THE BILE. 169 



Taurin can be formed synthetically by heating ammonium-oxy- 

 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 /C 2 H 4 .NH 2 



NH 3 -f S0 2 < = SO 2 < + HC1 



X)H \)H 



Chlor-ethyl-sul- Taurin. 



phonic acid. 



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



S0 2 < = S0 2 < -f H 2 



\O.NH. X OH 



).NH 4 



Ammonium oxy- Taurin. 



ethyl-sulphonic 



It can hence be regarded as am ino-ethyl-sul phonic acid (viz., 

 amino-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. 



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 

 hydrochlorate of glycocoll which thus results is found in the first 

 alcoholic extract. To isolate the glycocoll as such, the solution is 

 evaporated to dryness, the residue dissolved in water and treated 

 with plumbic hydrate. On filtering, the solution, which contains 

 the lead salt of glycocoll, is decomposed with hydrogen sulphide. 

 The resulting lead sulphide is filtered off, and the filtrate concen- 

 trated until crystallization occurs. The crystals are then dissolved 

 in water and decolorized with animal charcoal, and the solution is 

 evaporated until the crystals again separate out. 



Glycocoll. As has been shown before, glycocoll is a decomposi- 

 tion-product of most albumins, but is obtained in especially large 



