170 C H E M 
maceutical preparations of juices, extra£ls, effential falts, 
mucilages, oils, relins, gum-refms, aromatic waters, &c. 
the arts of the fugar-maker, confectioner, miller, baker, 
ltarch-maker, vine-dreil'er, brewer, diltiller, varnifher, 
dyer, paper-maker, indigo-maker, colour-man, flax-man, 
perfumer, oil-man, fo'ap-boiler, maker of charcoal, &c. 
THE FORMATION AND NATURE OF ANIMAL SUB¬ 
STANCES. 
It is an eflablifhed truth, that, without the aid of ve¬ 
getables, animals cannot fupport their exiftence : accord¬ 
ingly it has long been faid in natural hiitory, that vege¬ 
tables are formed from minerals, and animals from ve¬ 
getables. But, if this truth has been long known, the 
mode in which theft bodies are changed, or reciprocally 
converted into each other, has never yet been afcertained. 
On this point, however, the labours of chemifts fhould 
be principally exerted : for, were this problem once folv- 
ed, it would lead us to a precife knowledge of all that 
concerns the animal economy : and fome relults condu¬ 
cive to this grand inquiry are already afforded us by 
modern difcoveries.. The moll certain means of folving 
this important problem, are unqueftionably, firft, to ac¬ 
quire an accurate knowledge of animal fubftances, to 
compare them with thofe of the vegetable kingdom, and 
to invefcigate with care their difference or analogy. 
There is no doubt, were thefe differences once weii 
known, they would enable us to underhand the caufe 
from which they arife. 
If we compare the refults of all the modern analyfis 
made of the blood and humours, and of the folid parts 
which inanifeltly originate from the concretion of theft, 
•we {hall find, that animal fubftances differ from vegetable 
fubftances, in, i. The property of affording a ccnlider- 
able portion of ammoniac^ and very fetid products, by 
the adtion of fire : 2. In that of putrefying more eafily, 
and more fpeedily, and giving out a far more noifonie 
fmell: 3. In yielding, when adted upon by nitric acid, 
much more azotic gas : and, 4. In contributing Angu¬ 
larly to the formation of nitric acid. , 
All thefe differences feem to depend only on the pre- 
fence of one principle in animals far more abundantly 
than in vegetables; which is azot. It may be faid, there¬ 
fore, that the addition of azot to vegetable matters, would 
iuffice to convert them into animal fubftances. Yet it is 
proper to obferve, that to theft primary differences, which 
may be termed capital ones, fome other particular phe¬ 
nomena may be added, the influence of which, though 
undoubtedly inferior, on the animal compofition, onght 
by no means to be negledfed. Such, among others, is 
the prefence of phofphoric acid, and the different phof- 
pliats, particularly thofe of foda, lime, and ammoniac, 
in the animal humours. To thefe falts are owing the 
peculiar quality of the coal of animal fubftances, efpe- 
cially its being almoll incombuftibie. 
The peculiar principle, which is ft abundant in thefe 
fubftances, and more efpecially renders them different 
from vegetable matter, azot, appears, then, to be the 
efficient caufe of the properties which diftinguilh them, 
and particularly of that fort of concrefcibility, or plaf- 
ticity, which we fhail foon confider more at large. It 
may be affirmed, therefore, that, if we were to deprive 
animal fubftances of azot, they would become.again, in 
fome meafure, vegetables; as, to convert the latter into 
animal fubftances, it is fufficient to combine with them, 
or introduce into them, azot. Thus all the matters 
which form the bodies of animals may be confidered as 
fo many immediate principles, as was done in the pre¬ 
ceding fediion with regard to vegetables. In the fame 
manner each of thefe principles ought to be characteriz¬ 
ed by the enumeration of its molt ftriking properties. 
If we fo examine and defcribe the blood, milk, bile, fat, 
urine, &c. and the folids of animals, we fhail obtain a 
comparative l'cale, which will exhibit the relations and 
differences that form the objeCt of our refearch; viz. 
2 
I S T R Y. 
