acid can be formed from bodies by nitric acid, apocrenate of
ammonia is the  final product.   For instance, phloridzine is
converted into phloretine and  grape sugar by diluted nitric
acid; this grape sugar again into humic acid,  and the humic
acid into apocrenic acid,—all by the same nitric acid.   Thus
phloridzine, when acted upon by nitric acid, gives apocrenic
acid, though always  in combination with ammonia, as repre-
sented by the  formula :—
                C48H*2024-fNH3+2HO
   This is  the composition of a compound produced by the
action  of nitric acid  upon humic acid from  sugar, from soil,
and from turf, and dried at 284° Fahr., and which is thus an
apocrenate  of ammonia.  The same substance,  if saturated
with ammonia, and dried at 248° Fahr., gave
                C48H12024+3NH3, 3Aq.
And again, a lead-salt, from neutral acetate of lead and a solu-
tion of neutral apocrenate of ammonia, dried at 230° F., gave
            C48H12024+NH40-|-4PbO,Aq.
   It is probable, that the last atom of water might be separa-
ted at a higher temperature, but, as the salt  is readily decom-
posed and difficult to be dried,  this has not been attempted.
   We  are, therefore, entitled to call the artificial acid a five-
basic one.   Like the ulmic, humic, and geic acids, it belongs
to the  gelatinizing substances, which, like  alumina, exhibit
  Crenate of ammonia, from another cultivated soil, at 284° Fahr.
                  Found.          Atoms.         Calculated.
           C      4577           24             4553
           H       535           15J             511
           N       1-94             h             2-20
           O      46-94           18             4716
             =2(C24H 1201 6-f HO)-f NH3-f HO
  Crenic acid, from a third kind of arable soil, at 284° Fahr.
                  Found.          Atoms.         Calculated.
           C      4687           24             46-78
           H       497           15              477
           O      4816           19             48-45
                   = C24Hl20l6-|-3HO
  The crenates and apocrenates, separated from the cultivated soils as
well as the crenic acid, the analyses of which are above given, were all
in combination with oxide of copper. 
158
THE CHEMISTRY OF
 different characters  in  relation  to water, bases and acids,
 according  to the  difference  of  circumstances;—by which
 property it is enabled both to absorb a large proportion of wa-
 ter, and to combine with several bases at once.  Nay, it is by
 this  five-basic character that insoluble apocrenates—for in-
 stance, that of oxide of iron—are rendered soluble in water, by
 being combined into double salts with soluble apocrenates.  In
 virtue of this property, plants may, along with the four organic
 elements, either be supplied with several  bases  at once, or
 these bases may be alternately exchanged, according as the
 proportion of a more powerful base in the soil  is less, and that
 of a more feeble one, temporarily greater.   There may ex-
 ist, for example, apocrenates represented by the following for-
 mulae, which, being all soluble in water,  and existing in the
 soil, can be supplied as food to plants :—
     C48H12024+5NH40
     C48Hi2024-|-4NH40+KO
     C4 8 H12024-f-3NH40+KO-f-CaO
     C4 sH 12024-i-2NH40-f-KO-j-CaO+MgO
     C4 8Hi2024_j_ NH40+KO+CaO-fMgO+FeO
 For this reason, the apocrenic acid is of inestimable value to
 plants, and in the series  of substances which are useful to
 them, it deserves, no doubt, a much higher rank than the hu-
 mic class of acids.
  It is from the latter that the apocrenic acid  is produced in
 the soil.   We have seen, that when nitric acid acts upon hu-
 mic acid, apocrenate of ammonia is produced.   This action
takes place in such a way, that,  when nitric  acid is  poured
upon humic, ulmic, or geic acid, in whatever way these acids
may be prepared, formic and oxalic acids are  simultaneously
produced.  From two equiv. of humic acid, for example, and
NO4 5 (one of nitrogen, and 45 of oxygen) derived from nitric
acid, are formed,—
                                 C80   H30   N   O75
 1 equiv. of apocrenic acid,
 1 equiv. of ammonia,
12 equiv. of formic acid,
 4 equiv. of oxalic acid,
 3 equiv. of water,
C48

C24
C8
H12
H3
H12

H3
    Q24

N
    036
    012

    O3
C80   H3<>  N  O78 
VEGETABLE AND ANIMAL PHYSIOLOGY.       159
 During this action of nitric acid on humic acid, which takes
 place with much vehemence, deutoxide  of nitrogen is abun-
 dantly given off.
   It is thus that apocrenic acid  is  formed in the soil, but of
 course accompanied by the production of carbonic acid, in-
 stead of either oxalic or formic acid.  The ammonia of the
 soil,—produced in  it from the atmospheric  air it  has  ab-
 sorbed,—may, by the influence of decaying organic substances
 and water,  be converted into nitric  acid,  and no doubt is so,
 when the bases required  for nitrification are  present.  Salt-
 petre was  long extracted  from  the soil  exclusively,  as  in
 many places of Egypt, India, &c.   By the oxygen of the at-
 mospheric air contained in the soil, the  hydrogen and nitrogen
 of the ammonia—produced from the constituents of the air—
 are oxidized, water and nitric acid  being the products.  But
 this  nitric acid,  as* soon  as it is formed, meets with a sub-
 stance in the soil—humic acid or humin—which, by its influ-
 ence, is converted into apocrenate of  ammonia,  and, at the
 same time,  produces carbonic acid,  instead of formic or ox-
 alic  acids.   This change  of humic acid  into apocrenic acid
 takes place in minute quantities, as is the case with the form-
 ation of ammonia which precedes it.  Thus, to form 1 equiv-
 alent of apocrenic acid, there are required 2 equiv. of humic
 acid, 1 equiv. of ammonia, and 76 equiv. of oxygen, thus :—
                                 Geo  H33  N  O106

