URINE 299 



cloudiness appears, excess has been added and the whole 

 operation must be repeated. Calculate the amount of S0 3 

 present in 50 c.c. urine and in the 24 hour sample. 



15. Phosphates. 



When a solution of disodium phosphate acidified with acetic 

 acid is treated with a solution of uranium acetate, a white 

 precipitate of uranium phosphate is formed. To determine 

 the end point, a drop of the liquid is brought in contact with 

 a drop of potassium ferrocyanide on a white tile. Any excess 

 of uranium causes a brown color to appear. 



To 50 c.c. of urine in a small beaker, add 5 c.c. of a special 

 sodium acetate mixture (100 g. sodium acetate dissolved in 

 800 c.c. water plus 100 c.c. 30% acetic acid and the volume 

 made up to 1 liter). This changes any acid phosphate into 

 diacid sodium phosphate. Heat to boiling and from a burette 

 run in drop by drop a standard uranium acetate mixture 

 (1 c.c. is equivalent to 0.005 g. of P 2 5 ). Keep the mixture at 

 the boiling point. From time to time remove a drop with a 

 glass rod or dropper and bring it in contact with a drop of 

 potassium ferrocyanide on a white tile. If a glass rod is 

 used it should be rinsed before replacing it in the beaker. It 

 is convenient to arrange a tile with several drops of ferro- 

 cyanide before beginning the titration. The first appearance 

 of brown is taken as the end point. Calculate the weight of 

 P 2 5 represented by the phosphates in 50 c.c. of urine, and 

 from this the amount in the 24 hour sample. Calculate what 

 weight of phosphorus this represents. 



4. Pathologic Urine 



Some substances occur in pathological urine which are 

 absent from, or found only in traces in normal urine. Im- 

 portant among these substances are various proteins, carbohy- 

 drates, and the acetone bodies. 



I. Proteins. The proteins most frequently found are albu- 

 min, globulin, nucleo-protein, hemoglobin, glyeoprotein; of 



