.356 - C H E M : 
but the raoft Important phenomena is the change of fmell, 
and the volatilization of an acrid penetrating urinous 
principle, fintilar to ammoniac, and which, on examina¬ 
tion, is found to be that fubftance. Hence the,putrefac¬ 
tive fermentation has been diltinguifhed by the name of 
the alkaline fermentation, and the ammoniac has been 
confidered as its product. The penetrating fmell fh.es off 
by degrees, and is fucceeded by a naufeous faint fmell, 
not eafily defcribed. The decompofition is then at its 
height; the putrefying vegetable matter is then very 
loft, or fluid, like a fyrup; it experiences a great number 
of fucceffive modifications in the odorant principle which 
exhales. Laftly, It dries, its difagreeable fmell is difli- 
pated by degrees, and nothing remains but a blackifh, 
and, as it were, coally refidue, known by the name of 
-earth, humus <vegetah\lis, in which nothing is iound but 
.-certain faline and earthy fubftances. Such is the order 
of the phenomena obferved in the fpontaneous decom- 
polition of vegetables which putrefy: but this decom- 
■pofition, carried to that point in which bodies are re¬ 
duced to their faline or earthy fkeleton, requires a very 
long time ; and it may even be added, that it has not yet 
been properly obferved by any perfon. This reproach, 
■which is call on chemifts and philofophej's for their inat¬ 
tention to animal matters, is much more deferved with 
regard to vegetable fubftances. No pliilofopher has yet 
undertaken to obferve the complete putrefa&ion of thefe 
laft, though many have begun to defcribe .the pheno- 
■mena which take place in that of animal matters. We 
may therefore conclude our detail of the fpontaneous 
and natural analylis of vegetables, by adding, limply, 
that the fhort account we have given fliews, that vege¬ 
table putrefaction attenuates, volatilizes, and deftroys 
their humours, and reduces them to their earthy ftate. 
That nothing is yet certainly known concerning the 
phenomena and limits of this kind of putrefaction, which 
■requires to be properly diftinguilhed from that of animal 
matters. Laftly, As this fermentation is much more evi¬ 
dent, and has been better obferved, in the fluids and fo- 
"iids of animal fubftances, the detail we (hall enter into, 
refpedting thefe laft,, will complete our fketch of the 
.'known facts relating to putrefaction. 
■Of ANIMAL SUBSTANCES. 
Animal fubftances are diftinguilhed from vegetable, by 
■their texture, appearance, composition, See. Their moll 
remarkable differences are, i. The power of loco-motion 
in animals, 2. The irritability of all their organs. 3. 
Senfation arifing from the brain. 
Generic Characters. I. A frefh bone, in water, 
by. the aCtion of fire, in a retort, yields, 1. A heavy fetid 
oil, forming foap with alkalis. 2. Carbonic acid gas. 
3, Carbonated hydrogen gas, of an infupportably fetid 
odour. 4. A plentiful volatile oil. 5. A concrete fait, 
flicking to the fides of the retort, which is carbonat of 
ammoniac ; a plentiful refiduum, very difficult of Solu¬ 
tion, which is calcareous phofphat. 
II. AH animal fubftances pais to the putrid fermenta¬ 
tion : they yield ammoniac, nitric acid, a gas of a dan¬ 
gerous nature., very hurtful to miners, producing difor- 
ders in the (kin, and putrid fevers; from this decompo¬ 
sition arife jail-diftempers, &c. If the gas which is dif- 
engaged is loaded with fulphur, it is called Sulphurated 
hydrogen gas; if with carbon, it is carbonated hydrogen 
gas; if phofphorus, phofphorated hydrogen gas. 
III. Alkalisdiffolve all animal fubftances; they difen- 
gage ammoniac. With alkalis, an oil is obtained which 
did not exift before, but is formed during the operation. 
Chaptal availed himfelf of this property to fabricate foap 
from wool. He obferved during.this procefs, that heat 
dilengaged ammoniac formed by a part of the hydrogen 
and azot. The refidue, deprived of azot in the propor¬ 
tion of hydrogen, inclines to the oily ftate, which is only 
the combination of hydrogen with carbon. What palfes 
-i 
S T R Y. 
in this operation is the fame as the a£Hon of blue-Hone 
in a wound : ammoniac is formed and difengaged, and 
the efcar approaches to the oily ftate. 
