XANTHINE. 169 



XANTH i NE. C 5 H 2 N 2 O 2 . 

 Chemical Relations. 



Properties. This body, which has also been named uric oxide 

 and urous acid, occurs, when freshly precipitated, as a white powder, 

 which is neither crystalline nor gelatinous ; when dried, it forms 

 pale, yellowish, hard masses, which, on being rubbed, assume a 

 waxy brightness : it is very slightly soluble in water, is insoluble 

 in alcohol and ether, has no action on vegetable colours, arid when 

 heated, becomes decomposed without undergoing fusion, developing 

 much hydrocyanic acid and a very peculiar odour, but yielding no 

 urea. It dissolves with considerable facility in ammonia, but on 

 evaporation it loses the greater part of the ammonia, and separates 

 into a yellowish foliaceous mass. It dissolves freely in the caustic 

 fixed alkalies, from which, however, carbonic acid will separate it ; 

 it dissolves also in nitric acid without the development of gas, and 

 in sulphuric acid, to which it communicates a yellowish colour ; it is 

 all but insoluble in hydrochloric and oxalic acids. It does not 

 combine in definite proportions with acids, alkalies, or salts. 



Composition. As, from the want of definite combinations, the 

 atomic weight of this body cannot be ascertained, we can only give 

 the empirical formula which expresses the simplest relation of the 

 elements in xanthine. This substance was analysed many years 

 ago by Liebig and Wohler*, and recently by Bodo Ungerf, with 

 similar results : 



Carbon 5 atoms .... 39'47 



Hydrogen 2 .... 2'63 



Nitrogen 2 .... 36'84 



Oxygen 2 .... 21-06 



100-00 



This body has been regarded as uric acid (C 5 H 2 N 2 O 3 ) in a lower 

 state of oxidation ; but till some of its compounds or products of 

 decomposition are analysed, scarcely an hypothesis can be suggested 

 regarding its theoretical constitution. 



This body is only classified here with the animal bases, amongst 

 which it cannot properly be reckoned, because, in its elementary 

 composition it presents much similarity with them, and in a 



* Pogg. Ann. Bd. 41, S. 393. 



t Ann. d, Ch. u. Pharm. Bd. 58, S. 18. 



