220 THE URINE. 



0.01, indicates the amount of chlorides present in the 10 c.c. of 

 urine, calculated as sodium salt. 



The presence of albumins and sugar does not interfere with the 

 method. 



Quantitative Estimation of the Phosphates. 



To determine the amount of the alkaline and earthy phosphates 

 together, 50 c.c. of urine are treated with 5 c.c. of a solution con- 

 taining about 100 grammes of sodium acetate and 100 c.c. of a 30 

 per cent, solution of acetic acid to the liter. In this manner any 

 monacid phosphates that may be present are transformed into diacid 

 phosphates. A few drops of tincture of cochineal are then added, 

 and the mixture heated to the boiling-point and titrated with a 

 standard solution of uranyl acetate or nitrate until a greenish color 

 is noticed in the resulting precipitate of uranyl phosphate which 

 does not disappear on stirring. From the number of cubic centim- 

 eters employed the corresponding amount of phosphates is then 

 determined in terms of P 2 O 5 . The uranium solution is of such 

 strength that 20 c.c. represent 0.1 gramme of P 2 O 5 . 



The presence of sugar and albumins does not interfere with the 

 method. 



Separate Estimation of the Earthy and Alkaline Phosphates. 



Two hundred c.c. of urine are rendered strongly alkaline with 

 ammonia and set aside for several hours. The earthy phosphates 

 are thus precipitated, and are collected on a small filter, washed with 

 dilute ammonia (1 : 3), transferred to a beaker, and dissolved with 

 as little acetic acid as possible. Distilled water is added so as to 

 make the volume of the liquid about 50 c.c., when the solution is 

 boiled and titrated as above. In a second portion of the urine 

 the total amount of phosphates is then determined. The difference 

 between the two results indicates the amount of phosphates which 

 is present in combination with alkalies. 



If it is desired to remove the total phosphates from a specimen 

 of urine preliminary to some further step in analysis, the fluid is 

 rendered alkaline with the hydrate of an alkaline earth and pre- 

 cipitated with a soluble calcium or barium salt. Or we may pre- 

 cipitate directly with neutral or basic acetate of lead. In the first 

 instance, the excess of calcium or barium, and in the second, that 

 of lead, must then be removed. 



Quantitative Estimation of the Sulphates. 



To determine the amount of both mineral and conjugate sulphates, 

 100 c.c. of urine are treated with 8 c.c. of strong hydrochloric acid 

 and heated to the boiling-point. In this manner the conjugate sul- 



