of Elevtricilij, 111 



to ihc inside; whence it follows, that while the outside has 

 ■ too little, the inside has too much. Why so ? Because the 

 glass is impermeable. How is that proved ? Because in 

 the experiment abov^e recited the liuld is accumulated on 

 one side, while it is abstracted on the other. It is evident 

 that under this representation every argument returns into 

 itsell-", and is merely a play upon terms. I shall however 

 endeavour to show that this statement is neither pcrt'cctly 

 candid nor correct, and that the opinion alluded to is sup- 

 ported by more probal^ility than these objectors are willino' 

 to admit. 



In many instances we can form conclusions only from 

 the efiects. If two basons separated by a mound were iilled 

 with water, the pressure on all sides being equal, the mound 

 would be likely to maintain its situation. If we suppose, 

 one Hill and the other empty, with a slight communieatioa. 

 between them, the effort to restore the level would endanoer 

 the safety of the mound ; and if such mound were destroyed, 

 we should instantly conclude that it was occasioned by aii 

 accumulation of water on one side and a deliciency on th^ 

 other. May we not extend the aiialogy to the electric fluid? 

 It becomes visible only by the air's resistance to its passage; 

 axid it its effects are similar to those of water, may we liot 

 impute it to the same cause ? By the impervious nature of 

 those substances called electrics we are enabled to produce 

 a cliange, which by effects similar to those above alluded to 

 induces the conclusion, that they arc occasioned by an ac- 

 cuumlation of the fluid on one side, and its subsequent ef- 

 forts to restore an equilibrium. If the fluid as it entered 

 on one side passed through to the other, no change could 

 be effected in iIk.- glass : if the glass plate be too tliin, and 

 tlic charge too high, the fluid will force a passafc, leaving 

 it small hole or bur in the glass, sometimes cracklno- th^ 

 phjal all round, and in either case incapacitating it from 

 receiving another charge. It is singular, in the use of resin 

 asaeeuient to unite the coating and the glass, the phial 

 wiU not receive the least charge without forcnig such a pas^ 

 «iigc. 



The easy solution of the phaenomena of the Leyden phiai 

 on the Franklinian hypothesis has materially contributed to 

 ilrf reputation. Dr. Franklin proved cxperimentiilly that 

 when a plual is charged, one side has lost exactly wliat the 

 other has acquired ; taking a charged phial, he observed, that 

 when he aflbrded the fluid on the positive side an oppor- 

 tunity to escape, the other side became disposed lo receive, 

 aijd would iUtract anv light, body : bv insulating his rubby 

 ■^ '■ he 



