174 METHODS FOR THE ANALYSIS OF BLOOD 



nitric acid mixture are added, and the solution is treated as with 

 whole blood. If a 0.5 c.c. pipette is not available, the plasma 

 may be diluted with an equal volume of water and 1 c.c. taken. 



Corpuscles 



Plasma and corpuscles are separated by centrifugation for 

 ten minutes at about 4000 R.P.M., the plasma is removed as com- 

 pletely as possible, the corpuscles are washed once by shaking 

 with a volume of 0.9 per cent salt solution equal to the volume 

 of plasma, then centrifuged at once in the same way as before. 

 If this operation is performed quickly, the small remaining amount 

 of plasma is washed out without significant change in the phos- 

 phate content of the corpuscles (by dialysis). 0.08 c.c. of corpuscles 

 gives a total phosphate content of about the strength of the stand- 

 ard used. To obtain this amount, 1 c.c. of the corpuscles is meas- 

 ured with an Ostwald pipette into a 25 c.c. glass-stoppered, cali- 

 brated flask, the pipette rinsed clean with water, the rinsings are 

 added to the flask, and the mixture is made up to volume with 

 water, and mixed. 2 c.c. of this dilution (0.08 c.c. of corpuscles) 

 are measured into a large test-tube, then treated as in the case of 

 whole blood. 



Lipoid Phosphoric Acid (" Lecithin ") 

 Whole Blood 



Three c.c. of well mixed whole blood is measured into a 100 

 c.c. flask containing about 75 c.c. of a mixture of 3 parts 

 alcohol and 1 part ether (both redistilled). The blood is 

 made to enter in a slow stream of drops and the liquid in the flask 

 kept rotating rather rapidly so as to prevent the formation of 

 large aggregates of precipitate which are difficult to extract. 

 The flask and contents are then immersed in boiling water with 

 frequent and strong rotation (to prevent superheating) until the 

 liquid begins to boil, cooled to room temperature, made up to 

 volume, mixed, and filtered. For the determination 10 c.c. ( = 0.3 

 c.c. of blood) are measured into one of the large test-tubes, glass 

 beads added, and the whole is evaporated to dryness in a boiling 

 water bath. The tube should be shaken frequently until boiling 

 begins, after which the solution will proceed quietly to dryness. 



