398 CHEMISTRY OF THE LEVCOMAINS. 



tufts. Balke also described a crystalline modification. The syn- 

 thetic base forms a colorless indistinctly crystalline powder. 



It is very difficultly soluble in cold water ; much more easily in 

 hot water, and the solution thus obtained is neutral in reaction. 

 According to Fischer the solubility in boiling water is 1 :142. Bond- 

 zynski and Gottlieb tested a heteroxanthin which undoubtedly con- 

 tained 3-methyl xanthin (p. 406) and found it to be more soluble 

 in boiling water (1-109) ; in water at 18° the solubility was 1 to 

 1,592. It was more difficultly soluble in absolute alcohol and was in- 

 soluble in chloroform and in ether. It is easily soluble in ammonium 

 hydrate and like uric acid dissolves in piperazin. In 3.3 per cent, 

 sodium hydrate the solubility is about 1 to 2,100 (Kriiger and Salo- 

 mon). 



When slowly heated it partially melts and decomposes at 341°— 

 342° but on rapid heating it begins to sinter at about 360°, then 

 colors and finally melts at 380° with evolution of gas (Fischer). 



The hydrochlorid is characterized by its rather difficult solubil- 

 ity and ready crystallization (a distinction from the paraxanthin 

 salt). The salt forms large colorless tufts of crystals, which on 

 contact with water soon lose their transparency and become opaque ; 

 gradually their crystalline form disappears, till finally they com- 

 pletely decompose with the formation of heteroxanthin. This de- 

 composition is hastened by warming, either with or without addition 

 of ammonia. The nitrate is more difficultly soluble and crystallizes 

 from ten per cent, acid in bent rhombic plates. Platinum chlorid 

 produces in the hydrochloric acid solution a precipitate of crystalline 

 double salt. 



On evaporation with nitric acid on the water-bath (xanthin reac- 

 tion) it remains as a pure white residue, which on contact with sodium 

 hydrate develops only a trace of reddish coloration or none at all. 

 Weidel's test, with concentrated hydrochloric acid and a chlorate 

 (page 392) produces a splendid red color, which becomes blue on 

 the addition of sodium hydrate. Simple evaporation with chlorin 

 water gives a similar though not so strong a color reaction. By 

 electric reduction it yields desoxyheteroxanthin, C^HgN^O (Tafel 

 and Weinschenk '). 



On heating with concentrated hydrochloric acid, or with dilute 

 sulphuric acid, at 180°- 200° it decomposes and yields sarko- 

 sin and other products, according to the equation (Kriiger and Salo- 

 mon) : 



C,H,Np, + 5Hp = 2C0, -f- CO -f- 3NH, + 

 CH3.NH.CHj.COOH. 



On treatment with methyl iodid it yields caffein. 

 Silver nitrate produces in ammoniacal as well as in nitric acid 

 > BeridhU, 33, 3369. 



