38 Mr. M. Donovan on the supposed Identity of the Agent 



needle." M. Colladon says that the two electricities unite and 

 form a current which " produces" magnetism. Professor Faraday 

 says that electricity and magnetism are " essentially associated." 

 From none of these do we learn the nature of the connexion of 

 the two agents, or the manner in which they reproduce each other. 

 To have entered on this question would at once have led to the 

 disclosure that neutralized electric states or fluids cannot exert 

 any known agency. 



A word has of late years come inta common use, which, while 

 it explains nothing, conceals the solecism contained in the notion 

 of neutralized electricities retaining their respective energies. 

 This word, "the current," has the effect of keeping out of view 

 the counter-current, which is the grand difficulty, because it must 

 antagonize and destroy the current. This modern current cannot 

 have been derived from the old well-ascertained positive and ne- 

 gative currents of frictional electricity ; for these can be seen, 

 felt and understood. But the new current consists of both ; and 

 instead of being rendered powerless, as it was formerly the nature 

 of oppositely electrical currents to be when commingled, it is 

 only in this state of combination that the positive and negative 

 electricities are said to be capable of exerting peculiar powers. 

 The current seems to have been modified to meet the exigences 

 of recently discovered phsenomena ; but in its new acceptation, it 

 no longer harmonizes with those from which our knowledge of 

 the tnie current was derived. 



The current being now used in the explanation of every voltaic 

 fact, and its meaning not well-defined, it is important to discover 

 what is really intended to be conveyed by the term. Professor 

 Faraday says " it is a most important part of the character of 

 the current, and essentially connected with its very nature, that 

 it is always the same. The two forces are everywhere in it. 

 Any one part of the current, may, as respects the presence of the 

 two forces there, be considered as precisely the same with any 

 other part. It appears to me to be as impossible to assume a 

 current of negative force alone, or of two at once with any pre- 

 dominance of one over the other, as to give an absolute charge to 

 matter*." He explains that " a current is produced both by 

 excitement and discharge." "Excitement may occur in many 

 ways, as by friction, chemical action," &c.t We are therefore 

 to understand that these observations are applied to the streams 

 of electricity which pass from the conductors of an electrical 

 machine, as well as to the currents from the poles of a voltaic 

 series. The currents being in both cases, as is stated, always the 

 same, and in eveiy part the same, and the two forces everywhere 

 present in it, it is to be inquired what is the nature of the stream 

 * Researches, p. 618. t Ibid. p. 615. 



