CHOLOIDIC ACID. 13 



low, and is therefore an animal product ; yet its characters are 

 so similar to the acids belonging to the vegetable kingdom, that 

 it was thought requisite to place it among them, Accordingly 

 it has been described in the Chemistry of Vegetable Bodies (p. 31,) 

 to which work the reader is referred. It has been shown by 

 Dumas and Peligot that the atomic weight of this acid is 11.5, 

 and that its components are C 10 H 8 O 3 . 



SECTION VII. OF CHOLOIDIC ACID. 



This acid was discovered by M. Dema^ay in the year 1838.* 

 The process which he employed to obtain it was the following : 

 Dissolve ox bile in twelve or fifteen times its weight of water, and 

 boil it with an excess of muriatic acid for three or four hours, 

 and then let it cool. The choloidic acid will be found collected 

 at the bottom of the vessel in a solid mass. Decant off the liquid 

 portion, and melt the acid by heat three or four times successive- 

 ly in small quantities of distilled water. Finally, dissolve the 

 acid in alcohol, and agitate the solution with a little ether to dis- 

 solve out any cholesterin and margaric acid that it may contain. 

 After this treatment, if the solution be evaporated to dryness over 

 the water bath, there will remain choloidic acid nearly pure, but 

 still retaining a trace of common salt. 



Choloidic acid thus obtained is a solid fatty looking substance, 

 of a yellow colour, destitute of smell, and having a very bitter 

 taste. It does not melt till heated above 212. While solid, it 

 is brittle and easily reduced to powder. When heated in boil- 

 ing water, it melts into a brown, pasty magma. It is very 

 soluble in alcohol, even when weak, but little soluble in water, 

 and scarcely at all in ether. 



The solutions of this acid strongly redden litmus-paper, and 

 decompose the carbonates with effervescence. The choloidates 

 thus formed are little soluble in water, and even in alcohol ; but 

 they are neutral. Acids throw it down from these compounds 

 in yellow flocks, which unite when heated and liquefy. 



The choloidates of zinc, manganese, iron, lead, copper, and 

 silver are flocky precipitates, which, when cautiously heated, 

 become granular, and melt at about 176. They are all slightly 

 soluble in water. 



Demar9ay attempted to analyse the choloidates of lead, barytes, 



* Ann. de Chim. et de Phys. Ixvii. 198. 



