466 Historical 



glanders, and all diseases of a blood-poisoning nature will be cured, 

 or at least considerably shortened in their course and checked in their 

 severity by respiration in compressed air, which arterializes and 

 oxygenates the blood without any effort; experiments can easily be 

 carried out on animals. 



The venom of the viper, the virus of the rabies, of smallpox, etc. 

 perhaps will be neutralized locally some day, since they will encounter 

 in compressed air a very rich, essentially vital blood, which will 

 consequently refuse to serve as a vehicle for the poison, and they will 

 therefore be annihilated on the spot. What physician does not know 

 that contagious or transmissible diseases become so only when they 

 encounter persons who are predisposed, and who therefore form a 

 suitable breeding-ground for them? (P. 7.) 



The English authors, Babington and Cuthbert,- 3 who were wit- 

 nesses of the accidents at the bridge of Londonderry, tried like all 

 their predecessors to explain them. They too were surprised to 

 see that these symptoms occur exclusively in the phase of decom- 

 pression: 



The idea of a dangerous element in compressed air must be aban- 

 doned, because the workmen felt no ill effects during the period in 

 the cylinder, which lasted 3 or 4 hours. All cases of serious sickness 

 occurred when an excess pressure was removed more or less rapidly. 

 It seems reasonable, in the absence of any other cause, to suppose that 

 the sudden transition from compressed air to open air occasions all 

 these serious symptoms. 



But why does this change attack the nervous system? The brain 

 and the spinal cord, encased in their bony cavities, and having their 

 vessels protected thereby, cannot yield to the atmospheric pressure as 

 easily as the more elastic parts. So when the workman is under an 

 excessive pressure, if this pressure is removed from the surface, the 

 brain cannot adapt itself to this change as rapidly as the other organs; 

 the excess pressure on the brain and the spinal cord must be removed 

 through the narrow passages by which the blood leaves these organs. 

 The bony channels in which the blood vessels lie make this escape 

 more difficult, and the excess pressure presses upon the delicate nerv- 

 ous parts rupturing the little vessels, and producing the series of 

 dangerous symptoms which we have reported. (P. 318.) 



Dr. Sandahl - 4 is very definite in his explanations. In his opin- 

 ion, the physiological modifications observed are principally the 

 result of an increase in the quantity of oxygen contained in the 

 blood. The mechanical effect of the compression is exerted only 

 through the medium, so to speak, of the dissolved gases: 



The greater oxygen content of the compressed air naturally acts 

 more energetically upon diseased lungs than upon healthy lungs. Let 

 us assume that a healthy man makes 20 inspirations per minute, eacn 

 absorbing 30 cubic inches of air; if his lungs become diseased, and 



