TAURINE. 151 



origin from proteins has been shown by FRIEDMANN by the close rela- 

 tion that taurine bears to cysteine; and this is the reason why it is 

 treated here in connection with the amino-acids. 



Taurine is especially known as a cleavage product of taurocholic 

 acid, and may occur to a slight extent in the intestinal contents. Taurine 

 has also been found in the lungs and kidneys of oxen and in the blood 

 and muscles of cold-blooded animals. 



- Taurine crystallizes in colorless, often in large, shining, 4- or 6-sided 

 prisms. It dissolves in 15-16 parts of water at ordinary temperatures, 

 but rather more easily in warm water. It is insoluble in absolute alcohol 

 and ether; in cold alcohol it dissolves slightly, but better when warm. 

 Taurine yields acetic and sulphurous acids, but no alkali sulphides, 

 on boiling with strong caustic alkali. The content of sulphur can be 

 determined as sulphuric acid after fusing with saltpeter and soda. 

 Taurine combines with metallic oxides. The combination with mercuric 

 oxide is white, insoluble, and is formed when a solution of taurine is boiled 

 with freshly precipitated mercuric oxide (J. LANG J ). This compound 

 may be used in detecting the presence of taurine. Taurine is not pre- 

 cipitated by metallic salts. 



The preparation of taurine from ox-bile is very simple. The bile 

 is boiled a few hours with hydrochloric acid. The nitrate from the 

 dyslysin and choloidic acid is concentrated well on the water-bath, and 

 filtered hot so as to remove the common salt and other substances which 

 have separated. The solution is evaporated to dryness and the residue 

 dissolved in 5 per cent hydrochloric acid, and precipitated with 10 vols. 

 95 per cent alcohol. The crystals are readily purified by recrystalliza- 

 tion from water. 



The acid alcoholic solution can be used for the preparation of glycocoll. After 

 the evaporation of the alcohol, the residue is dissolved in water, treated with a 

 solution of lead hydroxide, filtered, the lead removed by H 2 S, and the filtrate 

 strongly concentrated. The crystals which separate are dissolved and decolor- 

 ized by animal charcoal and the solution then evaporated to crystallization. 



Though taurine shows no positive reactions, it is chiefly identified 

 by its crystalline form, by its solubility in water and insolubility in 

 alcohol, by its combination with mercuric oxide, by its non-precipitability 

 by metallic salts, and above all by its sulphur content. 



Z-Phenylalanine (phenyl-a-aminopropionic acid), 



C 6 H 5 

 CH 2 . 



COOH 



See Maly's Jahresber, 6. 



