244 DERIVATIVES OF URIC ACID. 



of sulphuretted hydrogen, deposits allantoine in crys- 

 tals on evaporation. In the last mother-liquor urea 

 remains. It is also produced, when uric or dialuric 

 acid is boiled with potassium nitrate and acetic acid ; 

 further, by the oxidation of uric acid with manganese 

 peroxide or potassium ferricyanide, and by the action 

 of ozone upon it. Colorless rhombohedric prisms, but 

 slightly soluble in cold water, more easily in boiling. 

 It combines with several metallic oxides. When a hot 

 solution of it is mixed with silver nitrate and ammo- 

 nia, a white precipitate of allantoine-silver, C 4 IKN" 4 3 Ag, 

 is deposited. Heated with sulphuric acid, it is resolved 

 into ammonia, carbonic anhydride, and carbonic oxide. 

 "When allantoine is dissolved in ordinary nitric acid, 

 dttanic acid, C 4 H 5 N 5 5 + H 2 0, is formed. This acid 

 crystallizes from a small amount of water in stellate 

 groups of needles. It is decomposed at 210-220, with- 

 out previously being fused. When a solution of allan- 

 toine in an excess of potassa-ley is left to itself for 

 several days, the potassium salt of a new acid, allantoic 

 acid, C 4 H 3 N 4 4 , crystallizes out on the addition of acetic 

 acid and a little alcohol. 



Glycolurile, C 4 H 6 ^ 4 2 , is formed by the action of 

 sodium-amalgam on a warm solution of allantoine. 

 Small octahedral crystals or lance-shaped needles. More 

 difficultly soluble in water than allantoine. 



Hydantoine (Glycolylurea), C 3 H 4 E" 2 2 = 



CO -j ATTT Vi/^ * s P r duced, together with urea, by heat- 

 ( ^NM.CO, 



ing allantoine with hydriodic acid ; and by boiling gly- 

 colurile with acids ; together with carbonic anhydride, 

 water, and free iodine, by heating alloxanic acid with 

 hydriodic acid. Is further formed by the action of an 

 excess of alcoholic ammonia on monobromacetyl-urea 

 (p. 231). Colorless crystals, easily soluble in hot water, 

 moderately in cold ; fuse at 206 ; do not react on lit- 

 mus paper ; taste sweetish. 



