60 ANIMAL ACIDS CONTAINING AZOTE. 



this solution add as much sulphuric acid as will exactly neutra- 

 lize all the soda in the solution, digest for two days in a mode- 

 rate heat, agitating frequently. Then evaporate to dryness over 

 the water-bath, and digest the residue in alcohol. The choleic 

 acid is dissolved while sulphate of soda in crystals remains be- 

 hind. Finally, distil off the alcohol, substituting water, and 

 evaporating to dryness over the steam-bath. 



Choleic acid thus obtained possesses the following properties : 

 It is a yellow, spongy, pulverulent matter, which rapidly absorbs 

 moisture from the atmosphere. Its taste is very bitter, with an 

 impression of sweetness. Its powder irritates the nostrils and 

 throat. It is insoluble in ether; but very soluble in alcohol,, 

 and pretty soluble in water. 



It cannot be distilled without decomposition. When heated 

 it melts, swells up and burns with flame, giving out smoke and 

 leaving a bulky charcoal, which may be burned completely with- 

 out leaving any residue. It melts imperfectly at 248, and is 

 not decomposed till heated considerably above 400. 



Its solutions redden litmus-paper, and decompose the alka- 

 line and earthy carbonates with effervescence. But in this 

 way we can form only bicholeates. The choleic acid thus 

 combined with a base is precipitated by acetic acid; though 

 that acid does not act on bile. The acids throw down choleic 

 acid in flocks, which soon collect into a brown viscid fluid. Mu- 

 riatic, sulphuric, and phosphoric acids decompose it into choloidic 

 acid and taurin* Nitric acid decomposes it, deutoxide of azote 

 is evolved, and a peculiar white substance formed. The caus- 

 tic fixed alkalies decompose it into cholic acid and ammonia. 



M. Demar9ay analyzed it by oxide of copper and obtained, 

 Carbon, . 62-82 , 

 Hydrogen, . 8.91 

 Azote, 3.30 



Oxygen, . 24-97 



100- 



He analyzed choleate of soda, and obtained for the atomic 

 weight of choleic acid 50-213. The number of atoms which agree 

 best with the atomic weight and analysis are, 



* The choloidic acid was described in the last chapter. Taurin is a crystal- 

 line substance obtained from bile, which will be described in a subsequent chap- 

 ter. 



