Alessandro Giuseppi Volta became one of the foremost celebrities of his day for his work with electrical currents. Volta was born on February 18, 1745, in Como, Lombardy, Italy. Most of his eight brothers and sisters entered the church, but Alessandro became engrossed in the study of with electricity. Influenced by a history on the subject written by Joseph Priestley, fourteen-year-old Volta announced his intention of becoming a physicist, and became educated on the subject.
In 1774 Volta was appointed professor of physics at the high school in Como. There he created one of his most significant inventions; the electrophorous. This device had the ability to store significant electrical charges, and replaced the Leyden jar which, up until that time, had been used for storing smaller charges.
The discovery that led Volta to the invention of the electrophorous actually began with the work of French physicist Charles-Augustine Coulomb. Coulomb had discovered that electrical charges were located on the surface of a charged body, and not in its interior. Volta's electrophorous used two metal discs; one was rubbed to produce a negative electrical charge, the second disk was brought close enough to the first to establish a positive charge on the one side, leaving a negative charge on the other. Volta used Coulomb's discovery to draw off the negative charge from one side of his charged disc, leaving just a positive charge on the opposite side. The electrophorous was the predecessor of the modern condenser, which stores electricity in circuits.
In 1776 Volta became involved with an entirely different subject. By studying the components of marsh gas, he was able to discover methane gas. He also exploded hydrogen gas to remove oxygen from air and was able to make the first accurate determination of the proportion of oxygen in the air. Later, around 1796, Volta discovered that the vapor pressure of a given liquid had nothing to do with the pressure of the surrounding atmosphere; it was solely dependent on temperature.
Meanwhile, the electrophorous had established Volta's reputation and, in 1779, he was appointed a professor at the University of Pavia. There he developed an electrometer that allowed him to measure electric currents. Then, in 1791, he was drawn into a controversy that erupted when his compatriot Luigi Galvani announced the existence of "animal electricity" that caused muscles in frog's legs to twitch when touched with metal probes of different composition. Volta did not believe such a thing possible and proceeded to experiment himself.
Volta experimented on numerous animals, including himself, and ultimately discovered there was no such thing as "animal electricity, " and that it was the action of the two different types of metal probes that was the source of the current. This fact was made painfully certain when Volta placed the two metal probes on his tongue. The result was definitely unpleasant. Volta was surprised to find that his own tongue was a more sensitive detector of electricity than his electrometer.
The controversy raged on until 1800. In that year Volta built a device that produced a large flow of electricity. He filled bowls with a saline solution and "connected" them with strips of different metals. One end of the strip was copper; the other end was tin or zinc. By bending his strips from one bowl into another, Volta was able to create a constant flow of electrical current; the world's first electric battery had been invented. Volta had proven that the metal was the source of the electricity, and animal electricity did not exist.
In the interest of making his battery smaller, Volta used round discs of copper, zinc, and cardboard that had been soaked in a saline solution. He stacked his discs one on top of the other. Attaching a wire to the top and bottom of his pile allowed the electric current to flow. The invention of this Voltaic pile marked the apex of Volta's career.
The Voltaic pile came to the attention of English chemist William Nicholson (1753-1815), who proceeded to build his own in the same year. Nicholson placed the ends of his wires in water and discovered the flowing current "electrolyzed" the water, breaking it up into hydrogen and oxygen. Henry Cavendish had shown those two elements could form water; Nicholson reversed the procedure.
The invention of the Voltaic pile, the earliest form of an electric battery, was the high point of Volta's life. He died on March 5, 1827, at the age of 82. In his honor, the unit of force that moves electric current was named the volt.