390 THE POPULAR SCIENCE MONTHLY 



To study the relative effect of the temperature and chemical purity 

 of the atmosphere I constructed a small experimental chamber of wood 

 fitted with large glass observation windows and rendered air-tight. 



On one side of the chamber were fixed two small electric heaters, 

 and a tin containing water was placed on these in order to saturate the 

 air with water vapor. On another side of the chamber was placed a 

 large radiator through which cold water could be circulated when 

 required, so as to cool the chamber. In the roof were fixed three 

 electric fans, one big and two small, by means of which the air of the 

 chamber could be stirred. The chamber held approximately 3 cm. of 

 air. In one class of experiments we shut within the chamber seven 

 or eight students for about half an hour, and observed the effect of the 

 confined atmosphere upon them. We kept them until the C0 2 reached 

 3 to 4 per cent., and the oxygen had fallen to 17 to 16 per cent. The 

 wet-bulb temperature rose meanwhile to about 80° to 85° F., and the 

 dry bulb a degree or two higher. The students went in chatting and 

 laughing, but by-and-by, as the temperature rose, they ceased to talk 

 and their faces became flushed and moist. To relieve the monotony of 

 the experiment we have watched them trying to light a cigarette, and, 

 puzzled by their matches going out, borrowing others, only in vain. 

 They had not sensed the diminution of oxygen, which fell below 17 

 per cent. Their breathing was deepened by the high percentage of 

 C0 2 , but no headache occurred in any of them from the short exposure. 

 Their discomfort was relieved to an astonishing extent by putting on 

 the electric fans placed in the roof. Whilst the air was kept stirred 

 the students were not affected by the oppressive atmosphere. They 

 begged for the fans to be put on when they were cut off. The same 

 old stale air containing 3 to 4 per cent. C0 2 and 16 to 17 per cent. 2 

 was whirled, but the movement of the air gave relief, because the air 

 was 80° to 85° F. (wet bulb), while the air enmeshed in their clothes 

 in contact with their skin was 98° to 99° F., wet bulb. If we outside 

 breathed through a tube the air in the chamber we felt none of the dis- 

 comfort which was being experienced by those shut up inside. Sim- 

 ilarly, if one of those in the chamber breathed through a tube the pure 

 air outside he was not relieved. 



E. A. Eowlands and H. B. Walker carried out a large number of 

 observations in the chamber, each acting as subject in turn. They 

 recorded the effect on the respiratory ventilation and on the pulse rate 

 both when resting and when working. The work consisted in pulling 

 a 20-kilogram weight about 1 meter high by means of a pulley and 

 rope. In some of the experiments the exhaled carbonic acid was 

 absorbed, and in others carbonic acid was put into the chamber. The 

 subjects inside could not tell when the gas was introduced, not even if 

 the percentage were suddenly raised by 2. The introduction of this- 



