2-12 HISTORY OF GALVANISM. 



was not completed till light had been thrown upon it from othei 

 quarters. The identity of galvanism with electricity, for instance, was 

 at first, as we have intimated, rather conjectured than proved. It 

 was denied by Dr. Fowler, in 1793 ; was supposed to be confirmed by 

 Dr. "Wells two years later ; but was, still later, questioned by Davy, 

 The nature of the operation of the pile was variously conceived. 

 Volta himself had obtained a view of it which succeeding researches 

 confirmed, when he asserted, 6 in 1800, that it resembled an electric 

 battery feebly charged and constantly renewing its charge. In pur- 

 suance of this view, the common electrical action was, at a later 

 period (for instance by Ampere, in 1820), called electrical tension, 

 while the voltaic action was called the electrical current, or electro- 

 motive action. The different effects produced, by increasing the size 

 and the number of the plates in the voltaic trough, were also very 

 remarkable. The power of producing heat was found to depend on 

 the size of the plates; the power of producing chemical changes, on 

 the other hancl, was augmented by the number of plates of which 

 the battery consisted. The former effect was referred to the increased 

 quantity, the latter to the intensity, of the electric fluid. We men- 

 tion these distinctions at present, rather for the purpose of explaining 

 the language in which the results of the succeeding investigations are 

 narrated, than with the intention of representing the hypotheses and 

 measures which they imply, as clearly established, at the period of 

 which we speak. For that purpose new discoveries were requisite, 

 which we have soon to relate. 



CHAPTER III. 



DISCOVERT or THE LAWS OF THE MUTUAL ATTRACTION AND REPUL- 

 SION OF VOLTAIC CURRENTS. AMPERE. 



IX order to show the place of voltaic electricity among the mechanico- 

 chemical sciences, we must speak of its mechanical laws as separate 

 from the laws of electro-magnetic action ; although, in fact, it was only 

 in consequence of the forces which conducting voltaic wires exert upon 

 magnets, that those forces were detected which they exert upon each 



Phil. Trans, p. 403. 



