Alessandro Volta (1745-1827)
Alessandro Volta was an Italian scientist whose skepticism of Luigi Galvani’s theory of animal electricity led him to propose that an electrical current is generated by contact between different metals. Volta’s theoretical and experimental work in this area resulted in his construction of the first battery. Known as the voltaic pile, Volta’s battery made available for the first time a sustainable source of electrical current. Using the innovative apparatus, a number of his contemporaries, such as William Nicholson and Sir Humphry Davy, made important scientific advances in the early 19th century.
Volta, whose full name was Alessandro Giuseppe Antonio Anastasio Volta, was born on February 18, 1745, in the town of Como in Lombardy, Italy. His family was part of the aristocracy but was not particularly wealthy. Volta’s father died when Volta was only 7, and the boy’s education was overseen by relatives associated with the church. Volta was expected to embark on an ecclesiastical career, but he developed an early interest in science and decided to follow a different path. He related many of his earliest scientific ideas to French physicist Jean-Antoine Nollet and prominent Italian men of science with whom he regularly corresponded while still a teenager.
Volta was particularly interested in electricity. His first published treatise, “De vi attractiva ignis electrici” (“On the forces of attraction of electric fire”), appeared in 1769. Two years later he published a work describing a new type of electrostatic generator he had built. The recognition Volta garnered from these early works helped gain him an academic appointment teaching natural philosophy at the Liceo of Como in 1774. The following year, he described to Joseph Priestley another of his inventions, the perpetual electrophorus. Others had known of the principle of electrostatic induction on which the device was based, but Volta’s electrophorus was the first practical instrument for transforming mechanical work into electrostatic charge without requiring constant rubbing action. The instrument quickly found its way into laboratories across Europe, boosting Volta’s renown.
In addition to electrical phenomena, Volta’s studies often involved gases. This interest was sparked during a 1776 visit to Lake Maggiore, where he noticed water bubble after he stirred the mud beneath it. He collected some of the gas responsible for the bubbling to study in his laboratory. Today that gas is known as methane, the primary component of marsh gas. While experimenting, Volta found the gas to be highly combustible. This line of research led to Volta’s construction of another novel apparatus. Volta’s pistol was a device that safely allowed an explosion to be sparked in a closed environment, and can be considered a predecessor of the internal combustion engine. Volta, however, used the pistol to gauge the force of gaseous explosions and deduce the amount of oxygen contained in combustible air samples – in other words, as a eudiometer.
In 1779, the University of Pavia offered Volta its chair of natural philosophy, and he accepted. At about this same time at the University of Bologna, another prominent Italian scientist, Luigi Galvani, was carrying out experiments with electricity in the same laboratory in which he dissected frogs. Galvani’s work in these seemingly disparate areas resulted in some very surprising observations. Galvani noticed that the dismembered legs of frogs seemed to twitch back to life under certain circumstances, such as during an electrical storm, or when he touched a steel scalpel against a specimen hanging from a brass hook. Galvani deduced that electricity was naturally present in the tissues of frogs and other animals. Published in 1791, these views regarding animal electricity were received favorably by some, with skepticism by others. Volta was the most vocal doubter, and embarked on a series of experiments to develop a different explanation for the strange phenomena.
Volta’s work led him to theorize that the tissue of the frog was not necessary for the generation of a current, but rather that the legs of the animal served simply as indicators of an electrical charge passing between dissimilar metals, such as steel and brass. The type of electrical activity theorized by Volta came to be known as metallic electricity. The disagreement between Volta and Galvani became a significant matter of debate at the time, with opposing camps aligning themselves with one scientist or the other. Both, however, were partly correct: muscular contractions are stimulated by electricity (as suggested by Galvani) and contact between dissimilar metals can produce a current (as proposed by Volta).
While attempting to prove his own theory, Volta experimented with various metals and electrolytes, eventually producing the voltaic pile. The pile consisted of a series of discs of zinc and copper (later other metals were used) arranged vertically and separated by pieces of cloth or cardboard soaked in an acid or salt solution. Glass rods provided support to the discs, the number of which Volta varied to produce stronger or weaker charges. In 1800 Volta announced his invention of a device that could continuously generate an electrical current, and the voltaic pile was enthusiastically received. He was invited to Paris in 1801 to demonstrate the pile to prominent French scientists and Napoléon. Duly impressed, Napoléon bestowed many honors on Volta, including a gold medal, a pension and appointments as a cavalier, senator and count.
In his later years, Volta’s political appointments left him less time for hands-on work in the laboratory. In 1819, he retired to a family estate in the country. He died on March 5, 1827. In 1881, the term volt was officially adopted in his honor to designate the unit of electric potential and electromotive force.