224 Kiruanian Society/ of Dublin. 



Attempts were made by Dr. WoUaston to reconcile the con- 

 tending hypotheses of Fabroiii and Volta : with the latter, he 

 supposes electricity to be the agent ;' but, with the former, he 

 considers chemical action to be the exciter, and extends oxida- 

 tion to the explanation of every case of electrical excitement. 

 Davy showed that oxidation was not the sole exciter, for sul- 

 phuration produced Galvanic appearances : this had been before 

 shown !n' Volta. The identity of Galvanism and electricity was 

 attempted to be ]3roved by Van Marum and I'faff, by comparing 

 the effects of the pile with, the common electric machine : they 

 concluded that oxidation was unnecessary. Biot, Cuvier, and 

 Desormcs jiroved that oxygen is absorbed by the pile in action. 

 l?ostock admitted that oxygen is necessary to the evolution of 

 electricitv in the pib, and conceived that iivdrogen is essential 

 to its conveyance, a combination taking place between both. 

 CiithbertsGii considered the production of electricity as depend- 

 ing on the metals in contact, and on the chemical action. Al- 

 dini and Lagrave showed that neither metallic contact nor che- 

 mical action on metals was necessary, by producing Galvanic 

 effects with different kinds of animal matter only ; and Jordan 

 and Flitter conceived that Galvanic aviangements could be 

 effected with n^agncts. Tliis period of the history concluded 

 v/ith the labours of Dr. Wilkinson. 



March 22. — Period III. The tliird period of the history of 

 Galvanism commenced with the well knovv'n generalizatio.is of 

 Hisingcr and jierzelius ; their experiments on the invisible trans- 

 fer of elements to a distance; and the explanation given by 

 Grotthus of the invisible transfer of the elements of water. The 

 announced decomposition of muriatic acid by Peele, Pacchioni 

 and others, was then detailed, and the discovery of the source 

 of mistake by the Galvanic Society, Pfaff, Biot, Thenard, and 

 Davy. Mr. Sylvester's well supported opinion, that the preci- 

 pitation of one metal by another is a Galvanic i)haenomenon, and 

 ills explanation of it, which was afterwards enlarged on by Grot- 

 thus, was the :i stated. Mr. Wilson's experiments with metallic 

 filings were conceived very much to weaken the grounds of the 

 Vokaic hypothesis, which supposed the electricity to be evolved 

 bv contact : Mr. Wilson showed that separation alone produces 

 electricity: on the other hand, the Voltaic liypothesis acquired 

 new probability from tlic experiments of Mr. Erhman, in which 

 it •was proved that Galvanism and electricity are conducted Jjy 

 the same bodies, and that the supposed anomaly arose from not 

 ^heing acquainted with a v.ew class of conductors, which are such 

 to one pole only of the ipile. The grand discoveriGS of Davy re- 

 lating to the alkaline metals, and of Berzclius, Pontin, and Davy 

 with regard to the earthy metal--, were det;ulcd ; also the pro- 



ductioii 