   1  equiv. of apocrenic acid,
   1  equiv. of ammonia,
 32  equiv. of carbonic acid,
 18  equiv. of water,

                                 C80  H33  N  O106
 In this production of apocrenic acid, the ammonia from the
 humate of ammonia  is only transferred to the apocrenic acid,
 but it performs an intermediate part,  namely, the  fixing of
oxygen.  Through the tendency of ammonia to form  nitric
acid, the oxygen of the atmospheric air contained in the soil
is combined with the  constituents of the humic acid,  the
ammonia itself  remaining  unchanged, neither leaving the
soil,  nor being  oxidized into nitric acid.   If there  be not an
abundance  of organic matter,  and  if  the air be moist, and
  Vol. I.                  15*
C48	H12 Q24
	H3 N
C32	064
	H18. O18
 
160
THE  CHEMISTRY  OF
lime, magnesia,  or potash,  be present, ammonia is first pro-
duced, and afterwards nitric acid.  If, on the contrary, instead
of these bases, organic substances are in excess, humic acid
is  formed by  their decay ; at  the  same  time, ammonia is
produced from the nitrogen of the  atmosphere ; and finally,
apocrenate of ammonia, carbonic acid, and water.
   This formation of apocrenate of ammonia by the oxidation
of humate of  ammonia, is continually going on in the  soil
during the warmth of summer, (except on the very surface,
which  is directly exposed  to  the air.)   Each minute portion
produced can  be taken up by the roots of plants, in the form
of double apocrenates  of  ammonia and various  fixed  bases,
provided there be a sufficient supply of  water  at  hand ;  and
whilst  in this way the soil loses its apocrenates, a new portion
of apocrenate of ammonia is formed from the humic acid or
humin, which is present in large excess.
   Thus we may call the production of apocrenic acid, in one
respect, an organic nitrification.*
   We have hitherto represented the apocrenic acid as formed
directly from  the humic acid.  But the  existence,  in the soil,
of a substance which is composed of C40H12014, instead of
C40H12012—namely, the geic acid—renders it probable
that the apocrenic acid derives  its origin, not from humic, but
from geic acid, the several acid  substances succeeding each
other in this order,—ulmic, humic, geic,  apocrenic acid.  This
series is concluded by a fifth important substance, a final pro-
duct of the oxidation  of organic substances before they are
entirely changed into carbonic acid and  water, namely, cre-
nic acid.
   The composition of this  acid,  as already mentioned,  is
C8*H120ltt.   It also is combined  with ammonia  in the soil,
and forms double salts which are soluble in water.t   These
exist,  along with the apocrenates, in all  kinds of water, which
have  been in contact with  organic substances in the  soil.
 They were first found by Berzelius, in  spring water;  they
 exist  also in  the water of ditches,  marshes, and bogs.   The
 crenate  of ammonia,  when combined  with oxide of copper,
 contains also  a  variable per centage of  water  and ammonia,
  * For the facts upon which these  propositions are founded,  see
Scheik. Onderz., Vol II.
  t See the note at p. 155. 
VEGETABLE AND ANIMAL PHYSIOLOGY.        161
like the apocrenates of ammonia obtained in the above men-
tioned  analyses  of different soils (p. 131).   The specimens
analyzed gave, after subtraction of  the oxide of copper:—
              C24H12016 -J-NH40+Aq.
            2(C24Hi2Oi6)_|_NH40+2Aq.
  According to the atomic weight of crenate  of ammonia, as
determined by Berzelius, the crenic acid is  four-basic.  Of
this acid, therefore, the following series of combinations may
exist in the soil:—
         C24H120*8+4NH40
         C24H12016-j-3NH40+KO
         C24Hi20i6_L.2NH40+KO+CaO
         C24H12016-f NH40-f-KO-j-CaO+MgO
Just as in the apocrenates, there will be in these salts a larger
portion of crenate of ammonia, according as the quantity of
ammonia in the soil is increased.  Now, during the warmth of
summer, the moist air, contained in the soil, has a continual
tendency to form ammonia.  Among  the bases of the cre-
nates,  therefore, the ammonia will be the most prevalent, just
as in the case  of the apocrenates.
  Berzelius has stated, that apocrenic acid is easily formed
from crenic acid, by the action of atmospheric air.  Oxygen
is absorbed, and nothing but water produced :—
                                      C   H  O
       2 equiv.  of crenic acid,    .    48  24  32
       1 equiv.  of apocrenic acid,       48  12  24

       Difference,      ...        12    8
       Add 4  of oxygen from the air,              4

        12 of water produced,      .        12  12
But Berzelius  has remarked that, on the other hand, apocre-
nic acid can be converted into crenic acid by nitric acid :—
                                       C   H   O
       1 equiv.  of apocrenic acid,        48   12  24
        1 equiv.  of crenic acid,     .     24  12   16

