376 CHEMISTBY OF THE LEUCOMAINS. 



tions of the salt as an oil which on cooling becomes crystalline. The 

 formation of these two compounds is analogous to the benzyl sub- 

 stitutions in adenin. 



Ethyl chloro-carbonate, acting on hypoxanthin in the presence of 

 sodium hydrate, produces a precipitate which, recrystallized from 

 hot water, forms elongated sharp-angled plates which melt at 185°— 

 190°. It is insoluble or difficultly soluble in cold or hot alcohol, in 

 ether, and in cold water ; easily soluble in hot water, in sodium 

 hydrate, and in hydrochloric acid. Its formula corresponds to 

 CjH3Np.CO.CjH5 . It is, therefore, considered by Kossel to be a 

 urethan of hypoxanthin. 



Phosphomolybdic acid precipitates hypoxanthin from acid solu- 

 tion, and in general the base gives the ordinary alkaloidal reactions. 



It is not precipitated by ammoniacal basic lead acetate. Copper 

 acetate does not precipitate it in the cold, but does on boiling. This 

 fact has been made use of in the isolation of hypoxanthin. Mer- 

 curic chlorid, as well as mercuric nitrate, produces a flocculent pre- 

 cipitate. 



Altogether, in its behavior to reagents it resembles xanthin to a 

 very considerable degree. The two can be separated, however, by 

 the different solubilities of the hydrochlorids in water, and more 

 especially by that of the silver salts in nitric acid. 



Physiological Action. — 25-100 mg. begin to act on frogs in from 

 six to twenty-four hours, and produce increased reflex excitability 

 and convulsive attacks ; 5-100 mg. are fatal (FUehne). (See also 

 page 345.) When injected subcutaneously into hepatotomized geese or 

 chickens, or when fed to chickens, a corresponding increase in uric 

 acid secretion is observed (v. Mach). A similar conversion of hypo- 

 xanthin into uric acid is effected by emulsions of the liver of certain 

 mammals (Wiener, page 343). This conversion is analogous to that 

 observed by Stadthagen in the case of guanin (pages 344, 379), and 

 shows that in the xanthin bodies we may have antecedents of uric 

 acid apart from the synthesis of the latter from ammonia in the liver, 

 or from the direct decomposition of nucleins. The process by 

 which this change is effected is undoubtedly one of oxidation. 



Guanin, C^H^NjO, was discovered, in 1844 by Unger, as a con- 

 stituent of guano, in which it is present in varying quantities accord- 

 ing to the region from which the guano comes. Thus the Peruvian 

 guano is reported as containing the largest proportion of this base, 

 and on that account this variety is employed when it is desired to 

 prepare guanin. 



Fischer accomplished the synthesis of guanin by changing di-chlor 

 hypoxanthin with ammonia into an amino-oxychlor purin which on 

 reduction with hydriodic acid gave guanin. Its isomer* (p. 341), 



'Berichte, 30, 2247. 



