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FARADAY, MICHAEL (1791-1867)

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Originally appearing in Volume V10, Page 175 of the 1911 Encyclopedia Britannica.
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FARADAY, See also:MICHAEL (1791-1867) , See also:English chemist and physicist, was See also:born at Newington, See also:Surrey, on the 22nd of See also:September 1791. His parents had migrated from See also:Yorkshire to See also:London, where his See also:father worked as a blacksmith. Faraday him-self became apprenticed to a bookbinder. The letters written to his friend See also:Benjamin See also:Abbott at this See also:time give a lucid See also:account of his aims in See also:life, and of his methods of self-culture, when his mind was beginning to turn to the experimental study of nature. In 1812 Mr See also:Dance, a customer of his See also:master, took him to hear four lectures by See also:Sir See also:Humphry See also:Davy. Faraday took notes of these lectures, and afterwards wrote them out in a See also:fuller See also:form. Under the encouragement of Mr Dance, he wrote to Sir H. Davy, enclosing these notes. " The reply was immediate, See also:kind and favourable." He continued to See also:work as a journeyman bookbinder till the 1st of See also:March 1813, when he was appointed assistant in the laboratory of the Royal Institution of See also:Great See also:Britain on the recommendation of Davy, whom he accompanied on a tour through See also:France, See also:Italy and See also:Switzerland from See also:October 1813 to See also:April 1815. He was appointed director of the laboratory in 1825; and in 1833 he was appointed Fullerian See also:professor of See also:chemistry in the institution for life, without the See also:obligation to deliver lectures. He thus remained in the institution for fifty-four years. He died at See also:Hampton See also:Court on the 25th of See also:August 1867.

Faraday's earliest chemical work was in the paths opened by Davy, to whom he acted as assistant. He made a See also:

special study of See also:chlorine, and discovered two new chlorides of See also:carbon. He also made the first rough experiments on the See also:diffusion of gases, a phenomenon first pointed out by See also:John See also:Dalton, the See also:physical importance of which was more fully brought to See also:light by See also:Thomas See also:Graham and See also:Joseph Loschmidt. He succeeded in liquefying several gases; he investigated the See also:alloys of See also:steel, and produced several new kinds of See also:glass intended for See also:optical purposes. A specimen of one of these heavy 'glasses afterwards became historically important as the substance in which Faraday detected the rotation of the See also:plane of polarization of light when the glass was placed in the magnetic See also:field, and also as the substance which was first repelled by, the poles of the magnet. He also endeavoured with some success to make the See also:general methods of chemistry, as distinguished from its results, the subject of special study and of popular exposition. See his work on Chemical Manipulation. . But Faraday's chemical work, however important in itself, was soon completely overshadowed by his See also:electrical discoveries. The first experiment which he has recorded was the construction of a voltaic See also:pile with seven halfpence, seven disks of See also:sheet See also:zinc, and six pieces of See also:paper moistened with See also:salt See also:water. With this pile he decomposed sulphate of See also:magnesia (first See also:letter to Abbott, See also:July 12, 1812). Henceforward, whatever other subjects might from time to time claim his See also:attention, it was from among electrical phenomena that he selected those problems to which he applied the full force of his mind, and which he kept persistently in view, 173 even when See also:year after year his attempts to solve them had been baffled. . His first notable See also:discovery was the See also:production of the continuous rotation of magnets and of wires conducting the electric current See also:round each other.

The consequences deducible from the great discovery of H. C. Oersted (21st July 1820) were still in 1821 apprehended in a somewhat confused manner even by the foremost then of See also:

science. Dr W. H. See also:Wollaston indeed had formed the expectation that he could make the conducting See also:wire rotate on its own See also:axis, and in April 1821 he came with Sir H. Davy to the laboratory of the Royal Institution to make an experiment. Faraday was not there at the time, but coming in afterwards he heard the conversation on the expected rotation of the wire. In July, August and September of that year Faraday, at the See also:request of R. See also:Phillips, the editor of the See also:Annals of See also:Philosophy, wrote for that See also:journal an See also:historical See also:sketch of electro-See also:magnetism, and he repeated almost all the experiments he described. This led him in the beginning of September to discover the method of producing the continuous rotation of the wire round the magnet, and of the magnet round the wire. He did not succeed in making the wire or the magnet revolve on its own axis.

