ElectrO'Mognetic Experiments. 4A 



to him that we owe that fine observation, that a melallk wire, 

 which communicates iviih the tivo cxtre7nities of a Voltaic elec^ 

 trical apparatus, acquires the very remarkable property of acting 

 at a distance on a magnetic needle. This mctaliic wire has been 

 named the conjunctive ivire. 



It was already known, that by augmenting the surfaces ot the 

 metallic plates which con^.pose the electrical apparatus of Volta, 

 and uniting the two wires which communicate with the extreme 

 plates of that apparatus, these wires become heated, redden, and 

 burn in atmospheric air. M. Thenard and myself had made that 

 experiment in 1801. (See No. 11 of the Journal of the Polytech- 

 nic School, p. 291.) The conjunctive wire, m tiie experiment 

 of M. CErsted, will become heated, but if it is of sufficient dia- 

 meter it will not burn ; and its action may be observed on a mag- 

 netic needle at some distance. 



, For twenty-three years the electric piles of Volta had been in 

 use, and no philosopher had yet thought of bringing a magnetic 

 needle near one of these piles in action. This inspiration was 

 reserved to M. CErsted ; and it must be confessed, that chance 

 had much less share in it than in many discoveries with which 

 physical science has been enriched. 



M Marcel de Serres translated from the German, and pub- 

 lished in 1807,a workof the Danish Professor entitled An Inquiry 

 into the Identity of Chemical and Electrical Forces. It may be 

 fieen from chapter 8 of that work, that the author had been led by 

 his subject to seek proofs of the identity of the magnetic and elec- 

 tric forces*. He had proposed to try whether electricity the 



most 



* There is nothing to be found in this chapter ^vhich establishes, in any 

 manner, the identity of inasnctism and electricity. It .s even remark- 

 able that when M. Oersted had discovered the action of the ec.njunctue 

 Ji c'of the Voltaic pile upon the .na.netic needle, he ^xpl^jned th.s nevv 

 ,,ha;non,enon by a hypothesis which supposes that the "'^Kf '^^ f ^^^ ^^^ 

 Lets only on the northern pole of the needle, and positive electnc.ty on the 

 s,",l"er.!: (so. Aun.ks ic/.«.e for Aug 1820, p. 24*0-a - . -^I-'^ 

 tvould estaUish a total dilTcrenco between the elect, .c and magncuc fluid. 

 ♦ince the magnetic flui.l, whether cons.dered as posuue or n^iJ" ;'^. ""M'J 

 to act equali; o.. both poles. To den.onstrate, by <-^^P^;""^^" ' ' ^ '^"'' J 

 of the electric and ma^etio fluids, it was necessary ''' ^''^ ^ f , '-'"^ J"^^^^^ 

 explain all the pha.non.ena which could be observed, ^vhether e m ual 



«clio., of two magnets, or in the action oi .. '^'^"J'f;'=«'«J [.," ^ ac n^ 

 i.etic needle, without a.hnittiag m a magnet ^"y." ''^^ ^'' , '\^" V \^,^V"^ 

 electric fluid, as in bodies which are not susceptible "'^"'^""^•f "';/".' 

 tell how this elertrlc fluid is disposed m the magnet. It is tins whicU 

 MAmVre has done, by demonstrating Ist, Th.at tNToeonjunct.ve wires, 

 o meta'unot n.agnetic, attract and repel through the ''■t--'";--;'^ « 

 dectric fluid alone; ad, that a magnet may be ^"^^''''f 'J '"^ ?"° ^,V „^ 

 conjunctive wires, without any change in the nature "'/'''i J'^"","^ ,;^i ,■;- 

 place; 3d, that the .erond cohpmctivc w,rc may be removed foi anotncr 



Vol.37. No. 273. Jr/«. 1821. V '"-''v-ut, 



