314 Common Science 



Experiment 94. Light a candle not more than 4 inches 

 long and stand it on the plate of the air pump. Cover it 

 with the bell jar and pump the air out. What happens to 

 the flame? 



Experiment 95. Fasten a piece of candle 3 or 4 inches 

 long to the bottom of a pan. Pour water into the pan until 

 it is about an inch deep. Light the candle. Turn an empty 

 milk bottle upside down over the candle. Watch the flame. 

 Leave the bottle over the candle until the bottle cools. 

 Watch the water around the bottom of the bottle. Lift 

 the bottle partly out of the water, keeping the mouth under 

 water. 



The bubbles that came out for a few seconds at the 

 beginning of the experiment were caused by the air in 

 the bottle being heated and expanded by the flame. 

 Soon, however, the oxygen in the air was used so fast 

 that it made up for this expansion, and the bubbles 

 stopped going out. When practically all the oxygen 

 was used, the flame went out. 



The candle is made mostly of a combination of hydro- 

 gen and carbon. The hydrogen combines with part 

 of the oxygen in the air that is in the bottle to form a 

 little water. The carbon combines with the rest of the 

 oxygen to make carbon dioxid, much of which dissolves 

 in the water below. So there is practically empty space 

 in the bottle where the oxygen was, and the air outside 

 forces the water up into this space. The rest of the 

 bottle is filled with the nitrogen that was in the air and 

 that has remained unchanged. 



About how much of the air was oxygen is indicated 

 by the space that the water filled after the oxygen was 

 combined with the candle. 