* 
Blood : A red fluid ; warm at a temperature of 93 0 
in man, quadrupeds, and birds; at the temperature of 
the medium they inhabit in oviparous quadrupeds, fer- 
pents, and fifties ; fweetifh ; coagulable by cold ;' milcible 
with water; Separating aimolt fpontaneoully into three 
different fubftances, white ferum, red ferum, or the co¬ 
louring part, and fibrous matter; exhibiting in each of 
thefe fubftances diftinguifhing characters ; namely, in the 
ferum, alkalinity, coagulability by fire, metallic oxyds, 
&c. coagulability, owing to the more intimate combina¬ 
tion of oxygen; the fame general nature in the red fe- 
l'um, which differs from the white only in the prefence 
of oxyd of iron; in the fibrous matter, or fibrin, fpon- 
taneous concrefcibility, and folubility in alkalis. Thefe 
principal characters ought to be confidered in the whole 
of the blood, which appears to be the primary principle 
of all animal fubftances, the common origin of all the 
humours and of all the folids. It has been called fluid 
fiefh, in confequence of the fibrin, which concretes in it 
on cooling. The caufe of its heat has been difcovered 
in the alteration and abforption of vital air in refpira- 
tion : and the renovation of the blood by the chyle, and 
the converfion of the chyle into animal matter, have, in 
like manner, been found to originate from the extrica¬ 
tion of a confiderable quantity of carbon and hydrogen, 
which appears to take place in the lungs. 
Milk: A white fluid, bland and Saccharine, formed 
of ferum, cheefe, and butter, intimately mixed, and ex¬ 
hibiting a true animal emulnon. In the ferum of milk 
we fhould particularly notice the fubftance called fugar 
of milk, which may be faid to have the character only of 
an incipient fugar, and the quantity of phofphat of lime, 
more abundant than in the other humours, which feems 
to indicate, that nature thought fit to place in the firft 
nourilhment of animals a quantity of ofieous bale, with 
a view to the neceffaiy celerity of the formation and 
growth of the bones in the earlieft ftage of their lives. 
The cheefe is a true albuminous matter. The butter is 
a concrete oil, the folidity of which, and its eafy repara¬ 
tion from the milk by finiple agitation, appear owing to 
the abforption of atmofpheric oxygen during the forma¬ 
tion of the cream. 
Bile: An oily faponaceous fluid; compofed of an 
oil approaching the ftate of fpermaceti and foda, min¬ 
gled with albuminous fluid; formed in the liver, a vifi- 
cus which itfelf contains a large quantity o-f oil. In the 
fyftem of the voluminous gland juft mentioned, every 
thing indicates a difpofition, an organization, defigned 
to feparate from the blood the large portion of fat, 
which arifes from the retardation of this fluid in the ve¬ 
nous fyftem of the abdomen. This confideration, def- 
tined fome day to become cue of the principal bafts of 
the phyfiology hinted at above, accounts for the bulk of 
the liver in the fcetus which has not breathed, as well as 
in animals which have no refpiratory organ fimilar to 
thofe of man, birds, and quadrupeds. It alfo explains 
the origin of fome difeafes of the liver, particularly of 
its concretions or gall ftones. 
Fat: A fort of oily matter; formed at the extremi¬ 
ties of the arteries, and as far as may be from the centre 
of motion and animal heat; affording a kind of refer- 
voir, in which that large quantity of hydrogen which 
could not be evacuated by the lungs becomes fixed; an 
oil united to a confiderable portion of oxygen, and con¬ 
taining befides febacic acid. This manner of confider- 
ing fat, is one of the molt ftriking points of modern 
phyfics as it regards animals. 
Urine: An excrementitious fluid; more or lefs co¬ 
loured, acrid, and faline ; remarkable for the large quan¬ 
tity of free phofphoric acid, and phofphat of foda, am¬ 
moniac, and lime, which it contains, and ftill more fo 
for the prefence of a peculiar acid not yet found in any 
other animal humours, which is now called lithic, be- 
caufe it forms the bafis of the ftones of the kidneys and 
bladder, which caufe the difeal'e known by the name of 
lithiafis. 
