Michael Faraday

gigatos | June 24, 2022

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Summary

Michael Faraday († August 25, 1867 in Hampton Court Green, Middlesex) was an English naturalist who is considered one of the most important experimental physicists. Faraday”s discoveries of “electromagnetic rotation” and electromagnetic induction laid the foundation for the emergence of the electrical industry. His vivid interpretations of the magneto-optical effect and diamagnetism by means of lines of force and fields led to the development of the theory of electromagnetism. By 1820, Faraday was already considered Britain”s leading chemical analyst. He discovered a number of new hydrocarbons, including benzene and butene, and formulated the basic laws of electrolysis.

Growing up in humble circumstances and trained as a bookbinder, Faraday, who was enthusiastic about natural research, found employment as Humphry Davy”s laboratory assistant at the Royal Institution, which became his most important place of work. In the Royal Institution”s laboratory he conducted his pioneering electromagnetic experiments, and in its lecture hall he helped to spread new scientific knowledge with his Christmas lectures. In 1833, Faraday was appointed the first Fuller Professor of Chemistry. Faraday conducted about 30,000 experiments and published 450 scientific articles. He summarized the most important of his publications on electromagnetism in his Experimental Researches in Electricity. His most popular work Chemical History of a Candle was a transcript of one of his Christmas lectures.

On behalf of the British state, Faraday trained the cadets of the Royal Military Academy in Woolwich in chemistry for more than twenty years. He worked for a variety of government agencies and public institutions, such as Trinity House, the British Museum, the Home Office, and the Board of Trade.

Faraday belonged to the followers of a small Christian minority, the Sandemanians, in whose religious life he took an active part.

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Origin and education

Michael Faraday was born on September 22, 1791, in Newington in the county of Surrey, which is now part of the London Borough of Southwark. He was the third of four children of James Faraday (1761-1810), a blacksmith, and his wife Margaret (née Hastwell, 1764-1838), a farmer”s daughter. Until early 1791, his parents lived with his two older siblings, Elizabeth (1787-1847) and Robert (1788-1846), in the small village of Outhgill in what was then the county of Westmorland in northwestern England (now Cumbria). When the effects of the French Revolution led to a decline in trade and the family was threatened with poverty, they decided to move to the immediate vicinity of London. Faraday”s father found work with ironmonger James Boyd in London”s West End. The family moved to Gilbert Street shortly thereafter and to Jacob”s Well Mews about five years later. Faraday”s younger sister Margaret (1802-1862) was born there.

Until the age of twelve, Faraday attended a simple day school where he was taught the basics of reading, writing and arithmetic. In 1804, he found employment as an errand boy with Huguenot emigrant George Riebau, who ran a bookstore on Blanford Street. One of Faraday”s duties was to take the newspaper to Riebau”s customers in the morning, pick it up again during the day, and carry it to more customers. After about a year as an errand boy, Faraday signed a seven-year apprenticeship contract with Riebau on October 7, 1805. In accordance with the customs of the time, he moved in with his master apprentice and lived with him during his apprenticeship.

Faraday proved to be a skilled, open-minded and inquisitive apprentice. He quickly learned the bookbinding trade and attentively read many of the books brought in for binding. These included Jane Marcet”s Conversations on Chemistry, a popular introduction to chemistry, published in 1806, and James Tytler”s contribution on electricity for the third edition of the Encyclopædia Britannica, as well as the story of Ali Baba and reference works and journals on art. Riebau allowed him to conduct minor chemical and electrical experiments.

Among the works Faraday studied was Isaac Watts” book The Improvement of the Mind (1741), which was aimed at readers who wanted to expand their knowledge and mental abilities independently. In his remarks, the author emphasized not only passively imparting knowledge, but also encouraging his readers to actively engage with it. Among other things, Watts recommended taking notes on articles, taking notes at lectures and seeking an exchange of ideas with like-minded people.

Under this impression, Faraday began in 1809 what he titled The Philosophical Miscellany, a collection of notes on articles on the subjects of art and science that he had read in various newspapers and magazines. In 1810, Riebau encouraged the 19-year-old Faraday to attend the scientific lectures held every Monday by the goldsmith John Tatum at his home. Tatum was the founder of the City Philosophical Society, established in 1808, whose goal was to provide access to scientific knowledge for artisans and apprentices. A fee of one shilling was payable for each lecture, which Faraday received from his brother Robert. With this support, he was able to attend about a dozen lectures from February 19, 1810, until September 26, 1811. During Tatum”s lectures, Faraday made notes, which he revised, summarized, and transferred to a notebook in his free time. At Tatum”s, he befriended Quakers Benjamin Abbott (1793-1870) and Edward Magrath (1791?-1861), as well as Richard Phillips (1778-1851). With Abbott he began a written exchange of ideas on July 12, 1812, which continued for many years.

Faraday, whose apprenticeship with Riebau was coming to an end, felt little inclination to spend his life as a bookbinder. He wrote a letter to Joseph Banks, the president of the Royal Society, asking for a lowly position in the Royal Society”s laboratories. Banks, however, did not feel it necessary to answer his request. On October 8, 1812, one day after the end of his apprenticeship, Faraday began working as a journeyman bookbinder for Henri De La Roche.

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Employment as laboratory assistant

In early 1812, Riebau showed Faraday”s notebook containing transcripts of Tatum”s lectures to the son of William Dance (1755-1840), one of his clients. Dance reported it to his father, who then took Faraday to Humphry Davy”s last four lectures, entitled The Elements of Chemical Philosophy, as professor of chemistry in March and April 1812. Davy was considered an outstanding lecturer and had earned a high reputation among experts for his discovery of the elements potassium, sodium, and chlorine. During Davy”s lectures, Faraday took numerous notes, which he revised and added drawings to, bound into a book and sent to Davy.

