320 BACTERIAL POISONS. 



from plants, meat extract, or guano. The amount of 

 xanthine bodies present in the urine is unaffected by phos- 

 phorus poisoning. Neither this base nor paraxanthine has 

 been found in bull's testicles ; xanthine is also absent, and 

 only hypoxanthine and guanine were found to be present. 

 Heteroxanthine forms a white amorphous powder, which 

 sometimes on prolonged contact with water forms micro- 

 scopic crystalline tufts. It is very difficultly soluble in 

 cold water ; much more easily in hot water, and the solu- 

 tion thus obtained is neutral in reaction. It is easily soluble 

 in ammonium hydrate, but is insoluble in alcohol and ether. 

 When heated it volatilizes without melting and at the same 

 time gives off a small quantity of hydrocyanic acid. On 

 evaporation with nitric acid on the water-bath (xanthine 

 reaction) it remains as a pure white residue, which on con- 

 tact with sodimn hydrate develops only a trace of reddish 

 coloration or none at all. Weidel's test (page 328) pro- 

 duces a splendid red color, which becomes blue on the ad- 

 dition of sodium hydrate. Simple evaporation with chlo- 

 rine water gives a similar though not so strong a color 

 reaction. 



Silver nitrate produces in ammoniacal, as well as in 

 nitric acid solutions, a precipitate which readily dissolves 

 on warming in even very dilute nitric acid ; from this 

 solution, if not too concentratfid, the heteroxanthine silver 

 nitrate compound crystallizes in well-formed plate-like 

 prismatic crystals. Copper acetate produces in the cold, in 

 solutions of heteroxanthine, a clear-green precipitate. It 

 is also precipitated by phosphotungstic acid, and by ammo- 

 niacal basic lead acetete. Picric acid does not give a yellow- 

 colored precipitate in solutions of the hydrochloride. Mer- 

 curic chloride readily precipitates heteroxanthine in the 

 form of a grayish-yellow compound, which on standing 

 twelve to twenty-four hours becomes converted into pure 

 white crystalline aggregations. This mercuric compound 

 can be converted directly into the corresponding silver 

 compound by the addition of silver nitrate and ammonia, 

 as described under paraxanthine. 

 The hydrochloride is characterized by its rather difficult 



