TAUROCHOLIC ACID. 399> 



The crystalline and washed mass is boiled with water, and on cooling 

 glycocholic acid crystallizes out, and then this is recrystallized from water 

 or from alcohol by the addition of water. The residue that remains after 

 boiling in water (paraglycocholic acid and glycocholeic acid) is converted 

 into their barium salts, and after a complicated method (see WAHLGREN) 

 the glycocholeic acid is obtained. The reader is referred to more exhaustive 

 works for other methods of preparation. 



Hyoglycocholic Acid, C^H^NOs, is the crystalline glycocholic acid obtained 

 from the bile of the pig. It is very insoluble in water. The alkali salts, whose 

 solutions have an intensely bitter taste, without any sweetish after-taste, are 

 precipitated by CaCl 2 , BaCl 2 , and MgCl 2 , and may be salted out like a soap by 

 Na 2 SO 4 when added in sufficient quantity. By precipitation with NaCl in such 

 quantity that the precipitate redissolves on warming, HAMMARSTEN l obtained 

 the alkali salt as macroscopic crystals on cooling. Besides this acid there occurs 

 in the bile of the pig still another glycocholic acid (JOLIN 2 ). 



The glycocholate in the bile of rodents is also precipitated by the above- 

 mentioned earthy salts, but cannot, like the corresponding salt in human or ox 

 bile, be directly precipitated on saturating with a neutral salt (Na 2 S0 4 ). Guano 

 bile-acid possibly belongs to the glycocholic-acid group, and is found in Peruvian 

 guano, but has not been thoroughly studied. 



Taurocholic Acid. This acid, which is found in the bile of man, car- 

 nivora, oxen, and a few other herbivora, such as sheep and goats, has the 

 constitution C 2 6H4 5 NSO7. On boiling with acids and alkalies it splits 

 into cholic acid and taurine. Taurocholic acid has also been prepared 

 synthetically by BONDI and MULLER, using the same method as they used 

 for glycocholic acid. 



Taurocholic acid can be readily obtained, by the method suggested 

 by HAMMARSTEN, 3 as groups of fine needles or as beautiful prisms on 

 slow crystallization. The crystals do not change in the air, but they 

 decompose above 100. They are soluble in alcohol but insoluble in 

 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. 



1 Not published. 



2 Zeitschr. f physiol. Chem., 12 and 13. 



3 Zeitschr. f. physiol. Chem., 43. 



