The Battery: How Portable Power Sparked a Technological Revolution - Henry Schlesinger (2010)
Chapter 3. The Tale of the Frog
“The language of experiment is more authoritative than any reasoning: facts can destroy our ratiocination—not vice versa.”
When it comes to the history of the battery, we find not one, but three, different versions of Luigi Galvani’s 1786 discovery. Even science historians love a good story. Can anyone—except a curmudgeon—deny Newton his falling apple or Archimedes his Eureka! moment in the bathtub? As long as the science is solid, then let the stories be told.
In one version of the tale, Galvani was in his lab preparing to sit down for a lunch of tasty frog when he saw his entrée’s leg twitch at the touch of a knife. In another and somewhat poignant account, he was dutifully preparing a lunch for his invalid wife when he spotted the same phenomenon. However, in the third and far more probable version—for those who insist on accuracy—the good professor of anatomy and obstetrics in Bologna, Italy, was in his lab preparing a frog for dissection on a metal plate. When he touched the blade of his scalpel to the deceased amphibian, its leg noticeably and quite unexpectedly twitched.
Galvani’s first thought was that electrical fluid had somehow jumped several feet from a nearby electrostatic machine to act upon the frog’s nerves. Given what was known at the time, this was not an altogether unreasonable theory. After all, just a few years before, he had demonstrated the electrical basis of nerve impulses. In that experiment, Galvani used just such a machine to stimulate movement in a partially dissected frog through the crural nerves that run downward from the lower back to the leg.
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Galvani was also not the first to make such an observation. In 1752, the Dutch biologist and entomologist Jan Swammerdam had witnessed the same phenomenon but gave the effect only a brief mention in his book Biblia Naturae. And too, the effects of an electrical jolt on the muscles of animals had been known since earlier experiments with Leyden jars. However, as Galvani had noted in these earlier experiments, it was the nerves and not the muscles that caused contractions when given a jolt of electricity.
What Galvani was witnessing at the touch of the metal blade was an entirely different and more complex phenomenon. Through a series of experiments, he quickly eliminated the electrostatic machine from the equation and soon published a paper that explained the jerk of the frog’s leg by a completed circuit through the crural nerve and the leg muscle. The twitching, he reasoned, was the result of electricity accumulated in the muscle traveling through the circuit. According to his 1791 paper, called De Viribus Electricitatis in Motu Musculari Commentarius (Commentary on the Effect of Electricity on Muscular Motion), the frog’s leg muscle acted like a charged Leyden jar to activate the nerve.
“Perhaps the hypothesis is not absurd and wholly speculative which compares a muscle fibre to something like a small Leyden Jar or to some similar electrical body charged with a two-fold and opposite electricity,” Galvani wrote. “And by comparing a nerve in some measure to the conductor of the Jar, in this way one likens the whole muscle, as it were, to a large group of Leyden Jars.”
He was, of course, wrong. But where else could the charge have originated? Electricity, already proven to stimulate nerves, must have come from somewhere. And the muscle was as good a candidate as anything else after the only likely external source of a charge—the electrostatic machine—was ruled out. Meanwhile, on the other side of Italy, Professor Alessandro Volta, a creator of scientific instruments, took exception to Galvani’s findings, summarily dismissing them as “unbelievable.”
Born into an old Lombard family, Volta was first tempted by the Jesuits and then steered by an uncle into law before turning to science. His decision, penned in something of a formal announcement while still a student, was in the form of a poem praising the ideals behind natural philosophy, specifically chemistry and electricity. Notebooks in which the young Volta ruminated on the soul of animals—theorizing that animals also had spiritual powers akin to those of people—could not have bolstered his standing among the Jesuits.
Precociously ambitious, while still a teenager he began an active, though somewhat one-sided, correspondence with the leading natural philosophers in Europe. Announcing his sweeping scientific theories, he sent off letters to Jean-Antoine Nollet, among others, but received only scant encouragement for his efforts. Undeterred, he continued his scientific studies.
Over time, Volta’s youthful passion mellowed somewhat and he turned from grand theories to making instruments to explore the mysteries of nature so that by middle age, he was very much an instrumentalist first and a theorist second. Theories, he had apparently learned, were risky propositions while devices capable of reliably consistent results were very much coming into their own throughout Europe’s scientific community. As instruments became more reliable and standardized, the emphasis shifted from theory to experiment. One of Volta’s favorite maxims was, “The language of experiment is more authoritative than any reasoning: facts can destroy our ratiocination—not vice versa.”
