1818.] their Combinations with Alkalies. 195 



with lime it combines in the proportion of 100 parts to 9-64 ; 

 with magnesia, 7-52 ; with oxide of zinc, 14-83 ; with peroxide 

 of copper, 13-93 ; the soap of copper was of a green colour; as 

 was also the case with the soap composed of the black peroxide 

 of copper and margarine. Soaps were also formed of the fluid 

 fat with the oxide of cobalt, which was of a bluish green 

 colour; with the oxide of nickel, of a yellowish green; and with 

 oxide of chrome, which was of a violet colour : in these last 

 cases the exact proportions in which the substances combine 

 were not ascertained. The above experiments establish in a 

 decided manner the strong analogy which exists between mar- 

 garine and the fluid fat and acids ; they have, like these bodies, 

 determined capacities for saturation, while their combinations 

 with salifiable bases may be regarded as forming a distinct class 

 of salts. The art of making soap consists, therefore, in convert- 

 ing fatty bodies into oily acids by means of alkalies ; and in 

 forming these acids into compounds subjected to definite pro- 

 portions. 



M. ChevreuPs Fifth Memoir* 



The subject of this memoir is adipocire ; by which is meant 

 the crystallized substance that enters into the composition of 

 human, biliary calculi, spermaceti, and the peculiar matter 

 obtained from dead bodies. The term adipocire was introduced 

 by Fourcroy, and was applied by him to the three substances 

 mentioned above, which he conceived to be varieties only of the 

 same primary compound ; and in the latter case, as obtained 

 from the muscular parts of animals that had experienced a pecu- 

 liar change in the earth to be converted into the state of a soap 

 by the addition of ammonia. These opinions of Fourcroy, 

 however, M. Cherreul supposes to be erroneous. He begins by 

 examining the crystallized matter of human, biliary calculi ; the 

 properties of this substance are described ; it melts at about 

 278°, and crystallizes by cooling into radiated plates ; it 

 appeared to be only partially decomposed by distillation ; it is 

 readily dissolved by boiling alcohol, but it seemed to be inca- 

 pable of forming a soap with potash. 



The properties of spermaceti are next examined ; it melts 

 at about 112° ; it is not much altered by distillation ; it dissolves 

 readily in alcohol, but separates as the fluid cools ; the solution 

 haa no effect in changing the colour of the tincture of litmus, a 

 circumstance, as it is observed, in which it differs from marga- 

 rine, a substance which, in many respects, it resembles. Sperm- 

 aceti is capable of being saponified by potash, with nearly the 

 I niie phenomena as when we submit hog's-lard to the action of 

 potash, although the operation is effected with more difficulty, 



* Abstracted from Ann. de Cbim. xcv. 1, 



n2 



