200 CONJUGATED ACIDS. 



by other acids, and on its separation at first forms a gelatinous 

 mass, (according to Fritzsclie,* a hydrates C 5 HN 2 O 2 . HO + 4HO) 

 which, however, soon changes into small glistening plates. 



Uric acid belongs to the weakest class of acids ; thus, as in the 

 case of the fatty acids, it does not directly expel carbonic acid from 

 carbonate of potash, but urate of potash and bicarbonate of pota'sh 

 are formed, if a sufficient amount of uric acid be added ; if the 

 solution of potash be concentrated, the urate of potash remains 

 un dissolved ; the behaviour of uric acid to the alkaline borates and 

 phosphates is similar, with the exception of this difference, that 

 the solution of phosphate of soda, which has an alkaline reaction, 

 reddens litmus when an excess of uric acid has been added to it, 

 in consequence of the formation of biphosphate of soda. 



Uric acid, when submitted to dry distillation) is converted into 

 urea, cyanic acid, cyamelide, hydrocyanic acid, and a little carbo- 

 nate of ammonia, leaving, as a residue, a brownish-black coal, rich 

 in nitrogen. 



On fusing uric acid with hydrated potash, carbonate and 

 cyanate of potash, with cyanide of potassium, are formed. On 

 boiling uric acid with 20 parts of water, and adding peroxide of 

 lead as long as the brown colour of the oxide continues to dis- 

 appear, there are formed oxalate of lead, urea, and allantoine, 

 ( 2C 5 HN 2 2 .HO + 20 + 3HO = C 2 H 4 N 2 O 2 + 2C 2 O 3 + C 4 H 3 N 2 O 3 ) . 



Moist uric acid, placed in chlorine gas, intumesces, and, giving 

 off carbonic and cyanic acids, is converted into oxalic acid and 

 hydrochlorate of ammonia ; dry uric acid in dry chlorine gas yields 

 much cyanic acid, chloride of cyanogen, and hydrochloric acid, 

 leaving only a small carbonaceous residue. Uric acid dissolves 

 with considerable readiness in dilute nitric acid, developing equal 

 volumes of nitrogen and carbonic acid, and yielding to the solution 

 several of the different products of decomposition which we shall 

 presently describe. On evaporating to dryness a solution of uric 

 acid in nitric acid, there is left a red amorphous residue, which, 

 especially if we expose it to the vapour of ammonia, assumes a very 

 beautiful purple tint ; on moistening the red mass (murexide) with 

 a little caustic potash, a beautiful violet tint is developed (Schloss- 

 berger.f) 



Composition. According to the above formula, deduced by 

 BenschJ from his analyses of the urates, uric acid consists of: 



* Bull, scient. de St Petersb. T. 1, Nos. 79 et 107. 

 t Arch. f. physiol. Heilk. Bd. 8, S. 294. 

 $ Ann. d, Ch. u. Phann. Bd. 51, S. 189-20& 



