Chemical Change and Energy 315 



FIG. 167. The water rises in the bottle after the burning candle uses up the oxygen. 



Carbon and hydrogen the chief elements in fuel. Car- 

 bon and hydrogen make up the larger part of almost every 

 substance that is used for fuel, including gas, gasoline, 

 wood, and soft coal; alcohol, crude oil, kerosene, 

 paper, peat, and the acetylene used in automobile 

 and bicycle lamps. Hard coal, coke, and charcoal are, 

 however, chiefly plain carbon. Since burning is simply 

 the combining of things with oxygen, it is plain that 

 when the carbon of fuel joins oxygen we shall get car- 

 bon dioxid (CO 2 ) . When the hydrogen in the fuel joins 

 oxygen, what must we get? 



