HANDBOOK FOR BIO-CHEMICAL LABORATORY. 25 



rapidly deliquesce in the air. It is readily soluble in water 

 and alcohol, yielding a solution with a bitter-sweetish taste. 

 Its salts are, as a rule, readily soluble in water, and the solu- 

 tions of the alkali salts are not precipitated by copper sulphate, 

 silver nitrate, or sugar of lead, but are precipitated, on the 

 contrary, by basic lead acetate. The aqueous solution of the 

 alkali salts foam like soap. On boiling with acids and alkalies 

 it splits into cholalic acid and taurin. Both aqueous and alco- 

 holic solutions of taurocholic acid are dextro-rotatory. Spe- 

 cific rotation of its alcoholic solution is (a) D = -{- 25. 



Cholalic Acid, C 34 H 40 6 . 



Preparation. 1. 500 c.c. bile are treated with 75 grms. 

 barium hydrate and the mixture boiled for 24 hours on the 

 sand-bath. The flask should be connected with a return con- 

 denser. Allow the liquid to cool, and filter. Add concen- 

 trated hydrochloric acid to the filtrate, which decomposes the 

 barium cholalate, depositing impure cholalic acid. These 

 crystals are separated from the mother-liquor and pressed, and 

 dissolved in a solution of caustic soda; the solution is then 

 mixed with 30 grms. animal charcoal and allowed to stand for 

 a few days. It is next filtered and the filtrate decomposed with 

 hydrochloric acid, filtered again and washed thoroughly and 

 the substance from the filter dissolved by the smallest possible 

 quantity of hot alcohol. The alcoholic solution is treated with 

 water until a slight turbidity appears. On the liquid being 

 cooled cholalic acid separates in the form of hard, transparent 

 tetrahedra or in clumps of radiating needles. For further 

 purification recrystallize from methyl alcohol. (Mylius.) 



2. Mix ox-bile with one fifth of its weight of a 30$ caustic- 

 soda solution and boil for 24 hours on water-bath, having the 

 flask connected with a return condenser. Now saturate the 

 liquid with C0 2 and evaporate to dryness. Extract the 

 residue with strong alcohol, which dissolves the sodium salts 



