358 CHEMISTRY OF THE LEUCOMAINS. 



position of the original salt, a varying mixture of CjH^AgNj and 

 CjHjAgjNj + HjjO. The solubility in nitric acid is about the same 

 as that of hypoxanthin silver nitrate. 



Adenin silver picrate, C^jLgTS^.C^^(^O^pYL + Hp, is ob- 

 tained as an amorphous voluminous yellow precipitate when silver 

 nitrate is added to a cold aqueous solution of adenin picrate. If 

 the latter solution is previously raised to the boiling-point, the pre- 

 cipitate soon becomes crystalline and rapidly subsides. The adenin 

 can thus be almost wholly removed from solution. The crystalline 

 form loses its water of crystallization at 120°, while the amorphous 

 form does not appreciably decrease in weight, and its composition 

 does not appear to be so constant as that of the corresponding hypo- 

 xanthin compound. On treatment with ammonium hydrate the 

 picric acid is removed, and adenin silver, CjH^AgNj , is left, stained 

 yellow by picric acid. 



Adenin mercury picrate, {Q^^^^g.2C^^QS0f>)f]iH., can be 

 prepared by treating a hot concentrated aqueous solution of adenin 

 picrate with an excess of sodium picrate, and then with mercuric 

 chlorid. It forms a yellow granular, crystalline precipitate (micro- 

 scopic needles) which rapidly subsides and increases in quantity as 

 the solution cools. Its composition apparently varies, containing one 

 to two molecules of water, according to the temperature of the solu- 

 tion. One molecule is given off at 100° and the second at 105°— 120°. 

 The latter preparation, then, on exposure to the air, rapidly absorbs 

 one molecule of water. The object of the sodium picrate in the 

 precipitation is to combine with the hydrochloric acid, which is set 

 free. The precipitate produced by mercuric chlorid in cold adenin 

 picrate solution shows yellow and white granules, and is not homo- 

 geneous. Bruhns considers it to be a mixture of the adenin mer- 

 cury picrate and the compound CjH^NjHgjClj ; if sodium picrate is 

 added, however, the pure adenin mercury picrate forms, since no 

 hydrochloric acid is set free. 



Adenin mercuric chlorid, CjH^NjHgCl, is thrown down as a white, 

 finely granular precipitate when a boiling aqueous adenin solution 

 is treated gradually with concentrated mercuric chlorid solution 

 (Bruhns). On neutralizing the filtrate from this precipitate a second 

 deposit forms. According to Kriiger, the reaction that takes place 

 is as follows : 



2C,H,N, + 2HgCl, = C,H,N,.HgCl + C,H,N,.HCl.HgCl,. 



C5HjN,.HCl.HgCl,-|-Na,C03=C5H,N,.HgCl+ 2NaCl + COj+Hp. 



Heated with alkyl iodids it does not give rise to substitution com- 

 pounds. Free hydrochloric acid is indicated by the reaction with 

 methyl orange. Treated with ammonium hydrate the chlorin is re- 

 moved, and there is formed apparently the compound CjH^NjHgOH. 

 If dissolved in warm dilute hydrochloric acid and allowed to crystal- 



