1258 



URIC ACID. 



tion of oxalyl (oxalic acid) gives parabanic acid, CO 



NH.CO 



I ; of 



-NH.CO 

 NH.CO 



tartronyl (tartronic acid), dialuric acid, CO' ;:CHOH: of 



X NH.CO X 

 NH.CO 

 mesoxalyl (mesoxalic acid), alloxan CO^ ^CO. These 



X NH.CO X 



substances are interesting as being also obtained by the artificial 

 oxidation of uric acid. 



2. Uric acid. C 5 H 4 N 4 O 3 . NH CO 



CO C NH 

 NH C NH 



CO. 



The chief constituent of the urine in birds and reptiles ; it 

 occurs only sparingly in this excretion in man (*2 1 grm. in 

 24 hours) and most mammalia. It is normally present in the 

 spleen, and traces of it have been found in the lungs, muscles 

 of the heart, pancreas, brain and liver. Urinary and renal 

 calculi often consist largely of this substance, or its salts. In 

 gout, accumulations of uric acid salts may occur in various 

 parts of the body, more especially at the joints, forming the 

 so-called gouty concretions. 



It is when pure a colourless, crystalline powder, tasteless, 

 and without odour. The crystalline form is very variable, 



Rapidly separated. Slowly separated. 



FIG. 211. CRYSTALS OF URIC ACID. (Krukenberg after Ktihne.) 



differing according to the concentration of the solution from 

 which the crystals are obtained, the rate at which they are 

 formed, and whether they are separated out spontaneously or 



