A New Study on Triboelectricity

P. E. Shaw. Experiments on tribo-electricity (Proc. Roy. Soc., November, 1917)¹.

The doctrine of electricity, as is well known, arose together with the first triboelectric experiments, or experiments on the excitation of electrification by means of friction (Thales, about 580 B.C.; Gilbert, 1600; Guericke, 1663). It is all the more surprising that at the present time, when

electricity has grown into an extensive science, which has separated out several disciplines, independent to a certain degree; the department on triboelectricity is neglected, almost no one studies it; the amount of information relating to it has hardly increased over the last hundred years (even in extensive courses of physics this information is usually accommodated on a few pages); the most fundamental theoretical questions concerning this field remain unresolved.

In the Proceedings of the Royal Society of London for November 1917, Shaw sets forth the results of his investigations on triboelectricity. Shaw gives a triboelectric series of 36 members²; the chief essence of his work consists in the fact that the members of the series were subjected by him to systematic investigation with respect to changes in surface conditions by various methods: by raising the temperature to heating and during it, by scraping, by grinding, etc.

It turned out that a change in the state of the surface of a given substance has an extremely strong influence on the place occupied by that substance in the series. Ordinary soda glass stands in 5th place if its surface is polished; but it moves to 21st place if its surface is made matte, and to 26th place if its temperature is raised to 245°. Mica, normally occupying 6th place, moves to 18th when its surface is made matte, and to 26th when it is heated to 270°. Here we have examples of substances which under ordinary conditions are preferentially charged with positive electricity, but after the indicated change in their surface conditions acquire, on the contrary, a tendency to be charged with negative electricity. Conversely, ebonite, when its surface is made matte, moves from 28th place to 27th; being heated to 100°, it is already in 21st place. All the changes taking place in this way obey, as Shaw indicates, the following simple rule: every substance standing above the 14th place in the series moves downward if it is heated or given a matte surface; and every substance standing below the 14th place, under the same conditions, strives to pass to a higher place. Thus substances standing at the ends of the series, as a result of the indicated changes of state, exhibit a tendency toward rapprochement (from this it follows that the difference in the electrical states obtained by them upon friction diminishes). The temperature at which displacement occurs as a result of heating is a quantity quite definite for the given material; it was determined for sixteen substances and found to lie within the limits from 70° to 300°.

A. Bachinsky.

1. Abstract in Nature, No. 2512, Dec. 20, 1917. ↩

2. The triboelectric series consists of substances arranged in such an order that each substance, when rubbed with any subsequent substance, becomes electrified positively. Such a series was first constructed by Young in 1807. We give here several members of the triboelectric series given by Faraday:

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   Cat’s fur
   Flannel
   Ivory
   Rock crystal
   Cotton paper
   Metals
   Sulfur

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