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History

It's Alive!

Galvani, Volta, animal electricity, and the first battery

By the late eighteenth century, experimenters knew how to generate static electricity, move it through conductors, insulate it, and store it in Leyden jars. But one mystery remained especially provocative: living animals themselves seemed to produce electrical effects.

Electric rays and electric eels had already made that idea difficult to dismiss. Their shocks could be transmitted through conducting paths and felt remarkably like the shocks produced by electrical apparatus. The question was no longer merely whether animals could be affected by electricity. Could electricity actually be part of the way living tissue worked?

This is where electricity and biology collide.
The resulting argument between Luigi Galvani and Alessandro Volta helped create both electrophysiology and the first practical source of continuous electric current.

Electric fish were already pointing the way

Long before Galvani's frog experiments, people knew that certain fish could deliver powerful shocks. By the eighteenth century, investigators were deliberately testing electric rays and electric eels with conductors and insulators and comparing their effects with laboratory electricity.

The electric organs of these animals are built from large numbers of specialized cells now called electrocytes or electroplaques. They are arranged in repeated layers or stacks so that their small individual electrical effects combine.

These are sometimes loosely pictured as “scales,” but they are not the animal's external scales. They are specialized electrical cells inside the electric organ. Their stacked arrangement is remarkably suggestive when we later look at Volta's pile of repeated metal-and-electrolyte layers.

Luigi Galvani and the twitching frog legs

In Bologna during the 1780s, physician and anatomist Luigi Galvani investigated the effects of electricity on dissected frogs. The most famous observation was startling: under the right conditions, touching exposed nerves with metal could cause the muscles of a dead frog's leg to contract sharply.

The leg was not alive in the ordinary sense, yet the muscle moved.

What Galvani could see

A frog leg had been dissected so that nerves and muscles were accessible.
Metal conductors contacted parts of the nerve-and-muscle preparation.
When the electrical path was completed, the leg contracted.
The effect could be repeated.

This made it reasonable to suspect that electricity had some intimate relationship with nerves and muscles.

Galvani's interpretation: animal electricity

Galvani concluded that animals possessed their own form of electricity and that the nerves and muscles were involved in storing, conducting, or releasing it. His work helped establish the idea of animal electricity.

This was not merely an odd theory about frogs. If living tissue actually depended on electricity, then electricity might be part of the basic mechanism of life itself.

Coulomb makes electric charge quantitative

At about the same time that Galvani was investigating frogs, the French physicist Charles-Augustin de Coulomb was measuring the forces between electrically charged bodies. Using a sensitive torsion balance, he showed that electrical force changes systematically with the amount of charge and with distance. His work helped turn “more electrified” and “less electrified” into a quantity that could be treated mathematically.

Measurement trail 4 — electric charge: the coulomb (C)

The quantity is electric charge, usually written Q. The SI unit is the coulomb, symbol C, named for Coulomb.

In the modern SI, the elementary charge e has the exact value 1.602176634 × 10⁻¹⁹ C. So one coulomb corresponds to approximately:

1 C ≈ 6.241509074 × 10¹⁸ elementary charges

Later we will gain an even handier circuit relationship: one coulomb is the amount of charge moved by one ampere in one second. We already know the second; the ampere will arrive when the history reaches Ampère.

Historically, the name coulomb was standardized long after Coulomb's own experiments. At the 1881 International Electrical Congress it was defined in relation to the ampere and second.

Volta agrees with the experiment — but not the explanation

The Italian physicist Alessandro Volta took Galvani's experiments very seriously and repeated them. But Volta became skeptical of Galvani's explanation.

He noticed that the strongest contractions often involved two different metals. Volta argued that the metals themselves were generating the electrical action, while the frog leg was acting as a sensitive detector.

Galvani	Volta
The animal itself contains an electrical force associated with nerves and muscles.	The contact of dissimilar materials is producing the electrical effect seen in the frog.
The frog preparation reveals electricity already present in living tissue.	The frog preparation can serve as a very sensitive detector of electricity produced elsewhere.

A dispute in which both men had part of the truth

Modern physiology tells us that Galvani was right about something fundamental: nerves and muscles really do operate through electrical changes across cell membranes.

Volta was also right that combinations of dissimilar materials and an electrolyte can create an electrical potential. His pursuit of that idea led directly to the battery.

Galvani even developed later experiments that avoided the use of two dissimilar metals and still produced contractions, strengthening the case that electrical activity belonged to the tissue itself and was not merely an artifact of metal contact.

This is a wonderful example of science advancing through disagreement:

Galvani helped reveal bioelectricity.
Volta helped reveal electrochemical electricity.

Volta removes the frog

Volta's challenge was simple to state: if the metals were responsible, could he produce electricity without using an animal at all?

The answer was yes.

In 1800 he announced the voltaic pile. Alternating discs of two different metals, commonly described as zinc and copper, were separated by material moistened with an electrolyte. Repeating the arrangement again and again increased the electrical effect.

metal → electrolyte → different metal → repeat → repeat → repeat

A pile that behaved like an artificial electric organ

The resemblance to electric fish was difficult to miss. A single biological electrical cell produces only a modest potential, but many such units arranged together can produce a much larger effect. Volta explicitly compared his new device with the electrical organs of animals.

The thin, repeated units in the electric organ of the torpedo ray were especially suggestive of a stacked source. Volta's pile likewise built voltage by repeating many small electrochemical units.

The important word here is stacked. The relevant parts of an electric fish are not ordinary skin scales; they are specialized internal electrical cells arranged in repeated layers.

Static electricity had met its rival: continuous current

A Leyden jar could produce a dramatic discharge, but once discharged it was empty until recharged. The voltaic pile was different. Chemical action could maintain an electrical potential and supply current for a much longer time.

Leyden jar	Voltaic pile
Stores charge supplied from somewhere else.	Produces electrical energy through chemical action.
Often associated with high voltage and brief discharge.	Could provide sustained current.
Ancestor of the capacitor.	Ancestor of the electrochemical battery.

The language survives

The names of both men remain embedded in electrical terminology.

Galvanic and galvanism preserve Galvani's name.
A galvanometer is an instrument for detecting or measuring electric current.
The volt, our unit of electrical potential difference, honors Volta.
A voltaic cell is an electrochemical cell that produces electrical energy from a spontaneous chemical reaction.

But the public imagination was about to seize on a different question:

If electricity could make dead muscle move, could it restore life?

< The Leyden Jar | Galvanism, Cadavers, and Frankenstein >