A
CHEMICO-MEDICAL
ESSAY
TO EXPLAIN THE OPERATION
OF
OXIGENE,
OR THE BASE OF
VITAL AIR
ON THE
HUMAN BODY.
By BENJAMIN DE WITT, M.P.M.S.
CITIZEN OF THE STATE OF NEW-YORK.
Whence in bright floods the VITAL AIR expands, 
And with concentric spheres involves the lands ;
Pervades the swarming seas, and heaving earths,
Where teeming nature broods her myriad births ; 
Fills the fine lungs of all that breathe or bud ;
Warms the new heart, and dies the gushing blood ;
With life's first spark inspires organic frame,
And, as it wastes, renews the subtile flame. 
DARWIN.
PHILADELPHIA:
PRINTED BY WILLIAM WOODWARD, No. 17,
CHESNUT-STREET.
1797. 

IMPRIMATUR,
J. WOODHOUSE. 

INAUGURAL THESIS,
SUBMITTED TO THE
EXAMINATION
OF THE
REV. JOHN EWING, S.T.P. Provost,
THE
TRUSTEES
AND
MEDICAL PROFESSORS
OF THE
UNIVERSITY OF PENNSYLVANIA,
FOR THE
DEGREE
OF
DOCTOR OF MEDICINE.
ON THE THIRD DAY OF MAY, 1797.
NON FUMUM EX FULGORF, SED EX FUMO DARE LUCEM COGITAT
HOR. 



TO
Dr. WILLIAM M'CLELLAND,
OF THE CITY OF
ALBANY,
THIS ESSAY IS INSCRIBED, 
AS A PUBLIC TESTIMONY
OF RESPECT and ESTEEM,
BY HIS
SINCERE FRIEND
AND FORMER PUPIL,
The AUTHOR. 



ESSAY, &c.
INTRODUCTION.
PERHAPS no branch of natural philoso-
phy has more engaged the attention of the learn-
ed, or been more successfully cultivated, than the
nature of the common air which surrounds us.
Philosophers formerly imagined it to be a pure,
simple, elementary fluid ; hence their attention
was chiefly engaged in investigating its mechanical
properties. Modern discoveries, however, evince
that it is by no means an elementary substance ;
but composed of different constituent parts, pos-
sessing chemical qualities, and having a very ex-
tensive and wonderful agency, in a great variety of
the operations, both of nature and of art.
THE knowledge of its being essential to the pre-
servation of animal life must have been coeval
with mankind ; it was from the beginning, as it is-
now " the breath of life:" But in what manner
this was affected has long remained an impenetra-
ble mystery. It was lest for modern chemists to
solve this difficult problem. By decompounding
the air which we breath, and by shewing the pro-
perties of its constituent parts they have enabled 

8
us to view some of the most important functions
of the animal system, in a very different light from
what our ancestors were accustomed to do.
THE beautiful experiments of Lavoisier prove
that atmospheric air is composed principally of
two elastic fluids. He procured them in a separate
state,* and found that in the one, an animal died
in a few seconds ; in the other it became remarka-
bly lively. A taper plunged into the one was im-
mediately extinguished ; in the other it burnt with
a dazzling splendor. In short, the one incapable of
supporting animal life and combustion ; the other
possessing that property in a high degree. The
first was called Azotic (or more properly Nitro-
gene) gas ; the other Oxigene gas, or vital air.
As a further proof of this important truth, if
we recombine these two elastic fluids in certain
proportions, we reproduce an air precisely similar
to that of our atmosphere, possessing the same pow-
ers of supporting combustion, respiration and cal-
cination.†
By other experiments it is found that atmos-
pheric air contains also a small portion of carbonic
gas (fixed air), and most probably likewise some
dydrogene gas (inflammable air) ; but neither of
these appear to be essential to its constitution.
As that property of air which renders it capable
of supporting life seems to reside essentially in one
of its constituent parts, it becomes an important and
interesting enquiry, which deserves to be minute-
ly investigated, What is its nature, and what its
effect upon the human body ?
* Lavoisier's Elem. Chemist. p. 82.
† See Lavoisier, Brisson, torn. ii. p. 35. 

9
OF OXIGENE GAS, or VITAL AIR.
THIS species of air was first discovered by the
celebrated Priestley, on the 1st. of August, 1774.*
He called it dephlogisticated or pure air. Scheele
called it empyreal air, and Lavoisier first named it
highly respirable or vital air. The French che-
mists afterwards gave it the name of oxigene gas.†
from its property of forming acids by combining
with certain substances. This discovery has been
emphatically stiled the "pride of modern philoso-
phy."
OXIGENE GAS exists in our atmosphere in the
proportion of twenty seven parts to the hundred,
according to Lavoisier.‡ It is compounded of a
base or radicle, and caloric (fire, heat, igneous
principle, &c.) which maintains it in a state of
elastic fluidity. Its radicle or oxigene has never
been obtained in a separate state or solid form, on
account of its great attraction for other bodies ;
it appears however to approach to this state, as
it exists in water in the proportion of 85 parts to
the hundred. It possesses the exclusive property
of supporting respiration and animal life: All the
other species of air hitherto discovered appear to
be inadequate, or perhaps injurious to that effect.
A LARGE portion of the oxigene of our atmos-
phere must be continually employed in the breath-
* Mr. Scheele, it is said, made the discovery also nearly
about the same time, though he did not know of Dr. Priest-
ley's experiments. Lavoisier says he also discovered it; but it
is more probable, that he received the hint in a conversation
with Priestley when in France.
† From the Greek words (oxus) "sharp or acid," and (gei-
nomai) "to beget or produce."
‡ Elem. Chemist. p. 86. 

