OR VOLTAIC ELECTRICITY. 385 



right understanding of the nature of voltaic 

 electricity, and its relation to caloric is, that its 

 character is modified by the size and number of 

 plates composing the battery. For example, 

 when it is composed of a few large plates of 

 zinc and copper, an imponderable fluid is 

 evolved, possessing all the properties of highly 

 concentrated caloric, which fuses and ignites 

 the hardest gems and densest metals submitted 

 to its action ; while it is destitute of nearly all 

 the properties by which common electricity 

 is characterized. The largest battery of this 

 description ever constructed, was that of Mr. 

 Children, which was composed of twenty plates 

 of zinc and copper, six feet long, and thirty-two 

 inches broad. When immersed in a strong acid 

 solution, it melted, ignited, and fused a large 

 platinum wire, six feet in length ; but communi- 

 cated little or no shock to the system; would not 

 charge a Ley den jar ; produced no sensible effect 

 on the electrometer ; and, unlike common electri- 

 city, was conducted slowly by metals, minerals, 

 fluids, fyc.* 



When the battery is composed of two exten- 

 sive coils of zinc and copper ; or of many plates, 



* The large battery of the Royal Institution, employed by Sir 

 H. Davy, which consisted of 2000 pairs of 4 inch plates, melted 

 platinum, quartz, the sapphire, magnesia, and lime, like wax, 

 both in vacuo and in the atmosphere; while charcoal, plumbago, 

 and the diamond were rapidly dissipated in the form of vapour. 



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