       Difference,       ...     24        8
       Oxygen from the  nitric acid,              40
24 equiv. of carbonic acid,        24      48 
162
THE  CHEMISTRY  OF
   By the continual tendency to nitrification in the soil, there-
fore, apocrenic acid must always be converted into crenic
acid, the series of ulmic, humic,  geic, and apocrenic acids,
thus terminating with crenic acid.   In the upper layer of the
soil, however, where the air is not  inclosed, and consequently
no tendency to nitrification exists, crenic acid  must  con-
versely be changed into apocrenic acid.
   All that we have said here, regarding the formation of the
apocrenic  and crenic acids from the ulmic, humic, and  geic
acids, through the influence of warmth and moist inclosed air,
applies also to charcoal, and generally to all coaly substances.
For we know that from charcoal apocrenic acid is formed by
the action of nitric acid.  We need not repeat  that charcoal
must, of necessity, promote  the growth of plants, because,
through the organic nitrification  already  described,  which
takes place in moist charcoal containing atmospheric air, first,
ammonia is formed, and then, as this becomes oxidized, nitric
acid and water.   By this acid, again,  the charcoal is changed
into apocrenic acid and ammonia, and this apocrenic acid, by
the progressive organic nitrification, is converted into  crenic
acid.  Thus it is not at all singular, that by means of moist
charcoal mixed with wood ashes, the growth of plants should
be promoted.
   This brief exposition of the peculiar changes  which take
place in the soil, may  now be brought to a close.  They are
sufficiently plain of themselves. One point, however, remains
to be noticed.   The ulmic acid is produced from organic sub-
stances—for instance,  from  those which are neutral, such as
cellulose (woody fibre), starch, &c.—carbonic acid being pro-
duced at the same time.  Thus if
                                       C  H   O
       From 2 equiv. of cellulose,      48  42   42
       We take 1 equiv. of ulmic acid,  40  14  12
       8 equiv. of carbonic acid,         8       16
      14 equiv. of water,    ,     .         14  14

       Or the sum,     .    .     .     48  28  42
—then, of  the 42 equivalents of hydrogen, 14 are still want-
ing, which, during the rotting or the slow decay of wood, must
be otherwise  worked up.  In fact, this hydrogen, in  the nas- 
VEGETABLE AND ANIMAL PHYSIOLOGY.       163
cent state, promotes the production of ammonia from the ni-
trogen of the air.  Such is the case, also, in the formation of
apocrenic and crenic acids.   For instance, if
                                        C   H   O
    From 2 equiv. of humic acid,   .     80  24  24
    We take 1 equiv. of apocrenic acid,    48  12  24
         There remain,   .    .     .     32   12
So that, by the absorption of 64 equivalents of oxygen from
the atmosphere, all the carbon would be converted into car-
bonic acid, and again 12 equivalents of hydrogen would be
left behind.
   It deserves particular notice, that hydrogen is always libe-
rated whenever those substances which are the most general-
ly diffused  in the vegetable kingdom, are changed into con-
stituents of the soil—that is, when cellulose, starch, gum, sugar,
&c. are in  a state of decay.   First, these substances are con-
verted into ulmic acid,  and that again becomes humic acid;
from this, geic acid is formed,, which again produces apocre-
nic acid, and from that, finally, crenic acid is derived.  This
whole series of transformations must be passed through, before
the organic substance  is converted  into carbonic acid and
water.  The  whole process  consists  in an oxidation, and so
may be called a slow  combustion.   It  is evident, from the
composition of the five snbstances mentioned, that during the
formation of humus a new quantity of oxygen is continually
fixed.  Thus—
      Ulmin and ulmic acid,     .     .    C40Hl4O12
      Oxygen from the air,      .     .           O2

      Form,     .    .     .     .     .    C40H14014
   Which is equal to—
      Humin and humic acid,    .     .    C40H12O12
      2 equiv. of  water,    .     .    .       H2 O2

                                          C40H14014
  Again,—
      Humin and humic acid,    .     .    C40H12012
      With oxygen from the air,       .            O2
Form geic acid,
C40H12O14 
164                THE CHEMISTRY OF

  Or, let us suppose that cellulose is at once converted into
a portion of each of the three acids—the ulmic, the apocrenic,
and the crenic acids.   Then we have—
           Ulmic acid,   .     .     C40  Hl4012
           Apocrenic acid,    .     C48  H12024
           Crenic acid,  .     .     C24  H*2016
           Making together,   .    C»»2 H3 8 O5 2
  When these three acids are thus produced from cellulose,
(carbonic acid and water being formed at  the  same time,)
thirty of hydrogen (H30) remain behind.  Thus—
  5 equiv. of cellulose,     .     .     .     C120H105O105

Ulmic, apocrenic and crenic acids as above,   C112H38 O52
 37 equiv. of water,       .    .     .         H37 O37
  8 equiv. of carbonic acid,     .     .     C8       O16
 30 equiv. of hydrogen,   ...         H30