10
ing of animals, the burning of fuel, the putrefaction
of substances, and numerous other operations car-
ried on in the great elaboritory of nature. This
consumption is incessantly supplied by the action of
the solar rays upon growing vegetables : hence an
equilibrium is maintained, in the proportion of the
constituent parts of the atmosphere. Priestley,
Ingenhousz, and others, have sufficiently proved
that most plants, exposed to the action of light,
perspire vital air, and absorb the mephitic : Man,
on the other hand, emits mephitic, and subsists up-
on vital air ; hence the vegetable and animal king-
doms appear to labour for, and mutually to supply
each others wants.
OF OXIGENE AS RECEIEVED INTO THE SYSTEM
BY THE LUNGS.
AIR taken into the lungs by respiration is di-
minished in quantity, and parts with its vital pro-
perty, which experiments shew to be absorbed by
the blood. Chaptal says, that the air in which
five sparrows had died yielded only 17/100 of Oxigene.
Count Morozzo placed ten sparrows in succession
under a bell of glass filled with this gass, inverted
over water. The first died in five hours and
twenty three minutes, by which the air was
greatly diminished; the second died in two hours
and ten minutes, with a further diminution of the
air, and the third in one hour and thirty minutes,
without producing any visible alteration. This
diminution by the breathing of man is 360 cubic
inches in an hour, according to the accurate ex-
periments of M. de la Metherie.*
* The calculations of Hales in his Statics, and the experi-
ments of Chaptal and Lavoisier vary somewhat from this. 

11
BLOOD we know has so strong an attraction for
oxigene as to absorb it from the air after it is drawn
out of the body ;* but as it does not come imme-
diately in contact with the air in the lungs, it was
difficult to conceive how they should unite ; and it
was supposed that the intervening membranes
would form a barrier to the reception of any part
of the air into the system. This difficulty was en-
tirely obviated by an experiment of Dr. Priestley :
He enclosed a quantity of blood in a bladder, ap-
parently more dense and impermeable to air than
the vesicles of the lungs, and upon exposing it, the
blood which it contained soon became as florid as
if it had been in the open atmosphere. Dr. Good-
wyn also found that even the coats of the vei in
different parts of the body, were no obstruction to
the process of floridification, which indicates the
reception of oxigene; the same effect is also pro-
duced though the blood being covered with a
stratum of serum to the depth of two inches or
more ; - oil, saliva or water however prevent its
action.
THE experiments of Darwin† and Luzuriaga,‡
however, prove that air does not, and cannot con-
sistently with animal life, exist in the blood in a
gaseous or aeriform state ; we must therefore ne-
cessarily conclude, that it takes on another form
on entering the system : This no doubt is effected
by its being decompounded, and parting with so
much of its caloric as was necessary to maintain
it in a state of elastic fluidity. In no other way
can it be so satisfactorily explained.
* See Girtanner's experiments.
† Med. Com. vol. vi. p. 35.
‡ Inaug. Dissert. Edin. 

12
THE air which is emitted from the lungs after,
having answered the purposes of respiration, is
found not only to have lost a portion of its oxi-
gene, but at the same time acquired a new princi-
ple, to wit, carbonic or fixed air: This is prov-
ed by causing the expired air to pass through lime
water, which instantly becomes turbid ; if receiv-
ed through tincture of turnsole, it reddens it, and
if through a solution of caustic alkali, it renders
it mild and effervescent.
THE nitrogene gas, which constitutes by far the
largest portion of the atmosphere, appears to un-
dergo no perceptible change, either in quantity or
quality, by being breathed.*
OF OXIGENE,
AS RECIEVED INTO THE SYSTEM, BY THE STO-
MACH AND INTESTINES.
THAT oxigene is taken into our bodies by the
stomach as well as by the lungs, is not so evident
from direct experiment. It can hardly be doubt-
ed, however, that it constitutes a large portion of
the constituent parts of our daily aliment, particu-
larly of acids and vegetables ; and in that state is
most probably absorbed into the blood, in some
measure to answer the purposes of the animal econo-
my. " No substances, (says Dr. Beddoes) are bet-
ter calculated than acids, at least, to impart oxi-
gene to the system ; they contain it in abundance,
and they easily part with it.† It does not appear
* See Priestley, Lavoisier, Chaptal, Goodwin, & c.
† Letter to Dr. Darwin. 

