Increased Pressure 1027- 



a proportion which must increase with the pressure, since the 

 diaphragm in its descent meets stronger and stronger obstacles. 



3. Sudden Decompression. 



I think I explained in Chapter VII all that relates to this ques- 

 tion, which is relatively simple enough, because it is purely of 

 physical nature. I have shown that all the symptoms, from the 

 slightest to those which bring on sudden death, are the consequence 

 of the liberation of bubbles of nitrogen in the blood and even in 

 the tissues when the compression has lasted long enough. 



These few lines are enough to summarize this part of our study, 

 to which we shall return in the following section. 



4. Practical Applications. Therapeutics and Hygiene. 



A. Therapeutics. I shall refrain, observing in this instance the 

 same prudence as when it was a question of rarefied air, from ex- 

 plaining and judging the applications made since the time of Junod, 

 Pravaz, and Tabarie of slightly compressed air in the treatment 

 of different diseases. However I can affirm, along with so many 

 others, the utility of this treatment in certain forms of asthma and 

 in anemia. But I prefer, after having mentioned these two diseases, 

 to say that the stay in apparatuses for compressed air seems to me 

 to act upon them in a different way: for asthma, I think it is the 

 mechanical action of which I have already spoken which is of 

 benefit; for anemia, I think that it is the chemical action, the more 

 perfect saturation of the hemoglobin. 



The interest of this distinction lies in the fact that in cases 

 where chemical action should be sought, and they are very prob- 

 ably those in which it will be a matter of changing the nutritive 

 processes, the stay in the compression cylinders can be satisfactorily 

 replaced by the respiration of superoxygenated air: a great advan- 

 tage, you will understand, in therapeutic practice, for the costly 

 apparatuses for compressed air can never be operated outside large 

 cities and watering-places, whereas nothing is easier than to pro- 

 cure oxygen at home. 



But one must be skilful in the use of oxygen inhalations. Since 

 the day when Priestley disputed with two mice "the honor of 

 having been the first to breathe dephlogisticated air" s up to the 

 present epoch, many attempts have been made to introduce respira- 

 tions of oxygen into the realm of therapeutics. 1 ' The enthusiasm of 

 the authors at the end of the last century and the beginning of this 

 one for the curative virtue of the vital air, was tempered by only 



