Experiments and Observations on Electricity Made at Philadelphia in America

By Benjamin Franklin

Page 47

from the mutual repulsion of its particles,
tends to dissipation, and would immediately dissipate _in vacuo_.--And thus
the experiment of the feather inclosed in a glass vessel hermetically
sealed, but moving on the approach of the rubbed tube, is explained: When
an additional quantity of the electrical fluid is applied to the side of
the vessel by the atmosphere of the tube, a quantity is repelled and driven
out of the inner surface of that side into the vessel, and there affects
the feather, returning again into its pores, when the tube with its
atmosphere is withdrawn; not that the particles of that atmosphere did
themselves pass through the glass to the feather.----And every other
appearance I have yet seen, in which glass and electricity are concern'd,
are, I think, explain'd with equal ease by the same hypothesis. Yet,
perhaps, it may not be a true one, and I shall be obliged to him that
affords me a better.

35. Thus I take the difference between non electrics and glass, an electric
_per se_, to consist in these two particulars. 1st, That a non-electric
easily suffers a change in the quantity of the electrical fluid it
contains. You may lessen its whole quantity by drawing out a part, which
the whole body will again resume; but of glass you can only lessen the
quantity contain'd in one of its surfaces; and not that, but by supplying
an equal quantity at the same time to the other surface; so that the whole
glass may always have the same quantity in the two surfaces, their two
different quantities being added together. And this can only be done in
glass that is thin; beyond a certain thickness we have yet no power that
can make this change. And, 2dly, that the electrical fire freely removes
from place to place, in and through the substance of a non-electric, but
not so through the substance of glass. If you offer a quantity to one end
of a long rod of metal, it receives it, and when it enters, every particle
that was before in the rod, pushes its neighbour quite to the further end,
where the overplus is discharg'd; and this instantaneously where the rod is
part of the circle in the experiment of the shock. But glass, from the
smallness of its pores, or stronger attraction of what it contains, refuses
to admit so free a motion; a glass rod will not conduct a shock, nor will
the thinnest glass suffer any particle entring one of its surfaces to pass
thro' to the other.

36. Hence we see the

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Text Comparison with Experiments and Observations on Electricity Made at Philadelphia in America

Page 0
CAVE, at _St.
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_Muschenbroek_'s wonderful bottle.
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EXPERIMENT XI.
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By candle light, even tho' the candle is at a foot distance: these do it suddenly.
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_A_, who stands on wax and rubs the tube collects the electrical fire from himself into the glass; and his communication with the common stock being cut off by the wax, his body is not again immediately supply'd.
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[Illustration] LETTER III.
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See s.
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Then taking the bottle in one hand, and bringing a finger of the other near its mouth, a strong spark came from the water, and the shock was as violent as if the wire had remained in it, which shewed that the force did not lie in the wire.
Page 16
I perceive by the ingenious Mr _Watson_'s last book, lately received, that Dr _Bevis_ had used, before we had, panes of glass to give a shock; though, till that book came to hand, I thought to have communicated it to you as a novelty.
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25.
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CONTAINING OBSERVATIONS _and_ SUPPOSITIONS, _towards forming a new_ HYPOTHESIS, _for explaining the several_ Phaenomena _of_ THUNDER-GUSTS.
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It is then plainly visible in the night; it appears at the stern and in the wake of every sailing vessel; every dash of an oar shows it, and every surff and spray: in storms the whole sea seems on fire.
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But easiest of all between L, C, M, where the quantity is largest, and the surface to attract and keep it back the least.
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10 the upper corner.
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It is this: place the bottle on a glass stand, under the prime conductor; suspend a bullet by a chain from the prime conductor, till it comes within a quarter of an inch right over the wire of the bottle; place your knuckle on the glass stand, at just the same distance from the coating of the bottle, as the bullet is from its wire.
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The particles of the electrical fluid have a mutual repellency, but by the power of attraction in the glass they are condensed or forced nearer to each other.
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Let us now see how it will account for several other appearances.
Page 47
You may lessen its whole quantity by drawing out a part, which the whole body will again resume; but of glass you can only lessen the quantity contain'd in one of its surfaces; and not that, but by supplying an equal quantity at the same time to the other surface; so that the whole glass may always have the same quantity in the two surfaces, their two different quantities being added together.
Page 50
For the globe then draws the electrical fire out of the outside surface of the phial, and forces it, through the prime conductor and wire of the phial, into the inside surface.
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II.