At the end of October 1812, however, Davy was not in London but, together with John George Children, was repeating an experiment in Tunbridge Wells by Pierre Louis Dulong, who had shortly before discovered a new compound of chlorine and nitrogen. During the experiments, a glass tube containing the resulting nitrogen trichloride exploded, severely injuring Davy”s left eye. Davy was immediately taken to London for treatment and found Faraday”s shipment there. Needing help to organize his notes because of his eye injury, he invited Faraday to his home at the end of 1812.

On February 19, 1813, a fistfight broke out at the Royal Institution between laboratory assistant William Payne and instrument maker John Newmann. Three days later, Payne was dismissed by the managers of the Royal Institution. Davy, who needed a new assistant, suggested Faraday for the vacant post. On March 1, 1813, the latter began his duties as laboratory assistant at the Royal Institution. His duties included supervising and assisting the lecturers and professors in the preparation and delivery of their lectures, cleaning the models in storage each week, and dusting the instruments in the glass cases each month. He moved into his predecessor”s two rooms and was given permission to use the laboratory for his own experiments.

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Journey through continental Europe

Napoleon Bonaparte had awarded Davy a gold medal for his contributions to electrochemistry, which he came to Paris to receive. Despite the ongoing Napoleonic Wars, he received permission from the French government to tour continental Europe. Davy and his wife Jane Apreece (1780-1855) therefore planned a trip through continental Europe in 1813, which was designed to last two or three years and would go as far as Constantinople. He asked Faraday to accompany him as his amanuensis (secretary and scientific assistant). This offered the latter, who had never been “further than twelve miles” from London, the opportunity to learn from Davy and to come into contact with some of the most eminent foreign naturalists.

On October 13, 1813, the traveling party of five left London. At Plymouth, it embarked for Morlaix, where it was searched and detained for about a week. It finally reached Paris on the evening of October 27. Faraday explored the city, which impressed him greatly, and visited the Musée Napoleon with Davy and the geologist Thomas Richard Underwood (1772-1835). In the laboratory of chemist Louis-Nicolas Vauquelin, Davy and Faraday observed the production of potassium chloride, which was different from the method used in England. On the morning of November 23, André-Marie Ampère, Nicolas Clément, and Charles-Bernard Desormes sought Davy out at his hotel, presented him with a substance discovered two years earlier by Bernard Courtois, and demonstrated some experiments that produced violet vapors. With Faraday”s help, Davy conducted his own experiments, including some in Eugène Chevreul”s laboratory at the Jardin des Plantes. On December 11, he realized that the substance was a new element, which he named iodine after the Greek word iodes for ”violet.” Davy”s experiments delayed the planned onward journey to Italy.

On December 29, 1813, they left Paris for the Mediterranean coast, where Davy hoped to find iodine-bearing plants for his investigations. Faraday witnessed the passage of Pope Pius VII in Montpellier in early February, returning to Italy after his liberation by the Allies. After a month-long stay, they continued on their way to Italy, accompanied by Frédéric-Joseph Bérard (1789-1828). Via Nîmes and Nice, they crossed the Alps over the Tenda Pass. During the arduous journey from town to town, Davy explained to Faraday the geological makeup of the landscape and familiarized him with ancient cultural sites.

In Genoa, bad weather prevented the onward journey. Davy took advantage of the delay to conduct experiments at the home of Domenico Viviani (1772-1840), who kept some “electric fish” in captivity, to see if the discharge of these fish was sufficient to decompose water. The results of his experiments were negative. On March 13, they crossed the Gulf of Genoa by ship. A day before the British army landed in Livorno, they passed Lucca and arrived in Florence on March 16, where they visited the museum of the Accademia del Cimento, which contained, among other things, Galileo Galilei”s observational instruments. Davy and Faraday continued their experiments with iodine and prepared an experiment to prove that diamonds were made of pure carbon. For this purpose, they used large burning glasses from the possession of Grand Duke Ferdinand III. On March 27, 1814, this proof succeeded for the first time. In the following days, the two repeated the experiment several more times.

The arrival in Rome took place in the middle of Holy Week. As he had done in other places, Faraday explored the city on his own. He was particularly impressed by St. Peter”s Basilica and the Colosseum. At the Accademia dei Lincei, Davy and Faraday experimented with charcoal to pursue some unanswered questions from the diamond experiment. On May 5, they were guests at the home of Domenico Morichini (1773-1836). There, Faraday unsuccessfully repeated under the householder”s guidance his experiment on the supposed magnetization of a needle by the violet spectral component of sunlight. Two days later, they left for a two-week excursion to Naples. There they climbed Mount Vesuvius several times. Caroline Bonaparte, the Queen of Naples, gave Davy a gift of a jar of ancient pigments, which Davy and Faraday later analyzed.

To escape the summer heat, the traveling party set off from Rome on June 2 in the direction of Switzerland. Via Terni, Bologna, Mantua and Verona, they reached Milan. Here Faraday met Alessandro Volta on June 17. They arrived in Geneva on June 25, 1814, and spent the summer at Charles-Gaspard de la Rive”s house on Lake Geneva, hunting, fishing, experimenting further with iodine, and collaborating with Marc-Auguste Pictet and Nicolas-Théodore de Saussure. On September 18, 1814, they traveled via Lausanne, Vevey, Payerne, Bern, Zurich and the Rhine Falls near Schaffhausen, finally reaching Munich, where they stayed for three days.

They returned to Italy via the Brenner Pass, visiting Padua and Venice along the way. In Florence, they investigated a combustible gas that escaped from the ground in Pietramala, which they identified as methane. In Rome, where they arrived on November 2, 1814, and remained until March 1815, Faraday experienced Christmas and attended several masquerade balls during Carnival. Davy and Faraday conducted further experiments with chlorine and iodine. Their original plans to travel on to Constantinople fell through. After passing through Tyrol and Germany, they finally reached London on April 23, 1815.

Development as a chemical analyst

After his return, Faraday was initially without employment in London. At the request of William Thomas Brande, who had taken over the position of professor of chemistry from Davy in 1812, and with the full support of Davy, who had been elected vice president of the Royal Institution a week earlier, Faraday was restored to his old post as laboratory assistant on May 15 and was additionally responsible for the mineralogical collection.