                                        CJ120JJ1050105
  Thus, in  whatever way we suppose the decomposition  of
cellulose, starch, gum, sugar, &c, to take place, there is al-
ways an excess of hydrogen.  This may be shown by two ad-
ditional examples:—
  First, suppose  ulmic acid to be changed into crenic acid.
Then—
      Ulmic acid,  ....    C40H14012
      With 36 equiv. of oxygen from the
         air,  .    .    .    .     .           O36
    Make together,    .    .     .    C40II14048

Which are equal to—
    Crenic  acid,      .    .     .    C24H12018
    16 equiv. of carbonic acid,   .    C16    O32
     2 equiv. of hydrogen,  .     .        H2
                                       C40H14O48
  Second, suppose all the carbon from ulmic, apocrenic, and
crenic acids to be oxidized by the oxygen of the air, then we
have— 
VEGETABLE AND  ANIMAL PHYSIOLOGY.        165
Ulmic acid,    .     .     .     C40  H14012
Apocrenic  acid,     .     .     C48  H12024
Crenic acid,    .     .     .     C24  H12016
                                C112H38052
Add to this 172 equiv. of oxy- )           Ql7
  gen from the air,     .      J
                                Ql 12JJ380224
And deduct 112 equiv. of car- )  pu2    0224
  bonic acid, which are formed, J
    And there remain 38 equiv. of)        „38
       hydrogen,      .     .      j

This hydrogen, when  liberated, is, no doubt, to a great ex-
tent, oxidized.into water ; but while becoming free, it promotes
the formation of ammonia from the nitrogen of the air, and
this again of saltpetre.  In  the  same way, as  we have  al-
ready seen, the repeated formation of apocrenic and crenic
acid in the  soil is effected.
  From what has been stated, the observation of De Saussure,
that the soil yields just as much carbonic acid, as it absorbs
of oxygen—cannot possibly be accurate ;  for the existence of
ulmic, apocrenic, and crenic acids in the soil, contradicts his
theory.
  We  now approach, in its  natural order, the important
question, whether plants take organic substances from the
soil—as crenates and  apocrenates, geates, humates, and ul-
mates, for  example—or  whether they live  only on  carbonic
acid, ammonia,  and water;  or whether they  do both.  It
were useless to enter here into a prolix exposition of what is
known on this subject, since  it more properly belongs to the
chapter on  the nourishment of plants.  We shall here, there-
fore, advert only to what is supplied to plants from the atmos-
phere and from the soil, in addition to the substances we have
hitherto spoken of, and which are never wanting in an arable
soil.  We intend to show what, besides the substances already
mentioned, they  may  absorb ; and inquire  afterwards  what
they do really absorb, and in what way the  component parts
of plants are thence built up. 
166                THE CHEMISTRY OF
  The black layer of soil, as  regards its organic portion, ia
composed of insoluble ulmin and humin, of soluble  ulmates,
humates, geates, apocrenates and crenates of ammonia, potash,
soda, lime, magnesia, and oxide of iron.  Till recently the
opinion prevailed, that the  humic acid  was the especial feed-
ing substance of plants;—that, in  certain circumstances, it
could become soluble in water ; and that this solution of humic
acid was absorbed by the roots of plants, new substances be-
ing formed from  it in the plant itself: for this humic acid is
composed of carbon, hydrogen and oxygen, three of the four
elements of which all the parts of vegetables and animals are
built up.  The fourth element, namely, the  nitrogen, caused
some difficulty.   It was not found in the humic acid, prepared
from sugar, and it was overlooked in the acid, which exists in
the soil.*   Thus, an essential part of what is required to form
organic substances, was still wanting.   Boussingault thought
that this fourth element, the nitrogen, was condensed  from
the atmosphere in the soil; he did not, however, indicate how
this takes place.
  The ancient idea was, that plants take all their food  from
the soil.   But this was contradicted by a great many observa-
tions.  First,  many plants  live  in the atmosphere  only ; of
others, the roots  are fixed  in  the soil, but in such  a soil as
contains only a small quantity of soluble, and even of organic
substances—at all events, much too little to supply nourish-
ment to the plants.  It is a known fact, that from  good  clay
soils, which  contain only a small proportion of organic sub-
stances, thousands of pounds of vegetable produce are reaped
every year, although few or no organic  substances—in  the
state of manures—be added to these soils.  Are the organic
constituents of such a soil  inexhaustible ?  The absurdity of
this supposition is palpable.   The example of our heath-lands,
however,  is still more striking.   A barren sandy soil, covered
with a thin layer of  organic  substances, is ploughed and
planted with pines.  Nothing more is needed to make such a
soil produce, in the  course of time, a thick layer of organic
substances, though nothing be laid on it from without.   Here,
therefore, the plants supply organic substances to the  soil,
that is, they do just the reverse of what the old theory supposes.
* Sprengel. 
           VEGETABLE AND ANIMAL PHYSIOLOGY.       167