This first success of Faraday in electro-magnetic See also:

research became the occasion of the most painful, though unfounded, imputations against his See also:honour. Into these we shall not enter, referring the reader to the Life of Faraday, by Dr Bence See also:Jones. We may remark, however, that although the fact of the tangential force between an electric current and a magnetic See also:pole was clearly stated by Oersted, and clearly apprehended by A. M. See also:Ampere, Wollaston and others, the realization of the continuous rotation of the wire and the magnet round each other was a scientific See also:puzzle requiring no mean ingenuity for its See also:original See also:solution. For on the one See also:hand the electric current always forms a closed See also:circuit, and on the other the two poles of the magnet have equal but opposite properties, and are inseparably connected, so that whatever tendency there is for one pole to circulate round the current in one direction is opposed by the equal tendency of the other pole to go round the other way, and thus the one pole can neither See also:drag the other round and round the wire nor yet leave it behind. The thing cannot be done unless we adopt in some form Faraday's ingenious solution, by causing the current, in some See also:part of its course, to See also:divide into two channels, one on each See also:side of the magnet, in such a way that during the revolution of the magnet the current is transferred from the channel in front of the magnet to the channel behind it, so that the See also:middle of the magnet can pass across the current without stopping it, just as See also:Cyrus caused his See also:army to pass dryshod over the Gyndes by diverting the See also:river into a channel cut for it in his See also:rear. We must now go on to the crowning discovery of the See also:induction of electric currents. In See also:December 1824 he had attempted to obtain an electric current by means of a magnet, and on three occasions he had made elaborate but unsuccessful attempts to produce a current in one wire by means of a current in another wire or by a magnet. He still persevered, and on the 29th of August 1831 he obtained the first See also:evidence that an electric current can induce another in a different circuit. On the 23rd of September he writes to his friend R. Phillips: " I am busy just now again on See also:electromagnetism, and think I have got hold of a See also:good thing, but can't say.

It may be a See also:

weed instead of a See also:fish that, after all my labour, I may at last pull up." This was his first successful experiment. In nine more days of experimenting he had arrived at the results described in his first See also:series of "Experimental Researches" read to the Royal Society on the 24th of See also:November 1841. By the intense application of his mind he had thus brought the new See also:idea, in less than three months from its first development, to a See also:state of perfect maturity. During his first See also:period of discovery, besides the induction of electric currents, Faraday established the identity of the electrification produced in different ways; the See also:law of the definite electrolytic See also:action of the current; and the fact, upon which he laid great stress, that every unit of See also:positive electrification is related in a definite manner to a unit of negative electrification, so that it is impossible to produce what Faraday called " an See also:absolute See also:charge of See also:electricity " of one kind not related to an equal charge of the opposite kind. He also discovered the difference of the capacities of different substances for taking part in electric induction- See also:Henry See also:Cavendish had before 1773 discovered that glass, See also:wax, See also:rosin and shellac have higher specific inductive capacities than See also:air, and had actually determined the numerical ratios of these capacities, but this was unknown both to Faraday and to all other electricians of his time, since Cavendish's Electrical Researches remained unpublished till 1879. The first period of Faraday's electrical discoveries lasted ten years. In 1841 he found that he required See also:rest, and it was not till 1845 that he entered on his second great period of research, in which he discovered the effect of magnetism on polarized light, and the phenomena of See also:diamagnetism. Faraday had for a See also:long time kept in view the possibility of using a See also:ray of polarized light as a means of investigating the See also:condition of transparent bodies when acted on by electric and magnetic forces. Dr Bence Jones (Life of Faraday, vol. i. p. 362) gives the following See also:note from his laboratory See also:book on the loth of September 1822: " Polarized a ray of lamplight by reflection, and endeavoured to ascertain whether any depolarizing action (was) exerted on it by water placed between the poles of a voltaic See also:battery in a glass cistern; one Wollaston's trough used; the fluids decomposed were pure water, weak solution of sulphate of soda, and strong sulphuric See also:acid; none of them had any effect on the polarized light, either when out of or in the voltaic circuit, so that no particular arrangement of particles could be ascertained in this way." Eleven years afterwards we find another entry in his notebook on the 2nd of May 1833 (Life, by Dr Bence Jones, vol. ii. p. 29). He then tried not only the effect of a steady current, but the effect on making and breaking contact.

