406 M. P. Riess on the Action of Non-conducting Bodies 



Diameter of metallic discs 4*46 inches. 

 Distance asunder . . . 1 # 65 



The majority of these experiments, therefore, confirm Fara- 

 day's statement, that by placing an insulating plate between a 

 charged and a neutral metallic disc, the induced electricity upon 

 the latter is increased. That this increase, however, is not an 

 essential property of the insulator is shown by the two expe- 

 riments with the mica plate, and the glass plate S, both of 

 which caused a diminution in the induced electricity, although 

 they are by no means inferior to gutta-percha in their insulating 

 capacities. Further, that this increase is not exclusively pro- 

 duced by insulating substances is proved by the following expe- 

 riments, in which, by employing perfectly conducting interme- 

 diate plates fixed to insulating pillars, the same phsenomenon is 

 apparent. 



It is manifest that with metals the difference between the 

 actions of two plates is solely due to their dimensions, so that 

 none of these results can appear strange. When both discs 

 stand alone, the neutral one is acted upon by a stratum of posi- 

 tive electricity l - 65 inch distant. By the interposition of a con- 

 ducting plate, two electric strata at a smaller distance are super- 

 added, of which the positive stratum lies nearer to the excited 

 disc than the negative. Both strata contain the same quantity 

 of electricity; but the distribution of these quantities in the strata 

 depends not only upon the dimensions and distance between the 

 * Commercial paraffine from the Augustinhutte, Bonn. 



