Merry Blogmas for December 10: Volta’s Pistol

Merry Blogmas for December 10: Volta’s Pistol

Our daily “Merry Blogmas” posts on fun bite-sized science topics will run until Christmas. Today we look at the invention of spark ignition in the strange contraption called Volta’s pistol.

Though originally scheduled for today, part III of the food science of hard-boiled eggs, will post tomorrow.


Alessandro Volta is important. A little over two centuries ago, Volta invented the battery. He also discovered methane. More important than either, he’s that so-and-so who came up with electrochemical potentials and the electromotive series. Yes, this is the guy who has made generations of high school chemistry students miserable. Because of Alessandro Volta, hundreds of millions have been tortured with the horrors of half-cell reactions. Now you know who to blame.

The volt is named after him.


Volta invented spark ignition because he wanted to demonstrate the concept of flammable gas. The contraption he made to do this is called Volta’s pistol:

  • He made a metal vessel into which he placed oxygen and hydrogen or methane.
  • he sealed the vessel with a tightly-fitted stopper of cork or some similar material.
  • There was a brass rod inserted through the side of the metal vessel. It was insulated from the metal vessel by a ring of glass insulation.

Interior view of Volta's Pistol

Back in those days, before Faraday invented the induction coil, the only way to produce high-voltage electricity was with a static-charge generator. That’s what Volta used as his source of electricity.

  • Holding the metal vessel of “Volta’s pistol” in his hand, he then touched the brass rod to the charged end of an static-charge generator.
  • With the hand-held vessel acting as the ground, the charges traveled into the vessel through the brass rod.
  • The static electricity then sparked between the end of the rod and the vessel wall.
  • This spark ignited the flammable gasses which then exploded.
  • The exploding gasses forced the expulsion of the stopper with a loud gun-shot-like pop.

In the nineteenth and early twentieth centuries, Volta pistols, cannons and mortars were popular for demonstrations of spark ignition in physics classes.


Volta’s invention of spark ignition was the first necessary step in the creation of the internal combustion engine. Without internal combustion engines, we’d still be boiling water to run everything with steam engines.

Both images today are from an 1877 edition of a text book called  “The Forces of Nature, A Popular Introduction to the Study of Physical Phenomena” by Amédée Guillemin, via Google Books.

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