LIGHTING THE HOME 37 



The principle involved in the burning of kerosene is the 

 same as with the candle, except that the substance used is a 

 liquid instead of a solid. The heat changes this liquid to a 

 gas which burns and gives off heat and light. One feature 

 which gives the kerosene lamp a great advantage over the 

 candle is the use of a chimney. This creates a draft which 

 furnishes a constant supply of fresh air to the wick, and in- 

 sures a steady light. In some lamps the wick is made cir- 

 cular so that the air is supplied from the inside as well as 

 from the outside. In one type of hanging lamp, the wick 

 and chimney are placed on the side, so that the light is thrown 

 downward. 



Capillarity. The process by which the kerosene rises 

 through the wick is called capillarity. Other illustrations 

 of capillarity are seen in the absorption of ink by a blotter 

 and in the rise of water through soils. When water stands in 

 a dish, the water at the side is attracted by the dish and rises 

 slightly, making a curved surface. If the container becomes 

 so small as to be a tube, the water inside the tube rises higher 

 than the surface outside, and the smaller the tube the higher 

 the water rises. The spaces between the threads of the 

 wick act like small tubes through which the kerosene rises. 



DEMONSTRATION 9 



Purpose. To study the structure and workings of a kerosene 

 lamp. 



Apparatus. Ordinary kerosene lamp, small tube, plate, two 

 pieces of glass of the same size, rubber band, two tumblers, red 

 ink, lump of sugar, blotting paper. 



Directions. I. Study the structure of the parts of the lamp. 

 What purpose does each part serve ? 



2. Light the lamp. After it burns for a minute blow it out 

 and quickly hold a lighted match above the wick. Try several 

 times to see how far above the wick the match can be held and 

 still light the wick. What does this show ? 



