412 
E*'L ECTRICIT Y. 
Jin. The abbe Nollet alfo made feveral experiments 
with this phial. He received a fliock from one, out of 
which tiie air had been exhausted, and into which the end 
of his conductor liad been inferted. He afcribed the force 
of the glafs, in giving a fhock, to that-property of it, by 
which it retains it more ftrongly than conductors do, and 
is not fo eafily diverted of it as they are. It was he alio 
who firrt tried the efleCt of the ele£tric fliock on brute 
animals : and lie enlarged the circuit of its conveyance. 
M. Monnier, it has been faid, was the firrt: who difco- 
vered that the Leyden phial would retain its electricity 
for a confiderable time after it was charged ; and that in 
time of froft he found it continued for thirty-fix hours.. 
It is remarkable too, that both the French and English 
philofophers made feveral experiments, which, with a 
i ma.11 degree of attention, would have led them to the 
diicovery of the different qualities of the electricity on 
the contrary fides of the glafs. But this difcovery was 
referved for the ingenious Dr. Franklin : who, in ex¬ 
plaining the method of charging the Leyden phial, ob- 
ierved, that when one fide of the glafs is eleClrified plus, 
or pofitively, the other fide is electrified minus, or nega¬ 
tively. Dr. Franklin having alfo found that glafs was 
impervious to electricity, and that as the equilibrium 
could not be reftored to the charged phial by any internal 
communication, it muff neceffariiy be done by conductors 
externally joining the infide and the outfide. Tliefe ca¬ 
pital dilcoveries lie made by obferving, that when a phial 
was charged, a cork ball fufpended by filk, was attracted 
by the outfide coating, when it was repelled by a wire 
communicating with the infide, and vic$ verfa. But the 
truth of this principle appeared more evident, when he 
brought the knob of the wire, communicating with the 
outfide coating, within a few inches of the wire commu¬ 
nicating with the infide coating, and fufpended a cork 
ball between them ; for then the ball was attracted by 
them alternately, till the phial was difeharged. 
Dr. Franklin alfo fliewed, that when the phial was 
charged, one fide loft exactly as much as tlw other gained, 
in reftOring the equilibrium. Hanging a fine liriep thread 
near the coating of an eleCtrical phial, he obferved that 
whenever he brought his finger near the wire, the thread 
was attraCled by the coating; for as the eleCtric fluid was 
drawn from the infide by touching the wire, the outfide 
drew in an equal quantity by the thread. He likewile 
proved, that the coating on one fide of a phial received 
juft as much electricity, as was emitted from the difeharge 
of the other, and that in the following manner: — He in¬ 
itiated his rubber, and then hanging a phial to his con¬ 
ductor, he found it could not be charged, even when his 
hand was held conftantly to it; becaufe, though the elec¬ 
tric fluid might leave the outfide of the phial, there was 
none collefled by the rubber to be conveyed to the infide. 
He then took away his* hand from the phial, and forming 
a communication by a wire from the outfide coating to 
the initiated rubber, lie found that it was charged with 
eafe. In this cafe it was plain, that the eleCtric fluid 
which left the outfide coaling, was conveyed to the infide 
by the way of the rubber, the globe, the conductor, and 
the wire of the phial. This new theory of charging the 
Leyden phial, led Dr. Franklin to obferve a greater va¬ 
riety of fa.Cts, relating both to the charging and difeharg- 
ing it, than other philofophers had attended to. And 
this maxim, that it takes in at one furface what it lofes 
at the other, led Dr. Franklin to think of charging feve¬ 
ral phials together with the fame trouble, by connecting 
the outfide of one with the infide of another; by which 
the eleCtric fluid that was driven out of the firrt would 
be received by the fecond, &c. By this means he found, 
that a number of jars might be charged with the fame 
labour as one only ; and on this principle lie firrt con- 
IhuCled an eleCtrical battery. 
