270 M. Chevreul on Fatty Bodies, and [Oct. 



goose is twiee as much so. The dairies of man, of the sheep, 

 the ox, the jaguar, and the hog, have a specific gravity of about 

 •915 ; that of the goose of about - 929. The elaines of the sheep, 

 the ox, and the hog, have the- same solubility in alcohol ; the 

 elai'ne of the goose is a little more soluble. On the other hand, 

 the margaric acids of man, of the hog, of the jaguar, and of the 

 goose, cannot be distinguished from each other ; those of the 

 sheep and the ox differ a few degrees in their melting point, and 

 a little also in their form. As for the slight differences which the 

 oleic acids present, they are not sufficiently precise for us to be 

 able to particularize them. 



M. Chevreul' s Seventh Memoir* 



This memoir consists of three parts ; the first of which is on 

 spermaceti, or as M. Chevreid technically calls it, "cetine. In 

 the fifth memoir, in which we have an account of many of the 

 properties of this substance, it was stated that it is not easily 

 saponified by potash, but that it is converted by this re-agent 

 into a substance which is soluble in water, but has not the sac- 

 charine flavour of the sweet principle of oils ; into an acid 

 analogous to the margaric, to which the name of cetic was 

 applied ; and into another acid, which was conceived to be ana- 

 logous to the oleic. Since he wrote the fifth memoir, the author 

 has made the following observations on this subject: 1. That 

 the portion of the soap of cetine which is insoluble in water, or 

 the cetate of potash, is in part gelatinous, and in part pearly ; 

 2. That two kinds of crystals were produced from the cetate of 

 potash which had been dissolved in alcohol ; 3. That the cetate 

 of potash exposed, under a bell glass, to the heat of a stove, 

 produced a sublimate of a fatty matter which was not acid. From 

 this circumstance M. Chevreul was led to suspect that the 

 supposed cetic acid might be a combination or a mixture of 

 margaric acid and of a fatty body which was not acid ; he accord- 

 ingly treated a small quantity of it with barytic water, and boiled 

 the soap which was formed in alcohol ; the greatest part of it 

 was not dissolved, and the alcoholic solution, when cooled, 

 filtered, and distilled, produced a residuum of fatty matter which 

 was not acid. The suspicion being thus confirmed, M. Chevreul 

 determined to subject cetine to a new train of.experiments, which 

 are now to be related. Being treated with boiling alcohol, in 

 the same manner with hog's-lard, as mentioned in the third 

 memoir, a cetine was procured which was fusible at 120°, and a 

 yellow fatty matter which began to become solid at 89 - 5°, and 

 which at 73-5° contained a fluid oil, which was separated by 

 filtration. 



Cetine in this state, fusible at 120°, was more sonorous, more 

 brilliant, and less unctuous than the spermaceti of the shops ; it 



* Abstracted from Ann. de Chira. et Pbys. ?ii. 155. (Feb. 1818.) 



