120 CHOLIC ACIDS. 



more expressive of its nature. We therefore retain the denomina- 

 tion which Demarcay, its discoverer, applied to it. 



Combinations. The cholates possess a bitter and at the same 

 time a slightly sweet taste ; they are all soluble in alcohol, but 

 water dissolves only the alkaline cholates and cholate of baryta, 

 and, to a very slight extent, cholate of lime. Cholic acid, with the 

 aid of heat, expels the carbonic acid from solutions of the alkaline 

 carbonates. 



Cholate of potash, KO.C 48 H 39 O 9 is obtained in acicular crystals, 

 by the evaporation of the alcoholic solution, or by the addi- 

 tion of ether to it. By spontaneous evaporation of the aqueous 

 solution it forms a kind of varnish ; the salt is insoluble in an excess 

 of solution of potash, and on the addition of caustic potash is 

 precipitated in a gelatinous state. Cholate of soda and cholate 

 of ammonia are very similar to it ; the latter of these two salts loses 

 the greater part of its ammonia on mere evaporation. Cholate of 

 lime, when obtained by precipitation, is amorphous, but it crystal- 

 lises on the addition of ether. Cholate of silver is only very slightly 

 soluble in water ; it crystallises, however, from a boiling solution. 



Products of its metamorphosis. Choloidic acid, as it exists in its 

 salts, is perfectly isomeric with cholic acid ; it is formed as we have 

 already mentioned, by boiling cholic acid with stronger acids. It 

 may, however, be obtained by boiling together for some hours 

 hydrochloric acid and that portion of the alcoholic extract of bile 

 which is precipitable by ether ; by solution in alcohol and precipi- 

 tation by ether, it may be readily purified. It is a peculiarity of 

 choloidic acid that in its isolated state it contains no basic water, 

 and may therefore be prepared in an actually anhydrous state ; 

 it forms a white, amorphous, resinous, pulverisable mass which is in- 

 soluble in water, but dissolves freely in alcohol, and slightly in ether. 

 The addition of water or of ether to the alcoholic solution causes a 

 milky appearance, and finally precipitates the acid in a resinous 

 form ; the alcoholic solution reddens litmus. When warmed, cho- 

 loidic acid softens; at 150 it fuses, and at 295 it becomes con- 

 verted into dyslysin, with the loss of 3 atoms of water. With con- 

 centrated sulphuric acid and sugar it gives the same reaction as 

 cholic acid. When distilled with nitric acid, it yields not only the 

 same volatile acids as oleic acid when similarly treated, but addi- 

 tionally choloidanic, cholesteric, and nitrocholic acids, and chola- 

 crole (Redtenbacher.*) 



Its salts have a purely bitter taste, without any sweet after- 

 * Aim. d. Ch. u. Pharm. Bd. 57, 8. 145-170. 



