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XVIII. On the supposed Identity of the Agent concerned in the 

 Phenomena of ordinary Electricity, Voltaic Electricity, Electro- 

 magnetism, Magneto-electricity, and Thermo-electricity, By 

 M. DoNOVANj Esq., M.R.I.A. 



[Continued from p. 41.] 



Section VII. 



ONE of the properties supposed in the early period of the 

 history of galvanism to constitute a difference between 

 the voltaic and electric agents, was the great power of the former 

 to cause chemical decomposition, aiid the total inefl&ciency, as 

 was then believed, of the latter. Dr. Wollastou first showed 

 that ordinary electricity could, by pecuhar methods, be made to 

 effect a few decompositions, although with difficulty. Faraday, 

 a few years since, found means to effect decompositions with 

 greater facility, thus removing, as he conceived, one of the chief 

 objections of those who still denied the identity of the two agents. 



It is not necessary to describe Faraday's experiments in detail. 

 His general method was to place paper soaked in a solution of 

 the substance to be acted on between the extremities of two pla- 

 tinum wires, one connected with the positive conductor of an 

 electric machine, through which the current of electricity entered 

 the solution, and the other with a discharging train consisting 

 of the gas-pipes and water-pipes of the street. On passing the 

 electrical curi-ent through the arrangement, he states that the 

 elements arranged themselves round the wire which transmitted, 

 and the wii-e which received the electricity, in the same manner 

 as they would have done if the same substances had been sub- 

 mitted to decomposition by the positive and negative poles of the 

 voltaic battery. This he conceived to be further confimiation 

 of the opinion, that the two kinds of decomposition are produced 

 by the same agent. 



It appears to me that these experiments go just as far to prove 

 difference as identity of the two agents. When a compound 

 body is to be decomposed by a voltaic series, the polar wires are 

 placed in contact with the body ; the results are, that the ele- 

 ments of the compound separate and arrange themselves into 

 two classes, and each class collects round its proper pole. So 

 constant a result is this division of bodies into two great orders, 

 that Berzelius has founded on it a classification of elements into 

 electro-positive and electro-negative. 



Such is the effect of the two polar wires ; but their conjoint 

 effect is indispensable ; I'emove either, and the other is power- 

 less, — the decomposition and all other symptoms of energy cease. 

 The negative wire attracts the more numerous denomination of 

 bodies round it ; but both are equally important. Mr. Gassiot 



