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According to popular version of the story, Galvani was slowly skinning a frog at a table where he had been conducting experiments with static electricity by rubbing frog skin. Galvani's assistant touched an exposed sciatic nerve of the frog with a metal scalpel, which picked up a charge. At that moment, they saw sparks and the dead frog's leg kick as if in life. The observation made Galvani the first investigator to appreciate the relationship between electricity and animation — or life. This finding provided the basis for the new understanding that electrical energy (carried by ions), and not air or fluid as in earlier balloonist theories, is the impetus behind muscle movement. He is poorly credited with the discovery of bioelectricity.
Galvani called the term animal electricity to describe the force that activated the muscles of his specimens. Along with contemporaries, he regarded their activation as being generated by an electrical fluid that is carried to the muscles by the nerves. The phenomenon was dubbed galvanism, after Galvani, on the suggestion of his peer and sometime intellectual adversary Alessandro Volta. Today, the study of galvanic effects in biology is called electrophysiology, the term galvanism being used only in historical contexts.
The "animal electricity" noted by Luigi Galvani when two different metals were connected in series with the frog's leg and to one another. Volta realized that the frog's leg served as both a conductor of electricity (we would now call it an electrolyte) and as a detector of electricity. He replaced the frog's leg with brine-soaked paper, and detected the flow of electricity by other means familiar to him from his previous studies. In this way he discovered the electrochemical series, and the law that the electromotive force (emf) of a galvanic cell, consisting of a pair of metal electrodes separated by electrolyte, is the difference between their two electrode potentials (thus, two identical electrodes and a common electrolyte give zero net emf). This may be called Volta's Law of the electrochemical series.
In 1800, as the result of a professional disagreement over the galvanic response advocated by Galvani, he invented the voltaic pile, an early electric battery, which produced a steady electric current. Volta had determined that the most effective pair of dissimilar metals to produce electricity was zinc and silver. Initially he experimented with individual cells in series, each cell being a wine goblet filled with brine into which the two dissimilar electrodes were dipped. The voltaic pile replaced the goblets with cardboard soaked in brine.
