214 ATMOSPHERE IN RELATION TO HUMAN LIFE AND HEALTH. 



of minor ailments; and where the exposure to foul air is prolonged, 

 as in workshops, offices, and mills, to a continued depression of vitality. 

 Various artificial means have been tried for improving the air of 

 crowded rooms, and some are successful, hut, on the whole, the direct 

 admission of plenty of fresh air in currents directed upward and the 

 removal of bad air by flues of sufficient diameter give in the long run 

 the most satisfactory results. 



The worst condition of air to which people are often exposed would 

 probably be found in closed railway carriages. The capacity of an 

 ordinary third-class compartment in England may be put at 240 cubic 

 feet; it is certainly not greater. Containing 10 persons, it provides for 

 each person 24 cubic feet of air at the beginning of a journey. Sup- 

 posing the air to be unchanged, in the course of one hour each person 

 will have breathed 17.7 of these cubic feet. Therefore, at the end of 

 one hour 177 cubic feet out of 240 in the compartment will have been 

 breathed out of the lungs of its occupants. Since an average man 

 breathes out 0.6 cubic feet of carbon dioxide per hour, the amount of 

 excess of this gas in the compartment at the end of an hour is 6 cubic 

 feet; or otherwise stated, the amount in the air, instead of the normal 

 proportion of 0.03 per 100 cubic feet, is 2.53 per 100 cubic feet. At the 

 same time the oxygen is reduced and a quantity of organic poison and 

 vapor is taken in with every breath. Practically, however, we must 

 take into account the facts that from the first minute every person in 

 the compartment breathes not a fresh parcel of air at every breath, 

 but an already contaminated product, and that an excess of carbon 

 dioxide has the effect of at once diminishing the quantity expired. 

 Thus the amount of carbon dioxide would not be so large as that cal- 

 culated, but may be estimated at one-half — 1.26 per cent. But the defi- 

 ciency in the carbon dioxide breathed out tells of carbon and other 

 matters remaining unoxidized in the human system. The case of the 

 compartment supposed air-tight is an extreme one and not quite exem- 

 plified in practice, but some approach to the condition described occurs 

 in thousands of railway compartments on every calm, cold, winter 

 morning and evening. Again, in traveling to the south of Europe in 

 tbe winter of 1893 it was noticeable that 48 persons were shut up in one 

 long carriage with a communicating passage between the compartments 

 and without any efficient ventilation even through a hole or chink, the 

 windows and doors all being made to fit closely. Twelve hours of 

 breathing the same air would be likely to bring the occupants to a 

 worse condition than where ten persons sleep in one small bedroom, 

 which is about the worst case actually occurring in large towns. More- 

 over, these carriages are largely used by invalids and consumptives, and 

 must become sources of infection to delicate persons. 



Experiment by means of the sense of smell has shown that air in a 

 room seems fresh when the carbon dioxide does not exceed 0.05999 per 

 cent, a little unpleasant when the proportion is 0.08004 per cent, offen- 

 sive and very close at 0.12335, and extremely close, when the sense of 



