Memoir upon Animal Fat. 73 
and ‘changes from a white to a yellow colour, without, 
however, acquiring any acidity. When the contact with 
the air is added to the solar rays, the same phanomena take 
place, and it always becomes acid. 
~ Caloric.—Fat melts at 32°34 of Reaumur (90:21 Fabr.). 
At this temperature it remains in fusion without undergoing 
decomposition ; but when the temperature is pushed be- 
yond 80° (174° Fahr.) it begins to be decomposed. 
The author did not think necessary to describe the distil- 
lation of hog’s lard: this operation has been already per- 
formed, and its products examined, by Messrs. Von Crell, 
Guyton and Thenard ; he only observes that fat, when well 
washed, does not yield ammonia upon distillation, while that 
which has not been washed yields very sensible traces of it. 
The water in which muscular substances have been washed, 
the cellular tissue of which is not exactly separated, takes 
away from it a notable quantity of gelatinous animal matter 
which accompanies the membranes ; it is this animal gela- 
tinous matter which produces the ammonia in distillation. 
Sulphur.—Fat mixed with half its weight of sulphur 
sublimed and washed, forms what is vulgarly called sulphur 
pomatum. 
This compound was examined four days after its prepara- 
tion, as well as a similar mixture a little older, and no traces 
whatever of sulphuric acid were discovered. By a slow 
fusion in B. M. we separated, by decantation, a quantity of 
fat ; and on passing the rest through fine linen, we obtained 
“e greatest part of the fat employed: it had a gray colour, 
a bitter, sharp, and very strong taste ; it congealed much 
more quickly than common fat when cooled, and it black- 
ened silver vessels. 
Thus there is sulphur dissolved in this compound ; it will 
even be found in solution, every time it is employed in fric- 
tion. The elevation of the temperature facilitates this solu- ' 
tion. 
We know how rapidiy sulphur penetrates through places 
far remote from the spot where it was made use of in the 
shape of pomatum: this is not so surprising when we res 
flect that the sulphur is in solution. I am ignorant, says 
‘ i M. Vogel, 
