Frog battery
Encyclopedia
A frog battery is an electrochemical battery
consisting of a number of dead frogs (or sometimes live ones), which form the cells
of the battery connected together in a series arrangement. It is a kind of biobattery
. It was used in early scientific investigations of electricity and academic demonstrations.
The principle behind the battery is the injury potential created in a muscle when it is damaged, although this was not fully understood at the time; the potential being caused incidentally due to the dissection of the frog's muscles.
The frog battery is an example of a class of biobatteries which can be made from any number of animals. The general term for an example of this class is the muscular pile.
Other constructions could also be used. For instance the complete rear legs could be used with the sciatic nerve
s exposed so that the nerve of one frog could be connected to the feet of the next. Whole frogs too could be used. Although it was more time consuming to prepare the thigh muscles, most experimenters preferred to do this since it gave better results.
The arrangement of inside surface connected to outside surface was on the basis of the not exactly correct theory that there was an electric current in muscles continually flowing from the inside to the outside. It is now known that the half-thighs were more successful at generating electricity because they had suffered the greatest injury to the muscle. This effect of increased electric potential
due to injury is known as demarcation potential or injury potential.
in the 1790s with a chain of 10 frogs. Valli had difficulty understanding all of his own results; he followed Luigi Galvani
in believing that animal electricity (or galvanic electricity) was a different phenomenon from metal-metal electricity (or voltaic electricity), even denying its existence. Alessandro Volta
's theory was proved correct when he succeeded in constructing the voltaic pile
without the use of any animal material. Because Valli found himself on the wrong side in this dispute, and refused to change despite the evidence, his work has become a bit of a backwater and his frog battery is little known and poorly documented.
Leopoldo Nobili
built a frog battery in 1818 out of complete frog legs which he called a frog pile. He used this to investigate animal electricity but his experiments were strongly criticised by Volta who argued that the true source of electricity was dissimilar metals in the external circuit. According to Volta, fluids in the frog merely provided the electrolyte.
The first well-known frog battery was constructed by Carlo Matteucci
which was described in a paper presented to the Royal Society
in 1845 by Michael Faraday
on his behalf. It later also appeared in the popular medical student physics textbook Elements of Natural Philosophy by Golding Bird
. Matteucci constructed his battery from a pile of 12 to 14 half-thighs of frogs. Despite the misguided theory behind the half-thigh battery, Matteucci's frog battery was nevertheless sufficiently powerful to decompose potassium iodide
. Matteucci aimed with this apparatus to address Volta's criticism of Nobili by constructing a circuit, as far as possible, entirely out of biological material and hence prove the existence of animal electricity. Matteucci also studied the effects vacuum, various gases, and poisons had on the frog battery, concluding that in many cases its operation was not affected even when the substance would be toxic or lethal to the living animal.
Frogs were not the only creatures to be press-ganged into serving as battery components. In 1803 Giovanni Aldini
demonstrated that electricity could be obtained from an ox head from a freshly killed animal. A frog galvanometer connected between the ox's tongue and ear showed a reaction when the circuit was completed through the experimeter's own body. A greater reaction was obtained when Aldini joined two or three heads together into a battery. Later, in the 1840s, 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 states that this design was based on a pre-existing battery of living frogs.
Battery (electricity)
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta and especially since the technically improved Daniell cell in 1836, batteries have become a common power...
consisting of a number of dead frogs (or sometimes live ones), which form the cells
Electrochemical cell
An electrochemical cell is a device capable of either deriving electrical energy from chemical reactions, or facilitating chemical reactions through the introduction of electrical energy. A common example of an electrochemical cell is a standard 1.5-volt "battery"...
of the battery connected together in a series arrangement. It is a kind of biobattery
Biobattery
Biobattery is an electricity generation device that utilizes energy sources such as carbohydrates, protein, amino acids, fat by digesting enzymes- Passive :...
. It was used in early scientific investigations of electricity and academic demonstrations.
The principle behind the battery is the injury potential created in a muscle when it is damaged, although this was not fully understood at the time; the potential being caused incidentally due to the dissection of the frog's muscles.
The frog battery is an example of a class of biobatteries which can be made from any number of animals. The general term for an example of this class is the muscular pile.
Background
In the early days of electrical research a common method of detecting electric current was by means of a frog's leg galvanoscope for which a good supply of live frogs was kept to hand by the researcher ready to have their legs prepared for the galvanoscope. Frogs were therefore a convenient material to use in other experiments. They were small, easily handled, the legs were especially sensitive to electric current, and they carried on responding longer than other animal candidates for this role.Preparation
It was usual to use the thighs of frogs for the battery construction. The legs of the frog were first skinned, then the lower leg was cut off at the knee joint and discarded. Damaging the muscle during this procedure would detract from the results. The thigh muscle was then cut in two transversely to produce two half-thighs. Only the lower, conical shaped piece 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 laid in cups of water sunk into the wood and formed the terminals of the battery.Other constructions could also be used. For instance the complete rear legs could be used with the sciatic nerve
Sciatic nerve
The sciatic nerve is a large nerve fiber in humans and other animals. It begins in the lower back and runs through the buttock and down the lower limb...
s exposed so that the nerve of one frog could be connected to the feet of the next. Whole frogs too could be used. Although it was more time consuming to prepare the thigh muscles, most experimenters preferred to do this since it gave better results.
