26 



THE WORLD WE LIVE IN 



with the element iron. Slow oxidation of chemical compounds is 

 constantly taking place in nature and is a part of the process of de- 

 cay and of breaking down of complex materials into simpler forms. 

 One of the most important effects of oxidation lies in the fact 

 that, when anything is oxidized, heat is produced. This heat 

 may be of the greatest use. Coal, in being oxidized, gives off 



heat; this heat boils 

 the water in the tubes 

 of a boiler; steam is 

 generated, wheels of 

 an engine are turned, 

 and work is performed. 

 The energy released by 

 the burning of coal 

 has been transformed 

 into work or power. 

 We shall find later 

 that the oxidation of 

 certain materials in 

 the bodies of plants 

 or animals releases 

 energy which is used 

 to perform work. 

 The heat of the hu- 

 man body is main- 

 tained by the constant 

 slow oxidation of food 

 materials within the 

 body. 



Forms of energy. Energy has been shown to be the power to 

 do work. The energy locked in the coal before it is released by 

 the process of burning is known as potential or stored energy. 

 The energy released by the burning process is kinetic or active 

 energy. The potential energy held in the water of the San 

 Francisquito dam became kinetic energy when the dam gave way 

 and let the great volume of water rush down the fertile Santa 

 Clara valley, bringing death and destruction to its inhabitants. 



Engineering News-Record 



The energy held in the water in this dam was sufficient to 

 uproot trees, sweep buildings from their foundations, and 

 dislodge rocks, when a wall of the dam broke. 



