Alessandro Volta, now known as the inventor of the electric battery and eponym of the volt, the unit of electrical potential, was a prominent figure in late eighteenth-century science. A younger son from a family of the lesser nobility, he was born in 1745 in the commercial town of Como, in Northern Italy, at that time part of Austrian Lombardy. He received an irregular education and did not attend university. As a sometime pupil of the Jesuits, however, he developed a lifelong interest in natural philosophy, combining it with a commitment to Enlightenment culture and the notion of "useful knowledge," then fashionable among the educated classes and the public administrators of Lombardy. Having chosen the science of electricity and chemistry as his fields of expertise, at twenty-four he published a treatise "on the attractive force of the electric fire." At thirty he embarked on a career as a civil servant and a teacher in the recently reformed educational institutions of Lombardy. Appointed professor of experimental physics at the University of Pavia in 1778, he held the position until he retired in 1820. He traveled extensively, sharing his enthusiasm for natural philosophy with colleagues in Switzerland, the German states, Austria, Britain, the Low Countries, and France where in 1782 he met Benjamin Franklin.
Regarded in some circles as "the Newton of electricity," by the 1780s Volta had won a European fame as an "electrician," a chemist specializing in the chemistry of airs (especially "the inflammable air found in marshes," i.e., methane, his discovery), and the brilliant inventor of intriguing machines. Volta's machines prior to the battery included the electrophorus, or the "perpetual bearer of [static] electricity," a eudiometer, the electric pistol, the "condensatore" (a device that made weak electricity detectable), and a straw electrometer. Volta's contributions to the science of electricity included the notions of tension, capacity, and actuation (an ancestor of electrostatic induction). Thanks to painstaking measurements taken throughout his life, Volta managed to combine these notions into simple, quantitative laws that offered effective guidance through the intricacies of eighteenth-century investigations into electricity. In 1794, the Royal Society of London awarded Volta the Copley Medal for his work on Galvanism. In 1801, in the wake of his discovery of the battery, Napoleon publicly rewarded him. Volta died in 1827 in Como.
The Voltaic battery conceived and built toward the end of 1799 in Como, was the first device to produce a steady flow of electricity, or electric current. The instrument enabled other natural philosophers, notably Humphry Davy, to develop electrochemistry as a new branch of science, and still others, notably Hans Christian Oersted and Georg Simon Ohm, to explore electromagnetism. Because of these later developments—showing that chemical, electrical and magnetic phenomena could be converted into each other—after the early 1840s the battery was a frequent topic for reflections on what was subsequently known as energy conversion, and energy conservation.
Volta saw the battery in a different light. He had conceived it as a demonstration device to show his contact theory of electricity at work. He had developed this theory to refute Galvani's notion of a special electricity intrinsic to animals. Volta claimed that the mere contact between different conductors (especially metals) was able "to set the electric fluid in motion." He also claimed that the electric fluid—one of the several, imponderable fluids then found in physics—was the same in organic and inorganic bodies. He built the battery after reading a paper by William Nicholson, who suggested imitating the electric organs of the torpedo fish by means of an apparatus combining many electrophoruses together. Having discarded his own electrophorus as unable to perform as Nicholson expected, Volta tried instead with pairs of discs of two different metals (like silver and zinc) that he knew could give weak signs of electricity. When he managed to pile up several such pairs, always in the same order and inserting a wet cardboard disc between each metallic pair, he found that an electric current was produced at the two ends of the pile, and that the power of the current increased with the number of pairs making the pile.
In the first circulated description of the battery—two letters addressed to the Royal Society of London on March 20 and April 1, 1800—Volta mentioned no chemical phenomena associated with the new apparatus. It was William Nicholson and Anthony Carlisle who, having had access to Volta's letters prior to publication, first observed the "decomposition of water" (electrolysis) while experimenting with the battery in London in May 1800. Nicholson, in particular, emphasized the chemical phenomena accompanying the operations of the battery. After that, a struggle between Volta's contact interpretation and the chemical interpretation of the battery developed; a struggle that Wilhelm Ostwald still regarded as unsettled in 1895. The struggle had obvious if complex implications for reflections on energy conversion and conservation; the more so because people like Nicholson already perceived the battery as the herald of a new family of machines, and wondered how the "intensity of action" of these machines could be measured.
Viewing things from the perspective of his physical theory of contact electricity, Volta was intrigued by the apparently endless power of the battery to keep the electric fluid in motion without the mechanical actions needed to operate the classical, friction, electrostatic machine, and the electrophorus. He called his battery alternately the "artificial electric organ," in homage to the torpedo fish that had supplied the idea, and the "electromotive apparatus," alluding to the "perpetual motion" (his words) of the electric fluid achieved by the machine. To explain that motion Volta relied, rather than on the concepts of energy available around 1800, on his own notion of electric tension. He occasionally defined tension as "the effort each point of an electrified body makes to get rid of its electricity"; but above all he confidently and consistently measured it with the electrometer.
Bibliography
Heilbron, J. L. (1981). "Volta, Alessandro." In Dictionary of Scientific Biography, edited by C. C. Gillispie, Vol. 14, pp. 69–82. New York: Charles Scribner's Sons.
Pancaldi, G. (1990). "Electricity and Life. Volta's Path to the Battery." Historical Studies in the Physical and Biological Sciences, Vol. 21. Berkeley: University of California Press.
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