484 



CHEMISTRY OF THE PROTEIDS 



CHAP. 



oxygen in combination with haemoglobin, while that given by the 

 pump includes also the oxygen in simple solution, and Haldane has 

 therefore " deducted from the result by the pump the percentage of 

 oxygen (about 0'63 with blood saturated at 13) which would be in 

 solution. This amount was calculated on the assumption that the co- 

 efficient of absorption of oxygen in blood is th less than it is in water ; 

 Paul Bert's experiments l on the nitrogen and oxygen of the blood of 

 animals in compressed air having shown that this value is probably 

 correct." 



The absorption coefficients of blood and of its constituents for 

 gases at 15 and 38, according to Bohr's 2 quite recent account, are 

 as follows (see the figure on p. 488) : 



Haldane, in addition to the correction for the absorption coefficient,, 

 made also a very slight additional correction in his ferricyanide 

 method, on the assumption that any excess of nitrogen over the- 

 percentage present in blood saturated with air at the same tempera- 

 ture, was due to the accidental presence of air in the pump. Com- 

 paring the results given by the blood -pump and the ferricyanide 

 method for defibrinated and for oxalated ox-blood, they were found 

 to be identical. Thus 100 volumes of blood yielded 2 2 -38 volumes 

 of oxygen by the blood-pump and 2 2 '3 9 volumes by the ferricyanide 

 method. The best apparatus for estimating the oxygen and the 

 carbonic acid in such small quantities of blood as 1 cc. is that of 

 Haldane and Barcroft, 3 which is also based on the potassium 

 ferricyanide method. On employing Haldane's ferricyanide method,. 



1 Paul Bert, Lapression barometrique, 1878, p. 661. Haldane remarks: "Bert's 

 experiments on blood saturated with compressed air outside the body apparently 

 indicate a much higher coefficient of absorption, but in all probability these experi- 

 ments were vitiated by the presence in the saturated blood of air-bubbles caused by the 

 shaking." 



2 Christian Bohr, ' Absorptionscoefficienten des Blutes und des Blutplasmas fiir Gase,' 

 Skand. Arch.f. Physiol. 17. 104 (1905). See also Nagel's Handbuch der Physiologic 

 des Menschen, vol. i. p.. 54 (1905). 



3 Haldane and Barcroft, Journ. of Physiol. 28. 232 (1902). 



