176 Mr. Goodman on the Cause of Dissimilarity in the 



Before proceeding, I may name to you that Dr. Faraday 

 states, in his Experimental Researches in Electricity (1177), 

 that *' it is impossible experimentally to charge a portion of 

 matter with one electric force independently of the other;" 

 (1684) that "the terms free charge and dissimulated electricity 

 convey erroneous notions, if they are meant to imply any dif- 

 ference as to the mode or kind of action." " The charge upon 

 an insulated conductor in the middle of a room is in the same 

 relation to the walls of that room as the charge upon the inner 

 coating of a Leyden jar is to the outer coating of the same jar." 

 "The one is not more free or more dissimulated than the 

 other;" and (1170) " as yet no means of communicating elec- 

 tricity to a conductor, so as to place its particles in relation to 

 one electricity, and not at the same time to the other in exactly 

 equal amount, has been discovered." 



In illustration of the two electrical states, let a metallic plate 

 A B, very smooth and with rounded edges, &c, supported by 



A C 



the insulating stand F, to which the pith -balls are attached 

 by the arm E, be charged with fluid from the prime conductor 

 of the electrical machine. The pith-balls will, as usual, di- 

 verge to a considerable extent. In order to prevent the trans- 

 mission of the charge through the atmosphere, the glass plate 

 U may be placed immediately in front of A B. Now bring 

 near the insulated metallic plate C D, or the metallic disc of 

 the condensing electrometer; and as the insulated plate ap- 

 proaches, the pith-balls or gold leaves of the electroscope will 

 be seen to collapse, until, when it has arrived at a given di- 

 stance, the former will be found in perfect apposition. Mark 

 also that before the approach of C D sparks of considerable 

 magnitude, equal to those from the machine itself, might be 

 obtained from the electrolyzed plate A B ; but when C D 