  If we consider, besides, that the luxuriant vine grows in a
handful of soil, which  is sometimes artificially  laid down in
the corners of the rocks ; that many Cacti  adhere to rocks,
living where no soil is found at all; that many Orchidea  are
really air-plants, and do not require soil at all, but  only an
atmosphere which is suited  to  their nature;  that in the natu-
ral  forests, whence thousands of pounds are every year carried
off  for use, without any thing being returned, the quantity of
organic substances,  with which the soil is covered, is con-
tinually increasing;  that not a few farms can wholly supply
their own wants, without laying any thing on the soil, except
the products  of the  farm itself, though immense  quantities of
beef, grain, fruit, &c, are yearly  carried off, and that such a
farm continues to be among the most  productive ; that  our
pastures are yearly deprived of immense quantities of organic
substances through  our  herbivorous stock, which carry  off
from the land immense quantities of beef and mutton, exceed-
ing greatly  the quantity of organic substances which they
receive; that from  meadows which are never supplied with
an organic substance, immense quantities of  hay are yearly
carried off;  finally,  that the naked  rock, where no soil is to
be  found  at  all, is, without any  artificial aid, covered first
with mosses, and  afterwards  with larger plants, till at last it
is adorned with  the most luxuriant woods, and covered with
a continually increasing layer of black soil ;* if  we add fur-
ther the numerous other examples, which will occur to every
one;—then the conclusion is incontrovertible, that  it is by no
means  indispensable that the  soil should contain all the sub-
stances which nourish plants.
  But since  plants require  to  be  fixed  in the soil, and have
roots for that purpose, are we  entitled to suppose that the soil
is not indispensable  to their nourishment ?  This can by no
means  be asserted ;  all that we maintain is, lhat  all the ma-
terials  upon  which,  in  certain  circumstances,  plants may
thrive, are not continually present in the soil, and do not re-
quire to be so ; that these substances need not constitute an es-
sential  part of the soil.
  In order, then to conceive by what means plants may live,
which have either no organic substances, or no sufficient sup-
       * Linnaeus, de Telluris Habitabilis Incremento.
Vol. I.                   16 
168                THE CHEMISTRY OF
ply of these to live upon, it must be borne in mind that they
receive nourishing substances,  if  not  from,  yet  certainly
through, the soil.
   By the rain-water, carbonic acid is carried down into the
soil, which  is already thoroughly penetrated by the atmos-
pheric air, and contains condensed ammonia besides.  Thus
the four organic  substances are at  hand in the soil.  The
water, atmospheric air, ammonia and carbonic acid, supply
to the small roots of plants four primary materials, from which
the plant may prepare all its organic parts.   Here, therefore,
we see food supplied to the roots of  plants through the soil,
but from the  atmosphere ;  and  we can conceive how a soil
may be poor in organic substances, and yet rich in plants.
   When the soil really contains organic substances, the plants
will thrive more  luxuriantly the more these substances are
enabled, by the  presence of water and atmospheric air, to sup-
ply carbonic acid and ammonia, which are the main requisites.
Here we see the vegetable kingdom appearing in a form pe-
culiarly its own.  The leaves which fall every year are thrown
upon the ground,  and after a time are withdrawn from sight.
If in  contact with a moist atmosphere,  they gradually turn
brown, decay, and form a powdery,  dark-colored substance ;
they putrefy, and  as this process goes on, they give off a large
portion of carbonic acid, which  is diffused through the atmos-
phere, to be taken up by other plants.  The brown, powdery
residue of the putrefied leaves is ulmin and ulmic acid, and of
itself  is not fit to  be taken up by plants in such a quantity as
is requisite for their nourishment.
   Finally, the  putrefying animal portions produce  ammonia,
and, at the same time, carbonic  acid ; and during their putre-
faction, yield  a  continually increasing  quantity  of these.
Hence the reason, why the arable soil is beneficial, nay in-
dispensable to the greater part of plants ; hence also the utility
of animal and  vegetable manures, which enter the roots of
plants, not in the form  in which they  are added to the soil,
but  in a state of  either partial or of  entire decomposition,
and so in the  form of carbonic  acid  and ammonia.   Hence
the  reason, also,  why soils, which  contain either few or no
organic substances, can  yet enable plants to live and thrive,
because the atmospheric air carried in by the rain-water can
introduce into the soil, though to a smaller  extent,  the same 
VEGETABLE AND ANIMAL PHYSIOLOGY.
169
substances which in arable land can be produced from humic
acid and manures.
   Though from all these incontrovertible facts, so beautifully
connected together by Liebig, we have  ascertained, that car-
bonic acid, water and ammonia, carried down from the atmo-
sphere  into the earth's crust and to the roots of plants, are a
very  healthy nourishment for many of them—we  are  not
thereby precluded from  asserting, that the ulmates, humates,
and geates in the soil, which are  soluble in water, as well as
the crenates and apocrenates, can  also be taken up by the
roots of plants ; nay, that to a great many they are absolutely
indispensable.   We shall return to this subject when  treating
of the  nourishment of plants.  Here we would only mention
that some plants, for instance the mosses, which grow upon
naked  rocks, are really fed  exclusively by means of the con-
stituents of the atmosphere, carried down into the  soil ;—
which  is, more or less, the case with all other plants;—this
fact  being as incontrovertible, as that very few plants  only
can live on carbonic  acid,  water, and ammonia alone, and
that by far the greater number must find organic matters in
the soil to live and  thrive  upon.   A simple  glance  at  the
practice of  the  horticulturist establishes this truth  in  the
clearest manner.*
  * Among the facts mentioned by Liebig, to demonstrate that carbonic
acid, water, and ammonia, do in truth exclusively supply nourishment
to plants, are those relating to their culture  in  powdered charcoal.
Having already (page 161,) investigated the value of this fact, I shall
here add only this further illustration :—
  Professor Numan informs me  of peculiarities with regard to this point,
which well deserve  to be stated.
  Rye, oats, buck-wheat, and turnips, were sown in dry sand, contained
in pots—the first three on the 21st of June, the turnips on the 29th of
July.  The uppermost layer was mixed with  some coarse charcoal
powder and peat-ash.
  The buck-wheat was full grown in the beginning of September, blos-
somed very well, and in the latter part of that month ran {o seed, which
ripened.
  The rye came up  at the usual time, namely, 10 or  12 days after sow-
ing.  It had a fresh dark-green color, and reached  in September the
height of about one  span and a  half.
  The oats also regularly advanced ingrowth, and had an uncommonly
beautiful greenish blue color.  The plants  reached the height  of 24
inches, and had broad and thick leaves.  In the end of September these
began to wither.  A few stocks ran to  seed, which, however, did not
attain ripeness. 
170
THE  CHEMISTRY OF
   We have, therefore, now become acquainted with  the at-
mosphere as  an important, though not the exclusive, source
of nourishment to the existing races of plants.
   The service performed by the inorganic substances of the
earth's surface must differ, according as they supply nourish-
ment to plants  from the  constituents  of  the  atmosphere, or
from organic substances in the soil.  Their relation to the
carbonic acid is not known; neither  is it  known how they
supply ammonia to plants, or how carbonic acid  and ammo-
nia are  influenced by decaying rocks, wherever  these two,
together with water, must exclusively  constitute  the  organic
nourishment of  plants.   Carbonate of  ammonia, if in contact
with the roots of plants, though  in a very diluted solution, has
always a poisonous effect.   It is still unexplained how those
plants which live only on the atmosphere are fed, and what
may be the  influence exercised upon plants by the powdery
substances in the soil, while supplying  this atmospheric food.
   As to  the organic feeding substances, their relations are not
unknown.   The bases combine with the acids, and enter into
the plants in the state  of ulmates, humates, geates, apocre-
nates, and crenates.  There is, however, among the inorganic
substances in the soil, one  base entitled to particular notice,
namely,  alumina.  In good arable land,  it ought  not  to be
absent.   Its use is of importance.  It combines with the apo-
crenic and crenic acids into  compounds  insoluble in water;
and it is, therefore, by this substance that the whole quantity
of these acids,  present in the soil, is  prevented  from  being
washed  out by  the  rains.  Sandy soils are especially liable
to this disadvantage.   The spring waters of our  moors  are
colored brown by apocrenates ;  while,  in our clay soils, these

