nd nerves of the frog's leg were touched by pieces of two
different metals, the leg would contract as before. Alexander Volta,
another Italian professor, who had invented the electrophorus, and was
possessed of great experimental skill, now turned his attention to the
experiment of Galvani, and very soon discovered that the origin of the
electricity that moved the frogs' legs was not in the legs themselves,
but in the metals used. The first form of the galvanic battery was the
result of Volta's investigations, and was called the Voltaic pile. This
pile consisted of alternate disks of zinc, flannel, and copper, piled
one on top of the other in constant succession in that order. The
flannel was moistened with salt and water, or with diluted sulphuric
acid. When the first zinc was connected with the last copper by means of
a wire, a powerful current of electricity was obtained. This form of
battery is not in use at all now, as much more efficient means are known
for producing electricity; but this in 1800, when it was first made
known in England, was very startling, and was one of those surprises
which have been so frequent since then in the history of electricity.

Surprising things were done by Sir Humphry Davy, with a large Voltaic
battery. Water was decomposed, and the metals potassium and sodium were
first separated from their compounds with oxygen. Bonaparte had offered
a prize of sixty thousand francs "to the person who by his experiments
and discoveries should advance the knowledge of electricity and
galvanism as much as Franklin and Volta did," and of "three thousand
francs for the best experiments which should be made in each year on the
galvanic fluid." This latter prize was awarded to Davy.

After Davy's successes in 1806, there was nothing of importance in an
experimental way added to the knowledge of electricity, until 1820, when
Oersted of Copenhagen announced that "the conducting wire of a Voltaic
circuit acts upon a magnetic needle," and that the needle tends to set
itself at right angles to the wire. This was a kind of action altogether
unexpected. This observation was of the utmost importance; and at once
the philosophers in Europe and America set themselves to inquire into
the new phenomenon. The laws of the motion of the magnetic needle when
acted upon by a current of electricity traversing a wire were
successfully investigated by M. Ampere of the French Academy. He
observed that whenever a wire throug