452 Historical 



Thence comes this conclusion, as yet wholly theoretical, that if a 

 constantly increasing pressure were exerted, we should see occurring 

 to a degree at present indeterminable intra-organic hemorrhages, 

 apoplexies, instead of the peripheral hemorrhages caused by the rarity 

 of the air. (P. 272.) 



But if it is the compression itself which causes the congestions, 

 why is it that they display their dangerous effect only at the time 

 of the decompression? Here is the odd reply made by the two phy- 

 sicians to this objection which might seem unanswerable: 



Rasori thought that congestions are invariably venous, and that is 

 beyond doubt when they are caused by an obstacle to the return of the 

 blood. But is this also true when they are the result of an arterial 

 afflux; would the circulatory stoppage which constitutes them be 

 located exclusively in the venous capillaries then also; in a word, 

 would the dark blood be the agent of the congestions under all circum- 

 stances, as the Italian physician thinks? 



The observations of M. Andral do not contradict this opinion; on 

 the contrary, they justify it, since the consequence is that the congested 

 tissues, red in the first phase, which according to M. Dubois of Amiens 

 is only an inflammatory stage preceding congestion, are brown in the 

 second phase and black in the third. 



Now let us admit by hypothesis that their harmful effect is due 

 rather to the narcotic effect of the dark blood than to the compression 

 resulting from an exaggerated supply, and it will follow that if the 

 inspiration of an excess of oxygen should arterialize the venous blood, 

 congestions, depending upon the quantum, should lose all or part of 

 their harmful power. 



Well, that is exactly what happened in our miners; on the one 

 hand, congestion without any symptoms; on the other hand, brignt 

 red venous blood. 



And as a counter-test, when the agent of the redness was removed 

 and its action destroyed or lessened to a certain degree, which took 

 a variable time, serious symptoms occurred which might be fulminant. 



So the congestions which result from the compression of the air 

 do not reveal their existence as long as this compression is exerted. 

 The compression consequently has its corrective within it. 



The decompression in a way reveals the congestions; it lets them 

 exert their full and complete effect; we might say that it makes them 

 effective instead of latent and potential. 



From that, we imagine that it must appear more dangerous in 

 proportion to its speed, and that to make it harmless, probably one 

 would need only to make it very slow, much slower than it has been 

 at Louches most of the time. (P. 260.) 



So the physicians of Douchy give to the superoxygenation of 

 the blood a role which is surely strange, but very important. It is 

 interesting to see, however, how vague an idea they had of the 

 conditions which in compressed air cause this superoxygenation. 