Faraday again attended the lectures of the City Philosophical Society and became a member of the society. On January 17, 1816, he gave his first lecture on chemistry there, followed by 16 more over the next two and a half years. In 1818, to perfect his skills as a lecturer, he attended Benjamin Humphrey Smart”s (1786-1872) Thursday evening rhetoric classes at the Royal Institution. Together with four friends, he founded a writing circle in the summer of that year. Organized according to the guidelines of the City Philosophical Society, members of the group wrote essays on topics of their own choosing or on set topics, which were submitted anonymously and evaluated collectively by the group.

In the laboratory of the Royal Institution, Faraday frequently conducted experiments on Davy”s behalf and in 1816 was instrumental in his investigations, which led to the development of the “Davy lamp” used in mining. For Brande, the editor of the Quarterly Journal of Science, Faraday compiled the Miscellanea titled pages beginning in 1816 and assumed full responsibility for the journal in August 1816 during Brande”s absence. In 1816, the Quarterly Journal of Science also published Faraday”s first scientific paper on limestone specimens originating in Tuscany. By the end of 1819, he had published 37 communications and articles in the Quarterly Journal of Science, including an investigation of the escape of gases from capillary tubes and remarks on “singing flames.”

In his laboratory, Faraday performed paper analyses for William Savage (1770-1843), the printer of the Royal Institution, examined clay samples for the ceramics manufacturer Josiah Wedgwood II (1769-1843), and undertook forensic investigations on behalf of a court. In early 1819, Faraday, together with James Stodart (1760-1823), who manufactured surgical instruments, began an extensive series of experiments concerned with improving steel alloys. He first examined wootz, a widely used starting material for steel, for its chemical composition. This was followed by numerous experiments on steel refinement, using platinum and rhodium, among others. The steel investigations extended over a period of about five years and were continued by Faraday alone after Stodart”s death.

On December 21, 1820, Faraday”s first paper intended for publication in the Philosophical Transactions was read to the members of the Royal Society. It described the two new chlorocarbon compounds he had discovered, tetrachloroethene and hexachloroethane. At this time, Faraday was already regarded as Britain”s leading chemical analyst. In 1821, he was appointed “Superintendent of the House” at the Royal Institution. On June 12, 1821, he married Sarah Barnard (1800-1879), the sister of his friend Eduard Barnard (1796-1867), whom he had met in the fall of 1819. Their marriage remained childless.

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Recognition as a naturalist

In 1821, Richard Phillips, by then editor of the Annals of Philosophy, asked Faraday for an outline of all known findings on electricity and magnetism. Shortly before, Hans Christian Ørsted had published his observations on the deflection of a compass needle by electric current. Faraday repeated in his laboratory experiments by Ørsted, André-Marie Ampère, and François Arago. His two-part Historical Sketch of Electro-Magnetism appeared, anonymously at his request, in the Annals of Philosophy in September and October 1821. Faraday succeeded for the first time in an experiment in which a current-carrying conductor rotated on its own axis under the influence of a permanent magnet. In the same month, he published his discovery in the Quarterly Journal of Science. The so-called “electromagnetic rotation” was an essential prerequisite for the development of the electric motor.

Already a few days after the publication of his discovery, friends of William Hyde Wollaston, including Davy, doubted the independence of Faraday”s work. They accused him of having stolen the idea of “electromagnetic rotation” from Wollaston and of not acknowledging the latter”s authorship. Faraday”s experimental proof, however, was completely different from the solution proposed by Wollaston, which the latter acknowledged. Since the public rumors about this did not die down, Faraday was forced to disclose the authorship of his Historical Sketch of Electro-Magnetism.

In 1818, Michael Faraday had described the soporific effect of “sulfuric ether”. In 1823, Faraday began to investigate the properties of the chlorine hydrate discovered by Davy. When he heated it under pressure, he succeeded for the first time in liquefying chlorine. In 1823 and again in 1844, when he returned to the subject, he succeeded in liquefying ammonia, carbon dioxide, sulfur dioxide, nitrous oxide, hydrogen chloride, hydrogen sulfide, dicyane, and ethene. Faraday was the first to recognize that a critical temperature existed above which gases could not be liquefied regardless of the pressure exerted. He proved that the states “solid”, “liquid” and “gaseous” could be transformed into each other and did not form solid categories.

In 1825, Faraday noticed liquid residues in cans of illuminating gas supplied to the Royal Institution by his brother Robert, who worked for the London Gas Company. He analyzed the liquid and discovered a new hydrocarbon compound, which he called the “bicarburet of hydrogen.” Eilhard Mitscherlich gave this substance, an aromatic hydrocarbon, the name benzene in the same year. Shortly thereafter, he discovered butene, a compound that had the same ratio formula as ethene but was completely different in chemical properties. In 1826, Faraday determined the composition of naphthalene and prepared two different crystalline samples of naphthalene sulfuric acid.

Chemical Manipulation was published in April 1827. This monograph by Faraday was an introduction to practical chemistry and was aimed at beginners in the field of natural chemical research. It covered all aspects of practical chemistry, starting with the proper set-up of a laboratory, through the proper conduct of chemical experiments, to error analysis. The first edition was followed by two further editions in 1830 and 1842.

On April 1, 1824, the Royal Society and the Board of Longitude founded a joint commission (Committee for the Improvement of Glass for Optical Purposes). Its aim was to find formulations for the production of high-quality optical glasses that could compete with the flint glasses produced by Joseph von Fraunhofer in Germany. The research initially took place at the Falcon Glass Works operated by Apsley Pellatt (1763-1826) and James Green. To more directly supervise the conduct of the experiments, a subcommittee was appointed on May 5, 1825, consisting of John Herschel, George Dollond, and Faraday. After the construction of a new melting furnace at the Royal Institution, the glass experiments were carried out at the Royal Institution from September 1827. To relieve Faraday, Charles Anderson, a former sergeant in the Royal Artillery, was hired on December 3, 1827. The glass investigations were Faraday”s main task for over five years, and at the end of 1829 they were the subject of his first Baker Lecture to the Royal Society. In 1830, glass experiments were halted for financial reasons. An 1831 report by astronomers Henry Kater (1777-1835) and John Pond, who tested a telescope with an objective made of a glass manufactured by Faraday, certified that the glass had good achromatic properties. However, Faraday considered the results of his five-year work inadequate.