By the time Galvani’s paper reached him, Volta was well into middle age and firmly established as a professor of physics at Pavia with a solid reputation as a skilled instrument maker. His scientific instruments, favorites among the well-heeled amateurs and serious natural philosophers, were beautifully built, though not particularly original. His specialty, developed over years of painstaking labor, was producing incremental improvements on already existing devices.
Adding to Volta’s reputation was the meticulous manner in which he presented his devices. With each piece of equipment, such as his electrophorus, a machine for generating an electrostatic charge, he included precise instructions for its use as well as a detailed list of experiments to be carried out. Still something of a self-promoter, Volta made certain his devices reached influential people and even traveled widely to give public demonstrations.
Although deeply suspicious of science conducted by mere physicians, at the urging of colleagues he successfully duplicated Galvani’s experiment in 1792, but maintained his reservations. Yes, the frog’s leg may have twitched, Volta conceded, but it certainly wasn’t because of electrical fluid held in the muscle. Some other, far more likely, explanation must be the reason. So the controversy began.
Given the participants, it was an odd debate. Galvani, the anatomist, had ventured into physics, while Volta, the physicist, was crossing over into anatomy. Cultured Europe, in which science was very much salonfähig, quickly began to line up on both sides of the issue.
Volta, for his part, was a strict adherent to the scientific method. Using a methodology very much like Franklin’s disassembling of a Leyden jar, he discovered that electrical fluid generated in the frog experiment was a product of the sum of its parts rather than a single piece. In a series of experiments, he systematically substituted various components of Galvani’s original experiment and soon found the secret resided not in the frog, but in the two dissimilar metals.
According to Volta, there was no “electrical-fluid imbalance” in the frog’s anatomy. The frog played a largely passive role as instrument to detect minute levels of electrical current generated by the two metals. What Galvani had done in his original accidental experiment was to bring two dissimilar metals—his scalpel and a metal plate—in close proximity with a conductor, presumably fluid or tissue from the frog. As electrons were lost from one metal via oxidation and picked up by the other, the frog’s nerve reacted to the flow of electrons—acting as a very sensitive voltmeter.
Placing two coins of different metals on his own tongue, he felt the distinct tingle of an electrical charge. Very soon Volta began ranking combinations of metals to determine which pairings produced the greatest electrical charge, or what he took to calling “electromotive force,” and found a combination of silver and zinc seemed to offer the best results.
Galvani’s error had been a reasonable mistake; he simply looked for the most likely source of the “electrical fluid” and settled on the once-living tissue rather than the inanimate metals. “He [Volta], in short, attributes everything to the metals, nothing to the animal; I everything to the former, as far as imbalance alone is concerned,” Galvani wrote, summing up the controversy.
Sadly, Galvani was driven even further off course when he decided to see if an atmospheric electrical charge could make the frogs’ legs twitch. Securing multiple frog legs to an iron fence by brass hooks, he detected slight twitching.
Then, in 1794, historians believe he followed up with an anonymous pamphlet that claimed the jerking of a frog’s leg had been observed without any metal nearby, through simply touching the sciatic nerve of one leg to the muscle of another. In retrospect, this can be seen as the desperate tactic of someone heavily invested in a theory, but unable to offer solid scientific proof. Why else publish the pamphlet anonymously?
However, Volta, heavily invested in his opposing position, was also having difficulty supporting the bimetallic theory. The problem he faced was in offering definitive proof, which meant duplicating Galvani’s experiment sans frog. In theory, it was easily accomplished; just substitute some other material for the moist tissue of an unlucky creature. Nothing could be simpler, except for the fact that the frog also acted as a voltmeter that measured the flow of electricity from one metal to the other. The frog may have played no significant function in the production of electricity, but its role in detecting electrical output was absolutely essential. At the time there was no other device, save the frog, sensitive enough to react to such low levels of electricity.
What Volta built was an updated version of an electrometer (also called an electroscope), created by William Nicholson, the English chemist and science writer. A simple device, it consisted of two sheaths of metal that attracted each other when an electrical charge was run through them. Volta’s innovation was in using straw, rather than Nicholson’s metal sheaths. He then combined the new meter with a device he invented for measuring atmospheric electricity called the condensatore, which was capable of collecting an electrical charge. A very simple device, the condensatore consisted of a metallic disk sitting flush on a nonconductive surface, such as marble. If a metal disk charged from a weak electrical source while on the nonconductive surface was lifted from the marble, the accumulated charge was greater than the current that flowed into it. Volta called this combination the “micro-electroscope.”
