The Voltaic pile is the first electric battery, invented by Alessandro Volta in 1800. Volta demonstrated that when metals and chemicals come into contact with each other they produced an electrical current. In his research, Volta placed together several pairs of alternating copper (or silver) and zinc discs separated by cloth or cardboard and soaked the cloth or cardboard in brine (salt water) to increase conductivity, and an electrical current was produced. On March 20, 1800, Volta wrote to the London Royal Society to describe the technique for producing electrical current using his pile.
William Nicholson and Anthony Carlisle discovered electrolysis of water using the Voltaic pile. Humphry Davy showed that electricity from Voltaic piles was caused by a chemical reaction (not by differentials between metals as previously believed). William Hyde Wollaston showed that electricity from Voltaic piles was identical to electricity produced by friction. Davy also used the Voltaic pile to decompose and discover materials.
Contact tension was an early theory that attempted to explain the action of the voltaic pile; it is now an obsolete scientific theory and has been replaced by the current theories of electrochemistry. A number of high-voltage dry piles were invented between the early 1800s and the 1830s in an attempt to determine the source of electricity of the wet voltaic pile, and specifically to support Volta’s hypothesis of contact tension. Indeed Volta himself experimented with a pile whose cardboard discs had dried out, probably accidentally. The first to publish was Johann Wilhelm Ritter in 1802, albeit in an obscure journal, but over the next decade it was announced again and again as a new discovery.
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