ALLOXANIC ACID. 45 



SECTION VI. OF ALLOXANIC ACID. 



This acid was discovered by Wohler and Liebig in 1838.* 

 They prepared it in the following way : 



Barytes water was added to a hot solution of alloxane.\ A 

 precipitate fell, which was soluble by a gentle heat. On 

 continuing to add barytes water, a point was reached at which 

 the whole liquor became muddy, and being left to itself, a ba- 

 rytes salt was deposited, crystallized in white heavy plates. This 

 salt assumed a red colour when the solution happened to contain 

 a little alloxantin. The liquid which covered these crystals was 

 an aqueous solution of the same salt, and contained nothing else. 

 This salt was alloxanate of barytes. 



We obtain the same precipitate, though not quite so pure, 

 when we add chloride of barium to a solution of alloxane, and 

 then pour in a little ammonia. The salt in that case is deposit- 

 ed under the form of a thick gelatinous magma, which is com- 

 pletely dissolved by the addition of a great deal of water, or by 

 a dilute acid, however weak. 



A similar salt is formed when alloxane is treated in the same 

 way with strontian or lime water, or by chloride of strontium, or 

 of calcium and ammonia. The strontian salt scarcely differs 

 in appearance from that of barytes. The salt of lime presents it- 

 self in the form of grains or short transparent prisms. All these 

 salts contain water of crystallization, which they lose when 

 heated to 248. Alloxane does not precipitate nitrate of silver ; 

 but, if we add ammonia to the mixture, a white precipitate falls, 

 which becomes yellow by boiling. 



Alloxanate of barytes is easily decomposed by sulphuric acid, 

 and the alloxanic acid obtained from it in a state of purity. 



Alloxanic acid possesses considerable power. It decom- 

 poses the carbonates and acetates with facility. When eva- 

 porated to the consistence of a syrup, it crystallizes in a few 

 days into a hard radiated mass, which does not absorb moisture 

 from the atmosphere. When combined with barytes it forms a 

 salt precisely similar to that from which it was obtained. With 

 ammonia it forms a crystallizable salt. Oxide of silver dissolves 

 in it, and when the solution is dried it resembles gum in appear- 



* Ann. de Chim. et de Phys. Ixviii. 284. 



} This substance, which is obtained by treating uric acid with strong nitric 

 acid, will be described in a subsequent chapter of this volume. 



