OXYHEMOGLOBIN IN DILUTE SOLUTIONS 141 



hydrosulphite. These three processes ran their courses until the whole 

 of the oxyhsemoglobin was reduced. 



It is necessary to be very clear that the events which took place 

 were precisely those which we have described; the other obvious 

 possibihty being that the oxyhsemoglobin was reduced directly by the 

 hydrosulphite by a process of double decomposition. The authors 

 investigated this matter in great detail and seem to have left no 

 reasonable doubt that their view is correct. 



0-05 010 



Fia. 42. Abscissa = time in seconds. Ordinate = Percentage oxyhaemoglobin ob- 

 servations obtained when oxygen pressure in solution was initially 

 (i) 7 mm. Hg, represented by striped rectangles; 

 (ii) 150 mm. Hg, „ circles; 



(iii) 450 mm. Hg, „ black rectangles. 



Temperature = 15-5° C. 



Here we have a reaction which, of course, gradually becomes 

 slower in the* sense that the amount of oxyhaemoglobin which breaks 

 down in any small moment of time is proportional to the remaining, 

 though ever decreasing, concentration of oxyhsemoglobin in the solu- 

 tion. This being so the logarithm of the quantity of oxyhaemoglobin 

 present, when plotted against the time which has elapsed since the 

 commencement of the experiment, should produce a straight hne. 



Figures 42, 43 and 44 illustrate the points which have been men- 

 tioned. Fig. 42 shows the course of three experiments, in each the 

 concentration of oxyhsemoglobin (i.e. the percentage saturation from 

 100 per cent, downwards) is plotted against the time which has 

 elapsed since the fluids came together. The curves are marked respec- 

 tively 7 mm. O2, 150 mm. Og and 450 mm. Og. These figures signify 