At around the same time, Volta ordered a series of books from a dealer in Leipzig, Germany, including Nicholson’s Journal of Natural Philosophy, Chemistry and the Arts. In it, the British writer meticulously outlined the likely workings of the torpedo fish (Torpedo nobiliana) known since ancient times for producing an electrical charge. Nicholson described the fish as containing anywhere from 500 to 1,000 columns or disks of a substance that was electrified oppositely, and divided by thin layers of a laminate. In his work, Nicholson went so far as to offer the conjecture that the “torpedo actually operates like a machine…” and then listed the individual components. It was an important point. In describing how the torpedo fish may have worked—essentially reverse engineering the creature—Nicholson sketched a rough blueprint for the first true battery.
With papers endorsing and refuting the two differing theories circulating between supporters of both sides, Galvani in some of his last writings proffered the idea of two different types of electricity—animal electricity and common electricity. Not quite a complete concession, the good doctor’s suggestion was closer to a compromise based on diplomacy and perhaps weariness with the debate rather than experiment or scientific fact.
Volta, still working hard to prove his bimetallic theory, offered up his own compromise. He would admit that animal electricity exists, but not in the way that Galvani described—accumulating in muscles, particularly in severed limbs and small pieces of muscle. Yes, the nerves may act as conduits for electric fluid, Volta allowed, but that fluid doesn’t originate in the muscles.
The debate probably lasted longer than necessary. Volta married, somewhat belatedly, at age forty-nine, and quickly fathered three sons in three years. The invasion of Italy by France also slowed his research when the occupying army closed the university in Pavia.
Then, on March 20, 1800, two years after Galvani’s death, Volta settled the matter once and for all. In a thousand-word description in French, the language of the European scientific community, he described in detail the construction for a working battery. The letter was sent to Sir Joseph Banks, the president of the Royal Society, with whom he had carried on a long-standing correspondence. Volta’s instruments were in wide use among the Society’s members and he had, in fact, received the Society’s highest honor, the Copley Medal, a few years earlier. A second letter soon followed that included a 5,000-word account, with diagrams. In this second letter, Volta compared his new device to the structure of the torpedo fish, a comparison he would make less frequently as time went on, and the real value of the battery in scientific research began to emerge.
The battery itself was a thing of stunning simplicity. Volta outlined its structure in his original letter in fewer than 400 words. Later, on May 30, a journalist for the London Morning Chronicle, penning the first description ever published regarding Volta’s invention, described it in less than 150 words.
A number of pieces of zinc, each the size of a half crown, were prepared, and an equal number of pieces of card cut in the same form; a piece of zinc was then laid upon the table, and upon it a half crown; upon this was placed a piece of card moistened with water, upon the card was laid another piece of zinc, upon that another half crown…Then a wet card, and so alternately until forty pieces of each had been placed upon each other; a person then, having his hands well wetted, touched the piece of zinc at the bottom with one hand, and the half crown at the top with the other; he felt a strong shock, which was repeated as often as the contact was renewed.
What Volta described in his letters to Banks would eventually become known as the “voltaic pile,” though in the latter part of the letter, he also outlined the construction for another apparatus, which he called the “crown of cups”—essentially a battery whose components were distributed between different containers either stacked on top of one another or arranged side by side. In writing to Banks, Volta portrayed the battery simply as “an apparatus…which should have an inexhaustible charge, a perpetual action or impulse of electric fluid.”
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Focusing nearly all of his attention on the instrument itself and its relevance to the controversy of animal versus bimetallic electricity, his theory of precisely how the instrument created the electrical charge was added almost as an afterthought. Volta’s best guess was that the charge was generated through contact of two different metals. It was enough that the battery worked and that the debate was settled.
After receiving the initial letter in mid-April (the second would arrive several weeks later), Banks quickly began circulating it among friends and colleagues, including Anthony Carlisle, who was then a doctor at Westminster Hospital. From Carlisle, the letter made its way to Nicholson and on April 30, the two began constructing their own battery, per Volta’s detailed instructions, made out of seventeen half crowns containing silver, several pieces of zinc, and plasterboard soaked in salt water. When this battery proved a success, they built an even stronger one on May 2, this time using thirty-six half crowns, and began experimenting.