" I do not think, therefore, that decomposing solutions or sub-stances will be found to have (as a consequence of decomposition or arrangement for the time) any effect on the polarized ray. Should now try non-decomposing bodies, as solid See also:

nitre, nitrate of See also:silver, See also:borax, glass, &c., whilst solid, to see if any See also:internal state induced, which by decomposition is destroyed, i.e. whether, when they can-not decompose, any state of electrical tension is See also:present. My borate of glass good, and See also:common electricity better than voltaic." On the 6th of May he makes further experiments, and concludes: " Hence I see no See also:reason to expect that any kind of structure or tension can be rendered evident, either in decomposing or non-decomposing bodies, in insulating or conducting states." At last, in 1845, Faraday attacked the old problem, but this time with See also:complete success. Before we describe this result we may mention that in 1862 he made the relation between magnet-ism and light the subject of his very last experimental work. He endeavoured, but in vain, to detect any See also:change in the lines of the spectrum of a See also:flame when the flame was acted on by a powerful magnet. This long series of researches is an instance of his persistence. His See also:energy is shown in the way in which he followed up his discovery in the single instance in which he was successful. The first evidence which he obtained of the rotation of the plane of polarization of light under the action of magnetism was on the 13th of September 1845, the transparent substance being his own heavy glass. He began to work on the 3oth of August 1845 on polarized light passing through electrolytes. After three days he worked with common electricity, trying glass, heavy optical glass, See also:quartz, See also:Iceland spar, all without effect, as on former trials. On the 13th of September he worked with lines of magnetic force. Air, See also:flint, glass, See also:rock-crystal, calcareous spar were examined, but without effect.

" Heavy glass was experimented with. It gave no effects when the same magnetic poles or the contrary poles were on opposite sides (as respects the course of the polarized ray), nor when the same poles were on the same side either with the See also:

constant or intermitting current. But when contrary magnetic poles were on the same side there was an effect produced on the polarized ray, and thus magnetic force and light were proved to have relations to each other. Thisfact will most likely prove exceedingly fertile, and of great value in the investigation of the conditions of natural force." He immediately goes on to examine other substances, but with " no effect," and he ends by saying, " Have got enough for to-See also:day." On the 18th of September he " does an excellent day's work." During September he had four days of work, and in October six, and on the 6th of November he sent in to. the Royal Society the nineteenth series of his " Experimental Researches," in which the whole conditions of the phenomena are fully specified. The negative rotation in ferro-magnetic See also:media is the only fact of importance which remained to be discovered afterwards (by M. E. Verdet in 1856). But his work for the year was not yet over. On the 3rd of November a new horseshoe magnet came See also:home, and Faraday immediately began to experiment on the action in the polarized ray through gases, but with no effect. The following day he repeated an experiment which had given no result on the 6th of October. A See also:bar of heavy glass was suspended by See also:silk between the poles of the new magnet. " When it was arranged, and had come to rest, I found I could affect it by the magnetic forces and give it position." By the 6th of December he had sent in to the Royal Society the twentieth, and on the 24th of December the twenty-first, series of his " Researches," in which the properties of diamagnetic bodies are fully described.

Thus these two great discoveries were elaborated, like his earlier one, in about three months. The discovery of the magnetic rotation of the plane of polarized light, though it did not See also:

