306 BACTERIAL POISONS. 



especially if an excess of silver nitrate is employed in the 

 precipitation. The explanation of this fact is probably 

 that given under Adenine, though presence of silver chlo- 

 ride may partly be the cause. On treatment with am- 

 monia it loses not only nitric acid but also half of the 

 hypoxanthine, and C 5 H 2 Ag 2 N 4 O.3H 2 O forms. The change 

 takes place readily even in the cold, and if during the 

 digestion an excess of silver nitrate is added, the hypo- 

 xanthine set free is converted into this compound, which is 

 wholly constant in composition compared with the hypo- 

 xanthine silver nitrate. The conversion is quantitative. 

 Very dilute hydrochloric acid, as well as hydrogen sulphide, 

 removes the silver from this compound. 

 Hypoxanthine-silver picrate, 



C 5 H 3 AgN 4 O.C 6 H 2 (NO 2 ) 3 OH (Ag = 22.88 per cent.), 



is gradually formed by adding silver nitrate to a boiling 

 solution of hypoxanthine picrate. The precipitate is granular 

 and of a lemon-yellow color, and consists of aggregations of 

 fine short needles. It is slightly soluble in hot, insoluble in 

 cold water. It is, therefore, applicable for a quantitative 

 determination of the base. Aqueous ammonia very readily 

 and completely removes the picric acid from the compound, 

 and the residue is hypoxanthine silver, which is slightly 

 colored yellow by a trace of picric acid ; half of the hypo- 

 xanthine passes into solution. Nitric acid with difficulty 

 converts it into hypoxanthine silver nitrate. 



Hypoxanthine mercuric chloride, C 5 H 3 N 4 OHgCl, is ob- 

 tained by adding an equivalent quantity of mercuric chloride 

 to a boiling solution of hypoxanthine. The precipitate, 

 which increases on cooling, is crystalline. 



A second compound, C 5 H 3 N 4 OHg 2 Cl 3 , is produced by 

 adding a strong excess of mercuric chloride, in the cold, to 

 an aqueous solution of hypoxanthine. It forms a heavy 

 granular micro-crystalline precipitate, which contains some 

 water of crystallization. 



By boiling the preceding compound with just sufficient 

 hydrochloric acid to effect complete solution, there is formed 

 on standing a precipitate of white roundish aggregates of 



