Experiments and Observations Tending to Illustrate the Nature and Properties of Electricity: In One Letter to Martin Folkes, Esq; President, and Two to the Royal SocietyWatson, William, Sir
History
Experiments and Observations Tending to Illustrate the Nature and Properties of Electricity: In One Letter to Martin Folkes, Esq; President, and Two to the Royal Society
Watson, William, Sir
Electricity -- Early works to 1850
IF an electrical Cake is dipp'd in Water, it is thereby made a Conductor
of Electricity, the Water hanging about it transmitting the electrical
Effluvia in such a manner, that a Person standing thereon can by no
means be electrified enough to attract the leaf Gold at the smallest
Distance; though the Person standing upon the same Cake when dry,
attracted a Piece of fine Thread hanging at the Distance of two Feet
from his Finger. We must here observe that the Cake being of an unctuous
Substance, the Water will no where lie uniformly thereon, but adhere in
separate Moleculæ; so that in this Instance the Electricity jumps from
one Particle of Water to another, till the Whole is dissipated.
FROM the Appearance of the Threads amongst which I rub the Tube, I can
frequently judge, though the Spirit may be many Feet distant from them,
whether or no it will fire; because when the Persons standing upon the
Wax are made electrical enough to fire the Spirit, the Threads repel
each other at their lower Parts, where they are not confin'd, to a
considerable Distance, and this Distance is in Proportion as the Threads
are made electrical.
IF two Persons stand upon electrical Cakes at about a Yard's Distance
from each other, one of which Persons, for the Sake of Distinction, we
will call A, the other B: If A when electrified touches B, A loses
almost all his Electricity at that Touch only, which is receiv'd by B
and stopp'd by the electrical Cake; if A is immediately electrified
again to the same Degree as before and touches B, the Snapping is less
upon the Touch; and this Snapping, upon electrifying A, grows less and
less, till B being impregnated with Electricity, though receiv'd at
Intervals, the Snapping will no longer be sensible.
THAT Glass will repel and not conduct the Electricity of Glass, has been
mention'd by others, who have treated of this Subject; but the
Experiments to determine this Matter must be conducted with a great deal
of Caution; for unless the glass Tube, intended to conduct the
Electricity, be as warm as the external Air, it will seem to prove the
contrary, unless in very dry Places and Seasons. Thus, I sometimes have
brought a cold, though dry, Glass Tube near three Feet long into a Room,
where there has been a Number of People; when upon placing the Tube upon
Silk Lines, and laying some Leaf Silver upon a Card at one End and
rubbing another Glass Tube at the other, the Silver has, contrary to
Expectation, been thrown off as readily as from an Iron Rod. At first I
was surpriz'd at this Appearance, but then conjectur'd, that it must
arise from the Coldness of the Glass, condensing the floating Vapour of
the Room; in Order then to obviate this, I warm'd the Tube sufficiently,
and this Effect was no longer produced, but the Silver lay perfectly
still.
Public-domain text, read in full here on John Shaqi.
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