154 THE DIGESTIVE FLUIDS. 



dilute alkalies. Its separation, indeed, necessitates the complete 

 destruction of the taurin, viz., the albuminous material, by boiling 

 with a Concentrated solution of sodium hydrate or by fusing with 

 potassium hydrate and potassium nitrate. Potassium sulphite, acetic 

 acid, ammonia, and hydrogen thus result in the first case, while in the 

 latter sulphates, carbon dioxide, ammonia, and water are obtained. 

 Taurin can be formed synthetically by heating ammonium-ox v- 

 ethyl-sulphonate to a temperature of 230 C., or from ammonia and 

 chlor-ethyl-sulphonic acid, as represented by the equations : 



/C 2 H 4 C1 



NH 3 + S0 2 < = S0 2 + HC1 



X)H 



Chlor-ethyl-sul- Taurin. 



phonic acid. 



X C 2 H 4 .OH /C 2 H 4 .NH 2 



SO/ = SO/ + H 2 



^O.NH, \)H 



Ammonium oxy- Taurin. 



ethyl-sulphonic 

 acid. 



It can hence be regarded as amido-ethyl-sulphonic acid (viz., 

 amido-isethionic acid). It crystallizes in the form of four- or six- 

 sided prisms, and is fairly soluble in hot water, slightly soluble in 

 common alcohol, and insoluble in absolute alcohol and ether. It 

 has a markedly acid character, and accordingly does not combine 

 with acids, but with alkalies, to form salts. Its compound with 

 mercuric oxide is quite insoluble. 



Whether or not a relation exists between taurin and cystin is as 

 yet unknown. The latter has thus far only been observed under 

 conditions which must be regarded as abnormal, and it would be 

 interesting to ascertain whether in such cases the formation of taurin 

 is possibly diminished or even suspended. 



Isolation of Taurin. Taurin is most conveniently prepared from 

 the bile of animals in which taurocholic acid is present. To this 

 end, the fluid is boiled for several hours with hydrochloric acid. 

 The dyslysin and choloidinic acid are filtered off. The filtrate is 

 concentrated on a water-bath to a small volume, and freed from the 

 sodium chloride and other substances that have separated out, by 

 filtering while still warm. The liquid is then evaporated to dryness 

 and the residue extracted with strong alcohol, which dissolves any 

 glycocoll hydrochlorate that may be present, while the taurin re- 

 mains behind. This is then dissolved with a little warm water, fil- 

 tered while still warm, and treated with an excess of warm alcohol. 

 The resulting precipitate is immediately filtered off. In the filtrate 

 the taurin crystallizes out on cooling, and can be identified by the form 

 of its crystals, their solubility in water and insolubility in alcohol, 

 and the formation of potassium sulphate when fused with potassium 

 hydrate and potassium nitrate. 



Should glycocholic acid be present in the bile at the same time, 

 this is likewise decomposed on boiling with hydrochloric acid. The 