When Dr. Franklin firrt began his experiments on the 
Leyden phial, he imagined that the eleCtric fluid was all 
crowded into the fub'ftance of the nou-eleCt'ric, in contact 
with the glafs. But he afterwards found, that its power 
of giving a fliock lay in the glafs itfelf, and not in the 
coating, by the following ingenious analyfis of the phial. 
To find where the ftrength of the charged bottle lay, 
having placed it upon a glafs, he fit 1ft took out the cork 
and the wire ; but not finding the electricity in them, he 
touched the outfide coating with one hand, and put a fin¬ 
ger of the other into the mouth of the bottle ; when ttie 
fhock was felt quite as ftrong as if the cork and wire had 
been in it. He then charged the phial again, and pouring 
out the water into an empty bottle which was in filiated, 
he expeCted that if the force refided in the water, it 
would give the fliock ; but he found it gave none. He 
therefore concluded that the eleCtric fluid muff either 
have been loft in decanting, or niuft remain in the bottle ; 
and the latter he found to be true; for, upon filling the 
charged bottle with frefh water, he found the fhock, and 
was fatisfied that the power of giving it refided in the 
glafs itfelf. The fame experiment was made with panes 
of glafs, laying the coating on lightly, and charging it, as 
the water had been before charged in the bottle, when 
the refult was precifely the fame. 
From this account of Dr. Franklin’s method of analy- 
fing the Leyden phial, the manner of charging and dif¬ 
eharging it will be eafily underftood. Fig. 6, in the Elec¬ 
tricity Plate I. reprefents a Leyden jar, coated with tin- 
foil on the infide and outfide, within three inches of the 
top, having a wire with a round brafs knob at its upper 
extremity. This wire paffes through the cork D, that 
flops the mouth of the jar, and, at its lower end, is bended 
and branched fo as to touch the infide coating in feveral 
places. Thus it is ready to be charged with the elec-, 
trie fluid, and then difeharged at pleafure, by applying a 
difeharger. 
Fig. 7, in the fame engraving, exhibits the form of the 
difeharging rod; which confirts of a glafs handle, and two 
curved wires, which move by a joint C, fixed to the brafs 
cap of the glafs handle. The wires B B are pointed, and 
the points enter the knobs D D, to which they are ferew- 
ed, and may be unferewed from them at pleafure. By 
this conflruction, the balls, or the points, may be ufed 
as occafion requires. The wires being moveable at the 
joint C, may be adapted to fmaller or larger jars at plea¬ 
fure. The method of charging and difeharging is as fol¬ 
lows : place the Leyden jar, prepared as above, near to 
the prime conductor of the eleCtrical machine, fo that 
the knob of the wire in the jar may be in contaCl with 
it; then, upon turning the winch of the machine, the 
index of Henley’s electrometer, which may be previoufly 
affixed to the conductor, will gradually rife as-far as ninety 
degrees nearly, and there reft; which thews that the phial 
has received its full charge ; then, holding the difeharger 
by its glafs handle, and applying one of its knobs to the 
outfide coating of the phial, the other being brought near 
the knob of the wire, or near the prime condu&or which 
communicates with it, a report will be heard, and lumi¬ 
nous fparks will be feen, between the difeharger arid the 
conducting fubrtances communicating with the (ides.of the 
phial ; and by this operation the phial will be difeharged ; 
But, inftead of ufing the difeharger, if a perfon touch 
the outfide of the phial with one hand, and bring the 
other hand near the wire of the phial, the fame fpark and 
report will take place, and a‘fliock will be felt, affeCiing 
the wrifts and elbows, and the bread too when the fliock 
is ftrong : a fliock may alfo be given to any fingle part of 
the body, if that part alone be brought in contact. If a 
number of perfons join hands, and the firrt: of them touch 
the outfide of the phial, while the lart: touches the wire 
communicating with tiie infide, they will all feel the fliock 
at the fame time. If the coated phial be held by the 
wire, and the outfide coating be prefented to the prime 
conductor, it will be charged as readily ; but with this 
difference, that in this cafe the outfide will be pofitive, 
and the infide negative ; alfo if the prime conductor, by 
being connected with the rubber of the machine, be elec¬ 
trified 
