88 DR. FARADAY'S EXPERIMENTAL RESEARCHES IN ELECTRICITY. (SERIES XII.) 



hibiting the same effects in consequence of the action of the same causes, the only 

 variation being one of degree in the different substances employed. 



1333. Judging on these principles, velocity of discharge through the same wire 

 may be varied greatly by attending to the circumstances which cause variations of 

 discharge through spermaceti or sulphur. Thus, for instance, it must vary with the 

 tension or intensity of the first urging force (1234. 1240.), which tension is charge 

 and induction. So if the two ends of the wire, in Professor Wheatstone's experi- 

 ment, were immediately connected with two large insulated metallic surfaces exposed 

 to the air, so that the primary act of induction, after making the contact for dis- 

 charge, might be in part removed from the internal portion of the wire at the first 

 instant, and disposed for the moment on its surface jointly with the air and sur- 

 rounding conductors, then I venture to anticipate that the middle spark would be 

 more retarded than before ; and if these two plates were the inner and outer coating 

 of a large jar or a Leyden battery, then the retardation of that spark would be still 

 greater. 



1334. Cavendish was perhaps the first to show distinctly that discharge was not 

 always by one channel*, but, if several are present, by many at once. We may make 

 these different channels of different bodies, and by proportioning their thicknesses 

 and lengths, may include such substances as air, lac, spermaceti, water, protoxide of 

 iron, iron and silver, and by one discharge make each convey its proportion of the 

 electric force. Perhaps the air ought to be excepted, as its discharge by conduction 

 is questionable at present ; but the others may all be limited in their mode of dis- 

 charge to pure conduction. Yet several of them suffer previous induction, precisely 

 like the induction through the air, it being a necessary preliminary to their dis- 

 charging action. How can we therefore separate any one of these bodies from the 

 others, as to the principles and mode of insulating and conducting, except by mere 

 degree? All seem to me to be dielectrics acting alike, and under the same common 

 laws. 



1335. I might draw another argument in favour of the general sameness, in nature 

 and action, of good and bad conductors (and all the bodies I refer to are conductors 

 more or less), from the perfect equipoise in action of very different bodies when op- 

 posed to each other in magneto-electric inductive action, as formerly described (213.), 

 but am anxious to be as brief as is consistent with the clear examination of the pro- 

 bable truth of my views. 



1336. With regard to the possession by the gases of any conducting power of the 

 simple kind now under consideration, the question is a very difficult one to determine 

 at present. Experiments seem to indicate that they do insulate certain low degrees 

 of tension perfectly, and that the effects which may have appeared to be occasioned 

 by conduction have been the result of the carrying power of the charged particles, 



* Philosophical Transactions, 1776, p. 197. 



