Kirwanlan Socieli/ of Dnl'l'm. .^OO 



Waving the objections to this part of the hypothesis, a trial 

 was made how far the phaenomena of gah-anism are explained 

 by the principle in question, supposing- it true. A series of ar- 

 guments were adduced, tending to show that the increasing po- 

 sitive and negative states of the pile towards the top and bot- 

 tom are not made necessary, but rather counterindicated by the 

 hypothesis : and that contact with both ends of the pile ought not 

 to be necessary in order to receive the shock. Experiments 

 made with a pile of a thousand plates of highly polished zinc 

 and copper plates were detailed, the results of which Avere con- 

 sidered to prove that the electric states of the extremities are 

 ver^ different from what has been supposed by Volta and others. 

 The effect of the saline solution interposed in the pile was 

 shown to have little relation to its conducting power, and the 

 efficacy of oxidation of the plates, a? supposed by Volta, was 

 considered highly improbable : but tliis ))art of the subject was 

 deferred for a future discussion. 



II. Examination of the hypothesis of Fabroni. — This hypo- 

 thesis is directly opposed to that of Volta : in the latter, electri- 

 city is supposed to be the cause, and tlie chemical phsenomena 

 no more than effects : in the former, the chemical action is con- 

 ceived to be the cause, and the electrical appearances are con- 

 sidered effects. That t!ic effects called galvanic are always pro- 

 duced in consequence of chemical action, and never else, the 

 author conceived to be a true proposition in its fullest extent; 

 and experiments to prove thatthere is not one militating instance, 

 had been already laid before the Society in the statement of a 

 new theory of galvanism. Tlie other principles of Fabroni's 

 hypothesis it was considered uimecessary minutely to investigate, - 

 as several facts and arguments adduced were plainly irreconcile- 

 able to them. The cou^deration of the main proposition of 

 tliis hypothesis, it was observed, came under discussion in a more 

 advanced period of the essay. 



III. Examination of the medium hypothesis adopted by the 

 British philosophers. — Drs. WoUaston and Eostock were the first 

 who attempted to reconcile the two preceding hypotheses: with 

 Volta they considered electricity the agent, but with Fabroni 

 supposed tliat this electricity was evolved in consequence of che- 

 mical action. Sir H. Davy proposed a further modification. 

 lie conceives with Volta, that the contact of the metals is the 

 primary exciting cause of the evolved electricity; that electricity 

 is the agent in galvanic phasnomena ; but with Fabroni he al- 

 lows that chemical changes are essential to the coritinued action 

 of the pile. The disturbance of the equilibrium by contau't, it 

 was observed, lies in this hypothesis under the same ol>jections 

 as in that of Volta. The exaltation of the two states of clectri- 



U 3 city 