At the instigation of his friend Richard Phillips, who had himself been admitted to the Royal Society shortly before, the motion to admit Faraday to the Society was read out for the first time on May 1, 1823. The motion bore the signatures of 29 members and had to be read at ten consecutive meetings. Davy, president of the Royal Society since 1820, wanted to prevent Faraday”s election and tried to get the motion withdrawn. With one vote against, Faraday was admitted to the Royal Society on January 8, 1824.

From March to June 1824, Faraday acted as temporary first secretary of the London club The Athenaeum, which Davy had co-founded. When it was proposed to him in May that he take over the post permanently for an annual salary of 100 pounds, he turned down the offer and recommended his friend Edward Magrath for the position.

On February 7, 1825, Faraday was appointed laboratory director of the Royal Institution and began to give the first lectures of his own there. In February 1826, he was released from the obligation to assist Brande in his lectures. In 1827 Faraday gave chemistry lectures at the London Institution and gave the first of his numerous Christmas lectures. He turned down an offer to become the first professor of chemistry at the newly founded University of London, citing his obligations at the Royal Institution. In 1828, he was honored with the Fuller Medal. Until 1831, he helped Brande edit the Quarterly Journal of Science and then supervised the first five issues of the new Journal of the Royal Institution.

Studies on electricity (1831 to 1838)

As early as 1822, Faraday noted in his notebook: “Convert magnetism into electricity”. In the laboratory diary he had begun in September 1820, he first noted an experiment on December 28, 1824, in which he tried to generate electricity with the help of magnetism. However, the expected electric current failed to materialize. On November 28 and 29, 1825, and on April 22, 1826, he conducted further experiments, but without achieving the desired result.

After a five-year break caused by the complex glass investigations, Faraday turned to electromagnetic experiments again for the first time on August 29, 1831. He had his assistant Anderson make a soft iron ring with an inner diameter of six inches (about 15 centimeters). On one side of the ring he attached three windings of copper wire, insulated from each other by twine and calico. On the other side of the ring were two such windings. He extended the two ends of one of the windings on one side with a long copper wire that led to a magnetic needle about three feet (about one meter) away. One of the windings on the other side he connected to the terminals of a battery. Each time he closed the circuit, the magnetic needle moved from its rest position. When the circuit was opened, the needle moved again, only this time in the opposite direction. Faraday had discovered electromagnetic induction, applying a principle that underlies the transformers he later developed. He interrupted his experiments, which lasted until November 4, for a three-week vacation with his wife in Hastings and a fourteen-day investigation for the Royal Mint. During his experiments, conducted in only eleven days, he found that a cylindrical bar magnet moved by a coil of wire induced an electric voltage in it. Electric generators work according to this basic principle.

Faraday”s report on the discovery of electromagnetic induction was presented by him to the Royal Society in late 1831. The form printed in the Philosophical Transactions did not appear until May 1832. The long delay resulted from a change in the conditions of publication for new articles. Until late 1831, a majority vote of the Committee of Papers was sufficient to publish an article in the Philosophical Transactions. The amended rules provided for individual peer review of articles. The review of Faraday”s article was written by the mathematician Samuel Hunter Christie and the physician John Bostock (1773-1846).

In December 1831, Faraday wrote to his longtime French pen pal Jean Nicolas Pierre Hachette, informing him of his recent discoveries. Hachette showed the letter to the secretary of the Institut de France, François Arago, who read the letter to the members of the institute on December 26, 1831. Reports on Faraday”s discovery appeared in the French newspapers Le Temps and Le Lycée on December 28 and 29, 1831, respectively. The London Morning Advertiser reprinted them on January 6, 1832. The press reports threatened the priority of his discovery because the Italians Leopoldo Nobili and Vincenzo Antinori (1792-1865) in Florence had repeated some of Faraday”s experiments and their results, published in the journal Antologia, appeared in the Philosophical Transactions before Faraday”s paper.

After his discovery that magnetism is capable of generating electricity, Faraday set himself the task of proving that regardless of how electricity is generated, it always acts in the same way. On August 25, 1832, he began working with the known sources of electricity. He compared the effects of voltaic electricity, frictional electricity, thermoelectricity, animal electricity and magnetic electricity. In his paper read on January 10 and 17, he concluded on the basis of his experiments “…that electricity, from whatever source it may have sprung, is identical in its nature”.

At the end of December 1832, Faraday asked himself whether an electric current would be able to decompose a solid body – ice, for example. In his experiments, he found that ice behaved like a non-conductor, unlike water. He tested a number of substances with low melting points and observed that a non-conducting solid body, after passing into the liquid phase, conducted the current and chemically decomposed under the influence of the current. On May 23, 1833, he spoke before the Royal Society On a New Law of Electricity Conduction.

These investigations led Faraday directly to his experiments on “electro-chemical decomposition,” which occupied him for a year. He reviewed the existing views, especially those of Theodor Grotthuß and Davy, and came to the conclusion that decomposition took place inside the liquid and that the electric poles only played the role of limiting the liquid.

Dissatisfied with the terms available to him for describing chemical decomposition under the influence of an electric current, Faraday turned to William Whewell in early 1834 and also discussed the matter with his physician Whitlock Nicholl. The latter suggested to Faraday that, to describe the process of electrochemical decomposition, the terms electrode should be used for the entry and exit surfaces of the current, electrolysis for the process itself, and electrolyte for the substance involved. Whewell, wishing to make the polar nature of the process more recognizable, coined the terms anode and cathode for the two electrodes and the terms anion, cation, and ion for the particles involved. At the beginning of the seventh installment of his Experimental Researches in Electricity, which he submitted to the Royal Society on January 9, 1834, Faraday proposed the new terms to describe the process of electrochemical decomposition (electrolysis). In this article he formulated the two basic laws of electrolysis:

With his investigations, Faraday excluded the influence of factors such as the concentration of the electrolytic solution or the nature and size of the electrodes on the process of electrolysis. Only the amount of electricity and the chemical equivalents involved were important. It was proof that chemical and electrical forces were closely related and quantitatively related. Faraday used this connection in his further experiments to precisely measure the amount of electricity.

