Alessandro Volta

Compiled by Peter Ellis

Today we take electric current for granted. We plug into the mains or slot in a new battery and we have power. Two hundred years ago there was no source of instant continuous electricity - that is until Volta invented his pile.

The young scientist

Alessandro Volta was born in Como in northern Italy in 1745. He was the son of a nobleman but the family had little money. After leaving school he had to find work and took the job of superintendent of schools in Como. He suggested that pupils should be taught arithmetic and French. His real interest however, was in science and electricity in particular. A friend had been the first to fit a lightning conductor to a building in Como and as early as 1769 he was writing about his investigations into static electricity. He wrote letters to well known scientists all over and by 1778 his work was respected enough for him to be made a professor at Pavia University south of Milan. He invented a way of storing electric charge called an electrophorus and compared the electrical properties of different substances.

Travel and love

In 1781 Volta travelled to Paris and London becoming friendly with many English scientists. He had an affair with an opera singer, Marianna Paris, which lasted four years from 1788 but was not allowed to marry her because of his noble birth. He even appealed to the Austrian Emperor, who ruled the state of Lombardy in which Como is situated, but to no avail. Instead in 1794 he married a noble lady nineteen years younger than himself, called Teresa Peregrini.

Controversy and discovery

By this time Volta was in dispute with the followers of Luigi Galvani. Galvani had discovered that frogs' legs jerked when connected to an electric charge. In fact they also twitched when they were simply hung on a metal hook. Galvani thought that animals contained a type of electricity that made the muscles jump. Volta disagreed. He carried out experiments and found that the frog's legs only moved when two different metals were touching them. He investigated the effect further but had many problems. This type of electricity was much weaker than the powerful shocks given by static electricity machines and he had no suitable apparatus for measuring the current. He improvised by using his tongue to detect the weak electric current and found that combinations of different metals produced different amounts of tingling when touched to his tongue. Zinc and silver gave the biggest effect. By 1799 Volta had completed his investigation but had no idea what to do next. Then he read about the torpedo fish that can deliver a powerful electric shock like electric eels. The electric organs of the fish apparently had alternating discs of material. This was the clue Volta needed. He arranged discs of zinc, silver and leather soaked in salt water in a column repeated up to thirty times. When he connected a wire to the top and bottom discs he obtained an electric current which didn't just produce one spark but kept on going. He had invented the Voltaic pile or battery.

A difficult announcement

Volta made his invention in1799 but now politics interfered. Napoleon of France had invaded Lombardy and Volta was reluctant to announce his discoveries. Then early in 1800 the Austrian army succeeded in driving the French out. Volta seized the opportunity and wrote off a letter describing his work to his friend Sir Joseph Banks in London. Banks was President of the Royal Society and when he read the letter he realised how important Volta's invention was. Straight away he arranged for the letter to be published along with Volta's diagram, in the Royal Society's journal, Philosophical Transactions. By the summer of 1800 the news of the voltaic pile was spreading across Europe.

Famous scientist

Later in 1800 the French re-took Lombardy and now Napoleon wanted to know more about the amazing invention of the Italian professor. He invited Volta to Paris in 1801 and Volta demonstrated his piles - large ones that could deliver a powerful current and small, pocket models. Napoleon rewarded Volta by making him a Count. For the rest of his life Volta was famous and he travelled around Europe demonstrating his invention. He died in 1827.