24 HANDBOOK FOR BIO-CHEMICAL LABORATORY. 



the smallest possible quantity of boiling water, which deposits, 

 on cooling, crystals in a colorless and pure state. (Hilfner.) 

 Properties. Glycocholic acid crystallizes in fine, colorless 

 needles or prisms. It is soluble with difficulty in water 

 (about 300 parts cold and 120 parts boiling water). Readily 

 soluble in strong alcohol, but with greater difficulty in ether. 

 The solutions have a bitter taste, but at the same time a 

 sweetish taste. The salts of the alkalies and alkaline earths 

 are soluble in alcohol and water, while the glycocholates of the 

 heavy metals are either insoluble or only sparingly soluble in 

 water. It is a monobasic acid. The solution of the alkali- 

 salts in water is precipitated by lead acetate, copper, ferric 

 salts, and silver nitrate. On boiling with acids or alkalies 

 it splits into cholalic acid and glycocoll. Glycocholic acid 

 or its salts are dextro-rotatory. Specific rotation of the acid 

 dissolved in alcohol is (a) D = -|- 29. 



Taurocholic Acid, C 96 H 46 NSO,. 



Preparation. Agitate dog's bile with animal charcoal and 

 alcohol, allow to settle, decant through filter. The clear 

 filtrate is evaporated to dryness and dissolved in a little hot 

 absolute alcohol and precipitated by the addition of ether. 

 This crystalline precipitate of sodium taurocholate is filtered, 

 dissolved in water, and precipitated by lead acetate and am- 

 monia, filtered, washed well, and then boiled with absolute 

 alcohol, filtered while hot, and the filtrate decomposed with 

 H 2 S until no further precipitation of PbS. occurs. This is 

 filtered, the filtrate concentrated by evaporation at a gentle 

 heat and then precipitated by an excess of water-free ether. 

 The precipitate consists of taurocholic acid which after a 

 time becomes converted into needle-shaped crystals possess- 

 ing a silky lustre. If the precipitate refuses to crystallize, 

 after a time add a drop or two of alcohol. (Parlce.) 



Properties. Taurocholic acid crystallizes in needles which 



