TAURIN, CHOLIC ACID, FELLINIC ACID. 104/ 



alcohol, and falls again, after evaporation and cooling, as a 

 white earthy mass. It has not been further investigated. 



Taurin, C 4 H 7 NO 10 , discovered by Demaryay, is a neutral 

 substance which crystallizes in colourless regular six-sided 

 prisms terminated by four or six-sided pyramids, of a weak taste ; 

 and is fusible by heat without decomposition. It is soluble in 

 fifteen and a half times its weight of water at 536 (12 centig.); 

 insoluble in absolute alcohol. It is dissolved without decom- 

 position by concentrated sulphuric and nitric acids, and gives no 

 reactions with the ordinary reagents. 



Taurin may be derived directly from unprepared bile, when 

 the latter, after precipitation of its mucus by hydrochloric acid, 

 is boiled for a long time with an excess of the same acid ; the 

 liquid is poured off from the precipitated resinous acids, con- 

 centrated by evaporation, mixed with alcohol and set aside. 

 The taurin crystallizes out mixed with common salt; the 

 former is purified by solution in boiling water and crystalliza- 

 tion. Taurin is the only one of these products that has been 

 analysed. 



Cholic acid may be prepared directly from bile, by precipi- 

 tating the latter with acetate of lead, boiling the filtered solution 

 with caustic potash, so long as ammonia escapes, and then 

 adding acetic acid. The cholic acid separates in large white 

 flocks, which soon assume a crystalline appearance. 



Cholic acid crystallizes in fine needles, which when pressed 

 together form a mass of a silky lustre, of which the taste is at 

 once sharp and sweet ; it is fused by heat, and burns like a fat. 

 It is sparingly soluble in water, highly soluble in alcohol. It 

 forms salts, with alkalies, of a sweet taste. 



Fellinic acid is contained, with bilin and cholinic acid, in the 

 plaster-like lead compound formed in the preparation of bilin, 

 and in the alcoholic solution of the resinous mass produced by 

 the treatment of bilin by hydrochloric acid. Its separation from 

 cholinic acid is effected by saturating the last mentioned alco- 

 holic solution with dilute ammonia and concentrating by eva- 

 poration : the cholinate of ammonia is then deposited as a hard 

 mass, while the fellinate of ammonia remains dissolved. The 

 addition of hydrochloric acid throws down the fellinic acid in 

 white flocks. 