  The turnips also grew very luxuriantly, and are still perfectly green,
(I saw them in January.)  They have  here  and there  very good tu-
bers, which, however, would be much larger had  the seed been more
thinly sown.
  It must be remarked, that from the 15th of August to the 15th of Sep-
tember, but Utile rain fell, so that the sand in the pots was completely
dry, and they all continued to grow luxuriantly, though no water  had
been supplied to them.
  The above seeds, sown in sand of which the upper layer was mixed
with charred turf powder, gave almost the same  results.
  In sand  alone, without the addition of charcoal, the seeds germinated
well, but the plants remained exceedingly small, and died without pro-
ducing seed. 
           VEGETABLE AND  ANIMAL  PHYSIOLOGY.        171

 waters are colorless, and almost free from organic substances,
 although  they are  equally penetrated  by a layer  of  humus.
 These two organic acids are  both  thrown down from their
 solutions by recently precipitated  alumina.*   The crenic acid
 can be again set free from  its combination with alumina, by
 ammonia.   In small quantities, therefore, it is supplied as food
 to  plants, ammonia being continually produced in the soil.
 By the alumina (clay), as well as  by the other bases in the
 soil, another important service is performed, namely, that of
 preventing these two acids from  being decomposed into car-
 bonic acid and  water, and thus preserving them unchanged,
 when once formed  in the soil, for a very long period of time,
 till plants begin  to grow, to take them up, and to convert them
 into food.
   In this  manner the decayed rocks again show their close
 and intimate  connexion with organic nature;  and we may
 thus understand how indispensable the dead earth is to every
 living  being which  now exists upon it.

        Note.— Upon the Organic Acids in the Soil.