lead to such important See also:practical applications as some of Faraday's earlier discoveries, has been of the highest value to science, as furnishing complete dynamical evidence that wherever magnetic force exists there is See also:matter, small portions of which are rotating about axes parallel to the direction of that force. We have given a few examples of the concentration of his efforts in seeking to identify the apparently different forces of nature, of his far-sightedness in selecting subjects for investigation, of his persistence in the pursuit of what he set before him, of his energy in working out the results of his discoveries, and of the accuracy and completeness with which he made his final statement of the See also:laws of the phenomenon. These characteristics of his scientific spirit See also:lie on the See also:surface of his work, and are See also:manifest to all who read his writings. But there was another side of his See also:character, to the cultivation of which he paid at least as much attention, and which was reserved for his See also:friends, his See also:family and his See also:church. His letters and his conversation were always full of whatever could awaken a healthy See also:interest, and See also:free from anything that might rouse See also:ill-feeling. When, on rare occasions, he was forced out of the region of science into that of controversy, he stated the facts and let them make their own way. He was entirely free from See also:pride and undue self-assertion. During the growth of his See also:powers he always thankfully accepted a correction, and made use of every expedient, however humble, which would make his work more effective in every detail. When at length he found his memory failing and his See also:mental powers declining, he gave up, without ostentation or complaint, whatever parts of his work he could no longer carry on according to his own See also:standard of efficiency. When he was no longer able to apply his mind to science, he remained content and happy in the exercise of those kindly feelings and warm affections which he had cultivated no less carefully than his scientific powers. The parents of Faraday belonged to the very small and isolated See also:Christian See also:sect which is commonly called after See also:Robert See also:Sandeman.

Faraday himself attended the meetings from childhood; at the See also:

age of See also:thirty he made public profession of his faith, and during two different periods he discharged the See also:office of See also:elder. His See also:opinion with respect to the relation between his science and his See also:religion is expressed in a lecture on mental See also:education delivered in 1854, and printed at the end of his Researches in Chemistry and Physics. " Before entering upon the subject, I must make one distinction which, however it may appear to others, is to me of the utmost importance. High as See also:man is placed above the creatures around him, there is a higher and far more exalted position within his view; and the ways are See also:infinite in which he occupies his thoughts about the fears, or hopes, or expectations of a future life. I believe that the truth of that future cannot be brought to his knowledge by any exertion of his mental powers, however exalted they may be; that it is made known to him by other teaching than his own, and is received through See also:simple belief of the testimony given. Let no one suppose for an instant that the self-education I am about to commend, in respect of the things of this life, extends to any considerations of the See also:hope set before us, as if man by reasoning could find out See also:God. It would be improper here to enter upon this sub- ject further than to claim an absolute distinction between religious and See also:ordinary belief. I shall be reproached with the weakness of refusing to apply those mental operations which I think good in respect of high things to the very highest. I am content to See also:bear the reproach. Yet even in earthly matters I believe that ' the in-visible things of Him from the creation of the See also:world are clearly seen, being understood by the things that are made, even His eternal See also:power and Godhead'; and I have never seen anything incompatible between those things of man which can be known by the spirit of man which is within him and those higher things concerning his future, which he cannot know by that spirit." Faraday gives the following note as to this lecture: " These observations were delivered as a lecture before His Royal See also:Highness the See also:Prince See also:Consort and the members of the Royal Institution on the 6th of May 1854. They are so immediately connected in their nature and origin with my own experimental life, considered either as cause or consequence, that I have thought the See also:close of this See also:volume not an unfit See also:place for their See also:reproduction." As Dr Bence Jones concludes " His standard of See also:duty was supernatural. It was not founded on any intuitive ideas of right and wrong, nor was it fashioned upon any outward experiences of time and place, but it was formed entirely on what he held to be the See also:revelation of the will of God in the written word, and throughout all his life his faith led him to See also:act up to the very letter of it." Published See also:Works.—Chemical Manipulation, being Instructions to Students in Chemistry (i vol., John See also:Murray, 1st ed.

1827, 2nd 1830, 3rd 1842) ; Experimental Researches in Electricity, vols. i. and ii., See also:

Richard and John See also:Edward See also:Taylor, vols. i. and-ii. (1844 and 1847); vol. iii. (1844); vol. iii. Richard Taylor and See also:William See also:Francis (1855); Experimental Researches in Chemistry and Physics, Taylor and Francis (1859) ; Lectures on the Chemical See also:History of a See also:Candle (edited by W. See also:Crookes) (See also:Griffin, See also:Bohn & Co., 1861) ; On the Various Forces in Nature (edited by W. Crookes) (Chatto & Windus, no date).

End of Article: FARADAY, MICHAEL (1791-1867)

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