282 On the Magnetism- impressed on Metals 



established between the opposite poles of the voltaic apparatus, 

 or even if we retard considerably its velocity, by joining its 

 poles with bad conductors, the magnetic power instantly ceases, 

 and the bodies which had received it return to their usual state 

 of indifference. 



This simple sketch already displays many new properties. 

 All the processes hitherto employed to magnetize bodies had 

 produced an effect on only three pure metals, iron, nickel, and 

 cobalt, and on some of their compounds, steel for example, 

 which is merely a carburet of iron. Till now it was never pos- 

 sible to render silver, copper, or the rest of the metals magnetic. 

 But the electric current gives all of them this property ; it 

 bestows it transiently by its presence ; and, as we shall pre- 

 sently see, it diffuses it through the whole mass, in a manner 

 equally singular, and which has no resemblance to what is 

 produced, when we develope magnetism by our ordinary pro- 

 cesses, which consist in longitudinal friction with magnetic 

 bars. 



To produce these novel phenomena in the simplest manner, 

 we must with M. Oersted, establish a communication between 

 the two extremities of the voltaic apparatus, by a simple 

 metallic wire, which may be easily directed and bent in all di- 

 rections. We place afterwards in the neighbourhood of the 

 battery, a very sensible magnetic needle, horizontally suspended. 

 As soon as this is settled in the direction due to the magnetic 

 force of the terrestrial globe, we take a flexible portion of the 

 conducting, or conjunctive wire, as M. Oersted calls it, and 

 having stretched it parallel to the needle, we bring it gently 

 near it, either from above, from below, from the right, or from 

 the left. We shall see an immediate deviation of the needle ; 

 but what is not the least remarkable circumstance, the direc- 

 tion of this deviation differs according to the side by which the 

 conjunctive wire approaches it. Duly to comprehend this as- 

 tonishing phenomenon and to fix its peculiarities with precision, 

 let us suppose that the conjunctive wire is extended horizon- 

 tally from north to south, in the very direction of the magnetic 

 direction in which the needle reposed, and let the nortfr extre- 



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