Frog Battery

Sep 1, 2022 0 comments

The term ‘battery’ was first used by Benjamin Franklin in 1749 to describe an apparatus he had designed to produce electricity. Franklin linked together a number of Leyden jar capacitors so that they would hold a stronger charge, and thus more power would be available on discharge. He called the device an ‘electrical battery’, a play on the military term for weapons functioning together.

The first true battery that stored and released a charge through a chemical reaction was invented by the Italian physicist Alessandro Volta (after whom the unit for electric potential ‘Volt’ is named). It was known as the voltaic pile. Although Volta actually didn’t understand how his invention worked (he believed the current was the result of two different materials simply touching each other), it was the only practical battery that provided steady current and made possible many new experiments and discoveries, such as the first electrolysis of water by the English surgeon Anthony Carlisle and the English chemist William Nicholson.

Before Volta demonstrated that electricity could be generated chemically, it was believed that electricity was a vital force which gave life to organic matter and was generated solely by living beings. The scientist who popularized this theory was Italian physicist Luigi Galvani, who discovered in 1780 that the muscles of dead frogs' legs twitched when struck by an electrical spark. Galvani discovered that the legs convulsed not only when an electrical charge was applied to the limbs but also when he pressed the brass hooks attached to the frog's spinal cord to the iron railing they were suspended from. He concluded that this was proof that animals produced electricity and this  electric power animated living things.

Alessandro Volta

Luigi Galvani.

Galvani’s research inspired many Italian physicists to share and discuss these ideas. Among them was Eusebio Valli, who wrote how his studies into “animal electricity” kept him awoke at nights. Valli became a respected exponent in this field throughout Europe; he gave public lectures on Galvani's experiments and published articles on this topic in various Italian and foreign cities, including Lausanne, Paris, and London.

In one particularly disturbing study Eusebio Valli strung together a chain of ten frog legs hoping to build a battery. Valli used the thighs of frogs, which he carefully skinned, and then chopped into two pieces. The upper thigh was discarded and only the lower section was kept. The half-thighs were then laid on an insulator of varnished wood so arranged that the inside surface of one was in contact with the outside surface of the next, with the conical ends of the outside surface being pushed into the cavity of the cut surface. The ends of the pile were placed in cups of water sunk into the wood and formed the terminals of the battery. The macabre configuration produced a current, which scientists today call ‘the current of injury’ or ‘injury potential’. It’s a phenomenon that causes an injured tissue to develop a potential that causes current to flow from healthy tissue to the injured tissue when connected by a conductor.

Eusebio Valli’s frog battery.

In 1803, Giovanni Aldini, another Italian physicist inspired by Giovanni’s work demonstrated that electricity could be obtained not only from frog legs but also from the head of a freshly killed ox. By connecting the ox’s tongue to the ear via a severed frog’s leg (which acted as a galvanometer), Aldini showed that the muscles of the frog’s leg contracted when the circuit was closed, thereby indicating the presence of a current. Aldini even joined two or three heads together into a battery to obtain a stronger reaction to the frog’s leg.

Galvani’s research also excited Alessandro Volta. Initially Volta was impressed with Galvani’s findings, but later began to believe that the electric current came not from the frogs’ tissues but from the contact of two different types of metal (the hooks on which the frogs were hanging and the different metal of the probe) and was merely being transmitted through the frogs’ legs. In order to prove his theory, Volta built what became known as the voltaic cell—the first electrochemical battery—consisting of stacks of layers of silver and zinc interspersed with layers of cloth or paper soaked in saltwater. When a wire was applied at both ends of the pile, an electric current flowed through the wire.

Alessandro Volta's electric battery at Tempio Voltiano in Como, Italy. Photo: Wikimedia

Volta dashed a letter to the Joseph Banks, then president of the Royal Society of London, in 1800, describing his find. It was a pretty big deal at that time and his invention earned him sustained recognition in the honor of the ‘volt’ being named after him.

Despite Volta’s demonstration with the voltaic pile, Galvani (and his followers) believed he was onto something, because you see, Volta wasn’t exactly right—the current was not generated by the contact of two metals but by chemical reaction between the metals and an electrolyte. When Volta publicly criticized Leopoldo Nobili, another Italian scientist, who built a frog battery out of complete frog legs, physician Carlo Matteucci sought to prove him wrong. In 1845, Matteucci built a frog battery completely out of frog parts without the use of metals thus proving that electricity was generated by the animal and not the metals in the circuit. Matteucci's frog battery was sufficiently powerful to decompose potassium iodide. Later, Matteucci also created eel batteries, pigeon batteries and rabbit batteries. Further, he created a battery out of living pigeons by connecting a wound made on the breast of one pigeon to the body of the next.

Matteucci's frog battery.

Matteucci’s work in bioelectricity directly influenced the research by German scientist Emil du Bois-Reymond, who tried the duplicate Matteucci's experiments and ended up discovering the nerve's action potential, or nerve impulse. In 1844, for these studies, Matteucci was awarded with the Copley medal by the Royal Society. By then, battery technology had also improved from the simple voltaic pile to one that generated electricity for sustained duration. Worth mentioning is the Daniell cell, invented in 1836 by British chemist John Frederic Daniell. It was the first practical source of electricity that soon became an industry standard and saw widespread adoption as a power source for electrical telegraph networks.

Battery technology saw rapid development throughout the 19th century. The first rechargeable lead-acid battery was invented in 1859. The lead-acid battery is still used today in automobiles, home inverters and other applications where weight isn’t a factor. The first dry cell made of zinc and carbon was invented in 1886. These were later replaced by zinc and manganese dioxide based alkaline batteries, which are still manufactured today and powers the likes of remote controls, clocks, toys and flashlights. Next came the rechargeable nickel–cadmium battery, which continues to be used today in small appliances.

Battery technology continues to be a major area of research, especially in the modern age when batteries have become more relevant than ever with the rise of portable electronics and electric vehicles. The 20th and the 21st centuries saw vast improvements in battery capacity, power, reliability and longevity. Lithium-based batteries were a major breakthrough that revolutionized the way portable appliances are powered today. In 2019, the Nobel Prize foundation awarded John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino, the Nobel Prize in Chemistry for their development of lithium-ion batteries, nearly 50 years after the first lithium-ion battery was invented.


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