CHEMICAL BASIS OF THE ANIMAL BODY. 169 



NH CO 

 Uric acid. CO C NH 



I II >co. 



NH C Nil 



An inspection of the above formula shows at once that uric 

 acid contains the residues of two molecules of urea. This cor- 

 responds to the fact that nearly all the possible decompositions of 

 uric arid yield either a molecule of urea along with the more spe- 

 citie product of the decomposition, frequently itself a derivative of 

 nrra, or else some substance which can by further change be de- 

 composed into urea and some other product which is as before 

 l'rei[Uemly a derivative of urea. The close chemical relationship 

 of urea and uric acid is thus clearly shown, and may be further 

 t-niphasi/ed by the following reactions, which illustrate and 

 amplify at .the same time the general statement which has 

 just been made. 



The decomposition of uric acid takes place in two stages, yield- 

 ing two series of products, of which one is headed by allox; n 

 and the other by allantoin ; from these two substances respec- 

 tively tin: other members of each series are derived by subsequent 

 decomposition. 



1. Alloxan series. 



By careful oxidation with nitric acid uric acid is decomposed 

 into a molecule of alloxan and one of urea. 



NH CO NH CM 



II II 



CO C NH CO CO NH, N 



| || ) CO || /CO. 



NH -C-NH +H,0+0 = NH CO + NH/ 



Alloxan is itself a substituted urea or ureide (antea, p. 164), 

 \\y.. mrsoxalyl-nrea, and by oxidation ran In- further converted 

 into parabauic acid (oxalyl-urea) and carbonic anhydride. 



NH CO NH CO 



CO CO CO 



NH CO + 0=NH CO + CO,. 



By heating with alkalis parabanic acid is hydrated and yields 

 oxaluric acid. 



MI CO MI CO 



CO 



CM 



Ml _CO + H,0 = NH, CO. OH. 



