CHEMICAL BASIS OF THE ANIMAL BODY. 



183 



with hypoxanthin, from xanthin. It also yields a readily crystalline 

 compound with picric acid, which is very insoluble in cold water (1 in 

 3500) and may be used for its quantitative separation from solutions 

 (Bruhns, loc. cit. ). It does not give the ordinary reactions characteristic 

 of the xanthin bodies, but like hypoxanthin shows a red colouration 

 on the addition of an alkali after treatment with hydrochloric acid and 

 zinc. 



7. Guanin. C 5 H 5 N^O. 



NH CH 



NH==C C NH 



\ CO (Fischer) 1 . 

 NH-C^N 



It was first obtained from Peruvian guano which still provides the 

 most convenient source for its preparation. 



The guano is finely powdered and boiled with milk of lime as long as it yields 

 a coloured filtrate. The residue is then repeatedly extracted with boiling solution 

 of sodium carbonate ; the filtrate on the addition of acetic acid yields a precipitate 

 of guanin and some uric acid, from which it is separated by boiling with somewhat 

 dilute hydrochloric acid. A hydrochloride of guanin is formed which is crystalline, 

 and from this compound the guanin is separated by the addition of concentrated 

 ammonia 2 . 



Guanin is also found in small quantities in the pancreas, liver 

 and muscle extract, and among the products of the action of acids on 

 some nucleins 3 . It may also occur in urine, more especially of pigs, in 



FIG. 29. GUANIN HYDROCHLORIDE, 

 C 5 H 5 N 5 . HC1 + H 2 0. (After Kiihne. ) 



FIG. 30. GUANIN NITRATE, 

 C 5 H 5 N 5 . HN0 3 + UH 2 0. (After Kuhne.) 



1 loc. cit. (sub xanthin). 



3 Strecker, Ann. d. Chem. u. Pharm. Bd. cxvni. (1861), S. 152. 



3 Kossel. Zt.f. physiol. Chem. Bd. vin. (1884), S. 404. 