   I  have  been  unwilling to interrupt the  narrative  of the
 author in this  very interesting  chapter, or farther to load the
 pages  with notes.  I have reserved, therefore, for this place,
 a few  remarks upon the organic  acids in the soil.   It is now
 several years  since I made, and  partly published, the results
 of an examination of some of these acids, and as these results
 add  something to the  facts stated above by Mulder, I shall
 here briefly explain them.
   1. At the bottom or towards the lower part of most of the
 old and deep peat bogs in Scotland and Ireland, a black com-
 pact substance is here and there  met with, in which no trace
of vegetable fibre  is to be observed, and whioh, when dry,
breaks with the fracture and lustre of coal.  I have analyzed
this  substance from both  Scottish and Irish  bogs, and  have
found it so far to agree with  the humio acid of  Mulder, as to
consist, in its organic part, of carbon and water only.  The
acid, however, is never in  an uncombined state.  It  always
contains a trace  of ammonia, with from 2 to 6 or 8 per cent.
        * Berzelius, Lehrbuch, Bd. 8, S. 401, and 410.
Vol. I.                   16* 
172                 THE CHEMISTRY OF
of alumina or lime alone, or of a mixture of these with oxide
of iron.
  2. Having received from Lord Willoughby de Eresby a
quantity of his compressed peat, prepared from the black,
soapy-looking peat of his estates in  Perthshire, I digested a
portion of it in fine powder in weak ammonia.  It swelled up
very much, became bulky, spongy, and difficult to wash, and
gave a dark-brown solution, from which muriatic acid  threw
down a dark-brown acid.   When dried and  analyzed,  the
black, coaly acid  was  found to  be a humic acid, containing
carbon and water only.  The salt of copper, however, gave
me for the formula of the acid C24 H12 O 12.   It differs,
therefore, in the weight of its equivalent, from any of the  hu-
mic acids  of Mulder.
  3. When treated with  solutions  of caustic potash, or of
carbonate of  potash, or carbonate of soda, the peat  did  not
swell up  as  in ammonia, and gave  a dark-brown  solution,
from which muriatic acid threw down a brown, flocky precip-
itate, very different in composition from  that yielded by  the
ammoniacal -solutions.  When  dried, this brown precipitate
had the same black, coaly aspect as the humic acid  already
described, but its  properties and composition differed consid-
erably.
  When heated  in the air, it gave off white vapors, and a
strong smell of burning peat.  By the application of  a taper,
the vapors took  fire and  burned with a  bright flame. The
humic acid obtained by ammonia gave off scarcely a trace of
these vapors, and only a faint  odor  of  burning   peat. The
smell appeared to indicate that the acid extracted  by  alkaline
carbonates, pre-exists in the natural peat—and the white com-
bustible vapors, that it contains more hydrogen than  the sub-
stance extracted by ammonia.
  This was confirmed by  the analysis of portions of  the acid
prepared at various times, and precipitated  by different acids.
The formula  for this acid is C24 H14 O9, agreeing therefore
with the ulmic acids of Mulder, in containing an excess  of hy-
drogen, but not being reducible to his ulmic group—the excess
of hydrogen being very much greater than in his ulmic acid,
and the equivalent containing only 24 of carbon, while that of
Mulder contains 40 equivalents of carbon.   The difference in
the proportions of hydrogen  in the two  acids, will  be most 
          VEGETABLE AND ANIMAL PHYSIOLOGY.        173

readily seen by comparing the  formulae for the  two acids,
supposing the equivalent of both to contain 40 of carbon (C4 °) :
                                           C  H  O
     Ulmic acid from Frisian  peat (p. 147),  40  17  15
     Ulmic acid from Scottish peat,  -     -  40  23  15

     Difference,     -                          6
  The acids here described  agree with those of Mulder in
their tendency  to unite with  several bases at once, and thus
to form compounds soluble in water containing bases, with
which, when alone, they form compounds nearly insoluble in
water.  They also, even when dry, absorb oxygen and  nitro-
gen from the air, producing  ammonia and acids, containing
more oxygen than the humic  and ulmic acids.  The dry acids
kept in well-corked bottles, after the lapse of  twelve months
had absorbed a considerable proportion of the air, and gave to
alcohol a soluble salt, containing an organic acid in combina-
tion with much ammonia.   It is  almost impossible, as I have
found, to prepare a portion of the acid from  peat by means
even of caustic potash, which will not give evidence of the
presence of ammonia, when  burned  with oxide of copper:
but it is only after a  prolonged exposure to the air that it con-
tains enough to give a decidedly dark-colored solution  when
boiled in alcohol.
   4.  It may naturally be  asked, how,  from the same peat,
ammonia and carbonated alkalies extract substances so differ-
ent in composition ?  Both acids  are soluble alike  in both
fixed alkaline and in  ammoniacal solutions ; both therefore, do
not exist ready  formed in the  peat.   From the resemblance of
the acid C24 H14 O9 to the peat  itself in giving  off a strong
odor of peat when burned, and, at a temperature of 500°  or
600° Fahr., white vapors, which condense among other pro-
ducts into a white solid carbo-hydrogen, I believe it to exist
ready formed in peat, and that the humic acid C24H12012,
is produced  from it.
  a. If, for  the sake of comparison, we  represent the two
acids by formulaj, in  which the number of equivalents of oxy-
gen is the same—we should have 
174                THE CHEMISTRY OF
                                C       II       o
    For the one acid (ulmic),     40       23       15
    For the other (humic),       30       15       15

