230 WATER, HEAT, AIR, AND LIGHT IN THE HOUSE 



Matches raise combustibles to their kindling temperatures. 



The fireplace is not only an ornament, but a means of ventilation. 



Cooking stoves have roundabout flues through which the hot 

 gases must travel; these heat the ovens. 



Gas stoves are Bunsen burners. 



Gasoline must be treated like an inflammable gas. 



Electric heaters are circuits with high resistance; they turn the 

 current into heat. 



Hot-water heating depends on convection currents in heated water; 

 steam heating depends on the heat given off in the condensation of 

 steam. 



The thermostat depends upon the unequal expansion and con- 

 traction of different metals. 



Ventilation is necessary for successful indoor living. It may be 

 natural or forced, but should not be left to chance. 



Proper amount of moisture is as necessary as proper amount of air. 



Cheap glass is a great civilizing agent. 



For lighting, man uses candles, oils, petroleum products, gas, 

 acetylene, electricity, etc. 



Incandescent mantles consist of oxides of certain metals. 



The gas meter records the amount of gas that passes from the 

 "mains" to the house. - " 



Electric circuits become hot from "short-circuiting." Fire is 

 prevented in such circuits by means of "fuse wires." 



Electric power is sold by the kilowatt-hour. 



Electric meters are small, finely-built motors. 



261 Exercises. 



1. What means of ventilation are there in your house? Are they 

 used? 



2. If you open the door of a warm room, and hold a burning match 

 at the top of the opening, in what direction will the flame be drawn? 

 In what direction will it be drawn at the bottom of the doorway? 

 Explain. 



3. Show that the hot-air furnace is simply an improved form of a 

 heating stove surrounded by a "drum." 



