1823.] On newl^ discovered Animal Acids* 20^ 



Article X. 

 On newly discovered Animal Acids, By M. Chevreul.* 



M. Chevreul has described five new animal acids, to which he 

 has given the names of butiric acid, capric acid, caproic acid, 

 hircic acid, and phocenic acid. 



The butiric acid is the odorous principle to which soap, made 

 with the butter of cows' milk, and the butter itself, more particu- 

 larly owe their smell, but not entirely, for these bodies contain 

 the capric and caproic acid, which also impart some odour to 

 them. Butiric acid has, however, by much the strongest 

 odour, resembling, when concentrated, the smell of strong 

 butter and acetic acid ; but when the acid is dilute, it smells like 

 butter. The taste of this acid is at first hot, and afterwards 

 sweetish, reserabUng that of nitric and muriatic ether. The 

 butiric acid is colourless and fluid, and does not solidify at 15^ 

 of Fahr. and at 77° its specific gravity is 0*9675. In the state 

 of hydrate it requires a higher temperature to boil it than water, 

 and distils unchanged . It unites in all proportions with water, 

 and when diluted with half its bulk of water, its specific gravity 

 is greater than that of water. Alcohol combines with it in all 

 proportions. When mixed with hogs'-lard, the butiric acid 

 gives it the smell and taste of butter ; the lard soon loses its 

 smell by exposure to the air. In volume it is composed of 



Oxygen ♦ . , . 3 



Carbon , 8 



Hydrogen 11 



One hundred parts of this acid saturate 97*58 of barytes. An 

 atom of hydrogen = 1, and of barytes 78; the weight of the 

 atom of butiric acid must be nearly 80. 



If the analysis had yielded 12 instead of 11 volumes of 

 hydrogen, the composition of this acid would be 3 atoms of oxy- 

 gen = 24, 8 of carbon i= 48, and 6 of water = 6 ; the weight of 

 its atom would consequently be 78, instead of nearly 80, as 

 deduced from the composition of butirate of barytes. 



Butirate of lime resembles its base in being more soluble in 

 cold water than in hot ; the butirate of barytes crystallizes in 

 long prisms ; 100 parts of water dissolve 36 of this salt. 



Capric acid is obtained from the same sources as the butiric 

 acid, and resembles it in being colourless, but it has a smell like 

 that of a goat. In taste it is similar to that of the butiric acid. At 

 5° of Fahr. it exists in the form of small crystals ; in the state of 

 hydrate it requires a higher temperature to boil it than water 

 does ; it distils unaltered. The specific gravity of capric acid 

 at 65° of Fahr. is 0-910 ; 100 parts of water dissolve only 0-12 

 of it, but with alcohol, it combines in all proportions. 

 * From the Annales de Chimie et de Physique, torn, xxiii. p. 1 6. 



New Series, vol. vi. p 



