VENTILATION 131 



the heat comes from a furnace, we can be careful to 

 see that the air supply is taken from outdoors through 

 a cold-air box and not from the cellar. This is a good 

 plan, because cellar air is likely to be impure, and, 

 at the best, is not equal to the outdoor atmosphere. 

 If our rooms are heated by stoves, there should be 

 sufficient draught to carry off poisonous gases, and 

 care should be taken that there are no leaking places. 

 Coal gas forms in large quantities when coal is first 

 put on a fire. For this reason, the drafts should be 

 previously so arranged that the gas will go up the 

 chimney and not get into the atmosphere of the living 

 rooms. This gas is very harmful, because the blood 

 takes it up from the lungs far more readily than it 

 does oxygen. 



A gas stove that does not require pipe is sold, the 

 claim being made by some dealers that it does not 

 vitiate the air. This claim is not true. Oxygen is 

 used up in the burning, and carbonic acid gas results 

 from it just as in any other combustion. Unless there 

 is very free ventilation, such a stove is sure to make 

 the air unfit for breathing. 



It should be possible to lower windows from the 

 top as well as to raise them from the bottom. Great 

 care should be taken to have the transoms of school 

 rooms open. If a few of the small ventilating win- 

 dows along the upper part of street cars are kept open, 

 there is a chance for both a free circulation of the 

 atmosphere and the escape of the impure air from 