    Difference,                 10        8
  This  difference is equal to two  equivalents of a  carbo-
hydrogen C5H4, which may be supposed to be present in the
acid with excess of hydrogen.   If, by  a cautiously regulated
heat, such a compound could  be driven off from  it, then the
humic  acid  would be  produced.   When the acid is dried at
too high a temperature, this sometimes takes place to  a cer-
tain extent, and the proportion of hydrogen is in consequence
diminished.
  b. Or the acid C24 H14 O9 may be  oxidized by the  action
of ammonia in the presence of the air.  If this takes place di-
rectly, then  each equivalent must absorb five equivalents of
oxygen  from the air.   Thus,
                                C       H       O
    To the acid,                24       14        9
    Add from  the air,     .                        5
     And we have,              24       14       11
which is equal to C2 4 H»» 011 -f 3HO.
  This is what 1 believe takes place either immediately or ul-
timately.  This opinion is  founded on the fact, that, when the
acid obtained by means of carbonate of soda and sulphuric
acid was dissolved in diluted ammonia, and boiled for a length
of time, the solution gradually acquired an acid reaction, and
threw down from a solution of sulphate of copper an insoluble
dark brown compound, the organic  part of which was repre-
sented by C24 H1 * O1 x—that is, the  one acid was changed
into the other.
  5. On certain parts of the rocky coast of Cornwall, where
caves occur, the surface water  is observed to trickle  through
the granite rock, and gradually to cover the sides of the caves
with a deposit of  greater or less  thickness.   This  deposit,
which was first collected  by a Mr. Pigot, has  been called
Pigotite by mineralogists.   It consists of an organic acid, in
combination with alumina in proportions which vary consider-
ably in different specimens, showing that, like other  acids, it 
VEGETABLE AND ANIMAL  PHYSIOLOGY.       175
forms with alumina  combinations  in which different propor-
tions of acid and base are  present.   Some portions of the
Pigotite have the aspect and semi-transparency of resin—be-
ing in fact the appearance which gelatinous alumina and nu-
merous gelatinous compounds assume when they are allowed
to dry slowly in  the air.   The quantity of water present in
this  native product is therefore in some degree variable, but
always large.  When dried at 212° Fahr., it loses about 26,
at 300° about 32 per cent.
   When heated in the air over the lamp, the compound black-
ens, but the carbon burns away with extreme slowness.  When
reduced to powder, it dissolves readily in a solution of caustic
potash, with  the aid  of  heat,  and  is thrown down again by
muriatic or sulphuric acid, apparently unchanged.  The pro-
portion of alumina in the precipitate may be changed by this
treatment, but the organic acid itself is not  altered in compo-
sition.  The acid itself is separated from the alumina with ex-
treme difficulty and slowness by caustic ammonia, and by car-
bonated alkalies.  In the silver salt it is  represented by the
formulaC12  H5 O8, and istribasic,—this quantity of acid uni-
ting  with 3 equivalents of oxide of silver.   In the native com-
pound of alumina, the acid is represented by—
                            C      H     O     Aq
     Native compound,       12      5      8      27
     Dried at 212°,          12      5      8       10
     Dried at 300°,          12      5     8        8
The  quantity of alumina present  being 4 double equivalents.
But,  as I have already stated, the water varies.  The alumina
also  varies from 44 to 48 per cent,  of the dry salt, and is pres-
ent, no doubt, in different states of saline  combination—per-
haps even in the state of hydrate.  Traces of nitrogen are al-
ways observed in  the analysis of this salt,  showing that, like
the other acids formed in the soil, it has a strong tendency to
unite with ammonia.  That  this  nitrogen,  however, does not
form a constituent part of the acid, is shown by the fact, that
when dissolved in caustic potash, and precipitated by an acid,
the composition of the organic part remains unchanged.
  This acid is obviously formed from the decaying vegetable
matter of the soil above,  with the alumina of which it com-
bines, and from which it is  washed by the rains or springs, 
176
THE  CHEMISTRY  OF
and descends through the crevices of the rocks into the caves
below.  The organic matter may not descend in the  form of
this acid, but may as it trickles down the sides of the cavern,
undergo a further oxidation, and be converted into this acid.
It  approaches very closely in composition to the crenic acid,
as analyzed by Mulder, and may even eventually be shown to
be identical.   Before Mulder's crenic acid was analyzed, I
had proposed for this acid the name of Mudesous acid.
   6. When the native Mudesite of alumina is treated with ni-
tric acid, red fumes are given off, the Mudesous acid under-
goes oxidation, and  a new acid—the Mudesic—is  formed,
which is represented by the  same formula as the Mudesous,
with the addition of two equivalents of oxygen.   Thus—
       The Mudesous,    .    .     .    C12H*08
       The Mudesic,      .     .    .    Cl2H501(>    .
There can be little doubt, I think, that  this oxidation takes
place in nature also, in favorable circumstances; and, there-
fore, that the Mudesic acid is sometimes formed  in the soil.
   7. From what is above stated, it appears that, to the acids
mentioned by Mulder, several others may be added as occur-
ring in certain circumstances in the soil,—forming successive
steps in the series of changes through which vegetable matter
passes, on its way from the substance of the living plant to the
state of carbonic acid and water, into which it is finally re-
solved.  There are three groups of acid and other compounds,
into  which the organic substances of the soil may be arrang-
ed :—
   a. The humic class, which may be  represented by carbon
and water only.
   b. The ulmic class, in which the hydrogen is in excess ; and
   c. The geic class, in which the oxygen is in excess.
   The acid extracted by ammonia from Scottish peat belongs
to the first;  that extracted by carbonate of soda,  to the se-
cond ; and the Mudesous and Mudesic acids, to the third.  An
unwillingness to lengthen this note, prevents me from further
expounding this view, which, to the scientific chemist, is per-
haps less necessary, as 1 shall hereafter treat of it more fully
in another work.—J. 
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