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Leyden vial, fuppoiing both communications to be 
made by canals of the lame length and fame kind. 
It appears plainly from the experiments which have 
been made on this fubjedl:, that the eledlric fluid is not 
able to pafs through the glafs ; but yet *it feerns 
as it it was able to penetrate without much diffi- 
culty to a certain Imall depth, perhaps I might fay 
an imperceptible depth within the glafs ; as Dr. 
Franklin’s analylis of the Leyden vial Ihews'that its 
eledlricity is contained chiefly in the glafs itfelf, and 
that the coating is not greatly over or undercharged. 
It is well known that glals is not the only fub- 
flance which can be charged in the manner of the 
Leyden vial ; but that the fame effedl may be pro- 
duced by any other body, w'hich will not fufler 
the eledtricity to pals through it. 
* Hence the pheenomena of the vial feem eafily 
explicable by means of the 2 2d propofltion. For 
let ACGM, fig. 20, reprefent a flat plate of glafs 
or any other fubftance which wnll not fufler the 
‘elefiric fluid to pafs through it, feen edgeways ; and 
let and ^efF, or B and as I ffiall 
call them for ffiortnefs, be two plates of condudl- 
ing matter of the fame fize, placed in contact with 
the glafs oppolite to each other ; and let be po- 
fitively eledrifled ; and let F.f communicate witli 
the ground; and let the fluid be fuppofed either 
* The following exp'icalion is ft: icily applicable only to that 
fort of J.eyden vial, wliicli confifts of a flac plate of glafs or 
othrr matter. It is eviJent, however, that the refuli niuft be 
nearly of the fame kind, though the glafs is made into the lhape 
cf a bottle as ufual, or into any other f >ini: hut I propofe to 
confiticr thofe fort of Leyden vials more parikularl) m a future 
paper. 
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