We're History: How Animal Electricity Got a Life of its Own in Chemical Engineering Progress
September 1, 2011 - New York, NY
By Michal Meyer
In the late 1780s, visitors passing through the pleasant garden of Dr. Luigi Galvani may well have been taken aback. This respected member of Bologna's medical community had been draping dismembered frogs over his trellises.
In 1791, Galvani's frogs, both living and dead, triggered a controversy. Galvani's frog experiments convinced him that he had proved the existence of an electricity inherent in living things - what he called an animal electricity. This caused an uproar in Europe, where anyone pretending to have an interest in science rushed out to find some frogs.
Prior to Galvani's work, a widely accepted theory held that muscular motion was caused by a nervous fluid that ran from the brain through nerve canals to the muscles. Some, including Galvani, said that electricity (then considered a type of fluid) was identical with this nervous fluid. His evidence? Touching the exposed crural nerve in a (recently) dead frog's leg with a metal scalpel caused the frog to kick.
Galvani designed and carried out further experiments. He stuck bronze hooks into the spinal columns of his prepared frogs and draped the bodies over an iron trellis in his garden. When he pressed the bronze against the iron, the frog muscles contracted. He tried the experiment indoors and varied the metals used, and he got the same results, although the contractions were stronger with some metals than with others, From these experiments, Galvani formulated his theory of an animal electricity generated by the animal's own tissue.
Univ. of Pavia physics professor Alessandro Volta was, like much of literate Europe, astounded by Galvani's results. He repeated Galvani's experiments and initially came to the Same conclusions. But he soon shifted to considering the effect of the metals. It was the contact between different metals, he decided, that was generating the electricity - the frog simply acted to complete the circuit. He named this phenomenon metallic electricity. No frog required.
In response, Galvani presented further experimental proofs of his theory. Volta responded with counter experiments. Finally, Galvani discovered that muscle contractions still occurred when he swung the dead frog so hard that the exposed sciatic nerve touched the muscle of the swinging leg. No metal required.
Volta invented the battery as his pièce de résistance - his final proof against a purely biological cause for electricity. However, it was now too late to change Galvani's mind. He had died in 1798, in poverty, after refusing to give an oath of allegiance to the new French-imposed Cisalpine Republic.
In 1800, Volta announced his best-known invention through the world's premier scientific society, the Royal Society of London. It became an instant hit throughout Europe. Volta had included building instructions, and batteries were soon made with coins, bits of zinc, pasteboard, and water. Volta even managed to impress Napoleon Bonaparte, who made him a count and a Senator of the Realm of Lombardy.
Volta considered his battery the last nail in the coffin of animal electricity, but he soon lost control of his own invention. In 1800, William Nicholson and Anthony Carlisle in England followed Volta's instructions for batterymaking, and noticed a gas being produced from the water. The battery was chemistry, not physics! Also in England, William Cruikshank carried on with battery-powered chemistry and developed electroplating. Humphry Davy continued the chemical approach, passing currents through many substances and producing - for the first time - the elements potassium and sodium. In 1810, he produced the first electric light using a giant battery underneath the Royal Institution.
Galvani's nephew, Giovanni Aldini, took animal electricity in a different direction, one later reflected in Mary Shelley's Frankenstein (1818). Aldini, appointed professor of physics at the Univ. of Bologna the year his uncle died, carried out his own experiments and later traveled throughout Europe giving demonstrations using animal and sometimes human bodies. He performed in Paris in 1802 and in England in 1 803, where his public displays were reported in the press and attracted the fashionable, including the Prince of Wales. Aldini's experiments led him to believe that he could restore life to those recently drowned or asphyxiated. In 1 804, he used Volta's battery to create strong muscle spasms in corpses, making it appear that the body was preparing to walk.
Perhaps the most striking demonstration was that performed by a Scottish chemist on an executed murderer. When current was passed through a nerve on the forehead, expressions of rage, horror, despair, and happiness passed across the murderer's countenance. One spectator fainted and several were forced to leave the room (and some of these were hardened medical men.').
Shocking, but true.
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