URINE 293 



Measure about 50-60 c.c. of distilled water into the tall cylin- 

 der. Add 1 gm. of finely powdered soy bean, 5 c.c. of urine 

 from a pipette, and kerosene or liquid paraffin to prevent 

 foaming. Connect with a receiving bottle containing 50 

 c.c. of tenth normal acid accurately measured and two 

 drops of alizarine red. Stand the cylinder in vessels con- 

 taining water at 35-40 C. The water in the outside vessel 

 should be kept at this temperature by the addition of hot 

 water as required. Run an air current through the series to 

 drive the liberated ammonia into the acid bottle where it will 

 be absorbed. As the air from the compressed air tap may con- 

 tain traces of ammonia it should be run through 10% sulphuric 

 acid washing bottles before being run into the urine cylinder. 

 After about an hour, disconnect the cylinder and add about a 

 gram of anhydrous sodium carbonate to the urine. Connect 

 again and run the air current for another hour. Titrate the 

 excess of acid in the acid bottle with N/10 NaOH. Subtracting 

 this value from the total amount of acid used will give the 

 amount of acid neutralized by the liberated ammonia. Calcu- 

 late the weight of nitrogen liberated from the volume of urine 

 used and from this, the amount present in the total 24-hour 

 specimen. This value represents the amount of nitrogen pres- 

 ent as urea + ammonia. Subtract the value found above for 

 ammonia. The result will be the amount of nitrogen present 

 as urea. Calculate the per cent of the total nitrogen which is 

 present as urea. 



6. Uric Acid. 



Folin-S chaffer Method. Phosphates and some organic ma- 

 terial are first precipitated and filtered off. The uric acid is 

 then precipitated as ammonium urate, and titrated with N/10 

 potassium permanganate. 



To 200 c.c. of urine in a beaker, add 50 c.c. of Folin-Schaf- 

 fer reagent (50% ammonium sulphate, 0.5% uranium acetate 

 and 0.5% acetic acid). Allow to stand for y 2 hour and filter 

 through a dry filter. Measure out 125 c.c. of the filtrate (cor- 

 responding to 100 c.c. urine), add about 5 c.c. of ammonia and 



