102 LABORATORY MANUAL OF GENERAL PHYSIOLOGY 



For values of the pH of blood determined by the glass electrode cf. 

 Haugaard and Lundsteen, Comp. rend. Labor. Carlsberg, Ser. chim. 21: 

 85, 1936. 



4. Determination of the O2 Capacity of Ox Blood. — This may be defined 

 as the volume of oxygen which may be extracted from 100 cc. of blood 

 when it is in equilibrium with atmospheric air. Place 2.5 cc. of blood in 

 the Van Slyke apparatus, draw in atmospheric air and shake the apparatus 

 for 3 minutes. It is not necessary to change the air. Drive out the air 

 through the cup and fill the bore of the stopcock which is on the side of 

 the cup with mercury from the small mercury bottle. Turn the upper 

 stopcock and through the outflow tube run all the blood in excess of 

 exactly 2 cc. Close the stopcock and rinse out the cup. Proceed with 

 the determination as follov/s: 



1. Place in the cup 



6 drops of 1% saponin 

 2 drops of caprylic alcohol 

 6 cc. of water 



2. Run into burette all but 1 cc. Wait one minute for haemolysis to 

 occur. 



3. Add 3 drops of 20% potassium ferricyanide to the contents of the 

 cup and run it in. 



4. Seal with a drop of mercury. 



5. Evacuate the bulb and shake the analyzer for 3 minutes. 



6. Absorb the CO2 with 0.5 cc. of 0.5 N sodium hydrate. 



7. Wait 2 minutes for drainage. Read. 



8. Wash the apparatus with distilled water. 



9. Subtract 0.115 from the reading for air dissolved in the reagent. 

 Correct the remaining figure for nitrogen dissolved in blood, and for 

 aqueous vapor, barometric pressure and temperature (see Table 3 on p. 112). 

 Calculate the per cent of haemoglobin. 



Blood is said to contain 100 per cent haemoglobin when its O2 capacity 

 is 18.5 volumes per cent. The per cent of haemoglobin in the sample is 

 consequently given by 



2i^f2 X 100. , 



5. Determination of the O2 Dissociation Curve. — Gas mixtures will 

 be provided containing a constant percentage of CO2 and varying per- 

 centages of O2. (Mixtures of 6% CO2 and 4.5% O2 and 2.5% O2.) 

 Calculate the partial pressure of each gas present in each mixture used. 



In the Van Slyke apparatus equilibrate blood with these mixtures, 

 taking care to change the gas mixture at least once as in determining the 



