CHEMISTRY OF THK LEUCOMAINES. 297 



water ; alcoliolic zinc chloride also yields a precipitate which 

 is soluble in excess of ammonium hydrate. Mercuric nitrate 

 also gives a precipitate. Cadmium chloride yields a pre- 

 cipitate which dissolves on warming, reappears on cooling, 

 and is soluble in ammonia. Basic lead acetate lias no effect. 

 Nothing definite is known in regard to the physiological 

 action of adenine, except that when fed to dogs it appears 

 to be eliminated as such, in part at least, by the urine. 



ADENINE-HYPOXANTHINE, C a H 5 N 5 + C 6 H 4 N 4 O. The 

 occurrence of this compound was observed by KOSSEL, but 

 it was isolated and studied for the first time by BRUHNS. 

 It can be prepared by cooling a hot aqueous solution of 

 t-ijual parts of the two bases. At first it is obtained as 

 thick, starch-like semi-transparent masses, which later in 

 part l>ecome white and chalky. By spontaneous evapora- 

 tion of its solution in very dilute ammonia it forms pearly 

 aggregates of very small radially arranged needles, which 

 contain water of crystallization. These effloresce some- 

 what and lose the water at 100. The compound is more 

 readily soluble in water than its components, but an exact 

 <l( t< naination of its solubility is impossible, inasmuch as 

 the separation from hot solutions is not completed for some 

 weeks. Any adenine present can be separated by recrys- 

 tallization. It forms a distinct crystalline hydrochloride, 

 which should be borne in mind-when examining microscopic- 

 ally for the two bases ; but the combination is loose, since 

 addition of gold chloride brings down the characteristic 

 gold salt of adenine. Ordinarily it does not form salts 

 with sulphuric or nitric acids, but more often is decomposed 

 by these, so that the difficultly soluble adenine crystallizes 

 out. Once, however, BRUHNS obtained a sulphate which 

 differed from the pure adenine and hypoxanthine sulphates ; 

 thus is perhaps explained the observation of KOSSEL that 

 adenine sulphate forms crystals belonging to two systems. 

 The compound can be decomposed into its constituents by 

 fractional crystallization of the sulphate or nitrate ; but 

 better by forming the picrates, which are very unequally 

 soluble in water. The existence of this compound undoubt- 



