The Science Book

EXPANDING HORIZONS 95

but Banks immediately spread
the word to anyone who might be
interested. Within weeks, people
all over Britain were making
electric batteries and investigating
the properties of current electricity.
Before 1800, scientists had had to
work with static electricity, which
is difficult and unrewarding. Volta’s
invention allowed them to find out
how a range of materials—liquids,
solids, and gases—react to a live
electrical current.
Among the first to work with
Volta’s discovery were William
Nicholson, Anthony Carlisle, and
William Cruickshank, who, in May
1800, made their own “pile of
thirty-six half crowns with the
correspondent pieces of zinc and
pasteboard” and passed the current
through platinum wires into a tube
filled with water. The bubbles of
gas that appeared were identified
as two parts of hydrogen and one
part of oxygen. Henry Cavendish
had shown that the formula of
water is H 2 O, but this was the first
time anyone had split water into its
separate elements.
Volta’s pile was the ancestor
of all modern batteries, used in
everything from hearing aids to

trucks and aircraft. Without

batteries, many of our everyday

devices would not work.

Reclassifying metals

In addition to kick-starting the

study of current electricity, and

thereby not only creating a new

branch of physics but rapidly

advancing the development of

modern technology, Volta’s pile

led to a whole new chemical

classification of metals, for he tried

a variety of pairs of metals in his

pile, and found that some worked

much better than others. Silver

with zinc made an excellent

combination, as did copper with

tin, but if he tried silver and silver,

or tin and tin, he got no electricity

at all; the metals had to be

different. He showed that metals

could be arranged in a sequence

such that each became positive

when placed in contact with the

next one below it in the series. This

electrochemical series has been

invaluable to chemists ever since.

Who was right?

An ironic aspect of this story is

that Volta started investigating the

touching of different metals only

because he doubted Galvani’s

hypothesis. Yet Galvani was not

entirely wrong—our nerves do

indeed work by sending electrical

impulses around the body—while

Volta himself did not get his theory

entirely right. He believed that

the electricity arose from just the

touching together of two different

metals, whereas Humphry Davy

later showed that something could

not come from nothing. When

electricity is being generated,

something else must be consumed.

Davy suggested that there was a

chemical reaction going on, and

this led him to further important

discoveries about electricity. ■

The language of experiment is

more authoritative than any

reasoning: facts can destroy

our ratiocination [logical

argument]—not vice versa.

Alessandro Volta

Alessandro Volta

Born in 1745 in Como, northern

Italy, Alessandro Giuseppe

Antonio Anastasio Volta was

brought up in an aristocratic,

religious family who hoped

that he would become a priest.

Instead he became interested

in static electricity, and, in

1775, he made an improved

device for generating it, called

the “electrophorus.” He

discovered methane in the

atmosphere at Lake Maggiore

in 1776, and investigated its

combustion by the novel

method of igniting it with

an electrical spark inside

a sealed glass vessel.

In 1779, Volta was

appointed professor of

physics at the University of

Pavia, a post he held for 40

years. Toward the end of his

life, he pioneered the remotely

operated pistol, whereby

an electric current traveled

30 miles (50 km) from Como

to Milan and fired a pistol.

This was the forerunner of

the telegraph, which uses

electricity to communicate.

The unit of electrical potential,

the volt, is named after him.

Key work

1769 On the Attractive Force

of Electrical Fire