13
improbable to me that oxigene may be also impart-
ed to the blood, circulating through the vessels
immediately on the surface of the intestines: When
we consider that the intestinal canal appears to be
the only interior part of the body, except the lungs
themselves, to which atmospheric air has access;
and that this elastic fluid is swallowed in consider-
able quantities : When we consider the astonishing
congeries of small blood vessels spread upon its
surface; and further, when we reflect with what
ease oxigene is admitted through mucous mem-
branes, and even through the coats of large veins
when laid bare; and finally, when we consider
the change which the air undergoes in its passage
through this canal, there can hardly remain a
doubt that oxigene may in this manner be impart-
ed to the blood in considerable quantity ; more es-
pecially as the area of the whole surface of the in-
testines is perhaps as large as that of the lungs.
OF OXIGENE AS TAKEN INTO THE SYSTEM
BY THE SKIN.
IT has been doubted whether oxigene could be
taken into the system by the surface of the body:
If, however, water is absorbed by the pores of the
skin, it is evident that in this way oxigene is taken
in, like that with the aliment by the intestines.
Whether the water after entering the system is
decompounded, and its oxigene set at liberty, to
answer other purposes of the animal economy, re-
mains perhaps yet to be determined. Girtanner
asserts, that from some of his experiments it is
clear that water is decomposed and recomposed
continually in organized bodies. But besides, we 

14
have some reason to conclude that oxigene is ab-
sorbed from the air by the skin, in a similar man-
ner to that by the lungs. This is rendered proba-
ble from the striking resemblance between the
matter of perspiration, and the exhalation from
the lungs. The experiments of the Count de
Milley, and the observations of Foquet prove that
the genuine matter of perspiration is carbonic gas,
the same with that exhaled from the lungs ; like
that it precipitates lime from its solution, and like
that it is incapable of supporting flame and respira-
tion. It appears further probable from those cases
in which the lungs have been almost totally de-
stroyed by disease ;* and from which patients have
survived for years, almost wholly deprived of the
advantage of respiration. In those cases the skin
or the intestines must have in some measure sup-
plied the office of the lungs in providing the sys-
tem with oxigene. What quantity the skin does
absorb is not yet ( so far as I know) proved by ac-
tual experiments, though Dr. Beddoes asserts (up-
on what authority I know not) that "it is found
" in equal times to take in three or four times as
" much oxigene air as any other." Dr. Fother-
gill also mentions that it has lately been discover-
ed that vital air is absorbed by the skin in consider-
able quantities.
* See Blumenbach.
† On the suspension of Vital action, 1795. 

15
OF THE EFFECTS OF OXIGENE ON THE BLOOD.
I. On the crassamentum or red globules.
LOWER, in his treatise de corde, long ago ob-
served, that the blood returned from the lungs by
the pulmonary veins, was of a more florid colour
than that in the arteries. The same was after-
wards observed by Boerhaave, Haller, Hewson,
and others ; and has since been noticed by almost
every author who has written upon the subject.
The cause of this difference in the colour of the
venous and arterial blood has much engaged the
attention of physiologists ; but no satisfactory ex-
planation could ever be given for it, until the im-
mortal Priestley discovered that it is owing to
what he calls dephlogisticated or vital air.* He
exposed a quantity of venous blood to common air,
and found that by agitation it immediately became
of a more florid colour, and that this effect took
place in a higher degree and in a shorter time when
exposed to oxigene gas. On the other hand, blood
exposed to any of the other airs, in a short time
lost its bright red colour, and became black ; but
resumed its floridity upon being brought in contact
with vital air. Goodwin inclosed a quantity of
* John Mayow in the obscurity of the last century (1668)
was acquainted with many of the properties of oxigene air,
though he did not procure it in a separate state. In his Tract de
respiratione, he proved by experiment that the air is diminished
both in respiration and combustion ; that the office of the
lungs is to separate from the air, and convey to the blood, one
of its constituent parts, which he called nitro atmolpherical,
or fiery air particles : He supposed this coloured the blood, and 
was necessary to all muscular motion, and especially to the
heart. his writings however seemed to be little taken notice
of.
See Dr. Beddoes on Exp. of a Phil, in the last. cent.
C

16
oxigene gas in a glass receiver, inverted over
mercury, and introduced into it 4 ozs. of blood,
drawn from the jugular vein of a sheep ; it instant-
ly became florid, and the mercury appeared to rise
in the receiver. Blood also becomes of a dark co-
lour when exposed in vacuo, according to the ex-
periments of Beccaria, which have since been re-
peated by Dr. Priestley with the same result.
THE blood returned from the extremities by the
veins, being of a darker colour than that in the ar-
teries, can only be explained by its having lost a
part of its oxigene in the course of the circulation ;
and not by its having acquired a larger portion of
hydro-carbonic matter, as has been conjectured by
some: for if oxigene gas be injected into a vein,
the blood becomes as florid as that in the arteries,*
without however having parted with its supposed
superabundance of carbone.
SEVERAL opinions have been offered as to the
nature of that principle or property in the crassa-
mentum of the blood, by which it is peculiarly
adapted to become floridified by an union with ox-
igene ; but I confess they all appear to me to be un-
satisfactory. The most probable opinion perhaps
is, that it is owing to iron reduced to a state of
red oxid: but it is difficult to conceive how so
small a portion of iron as the blood contains, should
diffuse that florid colour through so large a mass
of fluid ; and it does not appear to have so strong
attraction for oxigene at the ordinary tempera-
ture of the body, as to account for the instantane-
ous change which takes place in the blood circu-
lating through the lungs. Other causes might
perhaps be suggested with equal probability of
* See Hewson, Girtanner and others. 

