The Sun.
London, England, 1858-01-01 00:00:00

ROYAL INSTITUTION.

Professor Faraday delivered the second of his
course of lectures on electricity to a juvenile
audience, yesterday afternoon, at the Royal Insti-
tution. The branch of the subject to which he
directed attention was the consideration of the
consideration of the characters of the elects ia force.
He commenced by showing experimentally that
electricity repels as well as attracts, and that when
a :light substance has had a charge of electricity
imparted to it by contact with an excited glass rod,
it is afterwards repelled by the glass instead of
being attracted, and that it continues to fly from
the glass until it has touched some other body, and
thus been deprived of its electricity. He then
showed that a substance repelled by an excited
glass rod is attracted by sealing wax, gutta perdu'',
or sulpur, when excited. These different actions
of electric force were illustrated by a variety of ex-
pel intents, in which Professor Faraday made use
of severe ltoys as parts of his apparatus. The ex-
periment that gave most pleasure to the younger
pin of the audience wart one with the figure of a
fishwoman with a basket containing a number of
paper fish upon her head, which flew away in all
directions when she was placed on an insulated
stand and electrified. The opposite actions of the
force produced by the friction of glass, and of that
exerted by the friction of sealing wax, proved that
there are two kinds of electricity, each of which
attracts the other, but repels itself ; and Professor
Faraday showed that they have the power of
apparently annihilating each other. Thus, for ex-
ample, two lam. metallic balls were suspended
separately by silk strings to insulate them, and one
was elect rifit d negatively by touching it with the
coating of a Leyden jar, and the other was charged
positively from the knob. When either ball was
brought separately near the electrometer the gold
leaves diverged, indicating that both were electrical ;
but, after the balls had been brought into contact,
no trace of electricity was perceptible. Another
experiment, still more striking, was the following :
A small flannel cup was fitted on to the top of a
shell-lac, and the rod was twisted round in it
whilst held tight. By this action a quantity of
electricity was genet ated, but so long as the cup
remained on the rod there was no indication of its
presence ; the instant, however, that the cup was
withdrawn, both the flannel and the shell-lac acted
strongly on the gold leaves. On being placed to-
gether again their combined effect completely
neutralised each other, and the gold leaves remained
unaffected. Professor Faraday said there could be
no doubt, from these opposite manifestations of
force, that the electricities in the flannel and in the
shell-lac were different, and should call them the
the two electricities. At one time he was of
opinion there might be an intermediate electric
condition, but his investigations had tended to show
that there are only two. Notwithstanding the
the different character of the electricity generated
by glass from that generated by shell-lae, yet the
same substance may, under different conditions pro-
duce the opposite electricities. This fact was illus-
trated by a remarkable experiment, the rationate
of which is not yet understood. The gold leaves
of the electrometer having been made to diverge
with positive electricity by the friction of a glass
rod, the same rod was heated in the flame of spirits,
and when again subbed three or four times, its ap-
proach to the electrometer made the gold leaves
collapse, proving that it had become negatively
electrified ; but, after leaving been briskly rubbed
its original losition was restored, and the gold
leaves diverged still farther as it was brought near
them. Professor Faraday said that it might be
thought strange that he should thus bring before
the notice of his juvenile audience an experiment
which he could not himself understand, but he
thought it desirable that they should know there
are phenomena in electricity the elucidation of
which is yet to be accomplished, and that they were
all philosophers working together for the discovery
of truth.