The arrangement of inside surface connected to outside surface was on the basis of the not exactly correct theory that there was an electric current in muscles continually flowing from the inside to the outside. It is now known that the half-thighs were more successful at generating electricity because they had suffered the greatest injury to the muscle. This effect of increased electric potential
Electric potential
In classical electromagnetism, the electric potential at a point within a defined space is equal to the electric potential energy at that location divided by the charge there...
due to injury is known as demarcation potential or injury potential.
History
The first frog battery was constructed by Eusebio ValliEusebio Valli
Eusebio Valli was a physician from Lari, Pisa, Italy, who in the shadows of Luigi Galvani and Alessandro Volta also studied the phenomenon of animal electricity or bioelectricity.- Animal electricity :...
in the 1790s with a chain of 10 frogs. Valli had difficulty understanding all of his own results; he followed Luigi Galvani
Luigi Galvani
Luigi Aloisio Galvani was an Italian physician and physicist who lived and died in Bologna. In 1791, he discovered that the muscles of dead frogs legs twitched when struck by a spark...
in believing that animal electricity (or galvanic electricity) was a different phenomenon from metal-metal electricity (or voltaic electricity), even denying its existence. Alessandro Volta
Alessandro Volta
Count Alessandro Giuseppe Antonio Anastasio Gerolamo Umberto Volta was a Lombard physicist known especially for the invention of the battery in 1800.-Early life and works:...
's theory was proved correct when he succeeded in constructing the voltaic pile
Voltaic pile
A voltaic pile is a set of individual Galvanic cells placed in series. The voltaic pile, invented by Alessandro Volta in 1800, was the first electric battery...
without the use of any animal material. Because Valli found himself on the wrong side in this dispute, and refused to change despite the evidence, his work has become a bit of a backwater and his frog battery is little known and poorly documented.
Leopoldo Nobili
Leopoldo Nobili
Leopoldo Nobili, born in 1784 in Trassilico and died 5 August 1835 in Florence, was an Italian physicist who invented a number of instruments critical to investigating thermodynamics and electrochemistry....
built a frog battery in 1818 out of complete frog legs which he called a frog pile. He used this to investigate animal electricity but his experiments were strongly criticised by Volta who argued that the true source of electricity was dissimilar metals in the external circuit. According to Volta, fluids in the frog merely provided the electrolyte.
The first well-known frog battery was constructed by Carlo Matteucci
Carlo Matteucci
Carlo Matteucci was an Italian physicist and neurophysiologist who was a pioneer in the study of bioelectricity.-Biography:...
which was described in a paper presented to the Royal Society
Royal Society
The Royal Society of London for Improving Natural Knowledge, known simply as the Royal Society, is a learned society for science, and is possibly the oldest such society in existence. Founded in November 1660, it was granted a Royal Charter by King Charles II as the "Royal Society of London"...
in 1845 by Michael Faraday
Michael Faraday
Michael Faraday, FRS was an English chemist and physicist who contributed to the fields of electromagnetism and electrochemistry....
on his behalf. It later also appeared in the popular medical student physics textbook Elements of Natural Philosophy by Golding Bird
Golding Bird
Golding Bird was a British medical doctor and Fellow of the Royal College of Physicians of London. Bird became a great authority on kidney diseases and published a comprehensive paper on urinary deposits...
. Matteucci constructed his battery from a pile of 12 to 14 half-thighs of frogs. Despite the misguided theory behind the half-thigh battery, Matteucci's frog battery was nevertheless sufficiently powerful to decompose potassium iodide
Potassium iodide
Potassium iodide is an inorganic compound with the chemical formula KI. This white salt is the most commercially significant iodide compound, with approximately 37,000 tons produced in 1985. It is less hygroscopic than sodium iodide, making it easier to work with...
. Matteucci aimed with this apparatus to address Volta's criticism of Nobili by constructing a circuit, as far as possible, entirely out of biological material and hence prove the existence of animal electricity. Matteucci also studied the effects vacuum, various gases, and poisons had on the frog battery, concluding that in many cases its operation was not affected even when the substance would be toxic or lethal to the living animal.
Frogs were not the only creatures to be press-ganged into serving as battery components. In 1803 Giovanni Aldini
Giovanni Aldini
Giovanni Aldini , Italian physicist born at Bologna, was a brother of the statesman Count Antonio Aldini and nephew of Luigi Galvani, whose treaties on muscular electricity he edited with notes in 1791....
demonstrated that electricity could be obtained from an ox head from a freshly killed animal. A frog galvanometer connected between the ox's tongue and ear showed a reaction when the circuit was completed through the experimeter's own body. A greater reaction was obtained when Aldini joined two or three heads together into a battery. Later, in the 1840s, 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 states that this design was based on a pre-existing battery of living frogs.