We had for some time been of opinion that the electrical fire was not created by friction, but collected, being really an element.
Continuing Benjamin Franklin Experiments With Electricity,
the name of our selection from The Complete Works of Benjamin Franklin; Including His Private as Well as His Official and Scientific Correspondence, and Numerous Letters and Documents Now for the First Time Printed, With Many Others not Included in any Former Collection, Also, the Unmutilated and Correct Version of His Autobiography by John Bigelow (edited) and by Benjamin Franklin published in 1887. The selection is presented in a series of installments for 5 minute daily reading. For works benefiting from the latest research see the “More information” section at the bottom of these pages.
Previously in Benjamin Franklin Experiments With Electricity.
Time: July 11, 1747
[Franklin’s letter continues. – JL]
“The repellency between the cork ball and the shot is likewise destroyed, 1st, by sifting fine sand on it–this does it gradually; 2dly, by breathing on it; 3dly, by making a smoke about it from burning wood; 4thly, by candle-light, even though the candle is at a foot distance–these do it suddenly. The light of a bright coal from a wood fire, and the light of a red-hot iron, do it likewise, but not at so great a distance. Smoke from dry rosin dropped on hot iron does not destroy the repellency, but is attracted by both shot and cork ball, forming proportionable atmospheres round them, making them look beautifully, somewhat like some of the figures in Burnet’s or Whiston’s Theory of the Earth.
“N.B.–This experiment should be made in a closet where the air is very still, or it will be apt to fail.
“The light of the sun thrown strongly upon both cork and shot by a looking-glass, for a long time together, does not impair the repellency in the least. This difference between firelight and sunlight is another thing that seems new and extraordinary to us.
“We had for some time been of opinion that the electrical fire was not created by friction, but collected, being really an element diffused among and attracted by other matter, particularly by water and metals. We had even discovered and demonstrated its afflux to the electrical sphere, as well as its efflux, by means of little, light windmill wheels made of stiff paper vanes fixed obliquely, and turning freely on fine wire axes; also by little wheels of the same matter, but formed like water-wheels. Of the disposition and application of which wheels, and the various phenomena resulting, I could, if I had time, fill you a sheet. The impossibility of electrizing one’s self, though standing on wax, by rubbing the tube, and drawing the fire from it; and the manner of doing it by passing it near a person or thing standing on the floor, etc., had also occurred to us some months before. Mr. Watson’s ingenious Sequel came to hand; and these were some of the new things I intended to have communicated to you. But now I need only mention some particulars not hinted in that piece, with our reasonings thereupon; though perhaps the latter might well enough be spared.
“1. A person standing on wax and rubbing the tube, and another person on wax drawing the fire, they will both of them (provided they do not stand so as to touch one another) appear to be electrized to a person standing on the floor; that is, he will perceive a spark on approaching each of them with his knuckle.
“2. But if the persons on wax touch one another during the exciting of the tube, neither of them will appear to be electrized.
“3. If they touch one another after exciting the tube, and drawing the fire as aforesaid, there will be a stronger spark between them than was between either of them and the person on the floor.
“4. After such strong spark neither of them discover any electricity.
“These appearances we attempt to account for thus: We suppose, as aforesaid, that electrical fire is a common element, of which every one of the three persons above mentioned has his equal share, before any operation is begun with the tube. 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 supplied. B (who stands on wax likewise), passing his knuckle along near the tube, receives the fire which was collected by the glass from A; and his communication with the common stock being likewise cut off, he retains the additional quantity received. To C, standing on the floor, both appear to be electrized; for he, having only the middle quantity of electrical fire, receives a spark upon approaching B, who has an over quantity; but gives one to A, who has an under quantity. If A and B approach to touch each other, the spark is stronger, because the difference between them is greater. After such touch there is no spark between either of them and C, because the electrical fire in all is reduced to the original equality. If they touch while electrizing, the equality is never destroyed, the fire only circulating. Hence have arisen some new terms among us. We say B (and bodies like circumstanced) is electrized positively; A, negatively. Or rather, B is electrized plus; A, minus. And we daily in our experiments electrize bodies plus or minus, as we think proper. To electrize plus or minus no more needs to be known than this: that the parts of the tube or sphere that are rubbed do, in the instant of the friction, attract the electrical fire, and therefore take it from the thing rubbing; the same parts immediately, as the friction upon them ceases, are disposed to give the fire they have received to anybody that has less. Thus you may circulate it as Mr. Watson has shown; you may also accumulate it or subtract it, upon or from anybody, as you connect that body with the rubber or with the receiver, the communication with the common stock being cut off. We think that ingenious gentleman was deceived when he imagined (in his Sequel) that the electrical fire came down the wire from the ceiling to the gun-barrel, thence to the sphere, and so electrized the machine and the man turning the wheel, etc. We suppose it was driven off, and not brought on through that wire; and that the machine and man, etc., were electrized minus–that is, had less electrical fire in them than things in common.
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