Chapter I 



CHEMICAL CONDITIONS OF THE DEATH 



OF ANIMALS SUBJECTED TO DIFFERENT 



BAROMETIC PRESSURES IN CLOSED 



VESSELS 



The numerous researches I formerly made on the final composi- 

 tion of the air contained in closed vessels in which animals were 

 kept till death 1 decided me to begin the study of the influence 

 exerted on living organisms by modifications in the barometric 

 pressure, by analyzing the air which had become incapable of 

 supporting life in consequence of confinement, when this air is 

 subjected to pressures differing from the normal pressure. 



A certain number of preliminary experiments, details of which 

 it would be useless to give here, had already given me the idea 

 that the principal, if not the sole cause of this influence, of which 

 aeronauts on one hand and men in diving apparatus on the other 

 present the most striking examples, was the different composition 

 of the gases contained in the blood, as a result of the different 

 pressures. It seemed, therefore, that the shortest and best way of 

 settling the question would be to begin by installing and operating 

 the apparatuses necessary for studying these gases of the blood. 

 However, I gave up this idea, though it seemed the simplest, and 

 determined to attack the problem by the indirect method of study- 

 ing the confined air; for this I had two reasons. In the first place, 

 I thought that I should thus find some new ideas on the question 

 of asphyxia, in which I had long been interested; secondly, the 

 problem which I was undertaking to solve seemed to me to present 

 such apparent complexity that I thought it best not to go straight 

 to what it seemed a priori should give me the general solution for 

 fear of being too quickly satisfied, and letting escape certain ele- 

 ments which perhaps were very important. I hoped, if I may be 



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