When heated with urea, it forms oxalyl diureide, H 2 N [[Coco.
phys , 8, p. 235) concentrates the urine and precipitates the urea by nitric acid.
The urea oxalate is recrystallized and decolorized and finally decomposed by calcium carbonate (J.
Alkaline hypobromites or hypochlorites or nitrous acid decompose urea into carbon dioxide and nitrogen.
Dry chlorine gas passed into melted urea decomposes it with formation of cyanuric acid and ammonium chloride, nitrogen and ammonia being simultaneously liberated.