THE CONQUEST OF NATURE 



tions it effects are produced in solutions comparable to 

 those of the voltaic cell, the principles involved being those 

 pointed out in the earlier part of the present chapter. 

 By this means a metal may be deposited in a pure state 

 upon the surface of another metal made to act as a pole 

 to the battery; as, for example, when forks, spoons, and 

 other utensils of cheap metals are placed in a solution 

 of a silver compound, and thus electroplated with silver. 

 To produce the powerful effects necessary in the various 

 commercial applications of this principle, the poles of the 

 voltaic cell which cell may become in practice a large 

 tank are connected with the current supplied by a 

 dynamo. Various chemical plants at Niagara utilize 

 portions of the currents from the great generators there 

 in this way. Another familiar illustration of the prin- 

 ciple is furnished by the copper electroplates from 

 which most modern books are printed. 



It appears, then, that all the multifarious uses of 

 electricity in modern life are reducible to a few simple 

 principles of action, just as electricity itself is reduced, 

 according to the analysis of the modern physicist, to the 

 activities of the elementary electron. There is nothing 

 anomalous in this, however, for in the last analysis the 

 mechanical principles involved in doing all the world's 

 work are few and relatively simple, however ingenious 

 and relatively complex may be the appliances through 

 which these principles are made available. 



