URINE 339 



the uric acid solution a 20% filtered solution of sodium sulfite 

 should be available. Dissolve 1 gm. of uric acid in 125 to 150 c.c. 

 of 0.4% lithium carbonate solution and dilute to a volume of 500 

 c.c. Transfer 50 c.c. corresponding to 100 mg. of uric acid to 

 each of a series of volumetric liter "flasks. Add about 300 c.c. 

 of water and then add 500 c.c. of clear 20% sodium sulfite solu- 

 tion, mix, dilute to volume, and mix thoroughly. Fill a series 

 of 200 c.c. bottles and stopper very tightly. The reason a 

 series of small bottles is used as containers is, of course, to 

 reduce the absorption of oxygen from the air. 



2. A 10% sodium sulfite solution, kept like the uric acid 

 solution, in small tightly stoppered bottles. 



3. A 5% sodium cyanide solution. 



4. A solution containing 5% of silver lactate and 5% of lactic 

 acid. 



5. The uric acid reagent of Folin and Denis. Boil 100 gm. of 

 sodium tungstate with 80 c.c. of phosphoric acid (85%) and 

 700 c.c. of water for not less than 2 hours and dilute to 1 liter. 



Transfer from 1 to 3 c.c. of urine to a 15 c.c. centrifuge tube 

 and mix with enough water to make a volume of about 6 c..c. 

 Add 5 c.c. of the acid silver lactate solution and stir with a very 

 fine glass rod (diameter 1 to 2 mm.). Rinse off the rod with a 

 few drops of water and centrifuge. If enough silver solution 

 has been added the precipitate settles very quickly. Add a 

 drop of silver lactate solution so as to be sure that an excess is 

 present; if a preciptate is formed add more (2 c.c.) of the silver 

 lactate solution and centrifuge again. In point of fact the first 

 5 c.c. addition of silver lactate is almost always enough, but it is 

 not safe to omit the test. Pour off the clear supernatant liquid 

 as completely as possible. 



To the precipitate in the centrifuge tube add, from a burette, 

 4 c.c. of 5% sodium cyanide solution and stir until a perfectly 

 clear solution is obtained. Pour the contents into a 100 c.c. 

 volumetric flask and rinse tube and stirring rod, using for this 

 purpose about 15 to 25 c.c. of water. Add 5 c.c. of 10% sodium 



