444 CHEMISTBY OF THE LEUC0MA1N8. 



tion which in the above appears to be replaced by the second mole- 

 cule of acid (Schwantke), It can be obtained from the monochlorid by 

 repeated treatment with concentrated hydrochloric acid (Kutscher). 

 On slow crystallization it forms large glassy plates, except when 

 the salt is derived from histon, in which case it crystallizes slowly 

 and with different form. Differences in solubility have also been 

 noted. It sinters at 225° and finally melts at 231°- 233° with 

 evolution of ammonia. The latter is also given off on prolonged 

 heating at 140°. 



The nitrate, C,HgN30j.2HN03, was obtained by Kossel' in crys- 

 talline form, although Hedin was unsuccessful in doing so with the 

 nitrate or sulphate. With platinum chlorid and silver nitrate crys- 

 tallizable double salts are obtainable. A rather uncertain double 

 salt of barium chlorid has been reported (impure dichlorid ?). 



Mercuric chlorid precipitates the alkaline carbonate solution of 

 histidin and this fact was utilized at one time by Kossel ^ as a means 

 of separation from arginiu. 



Silver nitrate when added to an aqueous solution of the base pro- 

 duces no precipitate, but on addition of ammonia a voluminous pre- 

 cipitate forms which is easily soluble in excess (Hedin).' Its 

 formula is CjHyAg^NjOj + H^O. Instead of ammonia Kossel em- 

 ploys baryta, which on careful addition throws down the histidin 

 compound first and, subsequently in strong excess, precipitates the 

 arginin compound. These two bases can thus be easily separated 

 (see p. 427). 



Lysin, CgHj^N^O^. — The relation of this base to leucin, CjHjjNO^, 

 from which it differs by an NHj group led Drechsel * to regard it as 

 a di-amido caproic acid. He attempted, though unsuccessfully, the 

 conversion of lysin into cadaverin and even pointed out its possible 

 transformation into pyridin. Inasmuch as lysin appeared to be a 

 homologue of ornithin, CjHjjNjO^, EUinger* reasoned that, like the 

 latter, it should yield on putrefaction the diamin cadaverin, the 

 homologue of putrescin. Experiments with lysin derived from 

 casein and from auto-digested pancreas gave the expected cadaverin 

 and at the same time established the constitution of the former. 

 Lysin, therefore, is a — e di-amido caproic acid and is the next 

 homologue of ornithin. The cleavage into cadaverin can be repre- 

 sented by an equation similar to that for ornithin (p. 438). 



NHrCH,.Ca,.CH,.CHj.CH{NHj).COOH = NH,.CH,.CH,.CHj.CHj.CH,.NH, + CO,. 



Lysin. Cadavbbin. 



^ZeUs. phygiol. Ohem., 22, 195 ; 28, 383, 391. 



'Zeits. phyml. Chem., 22, 182 ; 31, 171. 



' ZeUs. phygiol. Chem., 22, 192; 31, 171 ; 25, 171 ; 28, 460. 



'eeriehU. 25, 2456, 3504. 



^ZeiU. ■phygiol. Chem., 29, 334, 1900. 



