Memoir upon Animal Fat. 77 
above its level 5 the gas which remained in the cylinder did 
not inflame in the air, but took fire immediately on the ap- 
proach of a lighted candle. 
' The gas was thus entirely decomposed, and the whole 
quantity of phosphorus was decomposed. I attribute the 
cause of this absorption not only to the loss.of phosphorus, 
which, without doubt, had diminished the volume of the 
gas, but also to its temperature ; since it was recently libe-~ 
rated, and had passed through the hot fat, which would con- 
sequently dilate its volume a little. 
The fat which remained had all the characters of phos- 
phorated fat ; it soon became acid in the air. 
The Acids.—As the sulphuric and muriatic acids are not 
very interesting, the latter having even no action at all upon 
fat, I directed my attention chiefly.to the phenomena pre- 
sented by the nitric acid. 
This .acid has become a valuable agent in the hands of 
the chemists. To the action of this acid upon organized 
bodies we are indebted for a great number of discoveries. 
It is well known how much facts have multiplied since 
we have been able to explain the changes which take place 
upon animal and vegetable compounds. 
. Berthollet has in some measure paved the way by his im- 
portant labours upon animal substances; and the experi- 
ments of Messrs. Fourcroy and Vauquelin have left us no- 
thing more to desire on that subject. These gentlemen 
have considerably enlarged the sphere of our knowledge in 
this department, so difficult of comprehension, and so use- 
ful in the science of medicine. 
M. Fourcroy was the first who ascertained the action of 
the nitric acid upon fat. M. Alyon and several other che- 
mists have since presented interesting results on the subject. 
I treated fat in the manner prescribed by Messrs. Four- 
eroy and Alyon for making the oxygenated pomatum. The 
Jatter observes, that it does not stand in need of washing, 
as it is not acid: I repeated the process prescribed by him 
with one ounce of acid at 32° to the pound of fat; I em- 
ployed afterwards nitric acid of an inferior strength, from 
80° down to 24°; the oxygenated fat was always acid. 
I made 
