ALLOXANE OR ERYTHRIC ACID. 113 



a solution of alloxane is gently heated with peroxide of lead, 

 pure carbonic acid gas is given out. After the process is over, 

 we obtain a white magma of carbonate of lead, containing merely 

 a trace of oxalate. The filtered liquor does not contain any 

 lead; but when evaporated, yields crystals of urea, mixed with a 

 very minute quantity of a white powder. Thus by the action of 

 peroxide of lead, alloxane is decomposed into carbonic acid and 

 urea. 



Alloxane was analyzed with much care in Liebig's laboratory. 

 The atoms of carbon were to those of azote as 4 : 1. The mean 

 of five analyses made with oxide of copper gave, 



Carbon, 30-22 or 8 atoms =6 or per cent 30 

 Hydrogen, 2*54 or 4 atoms 0-5 ... 2-5 



Azote, 17-63 or 2 atoms = 3-5 ... 17-5 



Oxygen, 49-61 or 10 atoms = 10-0 ... 50-0 



100-00 20-0 100. 



The theoretic constitution, or C 8 H 4 Az 2 O 10 , corresponds very 

 well with the analysis. 



When the crystals of hydrated alloxane are heated, the water 

 which they contain is disengaged, and they are converted into 

 small crystals of anhydrous alloxane. This, as is well-known, 

 is the case when sulphate of zinc is heated. The hydrated crys- 

 tals effloresce very quickly in a hot place or in a vacuum, be- 

 come opaque and white, and fall into powder. When de- 

 prived of their water by heat, they diminish in weight about 26-3 

 per cent. hence they are composed of, 



1 atom alloxane, 20 or 74*76 

 6 atoms water, 6-75 or 25-24 



100. 



When alloxane is heated, the crystals assume a slight shade 

 of red. 



The composition of alloxane being known, it is easy to explain 

 its formation by the action of nitric acid on uric acid. 



It has been already stated that uric acid may be considered 

 as a compound of an unknown acid and urea. 



1 atom of urea is . C 2 H 4 Az 2 O 2 

 1 atom of the acid, C 8 Az 2 O 4 



H 



