Page:The American Cyclopædia (1879) Volume VII.djvu/92

84: FARADAY problem of the cause of the collection of lyco- podium seeds and other light bodies upon the vibrating parts of sounding plates, instead of upon the nodal lines where sand is collected, by showing that the light bodies are prevented from settling on the nodal lines by minute whirlwinds formed in the air over the vibrating parts. In 1827 he published his "Chemical Manipulations" (1 vol. 8vo ; 2d ed., 1830; 3d ed., 1842). In April of this year he gave his first course of six lectures before the royal institution upon the atmosphere, gases, vapor, chemical affinity, definite proportions, flame, galvanism, and magnetism as evolved by elec- tricity. Between February and May he de- livered twelve lectures at the London institution on the subject of chemical manipulation. In December 'he commenced a course of lectures on chemistry to juvenile audiences. His power of imparting the elementary principles of science to youthful minds was wonderful, owing not only to the logical simplicity of his mind, but to his happy choice of and manner of making experiments. These courses of lectures suc- ceeded each other from year to year, and it was also his habit to deliver popular lectures on Friday evenings at the royal institution throughout nearly his whole scientific career. In 1829 he was appointed lecturer on chemis- try in the royal academy at Woolwich. In 1831 he commenced his celebrated series of electrical researches, which were continued through a great number of years. He investi- gated the induction of electric currents and the evolution of electricity from magnetism; and although Oersted was the' discoverer of electro- magnetism, and Ampere its expounder, Faraday made the science of magneto-electricity sub- stantially what it is at the present day. In this year he also began to develop his theory of lines of magnetic force. In 1833 he was appointed the first Fullerian professor of chem- istry at the royal institution, and during the same and the succeeding year he studied the laws of electro-chemical decomposition, and applied the word electrode in place of pole to the conductors connected with a decomposing cell, the fluid in which he called an electrolyte, and the act of its decomposition electrolysis. The positive electrode he called the anode, and the negative the cathode, and also applied the terms anions and cations to the chemical ele- ments of the electrolytes which pass respec- tively to the anode and cathode. He now applied himself to the determination of elec- tric quantity, and for this purpose devised his voltameter, by which he showed that the amount of electricity generated in a voltaic battery depends upon the amount of chemical decomposition, thus establishing the doctrine of u definite electro-chemical decomposition." He investigated the contact theory of Volta, and in doing so developed the ideas which he al- ways afterward entertained on the conservation of force, illustrating the fallacy of the contact theory of galvanism by showing that if true a force could be produced without drawing its supply from any consuming source. His first great paper on frictional electricity was sent to the royal society Nov. 30, 1837. In his inves- tigation of this subject he developed his induc- tive theory of electricity, and by numerous memorable experiments illustrated the " specific inductive capacity " of dielectrics, in which he supposed the molecules of the dielectric to form a chain of communication between the inducing and the induced body. He also, during the years 1836-'8, made experiments for the Trinity house on electric light for lighthouses, a subject which again in the latter part of his life en- gaged much of his attention. In 1840 he was elected an elder in the Sandemanian church, but held the office only for 3-J- years, during which period, when in London, he preached on alternate Sundays. His great labors had im- paired his health, and in 1841 he went with his wife to Switzerland, spending much of the time at Interlaken and at the falls of Giessbach, returning at the end of September in the same year. In 1842 he made experiments upon the generation of electricity by steam, prompted thereto by the invention of the celebrated hydro-electric machine of Sir William Arm- strong, and showed that it was caused by fric- tion, and not by vaporization, as had been supposed. He performed very little laboratory work till the end of 1844, indulging in the mean time in needful rest. In the beginning of 1845 he made a second series of experiments on the condensation of gases, and about the first of September began the investigation of the magnetic relations of light, which led him to the discovery of the peculiar phenomena of magnecrystallic action. In November he an- nounced his discovery of the "Magnetization of Light and the Illumination of the Lines of Magnetic Force." Whatever doubt there may be as to the soundness of his theory in every particular, his paper is full of the profoundest thought. "I have long," he says, "held an opinion almost amounting to a conviction, in common I believe with many other lovers of natural knowledge, that the various forms under which the forces of matter are made manifest have one common origin ; in other words, are so directly related and mutually dependent, that they are convertible, as it were, into one another, and possess equivalents of power in their action." He always held that the theory of gravitation, not as it existed in the mind of Newton, but as commonly under- stood, embraced an absurdity, by supposing that when the manifestation of attraction be- tween two bodies decreased in proportion to the square of their distance from each other, an equivalent of energy was lost ; thus denying the doctrine of " conservation of force," which he considered as established. In December of the same year he published a memoir ad- dressed to the royal society on the " Mag- netic Condition of all Matter," in which he discussed the phenomena presented by diamag-