17
truth.* It would afford an extensive subject for
much plausible reasoning to a speculative theorist,
but would lead too far into the field of conjecture.
Upon this, as well as many other subjects connect-
ed with the animal economy, we must consent to
remain in doubt, until by future experiments and
discoveries, we shall acquire a more extensive
knowledge of the sublime operations of the che-
mistry of nature.
OF THE EFFECTS OF OXIGENE
2. Upon the gluten, or coagulable lymph of the Blood.
THAT oxigene acts upon the red globules of
the blood, must now be evident to every one of
the slightest observation, by the instantaneous
change which it produces in its appearance, con-
verting it from a dark red to a bright vermillion
colour. But that it also produces essential effects
upon the other component parts of the blood, is
not so evident at first view : It is, nevertheless,
highly probable to me, that its agency upon the
coagulable lymph particularly, is no less considera-
ble and important. This opinion is rendered pro-
bable when we consider that in those cold blooded
animals, whose blood has no red globules, respira-
tion is as essential to their existence as any other.
In a number of very accurate experiments made
* Dr. Darwin supposes it to be owing to phosphorus, but I
believe only upon conjectural grounds, as appears from the fol-
lowing lines :
" When air's pure essence joins the vital flood,
" And with phosphoric acid dyes the blood,—"
BOTANIC GARDEN. 

18
by Doctor Beddoes,* in order to ascertain the
comparative effects of common and vital air upon
animals ; the blood appeared uniformly to coagu-
late much sooner and firmer, of those animals
which had for some time breathed oxigene air,
than of the others which lived upon common air,
and were killed in the same instant. On the other
hand, in most of those cases related by authors, in
which we may conclude with tolerable certainty,
that there was a deficiency of oxigene in the sys-
tem ; such as scurvy, for instance, and the cases
given by Dr. Sandifort, of Leyden† and others ; in
which, from organic affection of the heart, but a
minute portion of blood circulated through the lungs
to the oxidated ; so far as I can judge from their im-
perfect accounts of the state of the blood, it always
appeared to have lost in some degree its property
of coagulating. From these considerations I am
inclined to believe, that the coagulable lymph of
the blood owes its property as such in a great
measure to this vital principle of the air ; and that
the influence of oxigene is perhaps essentially ne-
cessary to bestow upon it that condition, which
renders it fit to become concreted into animal fi-
bres, and to nourish the solid parts of our body.
OF THE INFLUENCE OF OXIGENE IN PRODUC-
ING ANIMAL HEAT.
ANOTHER important effect accomplished by
the agency of oxigene received into the body, is
the production of animal heat. A very opposite
* On Factitious Airs, p. 16, and elsewhere.
† Observationes Anatomico-Patholog. Luqd. Batav. 1777, 
page 11.

19
circumstance to the whimsical notion of those,
who imagined the lungs to perform the office of a
bellows to cool the blood. Respiration, as we
have already seen, is to be considered as an opera-
tion by which vital air continually passes from a
gaseous to a concrete form ; it must therefore at
each instant abandon so much of its heat as was
previously necessary to maintain it in a state of
elastic fluidity ; this heat being set at liberty, now
manifests itself in a free and sensible form ; hence
an abundant source of animal heat generated in the
lungs.* Persons who have respired vital air all
agree in affirming, that they have perceived a gen-
tle warmth vivifying the lungs, and extending to
the more distant parts of the body. But the lungs
are not the sole focus or fire place where heat is
produced ; for we have the strongest reasons to be-
lieve that it is also evolved in the course of the cir-
culation, and particularly in the extremities of the
arterial system. If the lungs were the only source
of animal heat, the parts of the body would become
cold in proportion to their distance from this cen-
tre ; for we know that heat decreases as it recedes
from the source whence it originated. If this were
the case too, no part would be susceptible of an
increased heat, as is manifestly the case in topical
inflammation ; nor no part except the lungs would
refill the topical application of cold.
THOUGH oxigene in assuming the concrete
form, by combining with bodies, looses some por-
tion of its caloric, that is, so much as was necessa-
ry to keep it in an æriform state, it is nevertheless
certain, that it carries a large quantity of latent
heat along with it in assuming the solid form in
* See Crawford's experiments on Animal Heat. 

20
various combinations;* if then this be the case, as
it unites with the blood, it is easy to explain how
it should give out this heat, in the course of the cir-
culation, by entering into new combinations.
THAT the evolution of heat is intimately con-
nected with the action of the arteries, is a familiar
fact ; and it seems highly probable that their mi-
nute ramifications are of such importance to the ge-
neration of heat, that as their action is weaker or
stronger, a proportional diminution or increase
takes place, in the heat of a part or the whole of
the body. They appear to have the power of de-
compounding the blood, as in the various secretions,
and of recompounding it again; and as the affinity
for substances, is variously changed, when they un-
dergo any chemical alterations, it is easy to con-
ceive how blood when it undergoes these changes,
should throw out a large quantity of its latent
heat.
" As the evolution of heat" (says Dr. Darwin)
"attends almost all chemical combinations, it is
probable that it also attends the secretions of the
various substances from the blood, and that the
constant combination or production of new fluids
by means of the glands, constitutes the more gene-
ral source of animal heat. This Seems to be evinced
by the universal evolution of the matter of heat, in
the blush of shame or anger, in which at the same
time an increased secretion of perspirable matter oc-
curs."
FROM these general and uniform sources of ani-
mal heat in the body, we can easily explain, how
all the parts of the body retain nearly the same
* Sec Lavoisier Elem. Chemist. 

