OX FAT. 135 



nature of which has not yet been examined, but Chevreul consi- 

 ders it as analogous to caproic acid. 



Hog's lard, like all the other varieties of fat, has been shown 

 by Chevreul to consist of two distinct oily bodies ; the one solid 

 at the ordinary temperature of the atmosphere, and the other li- 

 quid at the same temperature. The first on that account has 

 been called stearin ; the second elain. Braconnot showed that 

 if hog's lard be subjected to pressure between folds of blotting- 

 paper, the elain is absorbed by the paper while the stearin re- 

 mains. According to his experiments, hog's lard is composed of 



Elain, . 62 



Stearin, . 38 



100 



The elain has a specific gravity of 0'915. 100 parts of abso- 

 lute alcohol dissolve 123 parts of it. 



The stearin is without smell, translucent, dry, and granular. 

 It melts when heated to 109^. On congealing, it assumes an 

 imperfectly crystallized texture. 



It has been shown that stearin is a compound analogous to a salt, 

 consisting of stearic add combined with glycerin. In like man- 

 ner, elain is a compound of oleic acid and glycerin. If we di- 

 gest lard with caustic potash ley, the acids gradually combine 

 with the potash, and constitute with it a soap while the glycerin 

 is disengaged. In this way it has been ascertained that pure 

 lard is composed of 



Stearic and oleic acids, 94'65 

 Glycerin, . 9 



When hog's lard is digested with nitric acid it is converted 

 into oleic and margaric acids.* 



2. ox FAT. 



The fat of oxen has a yellowish-white colour, and a slight but 

 peculiar smell. It melts when heated to 100. Boiling alcohol 

 of 0'82,1 specific gravity dissolves about the fortieth part of its 

 weight of this fat. 



Like hog's lard it is a mixture of stearin and elain. But, as it 

 is much firmer and harder than lard, we might infer that the 

 proportion of stearin which it contains is much greater than in 



* Bussy and Lecanu, Jour, de Phartn. xii. 605. 



