URINE. Ill 



otherwise more of the uranium solution must be added and 

 retested. 



From the number of c.c. of the uranium nitrate solution 

 required calculate the P 2 5 in the 25 c.c. of urine employed 

 and from that determine the total P 2 5 in the 24-hour 

 urine. 



EARTHY P 2 5 . 



In the precipitation of the earthy phosphates by means 

 of NH 4 OH various errors creep in which render the determina- 

 tion of doubtful value. Thus, in whatever form the earthy 

 bases (Ca or Mg) were present in the urine, they would form 

 insoluble phosphates when the fluid was made alkaline, and 

 the precipitate would therefore contain P 2 5 not originally 

 combined with the alkaline earths. 



The method is given because it is still employed. 



Quantitative Estimation. 



Place 50 c.c. of urine in a beaker and make it alkaline with 

 NH 4 OH. A precipitation of the earthy phosphates occurs. 

 Allow this to stand for a couple of hours and then collect the 

 precipitate upon a small filter. After having washed the 

 precipitate with very dilute NH 4 OH transfer it quantitatively 

 to an evaporating-dish by means of dilute acetic acid, which 

 dissolves the P 2 5 . Dilute the solution to about 25 c.c. and 

 titrate as outlined under total phosphates. The difference 

 between this amount and that of the total will be the amount 

 of alkaline P 2 5 . 



ORGANIC PHOSPHORUS. 



The method employed for the determination of the organic 

 phosphorus in the urine is based upon the same principle as 

 that in use for organic sulphur. The total phosphorus is 