21
degree of temperature, and why it is so little va-
ried, whether the subject be exposed to the rigors
of the coldest climate, or placed beneath the fer-
vors of a tropical fun.
OF OXIGENE AS A STIMULUS TO THE HEART
AND ARTERIES.
THE stimulating effects of Oxigene upon the
heart and arterial system is now established by a
multiplicity of experiments and observations. I
shall mention only one. A young man having
breathed pure undiluted Oxigene air for several mi-
nutes, his pulse which before the experiment was
64, now rose to 120 beats in a minute*. There is
so intimate a connection between the quantity of air
received by respiration, and the action of the heart
and arteries, that by accelerating or retarding respi-
ration by an effort of the will, any one may at plea-
sure greatly increase or diminish the action of his
pulse, both as to frequency and force. The con-
tinuance of the action of the heart and arteries dur-
ing life, seems to be very entirely owing to the
incessant influence of this vital principle of the air;†
for neither the stimulus of heat, nor the mechanical
stimulus of the blood, appear to be at all adequate
to this effect, as is abundantly manifested by the ex-
periments of Goodwin‡ and others ; and why does
not the circulation go on, when the lungs are dis-
* Minutes of the Society for Philosophic Experiments, by
Dr. Higgins, p. 146.
† Sir Isaac Newton imagined that the atmospheric air might
communicate an acid vapour to the blood of the lungs, which
was necessary to keep up the action of the heart. - Optics, p. 351.
‡ Connection of life with respiration, & c. 

22
tended with any other air which is inimical to life,
only in so far as it withholds Oxigene from the
blood ?
OXIGENE differs from many other stimulants,
perhaps, in this respect, that it does not appear to
diminish, but rather to increase the irritability of
the muscular fibre*. It seems indeed to be so inti-
mately connected with the irritability of the heart,
and so essential to its support, that in proportion
to the increased or diminished quantity of vital air
received into the system, there takes place a corres-
ponding change in the irritability of that vital or-
gan ; and moreover, as irritability in a great mea-
sure accompanies and keeps pace with animal heat
through life, it may be concluded with much plau-
sibility, that it depends upon the same principle ;
and hence, that Oxigene may be truly the source
and proximate cause of the irritability of the heart
and muscular fibres, which enables them to per-
form the functions of vitality. This doctrine re-
ceives additional stability by being long since
adopted†, and lately so well illustrated by the
learned Dr. Fothergill in his ingenious prize disser-
tation on the suspension of vital action.
EFFECTS OF OXIGENE UPON THE NERVES
BRAIN, AND MIND.
THAT Oxigene acts powerfully upon the sen-
tient extremities of the nerves, may be inferred,
from a a experiment mentioned by Dr. Ingenhousz,
and since several times repeated by Dr. Beddoes,‡
* Girranner's Experiments.
† Hints on Animation, 1783.
‡ On factitious Air, page 43. 

23
that if the finger be blistered, so as to lay bare
the naked and sensible skin, and exposed to common
air, a smarting pain occurs; in Oxigene air it is more
severe, but when exposed to azotic or carbonic gas,
it entirely subsides, and returns immediately upon
being withdrawn into atmospheric air.*
THE ingenious Dr. Darwin, thinks that Oxigene
taken into the system by respiration, " affords the
material for the production of the sensorial power,
which is suposed to be secreted by the brain, or me-
dullary part of the nerves, and that the perpetual
demand of this fluid, in respiration, is occasioned
by the sensorial power which is supposed to be pro-
duced from it, being too subtile, to be long con-
fined in any part of the system." — " The necessity
of perpetual respiration shews" (continues he in
another place,) " that the Oxigene of the atmos-
phere supplies the source of the spirit of animation,
whence it is probable that Oxigene gas may increase
the secretion of sensorial power, as indeed would
appear from its exhilirating effect on most pa-
tients."† Be this as it may, numerous facts and
experiments authorise us to say, that it uniformly
produces vivacity, cheerfulness, gentleness, and se-
renity of mind, exhilirates and enlivens all the intel-
lectual operations,‡ and produces alacrity and vi-
gor in all corporeal exertions. It is very remark-
able that Oxigene air, even when infused into the
cellular substance of dogs, appeared in a short time
to manifest stimulating effects : the animals became
* Dr. Thornton says he has seen a man whose finger was
amputated, receive immediate relief from pain, by plunging
his hand in fixed air.
† Zonomia, part 2. vol. 2. p. 377 & 399.
‡ "May not chemistry be able to exalt the powers of future
poets and philosophers."
BEDDOES. 

24
exceedingly lively (maxima alacritas) by the ex-
periments of Dr. Maxwell.*
OF THE EFFECTS OF OXIGENE UPON THE SKIN.
AMONG the numerous causes that have been
called forth to explain the variation of colour in the
human race, the agency of Oxigene has not been
neglected ; Dr. Beddoes was once nearly elated with
the hope of having discovered the method of turn-
ing the Ethiopian white, by means of the Oxigenated
"muriatic acid air: The arm of a negro was intro-
duced into a large jar, full of this air, and the back
of his fingers lay in some water impregnated with
it at the bottom of the vessel, they acquired an ap-
pearance as if white lead paint had been laid upon
them, but it did not prove permanent ; a lock of
his hair was whitened by this acid. Similar expe-
riments have been made by the professor of che-
mistry in this university, but without success ; it
produced no change either on the skin or the hair.
" Can the Leopard change his spots, or the Ethio-
pian his skin ?"
OF THE EFFECTS OF OXIGENE UPON THE BONES.
BY chemical analysis, the bones are found to be
composed principally of Phosphoric acid, and calca-
reous earth ; now as we know that phosphorus, as
well as every other substance, is reduced to a state
* Edin. 1787. 

