PHOSPHORIC ACID IN BLOOD 177 



c.c. is a sufficiently close approximation). The flask is filled to 

 the mark with water, and precipitations and readings are made 

 as usual. The determination should be made promptly after 

 filtering. (6) Where many determinations are to be made it is 

 advisable to make a special standard when determinations may 

 be made more simply as follows: 



Standard. Made by measuring 2 c.c. of the strong stock 

 standard phosphate solution ( = 1.2 mg. of HsPCU) into a 100 c.c. 

 flask, adding 80 c.c. of the acid ammonium sulfate, and making 

 up to 100 c.c. with water. Of this standard 5 c.c. contains 0.06 

 mg. of HsPO4. For the determination 5 c.c. of the filtrate ( = 0.6 

 c.c. of plasma) are measured directly into 25 c.c. of the strychnine 

 molybdate reagent in one 50 c.c. graduated flask, 5 c.c. of the 

 standard solution into another, and after mixing and standing three 

 minutes the flasks are filled to the mark, the solutions mixed, 

 and determinations made. 



Acid-Soluble. 10 c.c. of the filtrate are measured into one of 

 the large test-tubes, glass beads and 1.5 c.c. of sulfuric-nitric acid 

 mixture are added, and the mixture is digested. The digestion 

 presents some difficulties because of the large amount of ammonium 

 sulfate present. The first stage is passed over quickly, then in the 

 second stage of heating when the mixture thickens and begins 

 to foam, the heat is moderated and so continued until foaming 

 ceases and the salt fuses to a small volume in the tube. Heating 

 is then carried on for about ten minutes at a rate just sufficient to 

 prevent loss of ammonium sulfate from the tube by volatilization. 

 The tubes are then cooled, treated with one drop of 0.3 per cent 

 cane sugar solution, and reheated in the regular way. After 

 dissolving in water the solution is titrated with alkali, noting the 

 amount used. The standard contains 3 c.c. of the standard phos- 

 phate solution, 8 c.c. of the acid ammonium sulfate, and the 

 amount of alkali used to neutralize the test solution. The mixture 

 is neutralized and the phosphoric acid determinations are carried 

 out in the regular way. 



Corpuscles 



Five c.c. of corpuscles are measured with a pipette into 

 a 10 c.c. glass-stoppered graduated flask and the pipette is 

 rinsed clean with small portions of warm water. The rinsings are 



