VII. 



ANALYSIS OF BLOOD. 



If the blood has stood for any length of time, it must be* 

 thoroughly shaken in order to avoid errors which may arise 

 from the precipitation of the blood-corpuscles. Small quan- 

 tities of blood cannot be easily measured without rinsing out 

 the pipette, which is not permissible with aqueous solutions, 

 and also causes a small error in the case of blood. Instead 

 of this we may weigh off the necessary quantities, but in 

 this case we must refer the results to 1 kg. of blood (instead 

 of one liter). It is also very advantageous to dilute the 

 blood beforehand. Let 25 cc. of the blood flow into a 100- 

 cc. measuring-flask, rinse the pipette with distilled water, 

 and fill up to the 100-cc. mark. Take out portions, mixing 

 thoroughly by shaking each time before any of the blood is* 

 removed. 



1. For the determination of the water and ash 5 cc. of 

 the blood or 10 to 20 cc. of the diluted blood is sufficient. 



2. For the nitrogen determination heat 5 cc. of the blood 

 with 10 to 15 cc. of sulphuric acid and 0.5 g. of CuS0 4 (placing 

 60 cc. of fifth-normal acid in the receiver), or use 10 cc. of the 

 diluted blood (with 35 cc. of the fifth-normal acid in the 

 receiver), and titrate back with tenth-normal ammonia solu- 

 tion. 



3. For the phosphorus determination heat 5 cc. of blood 



or 20 cc. of the diluted blood with 30 g. of the oxidizing mix- 



231 