25
of acid only by uniting with oxigene, which seems
to be the universal acidifying principle in nature;
it is evident that its agency must be essential to the
formation of bones. Phosphorus by its strong at-
traction for Oxigene, probably unites with it as soon
as it is received into the system, this again combining
with the calcarious earth taken in with our aliment,
will probably give the true theory of the formation
of bones. This idea is farther confirmed, by a cir-
cumstance occurring in certain cases of disease in
which the bones become soft and flexible ; In many
of these cases the urine was found upon examination
to contain a very large quantity of phosphoric acid,
and sometimes a plentiful sediment of earthy mat-
ter. May not the other solids of our bodies be form-
ed by a chemical combination somewhat similar to
this?
OF OXIGENE AS A NUTRIMENT.
" SPIRITUS etiam alimentum est," are the
words of ancient Hippocrates. From the large
quantity of oxigene taken in, and from its entering
so largely into the composition of our bodies ; - it
may, I think, with propriety be classed among the
nutritious substances. It seems, indeed, when con-
sidered in this light, to be of much more immediate
consequence to the preservation of life, than any
of the other alimentary matters— "It is impossible
to doubt (says Dr. Beddoes) that we are nourished
by the lungs as truly as by the stomach, and that
what we take in at the former entrance, becomes 
like our food, a part of the substance of our solids,
as well as our fluids." 

26
OF THE EFFECTS OF OXIGENE ON THE FŒTUS
IN UTERO.
WHEN we contemplate the young and tender
fœtus, closely wrapped up in its mother's womb,
and apparently cut off from all communication with
the external air, we should at first be apt to imagine,
that it was entirely deprived of its genial influence;
but this cannot be, for without it, all animated na-
ture would become a lifeless mass. It must there-
fore be through the medium of its parent, that it is
continually supplied with this necessary fluid, and
the placenta we know is the only communication
that exists between them. It has generally been
supposed that the blood of the mother was trans-
mitted immediately to the fœtus through this me-
dium, and that its sole use was for the purpose of
conveying nourishment ; but I am rather disposed
to believe that no such communication takes place.
It is more probable that the maternal blood is only
conveyed by arteries to the placenta, and immedi-
ately returned by veins, after it has imparted its
superabundant oxigene to the fœtal blood circulating
through it, by an operation similar to what takes
place in the lungs of air-breathing animals, and the
gills of fishes ; in short, that the placenta serves the
office of a respiratory organ to the fœtus, while it
remains in the womb.* Oxigene communicated in
* This doctrine I endeavoured to establish and vindicate, in a
memoir read before the Philadelphia medical society on the 28th
of December, 1796. To have entered into, a detail of the ar-
guments here, would have been foreign to the subject. It is an
opinion that was held as early as the last century by John May-
ow, Sir Edward Hulse, and some others ; but since it was con-
troverted by the late Alexander Monro, it appears to have been
the prevailing opinion, that the placenta was an organ of nu-
trition only, "owing perhaps (as an ingenious author observes) 

27
this way from the blood of the parent, to that of
the child, sheds all that healthful influence upon it,
which it continually does upon animals who live in
the open air.
rather to the authority of so great a name than to the validity
of the arguments adduced in its support." That there is no di-
rect communication between the maternal and fœtal blood, may
be inferred,
1st. From the fact, that the vessels of the uterus cannot be
injected from the placenta.
2nd. From the fact, that if the child and placenta are both
delivered suddenly, and the child, though alive, does not yet
breath, the blood may be felt circulating with force through the
funis, and when it is slighty pressed, the arteries swell between
the pressure and the child, and the vein between it and the pla-
centa, from the surface of which, however, no blood flows.
3d. From the fact, that while the placenta adheres firmly to
the uterus, which remains still distended by a child, if the fu-
nis be divided no more blood flows from it, than seemed to be
contained by the placenta.
4th- From the umbilical vein carrying arterial blood. If that
blood was derived immediately from the mother, it must have
been changed from arterial to venous, as takes place in every
other part of the body.
5th. From the probable utter impossibility of the embrio heart
to propel forward the column of blood in the winding vessels of
the uterus, on its way to the mother's heart, &c. &c.
If, then, no direct communication exists between the blood
of the mother and child, the placenta may be inferred to be a
respiratory organ,
1st. From its structure, as demonstrated by Mr. John Hunter.
2nd. From the blood returning of a florid colour to the fœtus.
3d. From the fœtus immediately dying as soon as the placen-
ta is separated from the uterus.
4th. From its analogy with the mode of existence of fishes in
water, and the chick in ovo, &c. 

