690 Experiments 



less and less oxygen for equal units of time in proportion to the 

 progress of the experiment towards its fatal conclusion. 



Experiment CLXXXVII furnishes an example of this: here, 

 carbonic acid was absorbed by potash as it was formed, so that 

 comparison with pure expanded air is quite legitimate; in the first 

 two hours the dog had consumed 41 per cent of the oxygen of the 

 closed sack in which he was breathing, while in the following two 

 hours he consumed only 36 per cent, the total volume of the sack 

 being moreover much reduced in consequence of the absorption of 

 the carbonic acid. 



The experiments which will be reported in Chapter VIII (Sub- 

 chap. II) will give the same sort of evidence. So the lack of oxygen 

 in the air gives the same result as its expansion. 



As to the lowering of temperature, the experiments of Chapter 

 II, Subchapter IV, give us interesting figures. In Experiment 

 CLXXXVII, in which asphyxia lasted 4 hours and 45 minutes, the 

 temperature had fallen from 39° to 34.5°. In Experiment 

 CLXXXVIII: duration 4 hours 30 minutes; temperature, from 

 38.5° to 34°. There also the two terms which we are seeking to 

 compare at present are identical. 



If we consider respiratory and circulatory phenomena from 

 the simple point of view of number of movements, we find the 

 same general tendency and the same irregularities, in asphyxia 

 as in decompression. 



Figure 53 gives an idea of their trend: the unbroken line gives 

 the results of Experiment CLXXXVII, the dotted line those of Ex- 

 periment CLXXXVIII. The oxygen content of the air is inscribed 

 on the axis of the abscissae. The number of respirations (R) and 

 of the pulse (P) on the axis of the ordinates, on different scales. 



We see that in these graphs is shown, after a phase of uncer- 

 tainty and irregularity, a period of acceleration in the two types of 

 movement, followed by a period of sudden slowing up. 



In some cases, at the end of life, the heart again begins to beat 

 rapidly, but its beats are very weak. This occurred in one of the 

 experiments reported in Subchapter II of Chapter VIII, in which 

 the beats, after having fallen from 120 to 14 at the moment when 

 insensitivity of the eye appeared, rose suddenly to 60 for some 

 minutes, when respiration ceased. 



As to blood pressure, it drops slowly at first, then rapidly. 

 Figure 54, whose graphs relate to Experiment CLXXXVII, shows 

 the course of the maxima and minima, in proportion to the oxygen 

 content of the air. 



