HANDBOOK FOR BIO-CHEMICA 



formed. The liquid is decanted after standing 24 hours, and 

 the precipitate washed with small quantities of ice-cold water, 

 and while still moist added to boiling dilute hydrochloric acid 

 and kept boiling for some time, continually stirring. After 

 cooling the separated uric acid is filtered, thoroughly washed 

 with cold water, and dried. If not quite pure, it can be redis- 

 solved in alkali, precipitated by C0 2 , and treated again as 

 above, or it may be added to water and dissolved in the cold 

 by the gradual addition of sodium amalgam, and after the re- 

 moval of the impurities by filtration the uric acid may be re- 

 precipitated by HOI. 



2. Filtered normal urine is treated with 20-30 c.c. of 25$ 

 HC1 for each litre of urine. After 48 hours collect the crys- 

 tals and purify them by redissolving in dilute alkali, decolor- 

 izing with animal charcoal, and reprecipitating with hydro- 

 chloric acid. Filter, wash with ice-cold water, and dry. 



3. Uric acid may be prepared synthetically by melting 

 0.1-0.15 grms. glycocoll with 1-2 grms. urea in a test-tube 

 over a small flame. The mass is heated until solid, care be- 

 ing taken not to apply too strong (above 220 C.) a heat, also 

 not too low a heat. The cooled mass, which ought to be yel- 

 low or yellowish-brown, is dissolved in boiling water with the 

 addition of ammonia and filtered; the filtrate is precipitated 

 when cold with a mixture of magnesium mixture and ammo- 

 niacal silver nitrate solution. The precipitate is washed with 

 ammoniacal water, subdivided in hot water, and treated with 

 a solution of sodium sulphide. The filtrate from the silver 

 sulphide is acidified with HC1 and concentrated, when on 

 cooling impure uric acid will crystallize out. Test these crys- 

 tals with the murexid test, and if they do not give the reac- 

 tion reprecipitate with ammoniacal silver solution and proceed 

 as above, when comparatively pure uric acid will be obtained. 

 It is better to make several fusions of glycocoll with urea, and 

 adding these together and obtaining the uric acid therefrom 

 in larger quantities. (/. Horbaczeivski.) 



