CO 2 DETERMINATION 



123 



COj in solution in acidified blood, i.e., volume of 

 liquid (2.75 c.c.) X solubility coefficient (1.0)XCO 2 



(6) 

 in air in tube = 0.096 c.c. (7) 



Total CO 2 from blood, i.e., (6) + (7) = 0.479 c.c. (8) 



CO 2 reduced from barometric pressure 762 and tem- 

 perature 26 to 760 and 0, i.e., 



760 



273 



762 (273 + 18) 

 Volumes per cent CO 2 in blood, i.e., (9)XlOO =44.8 



= 0.448 c.c. (9) 



Q7 Q6 Q9 LO 1.1 \Z W '1.4 



Cc.COj. In solution in Ice. blood mixTare at given Temperature andT&Omm.pnEssureCQz., 



FIG. 8. Curves Expressing Solubility of CO?. The acid-blood mixture of 

 Curves 1, 2, 3, 4, and 7- was made as follows: ammonia 1.5 c.c., blood 

 1.0 c.c., tartaric acid 0.25 c.c. The mixture of Curves 5 and 6 was made as 

 follows: ammonia 2.0 c.c., blood 1.0 c.c., tartaric acid 0.5 c.c. Curves 

 1 and 2, fresh human blood; Curve 3, fresh cat blood; Curve 4, blood 

 of dog anesthetized with chloratone and alcohol; Curve 5, fresh pig blood; 

 Curves 6 and 7, human serum. 



Comoarison of the results obtained with the original Barcroft- 

 Haldane method and with this modification shows in every case 

 that the latter gives figures 2 to 3 volumes per cent higher than 

 those obtained with the older method. This is due to the fact 

 that the heavy precipitate by adding both ferri cyanide and acid 

 to blood renders it extremely difficult in the Brodie apparatus to 

 shake the last trace of CO2 out of the thick coagulum. 



