DERIVATIVES OF URIC ACID. 233 



hydrochloric acid, heated over the water-bath, allowed 

 to stand on the water-bath until the smell of hydro- 

 chloric acid has disappeared, and the uric acid then 

 precipitated by the addition of from twelve to fifteen 

 times the volume of water. The crude acid obtained 

 in this way is dissolved in alkali and purified, as above 

 directed. 



Properties. Light, white powder, consisting of fine 

 crystalline scales, without taste and odor, exceedingly 

 sparingly soluble in water, insoluble in alcohol and 

 ether. Soluble in concentrated sulphuric acid without 

 decomposition ; from this solution there crystallizes on 

 cooling a very deliquescent compound of uric acid 

 with sulphuric acid C 5 H 4 N 4 3 + 2SOH 2 , which is de- 

 composed by water. Easily soluble in nitric acid, 

 undergoing decomposition; on evaporating the solu- 

 tion, there remains a mass, which turns purple with 

 ammonium carbonate, and violet with potassa. By 

 distillation, it yields, among other products, a great 

 deal of hydrocyanic acid, a sublimate, consisting of 

 urea, cyanuric acid, and ammonium cyanide, and leaves 

 behind nitrogenous carbon. When heated with con- 

 centrated hydriodic acid to 160-170, it yields glycocol 

 (p. 84), ammonium iodide, and carbonic acid. 



Uric acid is a very weak, bibasic acid. The neutral 

 alkaline urates are white, granular, crystalline, diffi- 

 cultly soluble in water, but easily soluble in an excess 

 of potassa. Carbonic anhydride precipitates from the 

 solution the acid salt, in the form of a translucent 

 jelly, which soon becomes powdery. The acid ammo- 

 nium salt separates in the same form, when the dis- 

 solved potassium salt is mixed with sal-ammoniac. It 

 afterwards shrinks up, forming a white powder. 



From uric acid, a long series of transformation pro- 

 ducts can be produced. The most remarkable are the 

 following : 



Uroxanic acid, C 5 II 8 N 4 6 . When a solution of uric 

 acid, in an excess of concetrated potassa, is allowed to 

 stand for a long time in contact with the air, potassium 

 uroxanate, CTOlsro^ + sjpo, separates in the form of 



20* 