IV. Sulphuric acid carbonifes animal fubftances, pre¬ 
cipitates the carbon, and alio Separates ammoniac from it. 
V. Nitric acid afts upon them in abrifk and rapid man¬ 
ner ; it difengages azot, and turns them yellow, after¬ 
wards red. For a refiduum, there is Pruffic acid, ammo¬ 
niac, two or three vegetable acids, and a fat oil formed 
from the animal fubftance. 
VI. Azot is another general and diftinguifhing charac¬ 
ter of animal fubftances. 
Animal matters confift of liquids and Solids, which 
make up their texture. Liquids circulate in the veflels 
interpoied in the texture of the folids. Liquids are dif- 
tinguilhed into recrementive, excrementive, and com¬ 
pound or recremento-excrementive. Recremenilve, as 
blood, Serving to the nouriftiment of animals, not part¬ 
ing through the body but through difeate. Excrement I've, 
that which Separates from the bodjq as urine. Recremeto- 
excrcment'mje, as bile, which is Separated from the blood 
to be mixed with it again ; and milk, which is excre¬ 
mentive to the mother, alimentary to the child. The 
conftituent parts of animals’are divided into liquids, foft 
parts, and lolids. 
Of BLOOD. 
We are toconfider blood as a liquid, circulating in the 
arteries and veins, by means of the heart, which is the 
prltnum mobile. 
Blood is redder in thofe animals which have capacious 
lungs, and infpire a great deal of air; it is blacker in 
thole which live in the water. The changes which the 
blood feerns to undergo in various diforders, mull be at¬ 
tributed to the lymphatic fyftem, or the abforbent nature 
of its veflels ; for the nature of the blood itfelf is not 
altered. Its tafte is infipid with a flight fmell of garlic; 
it thickens fome time after being excluded from the body. 
Its temperature is from 28 to 32 0 of Reaumur. It may 
be regarded under fix heads, x. According to the part 
it is taken from. z. The age of the fubjedt. 3. The fex. 
4. The temperament. 5. Different Hates of difeafe. 6. 
The different claffes of animals. 
The experiments on blood are generally made from 
that of oxen or of men, which agree in iome refpefts; 
that of birds and fifties is different. It may be con¬ 
fidered alfo, 1. In a mafs, as arterial blood. 2. Separated, 
as venous blood. 3. Both thefe mixed together. 4. Its 
elements. In blood we diftinguiffi, 1. The coagulum, or 
colouring part. 2. The ferum. 3. The fibrous part. If 
venous blood be left in the veffel in which it was re¬ 
ceived, a part of it Hicks like glue to the fides of the vef- 
fel. To afeertain the nature of blood, it is to be ex¬ 
amined, 1. By heat. 2. By acids. 3. By alkalis. 
The blood, while hot, and in motion, remains con- 
ftantly fluid and red; when it cools at reft it takes the 
form of a folid mafs, which gradually and fpontaneoufly 
feparates into two parts ; the one red, which floats above, 
whofe colour becomes deeper, and which remains con¬ 
crete till .it is altered by putrefadlion, is called the coa¬ 
gulum ; the other, which occupies the lower part of the 
veffel, is of a yellow greeniffi colour, and adhefive ; it is 
called ferum, or lymph. By continuing expofed to the 
air, it becomes purple at the furface, and of a darker co¬ 
lour below. Expofed in a very wide flat-bottomed vef¬ 
fel, it thickens, changes colour, and becomes concrete in 
dried leaves like hyacinth. Combined with air, it takes 
more room in thefe veflels, as may be proved by the air- 
pump. Drawn from a vein at 24°, it folidifies as at a 
lower temperature. 
Expofed to a gentle heat, it changes colour, coagu¬ 
lates, looks like liver, becomes carbonated, and dries, 
giving out a liquid with the fmell of amber; this water 
is formed in the drying. In a water-bath, at a tempera¬ 
ture 
