1820.] Royal Academy of Sciences. 381 



M. Chevreul has made new and important additions to his 

 researches upon fatty bodies, with which we have ah'eady several 

 times entertained our readers. Having found that the matter of 

 bihary calcuh, which he calls cholesterine, does not form a soap 

 with the alkalies — a circumstance which distinguishes it com- 

 pletely from fats ; he thought he had also found, that spermaceti, 

 to which he gave the name of ckiiie, was reduced by the action 

 of alkalies into an acid analogous to one of those two acids that 

 the alkalies produced from fats ; namely, into that which he 

 called inargaric acid, but that the acid of spermaceti had a much 

 smaller capacity of saturation. He, therefore, judged it necessary 

 to give this acid a peculiar name, and called it cetic acid. A 

 continuation of these experiments has, however, convinced him 

 that this acid is in fact only margaric acid, whose properties 

 have been altered by some remains of a fatty matter not of an 

 acid nature. But dolphin oil, when treated by M. Chevreul's 

 method ; that is to say, converted into soap by means of the 

 alkalies, afforded, besides the two acids yielded by fatty sub- 

 stances, a third sort of acid, which he calls the delphinic, but 

 which is not yielded by common fish-oil. 



It must be noticed that oxygen is not found to be contained in 

 these new ternary acids prepared from fats, and that they are, 

 in respect to the common vegetable acids, the acetic acid, 

 the oxalic, &;c. the same as in the mineral kingdom, the 

 hydro-acids of Sir H. Davy are, in respect to the old and well- 

 known mineral acids, the nitric acid, the sulphuric, 8cc. 



Cochineal, that singular insect, which, on account of the 

 colouring matter that it yields, is become such an important 

 article in commerce, not having been studied as yet by 

 chemists with that attention which it deserved, JMM. Pelletier 

 and Caventou have made it the object of their experiments. 

 They have fouiid that the very remarkable colouring matter 

 which composes the principal part of it, is mixed with a peculiar 

 animal matter, a fat like common fat, and with different sorts of 

 salts. The fat having been separated by ether, and the residuum 

 treated with boiling alcohol, they either allowed the alcohol to 

 cool, or gently evaporated it, and by this means they obtained 

 the colouring matter, but still mixed with a little fat and animal 

 matter ; these were separated from it by again dissolving it in 

 cold alcohol, which left the animal matter untouched, and by 

 mixing the solution Vvith ether, and thus precipitating the colour- 

 ing matter in a state of great purity. It is well known that this 

 colouring matter is of a most beautiful red colour, and the 

 cliemists of whom we are speaking, give it the name of car- 

 mine (carminium). It melts at 5U° (122*^ Fahr.) becomes puffy, 

 and is decomposed, but does not yield ammonia. It is very 

 soluble in water, slightly in alcohol, and not at all in ether, unless 

 by the intermediation of fat. Acids change it from crimson, 



