BILIN. 



II 



of the dry residue of ox bile on the addition of ether. The crystals are very 

 soluble in water and have the peculiar bitter sweetness of bile. The solution 

 is dextrorotatory. With concentrated sulphuric acid it becomes resinous and 

 yields after a time a yellow liquid having a green fluorescence. If, after 

 adding a trace of cane-sugar, a liquid containing bilin is mixed with sulphuric 

 acid and kept at a temperature between 50 C. and 600 C., a purplish violet 

 solution is obtained, which shows before the spectroscope an absorption band 

 at E and another near F. Solution of ox-bile crystals is precipitated by the 

 addition of neutral acetate of lead. The heavy precipitate consists of lead 

 glycocholate. By treating its solution in hot alcohol with sulphuretted 

 hydrogen, filtering and adding water to the filtrate, glycocholic acid (C K H 43 

 NO 6 ) is obtained as a resinous precipitate. Glycocholic acid is sparingly 

 soluble in water, readily in hot alcohol, from which it crystallizes. When it 

 is boiled with strong hydrochloric acid it is converted into a soluble com- 

 pound of hydrochloric acid and glycocoll, which is very soluble in water, and 

 a resinous product, often called bile-resin, consisting of cholalic acid and 

 dyslysin (see Cholalic Acid). When the liquid from which the lead glyco- 

 cholate has been precipitated is treated with basic lead acetate, with the 

 addition of ammonia, a second precipitate is obtained of lead taurocholate. 

 By suspending the lead precipitate of dogs' bile in alcohol, decomposing it 

 with H a S, filtering, concentrating the filtrate, taurocholic acid (C^ H 4 , 5 NO 7 S) 

 is obtained in solution. On the addition of ether a syrupy precipitate is 

 formed, which afterwards crystallizes. It differs from glycocholic acid in being 

 excessively soluble in water, and splitting much more readily into cholalic 

 acid and taurin, than glycocholic acid does into cholalic acid and glycocoll. 



Glycocoll, Glycin or Gelatin-sugar (C 2 H 5 NO a or (as Amido-acetic acid] C 2 

 H 3 (NH 2 ) O 2 ) is obtained from glycocholic acid by prolonged boiling with 

 strong hydrochloric acid. The firm resin which is formed consists of cholalic 

 acid and dyslysin (see Cholalic Acid); this having been separated, the 

 remaining liquid yields on evaporation glycocoll-hydrochlorate (C 2 H 5 NO 2 , H 

 Cl). From the aqueous solution of this substance glycocoll is obtained by 

 treating it with hydrate of lead oxide and then decomposing the soluble lead 

 glycocoll, after separating the chloride, with sulphuretted hydrogen. Glyco- 

 coll is soluble in five parts of cold water, and insoluble in absolute alcohol 

 and ether. It crystallizes from hot dilute alcohol in hard rhombohedral 

 crystals. Its solution in water has an acid reaction and sweetish taste. 

 It is called "gelatin-sugar" because, along with the body Leucin, it is a 

 product which is obtained when gelatin is acted on by sulphuric acid. Glyco- 

 coll has been obtained synthetically by the action of monochloracetic acid on 

 ammonia. (C 2 H 3 Cl O 2 + NH 3 = HC1 + C 2 H 3 (NH 8 ) O 2 .) 



Taurin (C 2 H 7 NSO 3 ) is best obtained from the bile of the dog, in which 

 the whole of the bilin consists of taurocholate. By boiling bilin with hydro- 

 chloric acid, separating the resin and evaporating the acid liquid, a residue 

 is obtained from which (after the glycocoll-hydrochlorate has been removed 

 by extracting it with absolute alcohol), taurin can be procured by treating it 

 with boiling water. Taurin is soluble in fifteen parts of cold, and very soluble 

 in hot water, sparingly in cold alcohol. It crystallizes very readily in large 

 4- or 6-sided shining prisms, each of which ends in a 4-sided pyramid. The 



