400 THE LIVER. 



Taurocholeic Acid is a second taurocholic acid, detected by HAMMAR- 

 STEN in dog-bile and isolated by GULLBRING 1 from ox-bile, and has the 

 formula C 2 6H 45 NO 6 or C 2 7H 47 NS0 6 . Thus far it has been obtained 

 only in the amorphous form. It is readily soluble in water, and has a 

 disagreeably bitter taste. It is also readily soluble in alcohol, but insoluble 

 in ether, acetone, chloroform, and benzene. The alkali salt, soluble in 

 water, can be salted out by NaCl as a pasty mass. The solutions of the 

 salts can be precipitated by ferric chloride. The cleavage products are 

 taurine and choleic acid. 



The taurocholic acids are most simply prepared from bile, free from 

 glycocholic acid or poor therein, such as fish- or dog-bile, easiest from the 

 latter. The aqueous solution of the mucus-free bile is almost completely 

 precipitated by ferric chloride. The precipitate is worked for tauro- 

 choleic acid and the filtrate for taurocholic acid. The iron is first removed 

 from the filtrate by Na2COs, and then the faintly alkaline filtrate satur- 

 ated with NaCl. The taurocholate separates out and after further puri- 

 fication is decomposed by alcohol containing hydrochloric acid. The 

 taurocholic acid is precipitated from the alcoholic filtrate by ether and 

 recrystallized from alcohol containing water by the addition of ether. 

 The taurocholeic acid is obtained from the above iron precipitate by treat- 

 ing it with soda, and decomposing the alkali salt of the taurocholeic acid 

 with alcohol, containing HC1, and precipitating the acid from the alcoholic 

 solution with ether and repeating this precipitation from alcohol by ether. 



Cheno-taurocholic Acid. This is the most essential 'acid of goose-bile and has 

 the formula C 29 H 4P NSO 6 . This acid, but little studied, is amorphous and solu- 

 ble in water and alcohol. 



The taurocholic acids differ from the glycocholic acids in being 

 readily soluble in water. In the bile of the walrus, on the contrary, a 

 relatively insoluble, readily crystallizable taurocholic acid occurs which 

 can be precipitated from the solution of the alkali salts by the addition 

 of mineral acids, like glycocholic acid (HAMMARSTEN 2 ). 



As repeatedly mentioned above, the two bile-acids split on boiling 

 with acids or alkalies into non-nitrogenous cholic acids and glycocoll 

 or taurine. Of the various cholic acids the following have been best 

 studied : 



Cholic Acid or Cholalic Acid. The ordinary cholic acid obtained as a 

 decomposition product of human and ox bile, which occurs regularly in 

 the contents of the intestine, and also in the urine in icterus, has, accord- 

 ing to STRECKER and nearly all recent investigators, the constitution 



1 Hammarsten, Zeitschr. f. physiol. Chem., 43; Gullbring, ibid., 45. 



2 Not published. 