One of their first experiments was the successful decomposition of water—using an electrical charge to break water down into its two components. This made big news across Europe. Water, thought to be an element, was now definitively shown—with the help of Volta’s device—to be a compound composed of hydrogen and oxygen. In many reports the apparatus—the battery—that accomplished the decomposition rated only secondary mention.
On June 26, Banks read Volta’s letter to the Fellows of the Royal Society, and by September of that year, the letter was translated into English and published in Philosophical Transactions under the title “On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kinds.” From there, news of the miraculous invention spread quickly and by the autumn of 1800 experimenters throughout Europe were building and using their own voltaic batteries. The master instrument maker had designed an instrument that nearly anyone could construct.
News of the batteries’ success reached Volta not through British newspapers, but through a French paper called Moniteur universel, an official government publication. Volta, still true to his early instinct for self-promotion, set off on a tour of Europe to demonstrate his new device, traveling to Paris, London, and Vienna. He could not have picked a better time. In June 1800, Napoleon’s army took Lombardy, and the Austrians, who had shuttered the University of Pavia, left the city. In late 1801, he demonstrated the battery for Napoleon himself, who had a keen interest in science, both personally and as a public relations tool. Napoleon’s well-publicized interest in science seemed to have a somewhat calming effect on the ruling class, and in 1810, Napoleon made Volta a count.
Volta’s public demonstrations, including an engagement at the Royal Society, focused on the battery’s design and function rather than theory and touched only lightly on the controversy over animal electricity that had lasted eight years. Volta carried with him a small, pocket-sized battery as well, showing how the device could be scaled down for portability—though its diminutive size proved less impressive than the larger pile or crown of cups.
Soon, other natural philosophers began giving their own demonstrations of the device. One of the strangest public performances was offered up by Étienne-Gaspard Robertson. An entertainer and amateur scientist showman, Robertson ran a popular show in Paris called Fantasmagorie de Robertson. The primary attraction was his use of “magic lanterns” mounted on dollies to simulate moving ghosts, though another feature included an electrostatic machine. After reading a description of the voltaic pile, he quickly commissioned one for himself, which he called colonne métallique, and began experimenting. Oddly, Robertson began his experiments by touching the battery contacts to various parts of his own body and those of volunteers, including chin, eyes, and “…other parts of the body where the skin is especially delicate and sensible.”
Even as batteries were being built across Europe, there was still no clear consensus on just what to call the device. “New instruments should be given new names, depending not only on their form, but also on their effects or the principle on which they are based,” Volta wrote, then suggested two possible names for his new device. His first choices were organe electrique artificiel as compared to the organe electrique naturel in reference to the torpedo fish. The second name he suggested was appareil electro-moteur. Neither caught on. A variety of names began cropping up, like “pile” or “trough,” and then “voltaic pile,” “galvanic battery,” “Volta’s battery,” and other variations.
Volta never sought to patent his device. Indeed, the first patent for a battery would come several decades in the future, well into the nineteenth century and long after his death. Patents for electrical devices, of course, were difficult. It was necessary to show a useful application, and the few that did receive patents at the time often listed medical purposes.
NOT SURPRISINGLY, WITH A DEVICE capable of producing a continuous flow of electrical current, the debate surrounding animal electricity was soon forgotten. Unlike a Leyden jar, which required constant laborious charging and from which electricity exploded in an electrostatic burst, the battery was easily constructed out of readily available materials and provided a relatively long-lasting and steady flow of current with which to experiment. It’s also interesting to note just how little desire there was to explore the way in which the battery produced its charge. Even the most serious experimenters focused almost solely on what that electrical charge could be made to do in the laboratory. The fact that it worked was enough.
With the Industrial Revolution in full coal-burning, steam-hissing swing, many saw the battery’s future in medicine while others predicted electricity would eventually find use in movement and machinery with the potential to provide energy akin to steam.
However, the first practical applications for the battery were not in industry, but rather in science, specifically chemistry. Still not fully understood, the study of electricity was in its infancy and the battery found its first practical applications as a lab instrument. It allowed chemists to refine and redefine established theories, eventually laying the foundation of modern chemistry.
It would take decades before the battery would emerge in any significant role outside the lab, and even then, it came in an unpredicted area—that of communication via the telegraph.