CHEMISTRY OF THE LEUCOMAINES. 303 



filtrate from the adenine pi-rate (page 287) is raised to the 

 lx>iling-point and silver nitrate solution gradually added. 

 The precipitate is washed with cold water till the wash- 

 water is colorless, then dried at 100, when its composition 

 is represented by the formula C 5 H 3 AgN 4 O.C 6 H 2 (NO 2 ) 3 OH. 

 The calculated quantity of hypoxanthinc here is likewise 

 slightly higher than it should be. BRUHNS deducts 1.0 

 mg. from the calculated result. 



in the presence of hydrochloric acid, etc., the deter- 

 mination of hypoxanthine is somewhat circuitous since the 

 precipitated silver chloride must be separated from the 

 !i\ pnxanthine compound. The best procedure in this case 

 is to saturate the filtrate from adenine picrate with am- 

 monia and precipitate it completely with silver nitrate. 

 The precipitate is washed with hot water (a thorough wash- 

 ing is not necessary), then it is boiled several times with 

 nitric acid of 1.1 specific gravity. The acid each time is 

 rapidly decanted on to a small filter, and finally the residue 

 washed on the filter with 10 c.c. of the hot acid (total 100 

 c.c.). To the combined acid filtrate silver nitrate is added, 

 and the whole set aside for twenty-four hours. The pre- 

 cipitate is dried at 100. The amount of hypoxantliine 

 lost depends upon the quantity of silver chloride present. 

 The correction to be added is 3.1 mg. (BRUHNS). In 

 XKUBAUER-KOSSEL'S method the mixed adenine and hypo- 

 xanthine silver salts can be decomposed with a little hydro- 

 chloric acid and estimated in this way. 



Hypoxanthine is a white, colorless, crystalline powder, 

 sometimes in part amorphous ; according to BRUHNS, pure 

 hypoxanthine does not form floccules and bunches of micro- 

 scopic needles, but usually coherent crusts, which consist of 

 roundish, sharp-cornered granules; some resemble quadratic 

 octahedra. It is soluble in about 300 parts of cold water 

 (STRECKER). The base separates slowly from aqueous 

 solutions, and when pure the solubility, even in the begin- 

 ning, is less than 1 : 300. At the end of four days BRUHNS 

 found it to l>e 1 : 1880. It is more easily soluble in boiling 

 water (78 parts), and, on cooling, separates in the form of 

 white, crystalline floccules, thus differing from xanthine, 



