DEATH AND RESURRECTION. 109 



idea of the existence of such substances 

 as iron, copper, lead, etc. The metals 

 are chemical ingredients in our min- 

 erals and from these minerals they are 

 extracted by complicated, artificial proc- 

 esses. The ore is often lifted out of 

 the depths of the mountains; it goes 

 through a series of treatments which 

 the forces of nature cannot spontane- 

 ously undertake. We will here give 

 only a moment's attention to the proc- 

 ess of reduction, or the separation of 

 the metal from its natural compounds. 

 This, as we know, is done in our blast 

 furnaces, where the iron is reduced 

 through the presence of coal and other 

 suitable substances in certain propor- 

 tions. If we now remember that the 

 heat in our furnaces often reaches 

 about 2000° Centigrade we see at once 

 that the sun may shine on our moun- 

 tains throughout eternity without ever 

 producing the temperature necessary 

 for the reduction. 



But the engine is not yet completed. 

 The plates must be first rolled and 



