36 SCIENCE OF HOME AND COMMUNITY 



4. Light the candle and place a match on each side. On 

 the matches place the chimney. Does the flame act any dif- 

 ferently than in the previous experiments ? Why ? 



5. What do these experiments show that a candle needs in 

 order to keep burning ? 



6. To show what is given off when a candle burns, place a 

 candle about an inch long in a glass tumbler. Light the candle 

 and cover the tumbler with a piece of cardboard. After the 

 flame goes out, quickly remove the candle and pour some 

 limewater into the tumbler. Cover the tumbler and shake. 

 The white substance formed shows the presence of carbon 



dioxid. 



^ * 



Kerosene lamps. The kerosene lamp marked a great 

 advance over the candle as it gives a stronger and steadier 

 light. Kerosene is obtained from petroleum, a thick liquid 

 found in the earth. It contains a great variety of sub- 

 stances, which are separated from each other by heating the 

 petroleum. As this is heated the various liquids present 

 boil and are given off as gases which are caught and cooled 

 till they condense to liquids again. Those which boil at 

 the low temperatures are given off first. These gases are 

 caught in different vessels according to the temperature at 

 which they are given off, and thus the various liquids are 

 separated. Kerosene is one of the liquids that has a high 

 boiling point. If the oil we burn in lamps should contain 

 liquids that burn at a low temperature, there would be 

 danger of explosion, so the government as a protection 

 requires that kerosene shall have a flashing point of suffi- 

 ciently high temperature to be safe under ordinary con- 

 ditions. The flashing point is the temperature at which a 

 momentary flash is formed when a flame is brought near the 

 oil. The standard set is usually about no degrees. The 

 temperature at which a continuous flame would be main- 

 tained is from 40 to 50 degrees higher. This is called the 

 burning point. 



