URIC ACID. 205 



If a solution of alloxanic acid be submitted to prolonged ebulli- 

 tion, it evolves carbonic acid, and is decomposed into an acid 

 insoluble in water, leucoturic acid, C 6 H 3 N 2 O 6 , and into a soluble 

 indifferent body, diffluan; C 6 H 4 N 2 O 5 (Schlieper.) 



Two atoms of alloxan yield 1 atom of this new acid, and 1 atom 

 of diffluan, besides 4 atoms of carbonic acid and 1 atom of water, 

 for C 16 H 8 N 4 20 =C 6 H 3 N 2 6 + C 6 H 4 N 2 O 5 + 4CO 2 + HO. 



Mesoxalic acid, C 3 O 4 , is produced together with urea, when a 

 solution of alloxan is added by drops to a boiling solution of acetate 

 of lead : it is crystallisable, and reddens litmus. 



Alloxan becomes simply decomposed into 1 equivalent of urea 

 and 2 equivalents of mesoxalic acid, for C 2 H 4 N 2 O 2 +2C 3 O 4 

 C 8 H 2 N 2 I0 . 



Mykomelinic acid, C 8 H 5 N 4 O 5 , is formed when an excess of 

 dilute nitric acid is added to a supersaturated solution of alloxan, 

 and boiled for some time with ammonia; in its moist state it occurs 

 as a yellow gelatinous mass ; when dried, it is a yellow powder, 

 which is soluble in water, reddens litmus, and decomposes car- 

 bonates. 



This acid is formed from 1 atom of alloxan and 2 atoms of 

 ammonia with the separation of 5 atoms of water ; C 8 H 4 N 2 O 10 + 

 2H 3 N - 5 HO = C 8 H 5 N 4 O 5 . 



Parabanic acid, C 6 N 2 O 4 -f 2HO, is prepared by digesting 1 part 

 of uric acid or of alloxan, with 8 parts of moderately diluted nitric 

 acid, and evaporating the solution to the consistence of a syrup ; 

 after some time there is a separation of small plates or minute prisms 

 of parabanic acid ; it is unaffected by exposure to the atmosphere, 

 has an acrid, sour taste, dissolves readily in water, fuses when 

 heated, and partially sublimes without decomposition. 



Parabanic acid is produced in the following manner from uric 

 acid and nitric acid : the urea of the uric acid is decomposed as 

 usual by the nitrous acid which is formed, but 2 atoms of water 

 and 4 atoms of oxygen enter into combination with the urilic acid 

 with which they form 2 atoms of carbonic acid, and 1 atom of 

 parabanic acid, for C 8 N 2 O 4 + H 2 O 2 + 4O-C 2 O 4 =C 6 N 2 O 4 + 2HO. 



Alloxan with 2 atoms of oxygen becomes decomposed into 

 2 atoms of carbonic acid, 4 atoms of water, and 1 atom of 

 parabanic acid, for C 8 H 4 N 2 O 10 + 2Or=C 2 O 4 + H 4 O 4 + C 6 N 2 O 4 . 



Hydrurilic acid, C 12 H 3 N 3 O 9 -f 2HO, is formed at the same time 

 with alloxan under certain conditions not yet accurately under- 

 stood ; it occurs as a white flocculent powder, consisting of delicate 

 needles; it is difficult of solution in cold, but dissolves more 



