MICROCHEMICAL METHODS FOR BLOOD ANALYSIS 305 



Partly close the mouth of the flask with a funnel and small 

 watch glass and boil gently for two hours. Dilute to a liter. 



A still stronger reagent is obtained by heating the sodium 

 tungstate (100 gm.) and the phosphoric acid (80 c.c.) plus 

 water (700 c.c.) for 24 hours, instead of 2 hours; but the ad- 

 vantage gained, about 20%, is not needed. Dilute the solution 

 to 1 liter. 



6. A solution of 5% silver lactate in 5% lactic acid. 



To 10 c.c. of blood nitrate in each of two centrifuge tubes 

 add 2 c.c. of a 5% solution of silver lactate in 5% lactic acid, 

 and stir with a very fine glass rod. Centrifuge ; add a drop of 

 silver lactate to the supernatant solution, which should be al- 

 most perfectly clear and should not become turbid when the 

 last drop of silver solution is added. Remove the supernatant 

 liquid by decantation as completely as possible. Add to each 

 tube 1 c.c. of a solution of 10% sodium chlorid in 0.1 normal 

 hydrochloric acid and stir thoroughly with the glass rod. Then 

 add 5 to 6 c.c. of water, stir again, and centrifuge once more. 

 By this chlorid treatment the uric acid is set free from the pre- 

 cipitate. Transfer the two supernatant liquids by decantation 

 to a 25 c.c. volumetric flask. Add 1 c.c, of a 10% solution of 

 sodium sulphite, 0.5 c.c. of a 5% solution of sodium cyanid, and 

 3 c.c. of a 20% solution of sodium carbonate. Prepare simul- 

 taneously two standard uric acid solutions as follows: 



Transfer to one 50 c.c. volumetric flask 1 c.c. and to another 

 50 c.c. flask 2 c.c. of the standard uric acid sulphite solution 

 described above. To the first flask add also 1 c.c. of 10% sodium 

 sulphite solution. Then add to each flask 4 c.c. of the acidified 

 sodium chlorid solution, 1 c.c. of the sodium cyanid solution, 

 y and 6 c.c. of the sodium carbonate solution. Dilute with water 

 to about 45 c.c. When the two standard solutions and the un- 

 known have been prepared as described they are ready for the 

 addition of the uric acid reagent. Add 0.5 c.c. of this reagent 

 to the unknown and 1 c.c. to each of the standards, and mix. 

 Let stand for 10 minutes, fill to the mark with water, mix, and 

 make the color comparison. 



