1020 Summary and Conclusions 



All these results, which are in harmony with the data already 

 known, are explained, according to G. Liebig, by the mechanical 

 action of the increased pressure: 



The mechanical effects of pressure can be explained by the fol- 

 lowing comparison. Let us suppose a flask covered by an elastic 

 membrane; if one extracts the air from this flask by means of a tube 

 penetrating the interior, he will observe that the membrane is bent 

 inward. The greater the outer pressure, the deeper will be the 

 depression (in the membrane), and vice versa, since its own elas- 

 ticity acts in a direction opposite to that of the air pressure. 



During the inspiration, when the walls of the chest expand, and 

 the diaphragm contracts, a vacuum tends to form around the lungs, 

 and the greater the outer pressure of the air in relation to the elas- 

 ticity of the lungs, the more easily will this vacuum be filled. The 

 expiration will become more difficult, because the outer pressure of 

 the air offers resistance to the contraction of the lungs. 



Panum and Vivenot have shown that the walls of the chest and 

 the diaphragm take in compressed air a state of equilibrium different 

 from the ordinary state, with an enlargement of the thorax. These 

 walls then present a tension from within outwards which opposes the 

 inverse tension of the lungs; both of the two forces are in a deter- 

 mined equilibrium with the third active force, namely, the pressure of 

 the air. If this force is increased or diminished, a change in the 

 equilibrium of the system will be produced. (Page 516.) 



Dr. Leonid Simonony director of the aerotherapeutic establish- 

 ment of St. Petersburg, very recently published an important book 

 on barometric compression, from the medical point of view. The 

 physiological part contains a very interesting summary of previous 

 knowledge, and also an account of a certain number of personal 

 experiences on the variations of weight in patients subjected to 

 aerotherapeutic treatment. 



In the course of the year 1873, Dr. Katschenowsky made observa- 

 tions in my medical service on himself and other persons .... The 

 result is as follows: With quantities of food such that in ordinary air 

 there would be an equilibrium between the ingesta and the excreta, 

 the weight of the body diminishes successively under the influence 

 of a daily sojourn of two hours in compressed air. (Page 79.) 



But, M. Simonoff observes, the appetite constantly increases; now 

 if one satisfies it, instead of regulating the diet as Katschenowsky 

 did, the weight of the body increases. Out of 53 persons whom he 

 examined, 32 weighed more after the treatment (on the average, 

 1077 gm. per individual) ; two had not changed; 19 had lost weight 

 (an average of 786 gm. each) (pages 81-92) . We must note that all 

 these subjects were invalids, and that the increase of the weight of 

 the body and the appetite seemed to be only an indirect effect of 



