DUST AND DISEASE. 315 



Cotton-wool ^Respirator. 



I now empty my lungs as perfectly as possible, and 

 placing a handful of cotton-wool against my mouth and 

 nostrils, inhale through it. There is no difficulty in thus 

 filling the lungs with air. On expiring this air through a 

 glass tube, its freedom from floating matter is at once 

 manifest. From the very beginning of the act of expira- 

 tion the beam is pierced by a black aperture. The first 

 puff from the lungs abolishes the illuminated dust, and puts 

 a patch of darkness in its place ; and the darkness con- 

 tinues throughout the entire course of the expiration. 

 When the tube is placed below the beam and moved to 

 and fro, the same smoke-like appearance as that obtained 

 with a flame is observed. In short, the cotton-wool, when 

 used in sufficient quantity, and with due care, completely 

 intercepts the floating matter on its way to the lungs. 1 



The application of these experiments is obvious. If a 

 physician wishes to hold back from the lungs of his patient, 

 or from his own, the germs or virus by which contagious 

 disease is propagated, he will employ a cotton-wool res- 

 pirator. If perfectly filtered, attendants may breathe the 

 air unharmed. In all probability the protection of the lungs 

 and mouth will be the protection of the entire system. For 

 it is exceedingly probable that the germs which lodge in 

 the air-passages, or find their way with the saliva into the 

 stomach with its absorbent system, are those which sow in 



1 Since the first publication of these results, Professor Lister has 

 availed himself of the filtering power of cotton-wool in the treatment of 

 wounds. He first destroys the germs adhering to the wool, and by a 

 proper lotion kills those that may be scattered on the flesh. The cleansed 

 wool placed upon the wound permits of a free diffusion of the air, but 

 entirely intercepts the germs, and thus keeps the blood perfectly sweet. 

 It is here essential that no matter from the wound should reach the out- 

 side air, for such matter would open a highway to the organisms. 



