Recreating Volta’s pile

Earlier this month I was lucky enough to be invited to join the Naked Scientists radio show to build a voltaic pile in front of a live audience. You can listen here:

 The story of the development of the pile is an interesting one. In 1799 Alessandro Volta was experimenting with some curious phenomena that had been discovered by fellow Italian Luigi Galvani in the 1780s. Galvani had found that the muscles of dead frog’s legs could be made to twitch by touching the nerves with two pieces of metal. After several years work, and isolating the experiment from outside forces as well as he could, Galvani concluded that there was an “animal electricity” that came from within the frog. His work was intriguing, and easy to repeat. Interested natural philosophers from across Europe began experimenting and debating the new electricity.

Volta was one of those interested experimenters and, although initially agreeing with Galvani’s assessment, over time he began to consider that the electrical fluid, as it was then conceived, did not originate in the frog. He began to see the frogs’ legs as sensitive instruments, rather than the cause of the phenomena. To test his idea Volta sought ways to remove the frog from the experiment. He knew that the excitation of the leg muscles was more pronounced when two different metals were used to touch the nerves, and he suspected that metals were the key to understanding.

Volta’s breakthrough came in 1799 when he took two different metals, zinc and silver, and experimented with placing them together. A zinc disc was put down, then a silver disc, and finally a disc of damp cardboard. This was repeated several times to create a pile of discs, which if large enough was indeed capable of giving Volta an electric shock. Volta’s electrical pile was the first device that was able to produce a reasonably consistent source of electricity.

The full kit: sea salt, water, cardboard, zinc, copper and a buzzer to prove to the listeners there's some real electricity there!

The full kit: sea salt, water, cardboard, zinc, copper and a buzzer to prove to the listeners there’s some real electricity there!

The pile up close

News of Volta’s invention spread incredibly quickly within scientific circles, and through reports in newspapers of impressive public displays. Within weeks William Nicholson and Anthony Carlisle in London used a similar pile to decompose water into oxygen and hydrogen. A new discipline of electro-chemistry proved very fruitful in the coming years, enabling Humphry Davy to discover and isolate several new elements with the enormous pile he’d had built for his lab at the Royal Institution. By 1820 variations on Volta’s pile were common in scientific laboratories, giving the Danish scholar Hans Christian Oersted the tools he needed to discover the link between electricity and magnetism. His discovery paved the way for the electric telegraph, which revolutionised communication technologies.

Although Volta’s theories about the production of electricity were eventually discredited as new ideas came along, his name is still tightly linked with electrical science. His invention and theories fueled debate, experiment and still more theories. The electric battery as we know it today is crucial to our everyday lives as mobile phones demand great things from tiny devices, and electric cars continue to push the technology forward.

Google celebrated Alessandro Volta’s birthday on 18 March 2015 with a doodle in his honour.

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