552 Experiments 



Finally I report the results of an experiment made on an insect, 

 the poplar beetle (Chrysomelida) : 



Experiment LXXXVIII. August 3, 4 o'clock in the evening; 

 temperature 24°. 10 grams of beetles entered: 



A. In a bell- jar of 60 cc. at normal pressure. 



B. In a bell-jar of 800 cc. at a pressure of 9 cm. 



C. In a bell-jar of 1.5 liters at a pressure of 4 cm. 



On August 4, at noon, the insects are motionless and seem dead; 

 the air of the bell- jars no longer has a trace of oxygen; there as 18 

 to 20 per cent of CO--. The insects return to life about an hour after- 

 wards. 



3. Conclusions. 



The results which the data given in the present subchapter 

 have brought us can be summarized in the following conclusion: 



In a closed vessel, at pressures below one atmosphere, death 

 occurs when the tension 0. 2 x P of the oxygen of the air is reduced 

 to a certain value which is constant for each species, or at least 

 varies within narrow limits around an average (4.4 for adult cats; 

 3.6 for sparrows; 2.5 for guinea pigs; 2.2 for newborn kittens) . 



This average remains the same, whatever the initial composition 

 of the air used; but for super-oxygenated air the carbonic acid 

 must be absorbed as it is produced. 



Subchapter II 

 PRESSURES ABOVE ONE ATMOSPHERE 



1. Experimental Set-up. 



After studying the composition of confined air which had be- 

 come irrespirable under pressures less than one atmosphere, it 

 was quite natural to find out what would happen if one used higher 

 pressures. We have seen that, the weaker the pressure, the greater 

 is the proportion of oxygen remaining in the lethal air, or, in other 

 words, the less the air is exhausted. Would this law hold good at 

 higher pressures? Would there come a moment when a sparrow 

 would exhaust the oxygen of the air under pressure, as the beetles 

 of which I gave an account above did at weaker pressures? Apply- 

 ing the law and taking as an average of the exhaustion in oxygen 

 at normal pressure the figure 3.6, at 3.6 atmospheres we should find 

 only 1 per cent of oxygen in the air which had become lethal by 



