THE HAND CHEMICAL EXTINGUISHERS 213 



Cooling. Water is the most universal fire extin- 

 guisher. It has many properties which favor its use. 

 It can be thrown long distances in a steady stream. 

 It is non-combustible. One pound of it has greater 

 cooling effect than the same weight of any other sub- 



water, our best fire extinguisher. 



stance. On changing to steam it increases 1700 times 

 in volume. The change from liquid to steam absorbs a 

 large amount of heat, thus adding to its value as a cool- 

 ing agent. The steam also tends to smother the fire by 

 excluding air. 



The hand chemical extinguishers. The carbon tetra- 

 chloride and the carbon dioxide extinguishers are two types 



