174 



Chapter XI 



Thus a curve was obtained of the degree of reduction which took 

 place at any given time. 



The first experiment which I shall discuss was one in which 

 Nikiferowski helped me; it was on a dialysed solution of haemo- 

 globin, and at the temperature of the room 14 15 C. We 

 endeavoured to reduce the oxyhaemoglobin by passing commercial 

 nitrogen, which contained perhaps a millimetre of oxygen pressure, 

 through the tube at the rate of 30 bubbles in 15 seconds. 



This proved to be a hopeless affair; at the end of 150 minutes the 

 haemoglobin was still 90 per cent, saturated with oxygen, nor had it 

 become appreciably reduced in the last hour and three quarters of this 



40 



60 



80 



TOO 120 140 160 



FIG. 92. Relative rates of oxidation and reduction of a dialysed haemoglobin solution at 

 16 C. Ordinate = / saturation of the solution with oxygen. Abscissa = minutes of 

 time reducing gas nitrogen. Oxidising gas nitrogen + 100 mm. oxygen. 



time. Another experiment was performed on the same haemoglobin 

 solution. The haemoglobin was completely reduced at a higher 

 temperature, cooled down to 15 C. in the tube and then nitrogen 

 containing oxygen to the extent of about 100 mm. pressure was 

 bubbled through the haemoglobin at the standard rate. The haemo- 

 globin oxidised rapidly, in 10 minutes it was 63 per cent, saturated 

 with oxygen and in 15 more it was 93 per cent, saturated. 



The course of the experiment may be followed from Fig. 92. 



It may occur to the reader to ask why we chose this particular 

 mixture of oxygen and nitrogen for the oxidation process. The 

 reason is that we wished to imitate as nearly as might be the oxygen 

 pressure which is to be found in the lungs during normal respiration. 



