In 1791, Luigi Galvani interpreted the muscular contractions observed in frogs as proof of the existence of animal electricity. According to this hypothesis, the electric fluid accumulated in the tissues and discharged through a metallic arc, causing the muscles to move.
Volta initially received Galvani’s conclusions with interest, but by repeating the experiments he arrived at a different interpretation: the frog was not the source of electricity, but rather a detector. The phenomenon depended on the contact between two different metals, while the animal tissues played a secondary role.
Thus began a dispute that involved the entire European scientific community. Galvanians and Voltaians debated for years, while Volta refined his research and in 1792 announced the fundamental discovery: electricity is generated by the contact between different conductors.
To definitively prove his theory, Volta removed the frog from his experiments. By inserting a moist conductor between two different metals and closing the circuit, he obtained a permanent electric current. This was the principle of contact electricity, fully formulated in 1796.
Between 1794 and 1799, Volta experimented with numerous combinations of dry and moist conductors, eventually arriving at the decisive solution: alternating discs of zinc and copper separated by material soaked in an acid solution. Thus was born the battery, the first generator of continuous electric current in history.
On 20 March 1800, Volta announced his invention of the battery to the Royal Society in London. The paper, published in Philosophical Transactions, caused great astonishment. The battery ushered in a new era, paving the way for discoveries in electromagnetism and chemistry in the 19th century.
Seemingly simple, the battery is the basis for all subsequent research on electricity. As Einstein, Arago and Righi recognised, none of the great discoveries of the nineteenth century would have been possible without this instrument. Volta also intuited, well in advance, the possibility of transmitting electricity over long distances.
