102 . HEMOGLOBIN . 



to estimate the percentage of CO -haemoglobin in the mixture to give 

 all the information required. Of the total haemoglobin present the 



ratio of ^ ^., was the same as that of -^f^, - in the fluid contained 

 OgHb Hb 



in the tonometer, and hence we obtain the position of the point on 



the curve relative to the ordinate, whilst the CO pressure is easily 



calculated from a knowledge of (1) the volume of the saturator, 



(2) the amount of COHb broken down. 



In the preliminary experiments of the series the estimation of the 



COTTb 



- ^. jj, was made with the Hartridge reversion spectroscope, with the 



result shown in Fig. 29 for sheep's blood. 



'/o satvjrqtiOTi 



■the curve -fits fbe ctivation 



[HcHco] 



= O.03I 



o-a. C.3 o.y- 



co f«-nsioT» in WTO. 

 Fig. 30. Dissociation curve of CO-haemochromogen. 



Since that time more accurate methods for the estimation of the 

 CO-hsemoglobin have been introduced, replacing the reversion spectro- 

 scope by a photographic method. This method has been found by 

 Hecht and Morgan (ii), and later by Forbes, to give a hyperbola on 

 occasions, but not always. Therefore as things stand the hyperbola 

 has certainly been obtained and a curve of so definite a shape cannot 

 be obtained repeatedly, by chance, using accurate methods. It must 

 be assumed therefore that on certain occasions the curve really did 

 assume the hyperbolic form, though on other occasions it as certainly 

 did not. The cause of the difference is unknown, but experience 

 showed that the longer the solution was kept, even though it was kept 



