NEED OF VENTILATION 217 



6. In what way are gasoline cans commonly distinguished from 

 cans for kerosene? Why? 



7. What is the cause of the "pounding" often heard when steam is 

 first turned on in a cold radiator? 



246. Need of Ventilation. The changes that take 

 place in air during breathing have been given in 52. 

 Ventilation means the supplying of fresh air and the 

 removing of foul air. Our houses give us shelter, warmth, 

 and a host of comforts; but they usually rob us of air. 

 When the open fireplace was used, ventilation required 

 little thought ; for the large volume of air that passed out 

 through the chimney was constantly replaced by fresh 

 air drawn in through cracks around doors and windows, 

 and even through chinks in the walls. But as men have 

 built tight-walled houses, used weather strips and storm 

 windows in winter, and replaced the fireplace by stoves, 

 furnaces, and steam and hot water heaters, this natural 

 ventilation has largely disappeared. It is a common 

 experience of doctors that many people who are healthy 

 enough in warm weather, when doors and windows are 

 open, have ' ' colds " and throat diseases when cold weather 

 comes on. One reason for this is that they seal up most 

 of the openings through which fresh air can enter and 

 foul air be removed. We must have good air in our 

 houses, or we, as a race, are doomed. 



The way in which tuberculosis, or consumption, is now treated 

 shows the importance of fresh air. Instead of being protected from the 

 outer air the patient is now told to live in a tent, in the open air, 

 winter and summer, day and night. Pure air, with nourishing food, 

 has been found to be an almost certain cure for the disease in its early 

 stages. If the patient will do his part, it seems as though nothing can 



