62 ELEMENTS OF GENERAL SCIENCE 



62. Formation of water in the flame. By this rather long 

 route we have come back to the question with which we 

 started. How was the water formed in the flame ? After 

 what we have learned we should expect to find that the water 

 had been formed in the flame by some sort of chemical change. 

 This is the case. Hydrogen and oxygen unite to form water. 

 In fact, the flame is merely a place where chemical changes 

 are occurring. The formation of water is one of the most 

 important of the changes going on in the flame. 



The wax is a compound containing hydrogen ; the air is a 

 mixture containing oxygen and several other gases. When 

 the wax is melted and then turned into a gas by the heat of 

 the flame, this gas mixes with the air, and the atoms of hydro- 

 gen leave the other atoms and unite with the atoms of oxygen 

 which are in the air. The compound thus formed is water. 

 When hydrogen and oxygen unite, the union produces great 

 heat, and at the resulting high temperature the water remains 

 in a state of water vapor. It is only when this water vapor 

 is cooled, as by contact with a cold object, that it changes into 

 the liquid form and becomes visible as drops of water. 



The flame of the candle consists principally of gases heated 

 to a high degree by the changes which are taking place in 

 the flame. The gases in the candle flame with which we 

 are already somewhat familiar are the vaporized wax, water 

 vapor, and the gases of the air. A flame is always composed 

 essentially of burning gases, but these gases may not always 

 be of the sort that we have found in the candle flame. 



The chemical change which we have been discussing and 

 which takes place in the candle flame may be briefly stated 

 thus : Hydrogen unites with oxygen to form water. 



63. Other products from the flame. We shall not study the 

 water of the flame any further. There are other substances 

 formed by the burning of the candle. 



It was said that the candle wax is a compound, and that the 

 hydrogen which unites with the oxygen is taken away from 



