234 THE URINE. 



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 (Folin). 



In order to estimate the amount of mineral and conjugate sul- 

 phates it is best to determine the total sulphates in one portion and 

 the conjugate sulphates in another, the difference between the two 

 giving the mineral sulphates. 



Quantitative Estimation of the Total Sulphates. 



50 c.c. of clear filtered urine are treated with 5 c.c. of concen- 

 trated hydrochloric acid and 5 c.c. of a 4 per cent, solution of 

 potassium chloride. The mixture is boiled until it is colorless (5-10 

 minutes), and then treated while still boiling with 25 c.c. of a 10 per 

 cent, solution of barium chloride, drop by drop. It is then kept on a 

 hot water-bath or an asbestos plate, hot (but not boiling) for from one- 

 half to one hour. The precipitate is now collected on a Schleicher 

 and Schiill filter, the weight of the ash of which is known (No. 589). 

 Care should be taken never to allow the filter to run dry, and small 

 amounts of hot water must be added to the last cubic centimeters 

 remaining, the final traces being placed upon the filter with the aid 