In mid-January 1836, Faraday set up a cube in the lecture hall of the Royal Institution with sides 12 feet (about 3.65 meters) long, the edges of which were formed by a light wooden frame. The sides were netted with copper wire and covered with paper. The cube stood on four 5.5-inch (about 14 centimeter) high glass feet to isolate it from the ground. In experiments conducted on January 15 and 16, 1836, he connected the cube to an electrifying machine to charge it electrically. He then went inside the arrangement with a Goldblatt electrometer to detect any electricity that might have been induced in the air. However, every point in the room proved to be free of electricity.

The arrangement known as a Faraday cage, in which the electric field disappears inside a closed, conductive body, is used today in electrical engineering to shield electrostatic fields.

In 1837 Faraday thought about the way in which the electric force effect spreads through space. The idea of a long-distance effect of the electric forces, as implied by Coulomb”s law, made him uncomfortable. On the other hand, he suspected that space must play a role in the transmission of forces and that there must be a dependence on the medium filling the space. Faraday began to systematically investigate the influence of insulators and designed an experimental arrangement of two identical spherical capacitors. These spherical capacitors in turn consisted of two brass spheres placed one inside the other with a distance of three centimeters. The spheres were connected by a brass handle coated with insulating shellac, forming a Leiden bottle. Faraday first charged one of the two capacitors, then brought it into electrical contact with the other and, using a homemade Coulomb rotating balance, convinced himself that after the charge was equalized, both capacitors carried the same charge. He then filled the air space of one capacitor with an insulator and repeated the experiment. His measurement again showed that the capacitor with the insulator carried the larger charge. He repeated the experiment with different substances. Faraday obtained a quantitative measure of the effect of the insulators on the capacitance of the spheres, which he called “specific inductive capacity,” equivalent today to the dielectric constant. For a non-conducting substance located between two conductors, Whewell had proposed the term dielectric in late 1836, which Faraday also used. Faraday explained his experimental result in terms of a polarization of particles within insulators, where the effect is passed from particle to particle, and extended this idea to the transport of electricity within conductors.

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Exhaustion and recovery

In early 1839, Faraday summarized his articles on his investigations of electricity published in the Philosophical Transactions between November 1831 and June 1838 under the title Experimental Researches in Electricity. From August to November 1839, Faraday conducted investigations into the operation of the Voltaic column, which he published in December 1839 under the title On the Source of the Force in Volta”s Column. In it, he countered the Voltaic contact theory with numerous experimental proofs.

In late 1839, Faraday suffered a serious health breakdown, which he attributed to overwork, and the symptoms of which were headaches, dizziness, and temporary memory loss. His physician, Peter Mere Latham (1789-1875), advised him to take temporary leave from his many responsibilities and recuperate in Brighton. Faraday worked only sporadically in his laboratory for the next few years. In January and February 1840, he continued his investigations on the voltaic column on five days. In August and September he experimented again on five days. After September 14, 1840, he made no entry in his laboratory diary for about twenty months until July 1, 1842. In late 1840, the managers of the Royal Institution recognized the seriousness of Faraday”s illness and gave him a leave of absence until he fully recovered. For almost a year he gave no lectures. Together with his wife, her brother George Barnard (1807-1890) and the latter”s wife Emma, he set out on a three-month recuperative trip to Switzerland on June 30, 1841, where he went on extensive hikes in the Bernese Alps.

In 1840, William George Armstrong had discovered that electricity is generated when water vapor escapes into the air at high pressure. In the summer of 1842, Faraday began to research the cause of this electricity. He was able to prove that it was frictional electricity. After the completion of this work in January 1843, another longer phase followed, during which he hardly experimented. It was not until May 23, 1844, that Faraday began again with attempts to convert gases into the liquid and solid state, which lasted for more than a year. He continued his experiments of 1823. He succeeded in converting six gases into liquids and seven, including ammonia, nitrous oxide and hydrogen sulfide, into the solid state.

During this time, Faraday seemed to have doubts about whether he could continue to make important contributions as a naturalist. He compiled the 15th to 18th installments of his electricity investigations together with about 30 other papers into the second volume of Experimental Researches in Electricity, which appeared at the end of 1844.

Studies on electricity (1845 to 1855)

In June 1845, Faraday attended the annual meeting of the British Association for the Advancement of Science in Cambridge. There he met the young William Thomson, later Lord Kelvin. In early August, Faraday received a letter from Thomson inquiring about the influence of a translucent nonconductor on polarized light. Thomson told Faraday that he had performed such experiments in 1833 without results and promised to address the question again. Using a luminous Argand lamp, he repeated his experiments with different materials in late August to early September, but obtained no effect. The effect Faraday had been looking for, the electro-optical Kerr effect, was not demonstrated until thirty years later by John Kerr.

On September 13, 1845, Faraday sent polarized light through the previously used materials, which he subjected to the influence of a strong magnet. The first experiments with air and flint glass did not yield any results. When he used a lead borate glass made as part of his glass experiments in the 1820s, he found a weak but detectable rotation of the plane of polarization when he aligned the light beam parallel to the magnetic field lines as it passed through. He continued his experiments, first finding it in another of his old glass samples before demonstrating the effect on other materials, including flint glass, crown glass, turpentine oil, halite crystal, water, and ethanol. Faraday had provided evidence that light and magnetism were two related physical phenomena. He published his findings under the title On the Magnetization of Light and the Exposure of Magnetic Force Lines. The magneto-optical effect found by Faraday is now known as the Faraday effect.

Faraday immediately asked himself whether the reverse effect also existed and whether light could electrify or magnetize something. However, an experiment in which he exposed a coil of wire to sunlight failed.

