70 ELEMENTS OF GENERAL SCIENCE 



72. Formation of water in the flame. We now have come 

 back to the question: 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. Hydrogen and oxygen unite to 

 form water. The flame is merely a place where chemical 

 changes are occurring. 



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. 



73. Other products from the flame. It was said that the 

 candle wax is a compound, and that the hydrogen which 

 unites with the oxygen is taken away from the wax. The 

 wax is a compound containing a great deal of hydrogen and 

 carbon. When the hydrogen is taken away from this com- 

 pound that is, when the compound is decomposed the 

 carbon atoms are left. The small particles of carbon float 

 upward in the flame and are heated red-hot or white-hot. 

 The part of the flame in which the white-hot carbon is 

 present is the part from which the light comes. 



