METHYL XANTHIN. 395 



It is easily soluble in ammonia and in sodium hydrate, and unlike 

 heteroxanthin it forms an easily soluble sodium compound. The 

 barium salt unlike that of 3-methyl xanthin is very soluble. Unlike 

 3-methyl xanthin it is easily soluble in dilute mineral acids and 

 from these solutions on slow evaporation in the cold the correspond- 

 ing salts are obtained. 



The chlorid forms beautiful glassy rhombic plates or prisms. The 

 nitrate forms long four-sided prisms at times shortened to resemble 

 six-sided plates. These salts like those of xanthin and heteroxanthin, 

 are easily dissociated by water. 



The aurochlorid forms glistening rhombic prisms. The platinum 

 double salt crystallizes from concentrated solutions in stellate need- 

 les or in prisms. 



With ammonia and silver nitrate it gives a gelatinous precipitate. 

 The silver nitrate compound crystallized from dilute nitric acid 

 (1.1 sp. g.) forms, like xanthin, fine needles grouped in rosettes. 

 The solubility and crystalline form is such that the two bodies can- 

 not be distinguished and as pointed out by Kriiger and Salomon it 

 is probable that the xanthin as heretofore obtained may contain an 

 admixture of the methyl derivative. Copper sulphate and sodium 

 bisulphite produce in the cold a voluminous precipitate, and in 

 warm solutions a white flocculent deposit. Copper sulphate and 

 sodium thiosulphate precipitate only on heating. Mercuric chlorid 

 produces a cloudiness which disappears on heating ; but on the addi- 

 tion of soda a white flocculent precipitate results. 



On evaporation with concentrated nitric acid it gives the xanthin 

 reaction. With concentrated hydrochloric acid and a chlorate it 

 gives an intense murexid test. In the latter test the addition of 

 sodium hydrate also gives a purple red color which, when the dish 

 is cool, on the addition of a drop or two of water turns to a splen- 

 did bluish violet. The latter disappears on heating. The base 

 yields a bromin derivative which is no longer basic and is difficultly 

 soluble in water and in dilute acids and is not altered at 295°, It 

 dissolves easily in alkalis and in ammonia. The sodium salt crys- 

 tallizes in six-sided plates. 



When paraxanthin or 1-7-di-methyl xanthin is fed to rabbits a 

 part appears in the urine unchanged and in addition 1-methyl xan- 

 thin is present (Kriiger and Schmidt^). The 7-methyl group there- 

 fore is split off in the rabbit and this fact supports the view of Kniger 

 and Salomon that this base in man is derived from paraxanthin. 



3-metliyl xanthin, CgH^N^Ojj, has not been obtained from the 

 urine of man ; possibly because the methyl group in position 3 is 

 easily split off in the body. However, the line of cleavage depends 

 largely upon the species of animal. It was first found in the urine 



'BericMe, 32,2680(1899). 



