156 HEMOGLOBIN 



the velocity constants of both phases of the reaction are unchanged 

 by cH, the equiUbrium constant should have been found, by Barcroft 

 and Murray (6) on haemoglobin and by Douglas, Haldane and 

 Haldane(i) on whole blood, to have been so greatly influenced. 



In many ways the technique associated with research on carboxy- 

 hsemoglobin is simpler and runs more rapidly than that which involves 

 oxygen. An estimation with the Hartridge reversion spectroscope 

 takes only a few moments whilst a determination of percentage 

 saturation by gas analysis requires perhaps 45 minutes. Carbon 

 monoxide does not affect a hydrogen electrode as does oxygen, an 

 advantage which has probably disappeared with the introduction of the 

 glass electrode. There is always the chance of adventitious oxidations 

 taking place at the expense of the oxy haemoglobin, or of the atmo- 

 sphere to which it is exposed and so forth, and lastly, in the case of 

 dilute solutions of oxyhaemoglobin, it can scarcely be said that 

 methods exist of estimating the percentage saturation over the whole 

 range of a dissociation curve from to — 100 per cent. 



There has always been the hope therefore that the more important 

 facts regarding haemoglobin were to be obtained more easily by a 

 study of the carboxy- than of the oxy- body, and that having been 

 found out on CO-haemoglobin, the results could be transferred bodily 

 to oxyhaemoglobin. 



It was this hope which inspired the following technique. A given 

 quantity of a dilute solution of carboxyhaemoglobin is put into 

 each of a series of saturators of very different sizes. 



Suppose 5 c.c. of a solution of haemoglobin made by diluting blood 



fifty times are used, and the blood has a CO capacity of 1 c.c. = • 190c.c. 



of CO, then 5 c.c. of the dilute solution will have a CO capacity of 



•190 



-— r- X 5= -OlOcc. This is then put into a saturator which contains 



hydrogen which is free from any trace either of carbon monoxide or 

 of oxygen. Now if this tonometer is shaken sufficiently and if all 

 goes well, some of the CO will be shaken out and an equiUbrium will 

 be established. Suppose at the end an estimation shows that the 

 haemoglobin is 40 per cent, reduced Hb and 60 per cent. COHb, 



clearly - . x '019 c.c. of CO will have been ceded to the atmosphere. 



If this atmosphere occupies a volume of 5 litres the pressure of CO 



.„, -019 X 60 760 Ani-7 rru • 1 



will be — :r-p^ — X _-^7, mm. = -0017 mm. Thus a smgle measurement 

 100 oOOO 



