CARBON MONOXIDE— REDUCED HEMOGLOBIN 151 



Douglas, Haldane and Haldane(i') tend to cross those of Bohr, 

 Hasselbalch and Krogh(2) we must seek some other explanation. This 

 may perhaps be found in the fact that the latter curves were obtained 

 from the analysis of whole blood, the former from those of dilute blood. 

 (In both cases of course the equilibrium was struck on whole blood.) 



Within the last few years much additional interest has been added 

 to the equation 



CO + Hb ^^ HbCO 



by the work of Hartridge and Roughton(5), for they have taken the 

 reaction out of the region of statics, in which it had hitherto been, 

 and have removed it to the region of kinematics, having extended 

 their brilUant researches to the determination of the velocity constants 

 of the two phases of the reaction respectively. 

 Firstly, let us consider the reaction 



CO + Hb ^ HbCO. 



Their method was along the same hnes as that for the association 

 of oxygen with haemoglobin. They started with two separate solu- 

 tions (each free from oxygen), one containing reduced haemoglobin 

 in a strength of -2 to -4 per cent., the other containing distilled water 

 charged with carbon monoxide in solution, into which is introduced 

 some Na2S2 04. This latter material, which is a strong reducing agent, 

 ensures the freedom of the system from oxyhsemoglobin whilst itself 

 not affecting the reaction between CO- and reduced haemoglobin. The 

 two solutions are forced under pressure into a mixing chamber in 

 which they become intimately mixed in a time which is negUgible 

 as compared with that taken for the chemical irnion of the CO and 

 the haemoglobin. From the mixing tube the mixture passes along a 

 cyhndrical tube at a velocity of the order of 100 cm. per second. 

 The fluid at first does not show the bands of CO-haemoglobin, but 

 in proportion as the observation-spectroscope is moved further from 

 the mixing chamber so the bands become more intense, until at 

 last the reaction is complete. At last ! That is, in about one-tenth 

 of a second with such strengths of solution as were used by Hartridge 

 and Roughton. 



Here is a remarkable thing. A few pages back I said that the 

 affinity of carbon monoxide for haemoglobin was 245 times that of 

 oxygen for haemoglobin. I said so because haemoglobin saturates itself 

 equally whether in equilibrium with CO at '156 mm. pressure or with 

 oxygen at 38 mm. pressure and 38 is 245 times -156. It would have 



