ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 213 



About 67,200 cubic feet of carbon dioxide ' are given off by the burn- 

 ing of every ton of coal. Since about 405,480 tons are burnt daily in 

 England on an average (the quantity is much larger in winter), the air 

 over the country receives daily about 24,728,256,000 cubic feet of the 

 gas, or 1,200,000 tons. 



The perfect burning of ordinary coal gas gives rise to 200 cubic feet 

 of carbonic dioxide for every 100 cubic feet of gas consumed. Practi- 

 cally every cubic foot of gas burnt vitiates as much air as the respira- 

 tion of one person. So that in a large town during the evening hours 

 in winter the vitiation of the air is in main streets and in rooms many 

 times larger than during the daytime. 



Angus Smith, whose methods were not quite so precise as those later 

 in use, found the following amounts of the gas in air in the situation 

 described : 



Hills in Scotland. 1,000 to 4,406 feet high. ..„ '. 0.0332 



Bottom of same hills 0331 



In the suburbs of Dundee at night 028 



In Dundee at night 042 



In London parks 0301 



On the Thames 0343 



Where fields began around Loudon 0369 



In the streets in London in summer 0380 



In Manchester in usual weather 0403 



In Manchester in fogs 0679 



In workshops 300 



In the chancery court, 3 feet from the ground 203 



In the Standard Theater pit 323 



In very ill- ventilated Cornish mines 2. 50 



It appears from these figures that hill air, like that of the open coun- 

 try and of the seaside, contains little carbonic acid, but is not superior 

 in this respect to the air of the central parts of large parks in towns. 

 In the streets of a town the amount is decidedly larger by about 1 in 

 10,000 than the average amount of the country. During the preva- 

 lence of fogs, streets and confined places in towns often contain double 

 the natural amount. The condition of the air of workshops, theaters, 

 and crowded places generally is evidently foul and dangerous to health. 



In the central parts of London, within the city, Dr. W. J. Eussell 

 found a mean of 0.0122 for three winters, and 0.0379 for two summers. 

 During fogs the amounts were much higher, giving an average of 0.072, 

 and on one occasion a measurement of 0.141 was recorded. The lifting 

 of a fog was followed by a rapid decrease in the excess. On still dark 

 days the amount was large. On fine days, in strong winds, and on 

 holidays, the quantity was below the average. 



The deficiency of oxygen and excess of carbonic acid, which are 

 common to nearly all rooms, schools, churches, theaters, and workshops 

 where many persons are gathered, are very favorable not only to the 

 spread of various infectious diseases, but to the maintenance of a number 



1 Reduced to about the average temperature of the air in England, 50°. 



