146 CORRELATION OF THE PHYSICAL FORCES. 



action. I take these platinum plates again and 

 immerse them in this solution of copper from 

 which we formerly precipitated some of the 

 metal, when the platinum and zinc were both 

 put in it together. You see that these two 

 platinum plates have no chemical action of any 

 kind, they might remain in the solution as long 

 as I liked, without* having any power of them- 

 selves to reduce the copper ; but the moment I 

 bring the two poles of the battery in contact 

 with them, the chemical action which is there 

 transformed into electricity and carried along 

 the wires, again becomes chemical action at the 

 two platinum poles, and now we shall have the 

 power appearing on the left hand side, and 

 throwing down the copper in the metallic state 

 on the platinum plate ; and in this way I might 

 give you many instances of the extraordinary 

 way in which this chemical action or electricity 

 may be carried about. That strange nugget of 

 gold, of which there is a model in the other 

 room, and which has an interest of its own in 

 the natural history of gold, and which came 

 from Ballarat, and was worth 8000Z. or 9000L 

 when it was melted down last November, was 

 brought together in the bowels of the earth, 

 perhaps ages and ages ago, by some such power 