During a Friday evening lecture in early April 1846, Faraday expressed some speculations about “oscillatory radiations,” which he put in writing two weeks later in a letter to the Philosophical Magazine. In it, he outlined the possibility that light might be produced by transverse oscillations of lines of force. Faraday”s speculation was a stimulus for James Clerk Maxwell in developing his electromagnetic theory of light, which he formulated 18 years later.

The experiments with polarized light showed Faraday that a non-magnetic substance could be affected by magnetism. For his further experiments, he borrowed a powerful electromagnet from the Royal Military Academy in Woolwich. He attached a lead borate glass sample to two silk threads and hung it between the sharpened pole pieces of the electromagnet. When he closed the electric circuit, he observed that the glass sample moved away from the pole shoes and aligned itself perpendicular to the imaginary line connecting the pole shoes. It thus behaved differently than magnetic materials, which aligned along the line of connection. Faraday quickly found a variety of materials that behaved like his glass sample, including wood, olive oil, apple, beef and blood. He achieved the clearest effects with an ingot of bismuth. By analogy with the term “dielectric,” Faraday referred to these materials as “dimagnetic” in his laboratory diary on September 18, 1845. Again, Whewell helped Faraday with the term. Whewell corrected the prefix used by Faraday to dia for ”through”, since the effect was through the bodies (“diamagnetic”), and suggested that all substances that did not behave in this way should be called “paramagnetic”. In his laboratory diary, Faraday first used the term “magnetic field” in this context on November 7. Faraday”s discovery of diamagnetism led to the emergence of magnetochemistry, which deals with the magnetic properties of materials.

After his discovery of the influence of a magnetic field on polarized light, Faraday increasingly came to believe that lines of force could have real physical significance. The unusual behavior of diamagnetic bodies was difficult to explain by conventional magnetic poles and led to a dispute between Faraday and Wilhelm Eduard Weber, who believed he could prove that magnetism, like electricity, was polar in nature. In 1848, Faraday began new experiments to investigate the behavior of diamagnetic bodies under the influence of a magnet. He discovered that crystals orient themselves along certain preferred axes (magnetic anisotropy). This behavior could not be interpreted with the previously used concepts of attraction or repulsion. In his investigation report, Faraday spoke for the first time of a magnetic field that exists between two magnetic poles and whose effect is location-dependent.

In 1852, Faraday summarized his views on lines of force and fields in the article On the physical character of the lines of magnetic force. In it, he rejected a remote effect of gravitational forces and advocated the view of a gravitational field associated with the mass of a body.

Faraday”s interest in gravitation extended back to the mid-1830s. At the end of 1836, he read a paper by the Italian Ottaviano Fabrizio Mossotti in which he attributed gravitation to electrical forces. Faraday was initially enthusiastic about the work, had it translated into English, and spoke about it in a Friday evening lecture. Later, however, he rejected Mossotti”s explanation because he had come to believe that the differences in how gravity acts compared to other forces were too great. Over the next few years, Faraday frequently speculated about the ways in which gravity might be related to other forces. In March 1849, he began to consider how a relationship between gravity and electricity might be experimentally demonstrated. He envisioned gravity as a force with two complementary components, in which a body is positive when moving toward the earth and negative when moving away from it. He theorized that these two motions were associated with opposite electrical states. For his experiments, Faraday constructed a coil of wire, which he connected to a galvanometer and dropped from a great height. However, he could not prove any effect in any measurement. Despite the negative outcome of the experiments, he described his efforts in the Baker Lecture of November 28, 1850.

In February 1859, Faraday again began a series of experiments with which he hoped to prove a connection between gravity and electricity. Because of the expected small effect, he used lead masses weighing several hundred kilograms, which he dropped from the 50-meter-high scrap tower in Lambeth. With other experiments, he hoped to demonstrate a change in temperature when a mass was raised and lowered. On July 9, 1859, Faraday abandoned the experiments without success. He wrote about it the essay Note on the Possible Relation of Gravity with Electricity or Heat, which he completed on April 16, 1860, and which would appear as usual in the Philosophical Transactions. George Gabriel Stokes, who found that the paper was not worthy of publication because he had only negative results to show, recommended Faraday to withdraw his article, which he did immediately after receiving Stokes” letter.

Popularization of natural science and technology

Shortly after his appointment as Laboratory Director of the Royal Institution in early 1825, Faraday opened the Institute”s laboratories to meetings of Institute members. On three or four Friday evenings, he planned to give chemistry lectures accompanied by experiments to interested members. From these informal meetings he developed the concept of regular Friday evening lectures, at which topics in natural science and technology were to be presented in a manner understandable to laymen. At the first Friday evening lecture on February 3, 1826, Faraday spoke about rubber. Of the 17 lectures given that first year, he gave six on topics such as Isambard Kingdom Brunel”s gas liquefier, lithography, and the Thames Tunnel. In Faraday”s view, lectures should be fun, entertaining, educational and, above all, stimulating. His lectures became very popular due to their simple style of delivery and were always well attended. By 1862, Faraday had given a total of 126 of these one-hour lectures. As secretary of the committee for the “Weekly Evening Meetings,” Faraday saw to it that the lectures were published in the Literary Gazette and the Philosophical Magazine, thus making them accessible to an even wider audience.

In addition to the Friday evening lectures, at the turn of the year 1825.

In the public sector

In addition to his research and lecturing activities, Faraday was active in many ways for the British state. In the summer of 1829, Percy Drummond († 1843), Lieutenant Governor of the Royal Military Academy in Woolwich, approached Faraday and asked him if he would be willing to succeed the geologist John MacCulloch (1773-1835) as Professor of Chemistry at the Academy. After prolonged negotiations, mainly concerned with his duties and pay, Faraday agreed. Until 1852, he gave 25 lectures a year in Woolwich.

