360 CHEMISTRY OF THE LEUCOMAINS. 



which the crystallization takes place. Thus, the crystals may con- 

 tain almost two molecules of water, whereas when crystallization 

 occurs at above 60° the crystals are anhydrous. It is a rather 

 strong base and forms well characterized salts which are difficultly 

 soluble in cold water, more easily in the presence of an excess of 

 acid, from which it is thrown down as a white micro-crystalline pre- 

 cipitate by addition of ammonia. It is also formed from the orig- 

 inal dark-red body by treatment with sodium bisulphite, or better 

 by dissolving the body in ammonium hydrate, or, according to 

 Kriiger, by heating to 130°, then dissolving in sodium hydrate and 

 precipitating with carbonic or acetic acid. It is only difficultly at- 

 tacked by boiling alcohol or aqueous potash or alcoholic ammonia. 

 The atom of bromin cannot therefore be replaced by an amido or 

 by a hydroxyl group. Sodium alcoholate heated with brom-adenin 

 at 145° for hours has no effect. 



Brom-adenin is very easily and completely changed to adenin by 

 the action of sodium amalgam in the cold, or by boiling for several 

 hours with zinc dust. No azulmic acid is formed. It is not affected 

 by iron dust (Bruhns). According to Kriiger, it is affected by heat- 

 ing with concentrated potash at 180°- 190°, and the bromin is not 

 replaceable by radicals as phenol. 



The study by Bruhns of the decomposition of the dark-red body, 

 mentioned above, has shown that it is very probably a hydrobromid 

 of brom-adenin, tetra-bromid, CjH^BrNj.Br^.HBr. According to 

 Kriiger, this compound does not always form by the addition of 

 bromin to adenin. Ordinarily the hydrobromid of brom-adenin 

 forms, unless a very large excess of bromin is used. Compounds 

 similar to brom-adenin are formed by hypoxanthin, guanin, xanthin, 

 and caffein. Azulmic a«id reacts with bromin in much the same 

 way as adenin. 



The hydrochlorid, sulphate, and nitrate of brom-adenin have 

 been prepared and analyzed by Bruhns. 



Brom-adenin picrate, C5H^BrN5.C5H2(N02)30H -f- H^O, resembles 

 that of adenin, but is more voluminous. It is precipitated under 

 the same conditions as adenin. The solubility in cold water is 

 about the same (1:3220). It is likewise almost completely thrown 

 out of solution by sodium picrate. Under the microscope, how- 

 ever, it can be readily distinguished from adenin picrate, since it 

 does not form distinct crystals, but rather bundles of thin thread-like 

 needles. 



The metal derivatives of brom-adenin are analogous to those of 

 adenin. Thus, ammoniacal silver solution gives rise to a mixture 

 of CjHjAgBrNj and CjHjAgjBrNj.HjO. Silver nitrate produces a 

 gelatinous precipitate which, like the adenin silver nitrate, has an in- 

 constant composition ; on careful heating with nitric acid (1.1 sp. g.) 

 it can be obtained in needles which resemble exactly those of the 



