OXYHEMOGLOBIN IN DILUTE SOLUTIONS 135 



same units at which oxygen and haemoglobin united to form oxy- 

 haemoglobin. 



Clearly we should be putting our theory to a very rigorous test 

 by determining ¥ and h independently and then ascertaining whether 

 their ratio corresponded to the equiUbrium constant of the hyperbola 

 as determined. This latter may be obtained from Fig. 39 (i). 



Hill and I, and later Oinuma, made some tentative efforts in this 

 direction by bubbhng oxygen through haemoglobin solutions and 

 observing the rate at which the solution became oxidised, and con- 

 versely bubbling nitrogen through solutions of oxyhaemoglobin and 

 observing the period necessary for reduction (2), (3). It became evident 

 very early that, important as these results undoubtedly are from 

 another standpoint, we were observing something fundamentally 

 different from the velocity constants of the reactions in question. 

 Our ciu-ves reaUy indicated the rates at which the solution acquired 

 or lost oxygen, as will be shown in Chapter xvi. 



Data obtained in this way reflect, to some extent, the properties 

 of the equihbrium curves of the reactions involved. They do not, 

 however, yield any informartion concerning the time required for the 

 actual chemical process of union or disintegration of the haemoglobin 

 to take place. 



These latter involve intervals of time which are infinitesimal in 

 relation to those necessary for the oxygen to diffuse into the solution 

 when bubbled through it at a convenient rate. 



The independent measurement of k and k' for the reactions 



Hb + Oa — ^ HbOg 

 HbOa ^ Hb + O2 



has been undertaken and brought to a triumphant conclusion by 

 Hartridge and Roughton, Their researches are notable in physiology 

 as being the first in which the velocity constants of any so simple a 

 reaction in the body have been measured, and in chemistry as being 

 the first in which a reaction of such rapidity has been made to yield 

 its secret. 



Of the two reactions, the acquisition of haemoglobin by oxygen is 

 the more rapid and therefore the more difficult to measure. The time 

 interval which is involved in the measurement is expressed in 

 thousandths of a second. 



To give a detailed account of the complete fabric of this research 

 is beyond the scope of a chapter in the present book. I must satisfy 



