STUFFY ROOMS 387 



tion of the lungs. The very same thing happens when we take gentle 

 exercise and produce more C0 2 in our bodies. 



At each breath we rebreathe into our lungs the air in the nose and 

 large air-tubes (the dead-space air), and about one third of the air 

 which is breathed in by a man at rest in dead-space air. Thus, no 

 man breathes in pure outside air into his lungs. When a child goes to 

 sleep with its head partly buried under the bed-clothes, and in a cradle 

 confined by curtains, he rebreathes the expired air to a still greater 

 extent, and so with all animals that snuggle together for warmth's 

 sake. Not only the new-born babe sleeping against its mother's breast, 

 but pigs in a sty, young rabbits, rats and mice clustered together in 

 their nests, young chicks under the brooding hen, all alike breathe a 

 far higher percentage than that allowed by the Factory Acts. To 

 rebreathe one's own breath is a natural and inevitable performance, 

 and to breathe some of the air exhaled by another is the common lot 

 of men who, like animals, have to crowd together and husband their 

 heat in fighting the inclemency of the weather. 



In the Albion Brewery we analyzed on three different days the air 

 of the room where the C0 2 generated in the vats is compressed and 

 bottled as liquid carbonic acid. "We found from 0.14 to 0.93 per cent. 

 of C0 2 in the atmosphere of that room. The men who were filling 

 the cylinders and turning the taps on and off to allow escape of air 

 must often breathe more than this. The men engaged in this occu- 

 pation worked twelve-hour shifts, having their meals in the room. 

 Some had followed the same employment for eighteen years, and with- 

 out detriment to their health. It is only when the higher concentra- 

 tions of C0 2 are breathed, such as 3 to 4 per cent, of an atmosphere, 

 that the respiration is increased, so that it is noticeable to the resting 

 individual; but percentages over 1 per cent, diminish the power to do 

 muscular work, for the excess of C0 2 produced by the work adds its 

 effect to that of the excess in the air, and the difficulty of coordinating 

 the breathing to the work in hand is increased. 



Haldane and Priestley found that with a pressure of 2 per cent, of 

 an atmosphere of C0 2 in the inspired air the pulmonary ventilation 

 of a man at rest was increased 50 per cent., with 3 per cent, about 

 100 per cent., with 4 per cent, about 200 per cent., with 5 per cent, 

 about 300 per cent, and with 6 per cent, about 500 per cent. With the 

 last, panting is severe, while with 3 per cent, it is unnoticed until 

 muscular work is done, when the panting is increased 100 per cent, 

 more than usual. With more than 6 per cent, the distress is very 

 great, and headache, flushing and sweating occur. 



Divers who work in diving dress and men who work in compressed 

 air caissons constantly do heavy and continuous labor in concentrations 

 of CO, higher than 1 per cent, of an atmosphere, and so long as the 