From February 4, 1836, Faraday worked as a scientific advisor to Trinity House, the maritime authority that operated England”s lighthouses, among other things. He was responsible for the chemical analysis of the materials used in the operation of the lighthouses and examined new lighting systems that had been proposed to Trinity House for use. Faraday saw to the modernization of the English lighthouses. He was inspired by the French lighthouses, which used Fresnel lenses to improve luminous intensity. He also accompanied the first attempts to electrify them. In Blackwall on the Thames, there were two lighthouses built especially for his investigations.

On behalf of the government, Faraday was involved in the investigation of two sensitive accidents. On April 13, 1843, an explosion destroyed the gunpowder factory run by the Ordnance Office at Waltham Abbey (Essex), whereupon Faraday was entrusted with analyzing the causes. In his report to James Pattison Cockburn (1779?-1847), laboratory director of the Military Academy at Woolwich, he listed several possible causes and gave advice on how these problems could be avoided in the future. Together with Charles Lyell and Samuel Stutchbury (1798-1859), he was commissioned by the Home Office in October 1844 to investigate the explosion at the Haswell pit in Durham that had killed 95 people on September 28. Lyell and Faraday recognized that coal dust had played a major role in the explosion and recommended the introduction of a better ventilation system.

A significant part of Faraday”s advisory work dealt with the conservation of objects and buildings. From 1853, he advised the Select Committee on the National Gallery on the conservation of paintings. For example, he investigated the effect of gas lighting on paintings. In early 1856, Faraday was appointed to the Royal Commission that considered the future of the National Gallery site. Commissioned by Thomas Leverton Donaldson (1795-1885), he investigated for the British Museum whether the Elgin Marbles were originally painted. In 1859 he advised the Metropolitan Board of Works on the selection of a means of treating the limestones of the recently rebuilt Houses of Parliament, which were decomposing under the influence of the sulfurous London air.

Religious activity

Faraday was a deeply religious man. His father belonged to the small Christian sect of the Sandemanians, who had broken away from the Church of Scotland in the late 1720s. They based their faith and its practice on a literal interpretation of the Bible. There were about one hundred Sandemanians in Greater London at the time and about one thousand throughout Great Britain. Even as a child, Faraday accompanied his father to Sunday sermons. Shortly after his marriage to Sarah Barnard, who was also a member of the Sandemanians and whose father served the congregation as an elder, he took his oath on July 15, 1821, and became a member.

As a token of their high esteem, the London congregation elected Faraday a deacon on July 1, 1832, and one of the three elders on October 15, 1840. For the next three and a half years, one of his duties was to preach the sermon every other Sunday, for which he prepared as carefully as he did for his lectures. On March 31, 1844, Faraday was excluded from the congregation until May 5. The reasons for this are not entirely clear, but are not to be found in any personal misconduct on Faraday”s part, but are due to a controversy within the Sandemanians, as numerous members besides Faraday were expelled at this time. He was not re-elected to his position as an elder until October 21, 1860. By 1864, Faraday was again regularly responsible for preaching and maintained contact with other Sandemanian congregations, such as those in Chesterfield, Glasgow, and Dundee. His sermons consisted of a series of quotations from the Old and New Testaments, which he annotated. His religious views were a very private matter for him and he rarely expressed them to his pen pals or in public.

Last years

The third and final volume of Experimental Researches in Electricity, which Faraday compiled in early 1855, included all of his papers published in the Philosophical Transactions since 1846. In addition, he included two articles published in the Philosophical Magazine that followed the 29th installment of Experimental Researches in Electricity and continued his characteristic section numbering. A few shorter articles supplemented the volume. In all, Faraday published 450 scientific articles.

Through the mediation of Prince Albert, the Faradays moved into a house in Hampton Court Green in September 1858, which belonged to Queen Victoria and was in the immediate vicinity of Hampton Court Palace. In October 1861, the seventy-year-old Faraday asked the managers of the Royal Institution to dismiss him from the institute”s service. However, they refused his request and only relieved him of responsibility for the Christmas lectures.

On November 25, 1861, Faraday began a final series of experiments in which he used a spectroscope constructed by Carl August von Steinheil to investigate the effects of a magnetic field on the light spectrum of a flame. He made his last entry in the laboratory diary on March 12, 1862. The experiments were unsuccessful because of the insufficiently sensitive measuring arrangement; the Zeeman effect was not discovered until 1896.

On June 20, 1862, Faraday delivered his last Friday evening lecture, On Gas Furnaces, to an audience of more than 800, ending nearly four decades of lecturing for the Royal Institution. In the spring of 1865, by unanimous decision of the managers of the Royal Institution, he was relieved of all his duties. Until May 1865, he was still at the disposal of the Shipping Authority with his advice.

Faraday died at his home in Hampton Court on August 25, 1867, and was buried in Highgate Cemetery five days later.

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Formation of electrodynamics

Faraday”s concepts and his view of the uniformity of nature, which did not require a single mathematical formula, left a deep impression on the young James Clerk Maxwell. Maxwell set himself the task of translating Faraday”s experimental findings and their description by means of lines of force and fields into a mathematical representation. Maxwell”s first major paper on electricity, On Faraday”s Lines of Force, was published in 1856. Based on an analogy to hydrodynamics, Maxwell established the first theory of electromagnetism by introducing the vector quantities electric field strength, magnetic field strength, electric current density and magnetic flux density and relating them to each other by means of the vector potential. Five years later, in On Physical Lines of Force, Maxwell also considered the medium in which the electromagnetic forces acted. He modeled the medium by elastic properties. This showed that a temporal change of an electric field leads to an additional displacement current. It also revealed that light is a transverse wave motion of the medium, confirming Faraday”s speculation about the nature of light. Further elaboration of the theory by Maxwell eventually led to the formulation of Maxwell”s equations in 1864, which form the basis of electrodynamics and can be used to explain all of the electromagnetic discoveries found by Faraday. One of Maxwell”s four equations is a mathematical description of the electromagnetic induction discovered by Faraday.

