Alessandro volta

( 1745 – 1827 )

It is well known that Volta invented the primary battery and in so doing moved electrical science into an age of electrodynamics. What is less well known is that he proposed a fundamental unit of electric tension some years before that invention, when scientists were still deep in the age of electrostatics. It is perfectly appropriate then that the unit for electromotive force (a term he introduced) is named after him. We may be thankful, though, that his original unit was never accepted; it is roughly equal to 13 350 volts!

Volta was already an established scientist with a reputation for experimental work when he announced the invention of the "Pile", the first electric battery. The importance of the invention was instantly recognised as being of the first rank and it opened new avenues of enquiry, including electrochemistry and electrodynamics. It quickly led to experimental electric light and industrial electroplating.

Volta was born in Como in the duchy of Milan in Northern Italy on the 18th February 1745 and died there 82 years later on the 5th March 1827. On his mother's side he came from a family with a leaning towards the law¹; his father's family was devoted to the church. One of his three paternal uncles was a Dominican, one a canon, and the third an archdeacon.

Alessandro was seven when his father died. When he was 12 one of his uncles took charge of his education, which began at a Jesuit college and nearly led to him becoming a Jesuit. His uncles decided they did not want that and so his education continued elsewhere. It was a wealthy friend, Giulio Cesare Gattoni, who provided the books and equipment which helped him to begin studying electricity.

The uncles had by now chosen his future career: the law. Somehow he avoided this path and continued to study what he termed his genius: electricity. Boldly, he wrote to leading scientists to discuss problems he encountered. One, Beccaria, recommended his own writings and also told Volta to experiment. So Volta began to develop his gift for making inexpensive but effective instruments.

Slowly, from the mid-1760s he learned the science and practice of electricity and in October 1774 he received his first academic appointment, at the Gymnasium in Como. The next year he was appointed professor of experimental physics. About the same time he made his first important invention, the electrophorus, and followed that with the discovery of methane.

The electrophore was probably the most significant electrical invention since the Leyden Jar capacitor². After considerable experimentation, in June 1775, he announced his "elettroforo perpetuo". It was an inductive device for repeatedly charging a tin-foil covered shield which, in turn, was used to build up a large charge on a Leyden Jar capacitor. Whilst others had come close, only Volta produced a sturdy and usable instrument.

In 1776, he briefly turned to the study of gases and discovered a new gas which we know as methane. "Inflammable air" (hydrogen) had been isolated chemically ten years earlier and was known to exist naturally. Volta became intrigued by the "different kinds of air" and searched the countryside for the telltale bubbles until he found a new gas at Lake Maggiore. Hydrogen, however, was more explosive and it was hydrogen and air (oxygen), not methane, that Volta used in an "inflammable air pistol" which was fired by an electric spark. The pistol fired a lead ball, denting wood at 15 feet. From related experiments he concluded that about 20% of common air was oxygen. He narrowly missed synthesizing water³, but his method was successfully used later by Lavoisier, Laplace and Monge in France.

His discovery of methane obviously enhanced his scientific reputation and his reward was a travel grant, which took him to Switzerland and Alsace. The grant came from the Austrian government which then ruled Northern Italy. Then came Volta's appointment to the professorship of experimental physics at the University of Pavia; his popular professorship there ran for nearly 40 years. In 1781/82 he visited France and England, and in 1784 he went to Germany. On such state-financed trips he bought new equipment for the laboratory at Pavia. Most of the instruments he built up were destroyed in a fire in 1899.

Politically, Volta had much to be thankful for to the Austrians, but in l796 they were driven out of Northern Italy by the French, led by Napoleon. Volta was chosen in May of that year as one of a delegation to represent Como in honouring Napoleon. Later, he became an official of the new Government of Como but it was a position from which he soon resigned; his lingering loyalty to the Austrians, the damage done to his laboratory by French troops and his coldness towards the French led to his expulsion from Pavia for a while. It did him no harm, however, when the Austrians retook the country in 1799: though they closed the university, Volta remained free.

Thirteen months later the French were back. The university was reopened, Volta was once again a professor and accepted his status as a citizen of the new republic. A trip to Paris to express the university's thanks to Napoleon became a triumph for Volta. The primary battery was by then well known and its chemical power had made scientific headlines. Even Napoleon attended his demonstrations at the French Academy and Volta was awarded a gold medal.

In many ways Volta's discoveries captured Napoleon's heart and he continued to be an admirer. A prize of 60,000 francs was announced for "whoever by his experiments and discoveries makes a contribution to electricity and galvanism comparable to Franklin's and Volta's". Volta was later given a pension, and made a count and a senator ⁴ in the kingdom of Italy.