28
OF THE MORBID EFFECTS OF OXIGENE.
OXIGENE, though it is the support and staff
of life as it exists in its diluted state in our atmos-
phere ; yet, when pure and unadulterated, it can-
not be breathed without manifesting a hurtful ten-
dency ; and by producing as it were an excess, si-
nally extinguish life ; like Milton's darkness, from
an excess of light: " for as a candle burns out
(says Dr. Priestley) much faster in this than in
common air, so we might, as may be said, live out
too fast, and the animal powers be too soon ex-
hausted," Like sensual gratifications, in modera-
tion it is the cordial, in excess the bane of life.
Mr. Lavoisier found that animals died when con-
fined in oxigene air, long before it became unfit
for respiration : On dissection death seemed to have
been occasioned in every instance by an ardent fe-
ver and an inflammation ; the flesh was of a very
red colour, the heart livid and turgid with blood,
especially the right auricle and ventricle, the lungs
were very flaccid, but red, even externally ; they
were also turgid with blood.*
IN allusion to the above fact, concerning the
morbid effects of oxigene upon animals, Dr. Bed-
does asks, " May not the flower and differently
modified inflammation of the lungs in pthisis, ori-
ginate from a smaller excess of oxigene, thrown in-
to the system in a more gradual manner ?" This
the Doctor labours to establish by much ingenious
reasoning, and many plausible arguments.†
BUT whether there be really a superabundance
of oxigene in the systems of pthisical patients or
* Mem. de la Societé Roy. de Med. T. and p. 575.
† See his Treatise on calculus, scurvy, pthisis, &c. 

29
not, it is easy to conceive that the ordinary pro-
portion of oxigene in the air may exert morbid
effects, and aggravate this, as well as many other
inflammatory complaints, by acting as a powerful
stimulus disproportioned to the excitability of the
system : and hence, we need not wonder that in
twenty cases of this disease, in which oxigene air
was inspired, as described by Fourcroy, it uniform-
ly aggravated the complaint. Upon these princi-
ples too we might hope for the beneficial effects of
a lowered atmosphere, in many diseases of high ex-
citement, which is indeed already manifested by the
experience of Dr. Beddoes and others.
SINCE the active agency of oxigene upon the
body has become known, physicians have not fail-
ed to call in its assistance to explain that state of
the atmosphere which seems to dispose to epidemic
and malignant disorders. Dr. Rush* ascribes it to
a superabundance of oxigene, and Dr. Mitchell,† of
New-York, to a certain combination of oxigene
and azote, or nitrogene. But all our knowledge
upon this subject appears to me to amount, as yet,
to no more than plausible conjecture. I do not
know any facts or experiments which lead to a
knowledge of that precise condition in which it
consists ; and I might perhaps quite as well be con-
tented to call it the " divine something" of Hyp-
pocrates, the " mineral vapour" of Sydenham, or
the " marsh miasma" of the present day, as to at-
tempt to elucidate its nature by abstract reasoning
from our present data. However, we may ven-
ture to conclude from what we already know of
the properties of oxigene, that its morbid effects
in undue quantity will be found to keep pace with
* Med. Enquiries and Observations, vol. iv. p. 75.
† On the gaseous oxid of azote. 

30
the extent of its salutary influence over the human
frame. Under what circumstances this may hap-
pen, or when it takes place, experiment is perhaps
only adequate to determine.
ONE probable effect of oxigene, however, de-
serves to be taken notice of ; that is, the change
which it would seem to produce in the matter of
ulcerations, as of small pox, cancer, abcess, &c.
Dr. Darwin* says, "the blood in small pox will
not inoculate that disease, if taken before the com-
mencement of the secondary fever ; because the
contagious matter is not yet formed ; but after it
has been oxigenated, through the cuticle in the pus-
tules, it becomes contagious.†" The matter of can-
cers does not seem to acquire a contagious quality
until it is exposed to the air ; hence they are often
successfully extirpated in this state ; but after they
become ulcerated, a hectic fever often occurs, and
the neighbouring glands become swelled. The
matter of common abscess too, appears to be mild
and inactive, till it becomes changed by exposure
to air, when it acquires a stimulating and fever
producing property. Are not these morbid effects,
of oxigene ?— It is without doubt from this prin-
ciple of the atmosphere too, that we are to explain
the deleterious effects of air, when accidentally ad-
mitted into any of the large cavities of the body ;
and it is easy to account for the inflammation
which generally ensues, from the highly stimulat-
ing property of the oxigene which it contains.
From these obvious effects which it seems uniform-
ly to produce, it has been very ingeniously em-
ployed for the cure of hydrocele, by injecting it
* Zonomia, part 2, vol. i. p. 91.
† This is the reason, he says, why the fœtus in utero is
sometimes infected after the secondary fever, but never before
it. 

31
into the tunica vaginalis testis after evacuating the
water, and with constant success.
OF OXIGENE AS A REMEDY IN CERTAIN DI-
SEASE
OXIGENE, as being a powerful and durable
stimulus which seems to exert its influence over
the whole body, may be had recourse to with per-
haps singular advantages, in many of those cases
in which this class of medicines has been recom-
mended, as well as in those in which there may be
supposed to be a deficiency of that principle in the
system. When a super-oxigenated air is inspired
for some time, it increases the strength, and gives
an alacrity for motion ; produces gaiety and seren-
ity of mind ; mitigates pain, and disposes to sleep;
increases the appetite for food, and strengthens the
powers of digestion ; diffuses a gentle warmth over
the whole body, and imparts a degree of insensi-
bilty to cold ; gives life to the eye, and bloom to
the countenance. I shall briefly enumerate some
of the principal diseases in which its efficacy seems
already to be manifested.
Asphixia.—Suspended animation from submer-
sion, strangulation, and certain unrespirable airs,
being produced by the privation of oxigene, it
must be evident that the only probable method of
recovery is, to restore this to the blood by inflat-
ing the lungs. It is reasonable to believe that a
super-oxigenated atmosphere would be most effec-
tual;* at any rate, the method of inflating by the
* The superiority of vital air in restoring animation (says
Dr. Fothergill) has been confirmed by many respectable writers
both at home and abroad.
Suspension of Vital Action, p. 113. 

