CHEMISTRY OF THE LEUCOMAINES. 305 



chloride forms :i vellow, crystalline double salt, having the 



c,,m | 



The picrate f'nrnis yellow prisms easily soluble in water. 

 which solution is not a fleet 4 -d as that of adenine by sodium 

 pkmte. 



Ilypoxanthine silver, C,H 2 Ag 2 N 4 O.H 2 O. All attempts 

 tu obtain a eorapound containing but one atom of silver 

 in the molecule, corresponding to the adenine compound 

 O 5 H 4 AgN s , have failed. The above compound was first 

 prepared by STRECKER, and given the formula C 5 H 4 N 4 O. 

 1 : but the former is preferable, since on heating at 120 

 two and a half molecules of water are lost and 



2C 5 H 2 Ag 2 N 4 O -f- H 2 (Ag = 60.2 per cent.) results. 



At 140-150 it loses again in weight and becomes gradu- 

 ally gray ; on exposure to air it absorbs moisture. In this 

 tin-in li\ -poxanthinc can lie estimated quantitatively (see 

 I Age 302j 5 the presence of sodium picrate does not interfere, 

 but chlorides, etc., do. It is insoluble in hot water. The 

 compound, C 5 H 2 Ag 2 N 4 O.3II 2 O, is obtained in the form of 

 microscopic needles, by treating pure hypoxanthine silver 

 nitrate with excess of aqueous ammonia. On boiling with 

 ammonia-water it is but slightly dissolved, and appears to 

 slowly lose a part of its water of crystallization. As a 

 nsnlt of the decomposition one-half of the hypoxanthine 

 passes into solution and can be recovered on boiling with 

 addition of silver nitrate in the crystalline form ; or in the 

 cold, as the usual amorphous precipitate, C s II 2 Ag 2 N 4 O.H 2 O. 

 Hypoxanthine silver nitrate, C 5 H 4 X 4 O.AgNO 3 , (Ag = 

 .".">. _'! per cent.), is the best-known compound ; its formula 

 -talilished by STRECKER. It is obtained by dissolving 

 the above precipitate, produced by addition of silver 

 nitrate to an ammoniacal solution of the base, in hot nitric 

 acid, specific gravity 1.1 ; on cooling the hypoxanthine 

 silver nitrate crystalli/es in the form of tufts of microscopic 

 needles or plates. Heated at 100-120 it remains con- 

 stant in weight; the quantity of silver present, when deter- 

 mined, is always somewhat higher than the thn>nti<al, 



