_The prime conductor not being electrified, bring the excited tube
under the tassel, and the threads will diverge._
Part of their natural quantity is thereby driven out of them into the
prime conductor, and they become negatively electrised, and therefore
repel each other.
_Keeping the tube in the same place with one hand, attempt to touch
the threads with the finger of the other hand, and they will recede
from the finger._
Because the finger being plunged into the atmosphere of the glass
tube, as well as the threads, part of its natural quantity is
driven back through the hand and body, by that atmosphere, and the
finger becomes, as well as the threads, negatively electrised,
and so repels, and is repelled by them. To confirm this, hold a
slender light lock of cotton, two or three inches long, near a
prime conductor, that is electrified by a glass globe, or tube. You
will see the cotton stretch itself out towards the prime conductor.
Attempt to touch it with the finger of the other hand, and it will be
repelled by the finger. Approach it with a positively charged wire of
a bottle, and it will fly to the wire. Bring it near a negatively
charged wire of a bottle, it will recede from that wire in the same
manner that it did from the finger; which demonstrates the finger to
be negatively electrised, as well as the lock of cotton so situated.
_Turkey killed by Electricity_.--_Effect of a Shock on the Operator
in making the Experiment._
As Mr. Franklin, in a former letter to Mr. Collinson, mentioned his
intending to try the power of a very strong electrical shock upon a
turkey, that gentleman accordingly has been so very obliging as to
send an account of it, which is to the following purpose.
He made first several experiments on fowls, and found, that two
large thin glass jars gilt, holding each about six gallons, were
sufficient, when fully charged, to kill common hens outright; but
the turkeys, though thrown into violent convulsions, and then lying
as dead for some minutes, would recover in less than a quarter of
an hour. However, having added three other such to the former two,
though not fully charged, he killed a turkey of about ten pounds
weight, and believes that they would have killed a much larger. He
conceited, as himself says, that the birds killed in this manner eat
uncommonly tender.
In making these experiments, he found, that a man could, without
great detriment, bear a much greater shock than he had imagined: for
he inadvertently received the stroke of two of these jars through his
arms and body, when they were very near fully charged. It seemed
to him an universal blow throughout the body from head to foot, and
was followed by a violent quick trembling in the trunk, which went
off gradually, in a few seconds. It was some minutes before he could
recollect his thoughts, so as to know what was the matter; for he
did not see the flash, though his eye was on the spot of the prime
conductor, from whence it struck the back of his hand; nor did he
hear the crack, though the by-standers said it was a loud one; nor
did he particularly feel the stroke on his hand, though he afterwards
found it had raised a swelling there, of the bigness of half a
pistol-bullet. His arms and the back of the neck felt somewhat numbed
the remainder of the evening, and his breast was sore for a week
after as if it had been bruised. From this experiment may be seen the
danger, even under the greatest caution, to the operator, when making
these experiments with large jars; for it is not to be doubted, but
several of these fully charged would as certainly, by increasing
them, in proportion to the size, kill a man, as they before did a
turkey.
_N. B._ The original of this letter, which was read at the Royal
Society, has been mislaid.