THE LIVER. 147 



alkalies this acid, which is analogous to hippuric acid, is converted 

 into cholalic acid and glycocoll. 



Glycocholic acid crystallizes in fine, colorless needles or prisms. 

 It is soluble with difficulty in water (in about 300 parts cold and 

 120 parts boiling water), and is easily precipitated from its alkali- 

 salt solution by the addition of dilute mineral acids. It is readily 

 soluble in strong alcohol, but with great difficulty in ether. The 

 solutions have a bitter but at the same time sweetish taste. The 

 salts of the alkalies and alkaline earths are soluble in alcohol and 

 water. The salts of the heavy metals are mostly insoluble or soluble 

 with difficulty in water. The solution of the alkali salts in water 

 is precipitated by sugar of lead, copper-oxide and ferric salts, and 

 silver nitrate. 



The preparation of pure glycocholic acid may be performed in 

 several ways. We may precipitate the bile, which has been freed 

 from mucus by means of alcohol and the alcohol removed by 

 evaporation, by a solution of lead acetate. The precipitate is then 

 decomposed by a soda solution and heat, evaporated to dryness, and 

 the residue extracted with alcohol, which dissolves the alkali 

 glycocholate. The alcohol is distilled from the filtered solution and 

 the residue dissolved in water; this solution is now decolorized by 

 animal charcoal, and the glycocholic acid precipitated from the 

 solution by the addition of a dilute mineral acid. The acid may 

 be obtained in crystals either from boiling water, on cooling, or 

 from strong alcohol by the addition of ether. The reader is re- 

 ferred to more exhaustive works for other methods of preparation. 



Hyo-glycocholic Acid, CaTl^sNOs, 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 intense bitter taste without any sweetish after-taste, 

 are precipitated by CaCl 2 , BaCl a , and MgCl 3 , and may be salted out like a 

 soap by Na 2 SO 4 when added in sufficient quantity. Besides this acid there 

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



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

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

 bile, be precipitated on saturating with a neutral salt (Na 3 SO 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, 

 carnivora, oxen and a few other herbivora, such as sheep and goats, 

 and which is identical with the choleic of STRECKEB and DEMARCAY, 

 has the constitution C^H^NSOy. On boiling with acids and alka- 

 lies it splits into cholalic acid and taurin. 



