622 



Experiments 



Making averages for identical pressures, we can draw up the 

 following table: 



The results of this table are expressed in a very striking way 

 by the following graphs (Fig. 35), in which the pressures are 

 plotted on the horizontal axis, and the quantities of gas on the 

 vertical scale. 



Let us now examine the data for each of the three gases of the 

 blood, using the figure and the two tables. 



1. Oxygen. Its increase, we have said, is constant. But the 

 comparison of Columns 3, 8, and 12 of Table XI shows us that this 

 increase is, at the same time, very variable for the same pressure, 

 and very small even under the enormous pressure of 10 atmos- 

 pheres. 



The variety of results should not surprise us, after what we 

 have already seen in speaking of decreases in pressure, and after 

 the inequalities indicated by the diverse figures in Column 3. It is 

 impossible for us to connect this variety of results to any known 

 condition; but it is very interesting to observe, because it can 

 serve to give account of the intensity, very variable according to 

 the subjects, with which the air compression acts. 



As to the amount of this increase, it is really very curious to 

 see how slight it is. Its maximum, under a pressure of 10 atmos- 

 pheres, was 26.7 per cent, that is, in volume the quantity of oxygen 

 contained in 100 cc. of arterial blood rose from 19.4 cc. to 24.6 cc. 

 The figures relating to intermediary pressures have the same bear- 

 ing. The graph Ox and Column 2 of Table XII show this slowness 

 of increase with great definiteness. 



We had already seen, moreover, by experiments made in ex- 

 panded air, that the influence of barometric pressure, relative to 

 the quantity of oxygen absorbable, is less for pressures near 76 cm. 

 than for those which are much lower. So the figures in Column 14 

 of Table X show that in passing from 76 cm. to 56 cm. the oxygen 

 lessens only by 13.6- per cent, whereas in passing from 56 cm. to 

 36 cm. it lessens 43—13.6=29.4 per cent. So the graph Ox (Fig. 31) , 



