VENTILATION 



181 



would be needed for four people. Electric lights, of course, do not 

 vitiate the air at all. 



A candle will remove from the air in one hour about 10 cubic feet 

 of oxygen, while an adult will remove about one-quarter of a cubic 

 foot. A candle will produce about 7 cubic feet of carbon dioxide, 

 but a human being will produce less than a cubic foot of carbon 

 dioxide per hour. 



The following table is of interest because it shows the relation 

 between the air vitiated by different lights and by an adult person. 



The Relation of the Use of Gas to Vitiated Air. From the table it 

 might be thought that the use of gas as an illuminant would be 

 very unhygienic and would remove a great deal of oxygen from the 

 atmosphere. Of course gas flames do not remove as much oxygen 

 as candles. The gas flame produces carbon dioxide and a small 

 amount of sulphur dioxide, but gas burning in a room causes the 

 air to circulate very rapidly. It also burns up some organic impuri- 

 ties, since the temperature of the gas mantle is about 1500 Fahren- 

 heit when incandescent. To cause circulation of air, the gas burner 

 is often used in vents in order to drive obnoxious odors up the 

 flue. 



