326 THE POPULAR SCIENCE MONTHLY 



eter at Wesleyan University was so prophetic of worthy contributions 

 to science that he was chosen to organize and direct the work of the 

 Nutrition Laboratory of the Carnegie Institution, which is situated in 

 Boston. The Germans, as ever, have also been leaders in this experi- 

 mental work, an important contribution having come from the labora- 

 tory of Professor Fliigge of Breslau. The English have been and are 

 still contributing some of the most significant facts, especially a group 

 of men led by Dr. Haldane of the University of Oxford. The work of 

 Dr. Leonard Hill of London has become widely known through the 

 public prints. The eminence of these various men is indicative of the 

 interest which the homely subject of fresh air can arouse in us. 



Several of the investigators have placed men within small closed 

 experimental chambers, arranged with tubes passing through the walls 

 to the outside air, so that the subjects within can at will rebreathe the 

 hot, close, confined air or take in the fresh air from outside. Under 

 such conditions it is found that confinement within and breathing of 

 the unventilated air soon brings on the usual symptoms. If the sub- 

 jects then breathe through the tube the fresh cool air from outside they 

 obtain no relief. If they step outside relief comes instantly. If, on 

 the other hand, a person standing in the fresh air outside breathes 

 through the tube the stale air of the chamber, which has been breathed 

 over and over again by the subjects within, the unpleasant symptoms 

 do not appear ; if he steps inside, they begin to appear at once. If with 

 subjects within feeling the ill symptoms electric fans be started and 

 the stale air be vigorously stirred, thus driving the hottest air away 

 from the skin, relief comes at once. These fundamental experiments 

 have been performed in varied ways, and have been supplemented by 

 many others. Their results have accorded well with one another and 

 allow but one general conclusion, namely, that the evil effects exerted 

 upon human beings by air that has become vitiated by human beings 

 result not from a lack of oxygen, not from an increase of carbon 

 dioxide, not from the presence of an organic poison, not from any 

 chemical features of such air acting through the lungs on the tissues, 

 not in any manner from the rebreathing of such air, but solely from 

 the physical features of excessive heat and excessive humidity inter- 

 fering with the proper action of the skin in regulating bodily tempera- 

 ture. The problem of bad air has thus ceased to be chemical and 

 pulmonary, and has become physical and cutaneous. 



With this knowledge before us it is clear that in the ventilation of 

 the future attention should be focused less upon the chemical purity of 

 air, although of course there are ultimate limits to chemical purity, and 

 more upon the maintenance of a physiologically proper temperature 

 and humidity. What here constitutes physiological propriety varies 

 with individuals, with age, with clothing, with occupations and with 



