CHEMICAL URINALYSIS. ITT 



able sign in dropsical conditions. The presence of chlorides may 

 be tested by acidulating with nitric acid and adding silver nitrate. 

 A white precipitate of chlorides is formed. 



Quantitative test: Dilute 10 c.c. of urine with 100 c.c. of water; 

 add a few drops of potassium chromate solution; then add slowly 

 a solution of silver nitrate (17 grams to a liter of water) until the 

 color of the solution changes from yellow to red. Each c.c. of silver 

 nitrate (standard solution) used will precipitate 0.00354 gram of 

 chlorine, from which may be estimated the percentage by weight 

 of chlorine in the urine. 



6. Phosphates. The earthy phosphates are those of calcium and 

 magnesium; the alkaline phosphates are those of sodium and potas- 

 sium ; triple phosphate is ammonio-magnesium phosphate ; the acid 

 phosphates of the alkalies give the acid reaction to the urine, and 

 are represented by the formulas NaH 2 P0 4 and KH 2 P0 4 . An 

 excess of phosphates occurs in diabetes. A diminution generally 

 occurs in nephritis, gout, rheumatism, and acute infectious diseases. 



The earthy phosphates may be detected by adding ammonium 

 hydrate and gently heating; a white precipitate is formed, which 

 is dissolved by the addition of acetic acid. A quantitative deter- 

 mination may be made by filling a test tube whose diameter is two 

 centimeters with urine to the depth of 5.3 centimeters; to this add 

 a few drops of ammonium hydrate and heat until the phosphates are 

 precipitated; set aside and in fifteen minutes examine. If the 

 height of sediment be 1 centimeter, the quantity of earthy phos,- 

 phates is normal, but diminished or increased if the height should 

 be less or greater than 1 centimeter. 



To determine approximately the quantity of alkaline phosphates, 

 proceed as follows : Kemove the earthy phosphates by precipitation 

 and filtration, and to 10 c.c. of the filtered urine add 3 c.c. of mag- 

 nesium mixture. Magnesium fluid is prepared by dissolving magne- 

 sium sulphate and ammonium chloride, one part each, in eight parts 

 of distilled water and one part of ammonium hydrate. The amount 

 of turbidity formed by the precipitate indicates the quantity of 



alkaline phosphates present. If it is simply milky, the quantity is 

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