5o8 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



i c.c. of defibrinatecl (or hirudinised or oxalated) blood is added to 

 the contents of each bottle and well shaken so as to lake the blood and 

 saturate it with oxygen. 



Both taps are op.ned to the air and into the cup on one side (rig it) 0-2 

 c.c. of ferricyanide is put with a fine pipette. A strip of filter paper (2 cm. 

 long and i mm. broad) is put upon the cup so that it projects from the cup 

 but does not touch the ferricyanide. It facilitates the subsequent emptying 

 of the cup. 



Both bottles are fixed on their respective sides of the apparatus and placed 

 in the water-bath for 5 minutes. The pressure levels are noted, the taps 

 closed to the air and the levels noted again after i minute. If there be 

 alteration, the taps are opened for 5 minutes and closed again for i 

 minute. When there is no alteration after i minute, the ferric) anide is 

 upset into the bottle. The apparatus held in a vertical position is gently 

 shaken in a horizontal direction for i minute and replaced in the bath for 

 i minute. The pressure levels are read; shaking and replacement in the 

 bath for i minute are repeated till a constant maximal pressure is obtained. 



Supposing the difference be 49 mm. and the constant of the appa v atus 



is 373- 



v=pxk = 4gx 3'73 = 183 cmm. or -183 c.c. 



This volume is corrected for tempe ature and pressure and allowance must 

 be made for the i c.c. pipette delivering '96 c.c. of blood. The oxygen 

 capacity of the blood is 



X 83 x ^ x 22$ x = T79 c.c. per i c.c. of blood 

 289' 760 -gt> 



or 17-9 per cent. 



if 16 be the temperature and 753 mm. the barometric pressure. A duplicate 

 determination is carried out in the other bottle of the apparatus, if desired. 



Determination of the 'Oxygen Content of Blood. 



The bottles of the differential apparatus are cleaned and set up as in the 

 determination of the oxygen capacity. 



2 c.c. of ammonia are put into each bottle. 



i c.c. of the blood is carefully run under the a nmonia solution in one 

 bottle. 



i c.c. of the blood, saturated with oxygen, is carefully placed under the 

 ammonia in the other bottle. 



If the unsaturated blood is placed in the right-hand bottle and the 

 saturated blood in the left-hand bottle, *2 c.c. of potassium ferricyanide is put 

 in the right-hand cup with a strip of filter paper. 



The bottles are put upon the stoppers and the bottles placed in the water- 

 bith, care being taken not to disturb the layer of blood beneath the ammonia. 



The taps are closed to the air when the temperature is constant and there 

 is equilibrium. 



Tli'- blood is now mixed with the ammonia by gently shaking the apparatus 

 for at least 2 or 3 minutes so as to ensure complete laking. 



The f.rricyanide in the right-hand bottle is upset and the oxygen driven 

 off by shaking. 



The maximum pressure change is noted. 



Supposing it to be 17 mm., then the amount of oxygen is 



X 7 x 3*73 = 0*0634 c.c. per c.c. of blood 

 or 6-34 per cent. 



This amount is corrected for temperature and pressure and for the volume 

 delivered by the pipette. 



A further correct on of o'oi c.c. or i per cent, is added to allow for the 

 solub lity of oxygen and nitrogen in the plasma of the unsaturated blood. 



