26 PHYSIOLOGICAL AND PATHOLOGICAL CHEMISTRY. 



Conversion of the Hypoxanthine Silver Nitrate into 

 Hypoxanthine. 



(a) By Means of Hydrochloric Acid. Pierce the filter and 

 wash the precipitate into a flask. Add a few cubic centi- 

 meters of hydrochloric acid, shake thoroughly and continu- 

 ously, and finally warm gently. The hydrochloric acid de- 

 composes the silver compound with the separation of silver 



FIG. 1. Hypoxanthine Silver Nitrate. 



chloride. By thoroughly shaking and gently warming this 

 settles well. The completion of the decomposition is con- 

 trolled by a microscopical examination. Heating too strongly 

 is to be avoided, as otherwise the aqua regia formed may 

 destroy the hypoxanthine. 1 When the decomposition is com- 

 plete, filter, make the filtrate alkaline with ammonia, and 

 evaporate to dryness on the water-bath. Treat the residue 

 with a small quantity of water, which dissolves the ammo- 

 nium chloride and nitrate formed, but leaves the hypoxan- 

 thine undissolved. 



1 In order to avoid this it is advisable first to convert the hypoxan- 

 thine silver nitrate into the hypoxanthine silver compound (see below). 



