304 PHYSIOLOGICAL CHEMISTRY 



volumetric flask. Add 2 c.c. of normal acid and 10 c.c. of the 

 alkaline picrate solution and after 10 minutes standing dilute 

 to 50 c.c. The preparation of the standard must of course have 

 been made first so that it is ready for use when the unknown 

 is ready for the color comparison. The height of the standard 

 usually 20 mm., divided by the reading of the unknown and 

 multiplied by 6 gives the "total creatinine" in mg. per 100 c.c. 

 blood. 



In the case of uremic bloods containing large amounts of 

 creatinine 1, 2, or 3 c.c. of blood filtrate, plus water enough to 

 make approximately 5 c.c. are substituted for 5 c.c. of the undi- 

 luted filtrate. The normal value for "total creatinine" given 

 by this method is about 6 mg. per 100 c.c. of blood. 



Determination of Uric Acid in Blood. (Folin: Jour. Biol. 

 Chem., xxxviii, 81, 1919). SOLUTIONS REQUIRED FOR URIC ACID 

 DETERMINATIONS. 



1. The standard uric acid sulphite solution. In a 500 c.c. 

 flask dissolve exactly 1 g. of uric acid in 150 c.c. of water by the 

 help of 0.5 g. lithium carbonate. Dilute to 500 c.c. and mix. 

 Transfer 50 c.c. to a liter flask; add 500 c.c. of 20% sodium 

 sulphite solution; dilute to volume and mix. Transfer to small 

 bottles (cap. 200 c.c.) and stopper tightly. This standard uric 

 acid solution keeps almost indefinitely in unopened bottles, be- 

 cause the sulphite prevents the spontaneous oxidation of the 

 uric acid. In used bottles the standard usually remains good 

 for 2-3 months. 



2. A 10% sodium sulphite solution. 



3. A 5% sodium cyanid solution, to be added from a buret. 



4. A 1.0% solution of sodium chlorid in 0.1 normal hydro- 

 chloric acid. 



5. The uric acid reagent prepared according to Folin and 

 Denis. Introduce into a flask : 



750 c.c. of water, 

 100 g. of sodium tungstate, 

 80 c.c. of phosphoric acid (85% H 3 P0 4 ). 



