58 



1. A Solution of Cochineal prepared by boiling 40 grams 



of cochineal in 800 cc. of water. When cool add 

 200 cc. of alcohol and filter. 



Or a solution of potassium ferrocyanide. 



Potassium ferrocyanide, - 5 grams. 



Distilled water - 100 cc. 



2. Solution of Sodium Acetate. 



Sodium acetate, - 100 grams. 



Acetic acid, - - 100 cc. 



Distilled water to make 1000 cc. 



The following procedure is of use in standardizing the uran- 

 ium solution.' 



3. Standard Solution of Disodic Hydric Phosphate, made by dis- 

 solving 10.0845 grams of the crystallized salt in water and diluting to 1 

 liter. Each cc. of this solution contains .002 of a gram of P^Oj. In 5 cc. 

 there is 0.1 gram of P2O5. 



4. Uranium Acetate. Since this cannot be obtained sufficiently 

 pure to be weighed out and used directly we make a solution of it of 

 indefinite strength and standardize it with the other solutions. 



It has been found best to make the solution of uranic acetate of 

 such a strength that each cc. will precipitate .005 of a gram of P.Oj. 

 Consequently every 2 cc. of the uranium acetate should be made equal 

 to every 5 cc. of the sodic phosphate, or upon adding 20 cc. of the 

 uranium acetate to 50 cc. of the sodium phosphate and then touching 

 the plate or paper which has been moistened with the cochineal solution 

 with the drop of the mixture, we should just get the green color. 



Put 50 cc. of the sodium phosphate with 5 cc. of the sodium acetate 

 solution into a beaker. To this add slowly from the burette, the 

 uranium acetate, testing occasionally, for the color on the paper. Sup- 

 pose that on the addition of 8 cc. from the burette, the color is obtained, 

 then 8 cc. of the uranium acetate are as strong as 20 should be, and for 

 every 8 cc. of the uranium solution that we have, 12 cc. of water should 

 be added. If it should require more than 20 cc. to produce the color, the 

 uranium solution must be concentrated by evaporation or more of the 

 solid salt added. The solution has now been graduated or standardized. 



Application. 50 cc. of the clear urine, with 5 cc. of 

 the sodium acetate solution are poured into a beaker and 

 heated; to this the uranium acetate is slowly added from 

 the burette. The mixture is constantly st,irred with a glass 

 rod, which should be applied frequently to the cochineal 

 solution. As soon as the green color is obtained the 

 process is completed. Eead off from the burette the 

 amount of uranium acetate solution used. 



Example. Urine in 24 hours equals 1180 cc. Solu- 

 tion uranium acetate used equals 24.3 ee. 



