How could jealousy lead to an invention? And why would someone be jealous of a frog? Well, I’ll tell you and along the way I will talk about: academic dishonesty, reanimating corpses, scientific rivalries, tingly metals, and Napoleonic politics, and I will also show you how to light a LED bulb with pennies and vinegar and how to use pennies to make Oxygen! Ready?
In 1791, an Italian anatomy professor named Luigi Galvani accidentally discovered that a dead frog leg could jump if it was touched with a probe that was electrified with a static electricity machine. He then found that the leg could also move if it was touched by two different metals, without any static or atmospheric electricity in sight! In other words, the two metals with the frog somehow created electricity! Galvani correctly determined that electricity was connected to life itself. Not unexpectedly, Galvani’s paper took the world by storm.
One person who was very interested in this paper was Italy’s greatest electrical scientist, Alessandro Volta. Volta was a loud boisterous man, a world traveler who spoke many languages and was known by a contemporary as, “a genius who swore and cackled over his experiments, guzzled and disputed over his dinner, electrified the ladies…and understood more of electricity than anyone else in Europe.”
Volta first came to fame by, basically, stealing another person’s invention, an object that Volta called “the electrophorus”. In the following years, Volta made several discoveries that are not attributed to other people, like discovering methane, but most of his fame came from the electrophorus and his oversized persona.
Volta began to repeat Galvani’s work and found the results “unbelievable” and “miraculous”. Volta then got a live frog to jump with two different metals attached to each other and to the frog’s leg and back. Volta decided that Galvani was not re-animating the frog, as even a live frog would move if in contact with dissimilar metals. Volta decided that the electricity came from the different metals and the frog was merely responding to the electricity produced by the metals, just as it jumped from the electricity from machines and from lightning bolts.
Soon it became a big debate. Was the frog jumping because it had once been alive or was the frog jumping because two different metals created electricity? Quickly, the scientists of Italy and Europe began a battle between the Voltists and the Galvanists. By the way, both sides were partially correct and partially incorrect. Galvani was correct in that all living things use and produce electricity to make their muscles move and their nerves transmit signals, which is why if you artificially add electricity even a dead animal will react. Volta was correct in that the two metals were creating electricity, which had nothing to do with the frog previously being alive. The big thing that Volta missed was the acid in the frog’s leg that reacted differently to the different metals – in other words, he didn’t realize this was a chemical reaction and thus needed a chemical (an acid or a base) to work.
Galvani was not really a good debater for the Galvanists as in 1797 he lost his job and was restricted from publically speaking due to his objection to Napoleon taking over Italy. Depressed and impoverished, he died the next year from unknown causes. One of the biggest supporters of the “Galvanist” theory was Galvani’s nephew Giovanni Aldini. Aldini, despite being a professor of Physics, was much more of an entertainer than a scientist. For example, he liked to do public demonstrations twitching the eyes or mouth of a cow’s head and even a human head of a decapitated criminal. This, for obvious reasons, gained the public’s attention, and soon “Galvanists” throughout Europe were “entertaining” crowds with these gruesome shows. Years later a young woman had a scary dream about Galvanists and wrote it up as a horror story called “Frankenstein”! However, despite their public appeal, these dramatic displays did not help much in academia.
Volta had won a prestigious British award for explaining Galvani’s experiment. However, Volta was unhappy. He didn’t want awards for explaining other people’s work, he wanted an award just for himself. Volta needed a decisive experiment. Something that would prove that electricity came from the metals and not the frog. However, the only sensitive electroscope he had was a frog’s leg so he was in a bit of a quandary – to prove his thesis, he needed a more powerful system with only inorganic materials.
