Symptoms of Decompression 



695 



pressure of 7.5 cm.; the bird is very sick, and we have barely time 

 to open the cocks. 



The minimal tensions of oxygen have been successively 5.8; 6.3; 

 10; 9.2; 9.1. 



The bird survives. 



And so dangerous decompressions have become successively 

 harmless, because the percentage of oxygen in the air has been 

 sufficiently and progressively increased. We reached 12.5 cm. be- 

 fore the symptoms which announce imminent death reappeared, 

 and we saw a bird survive after having undergone the pro- 

 digiously low pressure of 7.5 cm. I do not doubt that we could go 

 even farther if we proceeded slowly enough. 



I have often repeated in public this very simple experiment, 

 which can be carried out in all physics laboratories, and which is 

 at the same time very conclusive and very impressive. Figure 

 55 shows the experimental set-up. 



By itself, it would be enough to bring conviction; but to in- 

 crease the convincing effect, one can complete it by the following 

 crucial experiment. 



Fig. 55— Bird in air increasingly expanded and increasingly oxygenated. 

 A. Bell-jar communicating at B with the pump, at C with a 

 barometric tube, at D with a bag full of oxygen O. 