32
vitiated breath of another, as is too often done,
appears to me very objectionable.
Scurvy.—It is probable that the efficacy of acids
and vegetables in the cure of scurvy, is in some
measure to be ascribed to the oxigene which they
impart to the system. What effects breathing an
oxigenated air would have, remains to be deter-
mined.
Typhus.-Dr. Thornton and Mr. Townsend
have found it of remarkable efficacy in this disease.
Dr. Wood from his own experience recommends
nitre, and ascribes its power to the oxigene which-
it imparts to the blood; " Nitre (says Dr. Beddoes)
is doubtless decompounded in the primæ viæ, and
capable of supplying much oxigene."
Asthma.—" In true asthmatic fits, its beneficial
effects have already been many times experienced ;
no sooner does it touch the lungs, than the livid co-
lour of the countenance disappears, the laborious
respiration ceases, and the functions of all the tho-
ratic organs, go on easily and pleasantly again."*
Cancer.—Inhaling oxigene air seems to have been
useful in, if not entirely removed this dreadful com-
plaint.
Schrofula. - Schrofulous ulcers, tumors, and op-
thalimia's, have yielded to it, and been completely
cured, as attested by Dr. Thornton and others. Is
the remarkable efficacy of the juice of sorrel in cu-
ring schrofulous ulcers, owing to the oxigene which
it imparts to them? In every ulcer to which it is
applied, there takes place a change from a dead pale
to a scarlet colour.
* Beddoes. 

33
Herpes. - A case of eruptions on the face, purple
blotches on the body, hard scales on the arms, a
dark coloured deep ulcer on the leg, and loss of
sight, that had resisted every remedy for thirty years,
was radically cured in a few weeks, by breathing
oxigene air.
Hypochondriasis.— Vital air might be supposed a
priori, to be useful in this disorder, it has according-
ly been found so in a number of cases.
Chlorosis.— Its undoubted efficacy in this affection
is well attested by a number of physicians.
It has also been found of great benefit in a num-
ber of other diseases ; cured some, and relieved
others ; as dyspepsia, melancholia, hysteria, anasar-
ca, ascites, palsy from lead, opium, &c. the ad-
vanced stage of consumption, and diseases of preg-
nancy. For a full account of cases, I refer to Dr.
Thomas Beddoes' considerations on the uses of fac-
titious air. From the formidable list of diseases,
many of them classed amongst the incurables of our
art, in which vital air has been found serviceable, it
promises to become a most valuable acquisition to
the materia medica. " In desperate cases (says
Chaptal) it is most certainly a precious remedy,
which can spread flowers on the borders of the
tomb, and prepare us in the gentlest manner for the
last dreadful effort of nature." 

CONCLUSION.
THUS I have endeavoured in a compendious
method to trace the influence of this active
agent upon the human body. My object has been
chiefly to develope the fundamental principles of
its operation. In doing this I have avoided as much
as possible, straying into the flowery path of imagi-
nation, or launching into the open field of conjec-
ture. I lament that I have not been able to throw
more light upon this important subject by new ex-
periments, but my time has been hitherto necessa-
rily exhausted, in a close attention to the various
other branches of the boundless science of medi-
cine.
IN taking a review of our subject, we are natu-
rally led trace the progress of the powers of the
mind, in acquiring a knowledge of the laws and
operations of nature; but a few years ago, philoso-
phers like the "children of the world*," amused
themselves with calculating the elasticity, the den-
sity and pressure of the air, without, perhaps, the
most distant idea of its having those more important
chemical properties, which we now know it to pos-
sess. If our science has already made such rapid ad-
vances, as to analyze and divide asunder, the invisi-
* Lord Bacon. 

35
ble atmosphere which envelopes us ; and to collect
and administer its different parts with the utmost
facility, for the cure of diseases.— If it can already
command the powers of the air to its assistance, in
mitigating the pangs of sickness, and alleviating the
distresses of suffering humanity, what may we not
expect from time and persevering industry ? Go on,
ye enlightened physicians and philosphers, in your
noble career ! boldly press forward, into the rich
and fruitful field for discovery and cultivation,
which is opened to your view ; led by the faithful
hand of experiment, and illuminated by the torch
of reason ; draw aside that veil of nature which
hides from our eyes so many of her sublime opera-
tions ! and
-"Explore with eagle eye,
" Where wrap'd in night retiring causes lie ;
" Trace their slight bands, their secret haunts be-
tray,
" And give new wonders to the beam of day ;
" Till, link by link, with step aspiring trod,
" You climb from nature to the throne of God."
BILLSBORROW.
And ye, Illustrious PROFFESSORS OF THE UNI-
VERSITY OF PENNSYLVANIA, accept my warmest
acknowledgments of gratitude, for those valuable
instructions which I have received from your lec-
tures : and my sincerest wishes for your individual
happiness. Long, very long may ye continue with
united splendor, like the bright: orb of day, to diffuse
the salubrious rays of medical science, in every di-
rection, to the most distant parts of our western
world ; to cherish and nurture those tender plants
of science, which are just putting forth their blos-
soms!
"Vive, Valeque."