CHEMISTKY OF THE LEUCOMAINES. 317 



plates, often ibrming aggregations. Its solution does not 

 precipitate platinum chloride. The nitrate forms fine yellow 

 crystals. 



The sulphate, C^U^TSfi^.U^O, + Hfi, crystallizes in 

 microscopic glistening rhombic plates, decomposable by 

 water. 



With baryta water xanthine forms the difficultly soluble 

 compound CjH4N'402.Ba(OH)2, which corresponds to the 

 hypoxanthine salt C5H4]Sr^O.Ba(OH)2, and to that of 

 guanine. 



From ammoniacal solution, silver nitrate precipitates the 

 compound CjH^N^Oj.AgjO, which is insoluble in ammonia, 

 but soluble in hot nitric acid. From the nitric acid solu- 

 tion, on long standing, there separates the compound 

 CjH^N^Oj.AgNOj, which, on contact with water, decom- 

 poses, giving off nitric acid. The ammoniacal solution is 

 also precipitated by lead acetate — separation from hypo- 

 xanthine — also by calcium and zinc chlorides. Cupric 

 acetate gives a precipitate only on boiling. The aqueous 

 solution is not precipitated by lead acetate, but is by phos- 

 phomolybdic acid, phosphotungstic acid, by mercurous and 

 mercuric salts. Picric acid gives an easily soluble com- 

 pound, which resembles that of hypoxanthine, but differs 

 from that of guanine. 



As to the physiological relation of xanthine very little 

 need be said. It bears the same relation to guanine that 

 hypoxanthine does to adenine, and, like the latter, is to be 

 looked upon as an intermediate compound, a step lower 

 than guanine, and nearer the limit of oxidation — uric acid. 

 It is quite probable that in the body it is oxidized about 

 as rapidly as it is formed. Like hypoxanthine, it is to 

 be regarded as a true muscle stimulant, especially of the 

 heart. (Baginski). According to Filehne it produces 

 in frogs a decided muscular rigor and paralysis of the spinal 

 cord. The heart muscle is also affected, which is not the 

 case with caffeine or theobromine. The fatal dose is less 

 than one-half pro mille. In its action it is stronger than 

 theobromine, while caffeine is weaker than either of the 

 two. Paschkis and Pal hold that the reverse is true. 



