756 UREA AND ITS ALLIES. [AFP. 



that formed with barium. For preparation and other particulars see 

 Liebig 1 and Schultzen and Schmiedeberg 2 . 



Glycin. C 2 H 2 (NH a ) (OH). Also called Glycocoll and Glycocine. 



Does not occur in a free state in the human body, but enters into 

 the composition of many important substances, ex. gr. hippuric and bile 

 acids. It crystallises in large, colourless, hard rhombohedra, which are 

 easily soluble in water, insoluble in cold, slightly soluble in hot alcohol, 

 insoluble in aether. It possesses an acid reaction, but a sweet taste. It 

 has also the property of uniting with both acids and bases, to form 

 crystallisable compounds. In this it exhibits its amide nature, and that 

 it is an amide is rendered evident from the methods of its synthetic 

 preparation; thus mono-chlor-acetic acid and ammonia give glycin and 

 ammonic chloride : C a H,Cl O 2 + 2NH 3 = C 2 H 2 (NH 2 )0(OH) + NH 4 CL It 

 is amido-acetic acid. Heated with caustic baryta it yields ammonia 

 and methylamine. 



Preparation. From glutin by the action of acids or alkalis; from 

 hippuric acid by decomposing it with hydrochloric acid at a boiling 

 temperature and removing by precipitation the simultaneously formed 

 benzoic acid. 



Taurin. C 2 H 7 NO.S. 



In addition to entering into the composition, of taurocholic acid (see 

 p. 763) taurin is found in traces in the juices of muscle and in the lungs. 



It crystallises in colourless, regular, six-sided prisms; these are 

 readily soluble in water, less so in alcohol. The solutions are neutral. 

 It is a very stable compound, resisting temperatures of less than 240 0; 

 it is not acted on by dilute alkalis and acids, even when boiled with 

 them. It is not precipitated by metallic salts. 



Taurin is amido-isethionic aoid; and may be synthetically prepared 

 from isethionic (ethyl- sulphuric) acid by the action of ammonia; thus: 



S0 4 + NH 3 S0 3 * HA 



Preparation. As a product of the decomposition of bile, and is 

 purified by removing any traces of bile acids by means of lead acetate, 

 and then successively crystallising from water. 



Leucin. C 6 H 13 N0 2 . 



Is one of the principal products of the decomposition of nitrogenous 

 matter, either under the influence of putrefaction or of strong acids and 

 alkalis. It occurs however normally in the pancreas, spleen, 



1 Op. cit. 2 Ann. d. Cherr.. u. Pharm. Bd. 164, S. 155. 



