78 THE SUN'S GIFT OF HEAT 



manufacturing of practically everything we use, fur- 

 nishes power for most of our transportation, and in fact 

 makes life livable. But when fire gets out of control it 

 ruthlessly destroys almost everything it can touch. The 

 control of fire is, therefore, exceedingly important. We 

 have seen (page 70) that fire cannot exist unless oxygen is 



FIRE OUT OF CONTROL 

 Fighting the great conflagration at the Chicago stockyards in 1910. 



present. Therefore to control fire it is only necessary to 

 shut off the oxygen. Closing the draft of a stove cuts down 

 the supply of oxygen. 



When water is put on a fire it not only shuts off the supply 

 of oxygen but it also cools the burning material below its 

 kindling temperature. Water, however, is not serviceable 

 for extinguishing such substances as burning oils, since the 



