422 THE LIVER. 



ether, benzene, and acetone. Taurocholic acid is very soluble in water, 

 and the solution has a very sweet taste, with only a slight bitter taste. 

 It can hold the difficultly soluble glycocholic acid in solution. This is 

 the reason why a mixture of glycocholate with a sufficient quantity of 

 taurocholate, which often occurs in ox-bile, is not precipitated by a dilute 

 acid. Its salts are, as a rule, readily soluble in water, and the solutions 

 of the alkali salts are not precipitated by copper sulphate, silver nitrate 

 or lead acetate. Basic lead acetate gives, on the contrary, a precipitate 

 which is soluble in boiling alcohol. The alkali salts are not only pre- 

 cipitated from their solution by the same neutral salts that precipitate 

 glycocholic acid, but also by potassium chloride, and by sodium and 

 potassium acetates. 



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

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

 formula C26H45NS0 6 or C27H4?NSO6. 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 Na2CO3, and then the faintly alkaline filtrate satu- 

 rated with NaCl. The taurocholate separates out and after further 

 purification 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 CHN8Oe. 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 



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



