214 Mr. J. Prideaux on the 'Theory of Voltaic Action. 



difficult conduction, as platinum ; connecting the other end 

 with the ground, through an imperfect conductor, as hot glass, 

 or the finger*. 



6. Though these observations leave unanswered many of the 

 objections to the identity of voltaic and common electricity, 

 those objections do not seem to me sufficient, after the striking 

 experiment of Dr. Wollastonf, to establish any other distinc- 

 tion between them than difference of tension ; nor will any 

 other distinction be considered, in the following pages, between 

 the electrical and chemical effects of the pile. Tension is even 

 well known to expedite and facilitate the decomposition of water 

 and salts by the voltaic current. 



Sect. II. Of the received Voltaic Theories, 



7. The insufficiency of the theory adopted by the acute 

 philosopher, whose name stands for ever enshrined in this 

 branch of electrical science ; by which the action of the pile 

 was referred solely to the electromotive force of the metals; 

 that is, its inadequacy to account, without noticing the decom- 

 position of the charge, for the copious flood of electricity which 

 distinguishes its operation, — was early perceived. And it has 

 since been shown by experiment, varied in a multitude of 

 ways, that decided electrical action may be produced by two 

 pieces of the same metal, in the same fluid (40, 41, 45) ; and 

 that the efficacy of the liquid charge depends more on its fa- 

 cility of decomposition than on its conducting power. 



8. To Dr. Wollaston is generally attributed another theory, 

 which imputes the effects of the pile to decomposition of the 

 liquid charge, and its chemical action on the zinc. He has 

 been followed by Professor De la Reve, of Geneva, who goes 

 further than Wollaston probably ever intended to do, attri- 

 buting the effects entirely to the chemical action; and dis- 

 puting the validity even of Volta's leading experiment, the 

 production of electricity by contact of zinc and copper f. But 

 the electromotive effects of the metals are established by nume- 



* Becquerel, Ann. de Chim. et de Phys. for August 1829. 



t Dr. Wollaston's experiment here alluded to, is that in which copper 

 was deposited on the negative wire, and redissolved, by reversing the con- 

 nexion. A gross analogy with voltaic decomposition may he also noticed 

 in an experiment where the difficulty of Obtaining continuity in common 

 electricity is obviated: — 



Pass a negative ball over the face of a cake of resin, in fanciful lines of 

 any kind, and a positive ball over the tame face in other lines. Dust the 

 plate with a mixture of powdered sulphur and red lead. The powders will 

 separate according to their electrical character, and mark out the lines 

 described by the respective electricities, in red and yellow. 



* Ann. dc Chim. ct de Lhys. for November lS^fc. 



