URIC ACID. 35 



and heated, a solution immediately takes place : 1 part of lithia, 

 and 1 of uric acid, dissolve in 90 parts water, at the temperature 

 of 122, and they remain in solution when the liquid is cooled. 

 At the boiling point, 1 part of lithia, and almost 4 parts of uric 

 acid dissolve in 90 parts of water, with the evolution of much car- 

 bonic acid. On cooling, the whole concretes into a gelatinous 

 mass, easily redissolved by heat. Urate of lithia at 122 is so- 

 luble in sixty times its weight of water. Caustic lithia dissolves 

 about six times its weight of uric acid. Urate of lithia is com- 

 posed of 



Uric acid, 85-54 or 10-35 or 1 atom. 



Lithia, . 14-46 or 1*75 or 2 atoms. 



100-00 



M. Lipowitz proposes lithia as an excellent reagent for sepa- 

 rating uric acid from the other ingredients in calculi. We have 

 only to heat the powdered calculus with a solution of lithia ; 

 filter and add muriatic acid ; pure uric acid falls down. He 

 boiled lepidolite in fine powder with uric acid. On dropping 

 muriatic acid into the filtered liquid, uric acid precipitated. The 

 same experiment succeeded with spodumen, containing lithia. 



When dry uric acid is heated in chlorine gas, cyanic acid, 

 muriatic acid, and chloride of cyanogen are formed. When moist 

 uric acid is subjected to the same treatment, the substances form- 

 ed are carbonic acid, ammonia, and oxalic acid. When it is long 

 boiled in caustic potash ley ammonia is given out, and oxalic 

 acid formed. 



According to Braconnot it combines with the alkalies in two 

 proportions, forming with each, urates and diurates. The diurate 

 of potash, according to his analysis is composed of 

 Uric acid, . 66-4 or 23-1 

 Potash, 33-6 or 12- 



100- 



According to this analysis its atomic weight is 23. 

 When the alkaline urates are heated to redness in the open 

 air, the residue is a mixture of charcoal and carbonate of the al- 

 kali. But when the experiment is conducted in close vessels, 

 cyanodide of the alkali, cyanate and carbonate are formed, as 

 appears from the experiments of Lipowitz.* 



* Ann. der Pharm. xxxviii. 356. 