The first thing Volta did was to determine which metals worked the best on the poor frog and found that silver and zinc seemed to have the greatest effect. He then put a piece of silver and zinc in his OWN mouth and he felt a slight tingle. However, if he connected the silver and zinc to wires and put the wires on his tongue, he felt nothing. Volta started to wonder if the metals had to be wet. Therefore he put the metals in a cup of water. Suddenly, there was enough voltage to be noticeable on his tongue! He then added cups of water in a row and got a stronger “tingle”. Volta then turned the experiment on its side. He put wet thin cardboard between a pair of silver and zinc disks and stacked them together to get a pile. In this way, he got a relatively strong tingle. Moreover, you could get more tingling by just adding more disks (and by using saltwater instead of plain water). If you wet your hands you could even feel a shock through your whole body! Here was a non-organic object that would create continual electricity with no rubbing required. In fact, Volta had just invented the battery! He published his work in 1800 to tremendous acclaim.
Of course, Volta did not actually call his device a battery. In fact, “a battery” was a term already in use for a set of Leyden jars – the most powerful electrical device available at the time. Now Leyden jars are stored and gave electricity in a jolt and the battery gives a continuous flow of electricity, so they are very different. However, as Volta was trying to pump up his accomplishment he often referred to his discovery as resembling, “an electric battery” so you can see how the name got co-opted.
Volta’s victory was complete. Napoleon was quite impressed with the device and made Volta a Count for his accomplishments. The potential of a battery is measured in Volts (named after him) and is often referred to as Voltage in his honor. Volta won many awards and retired a wealthy man, never to do anything else worthy of publishing. Interestingly, in his famous paper of 1800, he still found time to insult his old rival Galvani who had died two years earlier by writing that his research was initiated because “I found myself obliged to combat the pretended animal electricity of Galvani”
How does Volta’s pile of metal and saltwater compare to a modern battery? Well, to answer that question I need to talk about two things: 1) Voltage and 2) Maximum Current. Voltage is like the power in the water pump that adds water pressure to your pipes, it is there even when no water is flowing. The battery in your cell phone has 3.7 Volts of potential. A typical pile that Volta used would produce 5, 10, and even 20 Volts!! You can actually make your own pile quite easily with copper pennies and zinc washers, and paper soaked in vinegar! Just like Volta, you can pile up the zinc, vinegar-soaked paper, and pennies to make a homemade battery. This pile of just ten pennies creates an astonishing 8 volts of potential!!
So, can I power my cellphone with a pile of pennies? Unfortunately not, and it has to do with something called current. Current is like the amount of water flow you can get from the pipes. There are two numbers with the maximum current, one is the amount you can get for a second before the battery breaks down or lights on fire – that is not really a useful number. The other is the amount you can safely get flowing steadily for a long period of time – that is what you need to run your phone. Your phone uses between 100 and 400 mAmps of current to talk and text and what have you. The most current you can get from a voltaic pile even for a second is around 15 mAmps. The maximum you can get to steadily flow is around 0.5 mAmps, which is not very much and nowhere near enough for your phone. However, it is enough to light up a LED light bulb. Which is pretty magical.
So what did people do with Volta’s battery before LED light bulbs? Well, they could give themselves shocks. And they could animate dead animals and people. But, the most useful thing they did with batteries in the early 1800s had to do with Chemistry. See, in the very same week that Volta published his paper on how to build a battery, a pair of English friends accidentally put the ends of the battery into a container of water. Soon the ends started to make bubbles. One probe would get bubbles of Hydrogen and one would get bubbles of Oxygen! Plus you had about twice as much hydrogen as oxygen. They had proven that water was made of H2O!
This experiment inspired a young and handsome Chemist named Humphry Davy to make the world’s strongest and largest battery with over 2,000 plates of copper and zinc in an acid bath. From 1807 to 1808 Davy managed to electrically isolate 8 new elements and increase the total number of known elements by 20%! Humphry Davy’s story is also a tale of how good looks, dramatic demonstrations, and prolific drug use made him a Scientific Rock Star! And that wild story is next time on The Secret History of Electricity!
Thanks for watching my video. If you enjoyed it please remember to give it a thumbs up. Also, I give descriptions of how to make a voltaic pile in the comments as well as how to make hydrogen and oxygen out of water. Both are surprisingly simple experiments to do! Also, if you are interested in learning more about Galvani and his frog Tortura check out my video “How Luigi Galvani Made a Dead Frog Jump”. If you want to know how a battery works check out my video “How a Battery Works” .