1002 CYANOGEN COMPOUNDS. 



URIC ACID AND THE PRODUCTS OF ITS DECOMPOSITION. 



These form a well defined class of compounds, which appear 

 from their analysis to contain cyanogen and carbonic oxide. 

 M. Liebig connects the different members of the class by 

 supposing them to contain a compound radical in common, 

 urile, which is itself a combination of 2 atoms of cyanogen and 

 4 atoms of carbonic oxide. Urile, 2CyH-4CO=C 8 N 2 O 4 , being 

 indicated by Ul, then the compounds are represented by the 

 formulae : 



Empyrical 

 Rational formulae. formulae. 



2U1+1 atom urea =Uric acid =C 10 N 4 H 4 O 6 



2U1 + O 2 + 4HO =Alloxan =C 8 N 2 H 4 O 10 



2U1 + O -J- 5HO =Alloxantin=C 8 N 2 H 5 O 10 



2U1+1 atom ammonia H-2HO=Uramile =C 8 N 3 H 5 O 6 



URIC ACID. 



Formula, C 10 N 4 H 4 O 6 , or 2U1 + (C 2 O 2 + 2NH. 2 ). An acid 

 which exists in the urine of all carnivorous animals, and forms 

 the basis of most urinary concretions. It forms in combination 

 with ammonia, the white part of the excrement of birds ; and 

 vast accumulations of that urate exist in the guano, or decom- 

 posed excrement of aquatic birds, by which many of the small 

 islands on the coast of Peru and Chili are covered, and which 

 is used as manure. 



Uric acicl is conveniently prepared from the chalk-like excre- 

 ment of serpents. The solid urine of the Boa is reduced to 

 fine powder and added to a boiling and very dilute solution of 

 potash, sufficient only for the solution of a portion, and ebulli- 

 tion continued until the undissolved mass appears quite white. 



The whole is then allowed to cool, thrown upon a calico filter, 

 and washed until the water passes off very nearly colourless. 

 The washed white mass, which consists of urate of potash, is 

 next dissolved in another portion of caustic alkali, filtered, and 

 slowly added to an excess of dilute hydrochloric acid maintained 

 in a state of ebullition. The uric acid which precipitates, may 

 be washed first by decantation, and afterwards more completely 



