172 On the Excitement of Voltaic Plates, 



cxperimeuts, and without giving the grounds for his opinion, 

 contends that the action of the pile does not depend on a sepa- 

 ration of tlie binary groups of metals ijy a liquid or wet body, 

 but requires only that the separation be produced '*' by the best 

 non-metallic conducting substance." He thinks that in writing- 

 pafjer he lias found such a substance: but let me remind him 

 that ail paper attracts moisture very powerfulh', that it is ex- 

 tremely diflicuit to deprive it entirely of moisture, and that, when 

 it has been perfectly dried, it very soon reacquires moisture. 

 Ti!U3 in an experiment (mentioned by Mr. De Luc) in which the 

 paper had been completely dried, the pile did not even affect 

 the electrometer, until during the time occupied in carrying it 

 from one room to anotlier it acquired some degree of moisture : 

 it then affected the electrometer in a very slight degree. In 

 fact, I believe it might be stated, that whatever conducting power 

 paper mav possess, is dependent on the moisture it contains. 

 Thiis in every instance of excitement, moisture {tlie decomposalle 

 JhiJd) has been present : and from this view of the subject, I am 

 somewhat inclined to think that the spontaneous electric column 

 might be employed for hygroscopic purposes. 



i would wish, sir, your philosophical readers to ascertain the 

 legitimacy of the inferences I have talcen the liberty to draw 

 irnm the experiments contained in Mr. De Luc's analysis of the 

 Galvanic pile, and to declare whether tliere are any facts dedu- 

 cible from those experiments, which tend to show a necessity 

 for tv/o metallic surfaces to be in contact to produce excitement; 

 I'.hetlier the facts do not establish a contrary opinion ; and 

 whether the results of all his experiments do not tend to prove, 

 that " the Galvanic apparatus can onlv be excited by a decom- 

 posable fluid." Nevertheless, iVIr. De Luc states the elementary 

 principles of the pile to be as follows : 



1. "In each binary group the zinc plate takes some electri: 

 fluid from its associate the copper." 



2. " In each gronjj also the z-iuc plate communicates through 

 the paper some of its excess of the electric fluid lo ihe copper of the 

 next group on its side." 



The first position is in direct opposition to my experiments ; 

 the second, M. DeLuc draws from his tliirty-fourth experiment: 

 vet, as far as I cui understand it, that experiment simply proves, 

 that, the pile being excited, an insulated conductor will convey 

 the charge of either extremity to the electrometer. 

 [To be continued.] 



XXXVII. On 



