FAEADAY. 787 



A specimen of one of these heavy glasses afterwards became historically im- 

 portant as the substance in which Faraday detected the rotation of the plane 

 of polarization of light when the glass was placed in the magnetic 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 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 com- 

 pletely overshadowed by his electrical discoveries. The first experiment which 

 he has recorded was the construction of a voltaic pile with seven halfpence, 

 seven disks of sheet zinc, and six pieces of paper moistened with salt water. 

 With this pile he decomposed sulphate of magnesia (first letter to Abbott, 

 July 12, 1812). Henceforward, whatever other subjects might from time to 

 time claim his 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, even when year after year his attempts 

 to solve them had been baffled. 



His first notable discovery was the production of the continuous rotation 

 of magnets and of wires conducting the electric current round each other. 

 The consequences deducible from the great discovery of Orsted (21st July, 

 1820) were still in 1821 apprehended in a somewhat confused manner even by 

 the foremost men of science. Dr Wollaston indeed had formed the expectation 

 that he could make the conducting wire rotate on its own 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 request of 

 Mr Phillips, the editor of the Annals of Philosophy, wrote for that journal 

 an historical sketch of electro-magnetism, and he repeated almost all the ex- 

 periments he described. This led him in the beginning of September to dis- 

 cover 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 electromagnetic research became the occasion of the most painful, though 

 unfounded, imputations against his honour. Into these we shall not enter, re- 

 ferring the reader to the Life of Faraday, by Dr Bence Jones. 



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