Preparation of Soy Bean Urease. 



57 



cent. KiHP0 4 is added before the urease. Time law of urease 

 action: The velocity of urea decomposition is expressed by the 

 isotherm, 



where / is the time of reaction, e the enzyme concentration, and x 

 the concentration of ammonia formed. The derivation of the 

 equation will be given later. 



A method for the estimation of sugar in small quantities of blood. 

 By Robert C. Lewis and Stanley R. Benedict. 



[From the Chemical Research Laboratory, General Memorial Hospital, 



The red color obtained by heating a dextrose solution with 

 picric acid and sodium carbonate is employed as the basis of the 

 present method for the determination of blood sugar, the reaction 

 being so delicate that it is possible to determine the dextrose in as 

 little as 0.5 c.c. of blood. Following is the method in detail as 

 ordinarily used by us. 



Two c.c. of blood are drawn from a vein through a hypodermic 

 needle into an Ostwald pipette, a little potassium oxalate in the 

 tip of the pipette preventing clotting. The blood is discharged 

 immediately into a 25 c.c. volumetric flask containing 10 c.c. of 

 N/100 acetic acid previously heated in a boiling water bath. The 

 pipette is rinsed once with distilled water. The flask is replaced 

 in the boiling water bath and shaken occasionally for five minutes. 

 After cooling, 1 c.c. of 5 per cent, dialyzed iron (Merck) is added 

 to precipitate any protein still in solution. Distilled water is 

 added to the mark, the contents of the flask are filtered, and an 

 aliquot of the clear filtrate (10 c.c. or 15 c.c.) is measured into a 

 large Jena test tube (200 X 22 mm.) and evaporated to 1 c.c. or 

 below (but not to dryness) over a direct flame, two glass beads 

 being used to prevent bumping. Two c.c. of saturated picric 

 acid solution and 3 c.c. of 20 per cent, sodium carbonate are added 



34 (851) 



New York City.] 