Public perception

By the end of the 19th century, Faraday was noted as the inventor of the electric motor, the transformer, and the generator, as well as the discoverer of benzene, the magneto-optical effect, diamagnetism, and the creator of electromagnetic field theory. In 1868, John Tyndall”s biography Faraday as a Discoverer was published. In it, Tyndall, who succeeded Brande at the Royal Institution, described mainly Faraday”s scientific discoveries. Hermann Helmholtz, who translated Tyndall”s biography into German, supplemented it with numerous biographical notes. Shortly thereafter, Henry Bence Jones, secretary of the Royal Institution and Faraday”s physician, published a typical Victorian “life-and-letters” biography, for which he drew on Faraday”s letters, his laboratory diaries, and other unpublished manuscripts and used excerpts from Tyndall”s biography. Bence Jones”s two-volume biography is still an important source today, as some of the letters and diaries cited in it can no longer be found. These and other accounts of Faraday led to an image of a researcher who, alone and in the seclusion of his laboratory at the Royal Institution, got to the bottom of the mysteries of nature.

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Instrumentalization

After the end of the First World War, the established gas industry and the emerging electrical industry, whose goal was the comprehensive electrification of Great Britain and which was thus in direct competition with the gas industry, attempted to use Faraday”s fame for their respective goals in the 1920s. To mark the one hundredth anniversary of the discovery of benzene, a committee was constituted under the chairmanship of the chemist Henry Edward Armstrong, consisting of members of the Royal Institution, the Chemical Society, the Society of Chemical Industry and the Association of British Chemical Manufacturers. During the celebrations in June 1925, the importance of Faraday to the modern chemical industry was emphasized, and he was celebrated as the “father of the chemical industry.”

On the initiative of Walter Adolph Vignoles (1874-1953), director of the Electrical Development Association, and with the support of William Henry Bragg, director of the Davy-Faraday Research Laboratory at the Royal Institution, a nine-member committee was appointed in February 1928 to organize the celebrations to mark the centenary of the discovery of electromagnetic induction in 1931. From September 23 to October 3, 1931, an exhibition honoring Faraday and his discovery was held at the Royal Albert Hall. The centerpiece of the exhibition was a copy of the sculpture created by John Henry Foley (1818-1874) and Thomas Brock (1847-1922), which had been in the Royal Institution since 1876 and showed Faraday in academic dress with his induction ring. In close proximity to the sculpture were the simple things Faraday used to conduct his first experiments: a wire, a magnet, and a drop of mercury. The sculpture formed the focal point for the exhibition stands arranged in a circle around it. The stands closest to the sculpture displayed the apparatus Faraday used for each experiment and his associated records. The outer booths demonstrated the modern electrical industry technologies that resulted. A 12-page booklet accompanying the exhibition, of which about 100,000 copies were distributed, was entitled Faraday: The Story of an Errand-Boy. Who Changed the World (Faraday: The Story of an Errand-Boy Who Changed the World). The lavish 1931 exhibition and associated celebrations were, on the one hand, indebted to the electrical industry”s efforts to turn electricity into marketable products. On the other hand, they also supported the efforts of natural scientists to show how basic research can contribute to the development of new technologies.

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Awards and recognition

Faraday”s biographer Henry Bence Jones lists a total of 95 honorary titles and awards. Faraday was first honored by a learned society in 1823 by the Cambridge Philosophical Society, which accepted him as an honorary member. In 1832 he was elected to the American Academy of Arts and Sciences, in 1835 to the Göttingen Academy of Sciences and the Royal Society of Edinburgh, and in 1840 to the American Philosophical Society. At the instigation of Jean-Baptiste André Dumas, Faraday was elected to the Académie des sciences in 1844 as one of its eight foreign members. In 1847 he was admitted as a foreign member of the Bavarian Academy of Sciences. In 1857 he was elected a member of the Leopoldina. In 1864 he was honored for the last time by the Società Reale di Napoli, which listed him as an associate foreign member. Also in 1864, he was elected to the National Academy of Sciences.

The Royal Society awarded him the Copley Medal (1832 and 1838), the Royal Medal (1835 and 1846), and the Rumford Medal (1846). Faraday turned down the offer to become president of the Royal Society twice (1848 and 1858). In 1842 Faraday received the Prussian Order of Merit Pour le Mérite.

A cable lug specially built for laying submarine cables, the Faraday, was named after Faraday in 1874 by its designer, Carl Wilhelm Siemens. The Congrès international d”électriciens (International Congress of Electricians), meeting in Paris, decided on September 22, 1881, to name the unit of electrical capacity Farad in his honor. Likewise, the lunar crater Faraday and the asteroid Faraday are named after him. William Whewell honored Faraday and Davy by naming one of his “Epochs of Chemistry”.

On June 5, 1991, the Bank of England issued a new 20-pound sterling banknote bearing Faraday”s likeness, which was legal tender until February 28, 2001.

Several prizes are named after him, including the Faraday Medal (IOP), Faraday Medal (IEE), and the Michael Faraday Prize of the Royal Society.

The plant genus Faradaya F.Muell. from the Lamiaceae family is named after him.

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Estate and correspondence

Faraday”s written legacy is probably the most extensive left by any naturalist in the history of science. It includes his laboratory diaries, journals, commonplace books, notes, manuscripts, letters, books, and more. The estate contains records of some 30,000 experiments performed by Faraday.

In early 1855, Faraday gave the first instructions for settling his estate. He left his laboratory diaries, some offprints and other personal items to the Royal Institution. After Faraday”s death, the Royal Institution received further material from his wife Sarah. She left to Trinity House the files containing his papers for the Institution. These are now in the Guildhall Library. She gave several pieces to friends and relatives in memory of Faraday. Some of them came into the possession of the Institution of Electrical Engineers at the end of 1915. The manuscripts of Faraday”s articles for the Philosophical Transactions, after he submitted them for publication, became the property of the Royal Society. Half of them have been preserved. Of Faraday”s correspondence, some 4800 letters have survived and are in 230 archives around the world.

Current German editions

After the 1889-1891 edition translated from the English by Salomon Kalischer, with an introduction by Friedrich Steinle:

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Biographies

Classic

Modern

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On the reception of his work (selection)

Sources