Positive and Negative Electricity

Abstract

When once the two kinds of electricity and their respective actions were known, it was only natural to apply to them the terms positive and negative. By attaching algebraic signs to the charges e and e′ of two bodies one could sum up the rules for their mutual action in a simple formula; the force at a distance r can be represented by ee′/r ², where one can tell from the sign of the product ee′ whether one has to deal with a repulsion or with an attraction. The words positive and negative were also in accordance with the empirical fact that out of a neutral state two equal and opposite electric charges can arise and that vice-versa two such charges can, on combining, disappear altogether. And yet many phenomena occur showing differences which are not adequately rendered by opposite algebraic signs only. The well-known figures of Lichtenberg, for example, show that the two electricities do not spread in the same way over the surface of a plate of resin. Everyone knows the different luminous phenomena visible at the two sets of sharp points of a Holtz machine, long pencils at the one side, at the other small spots of light, and in the same way the difference between the positive and the negative light in a discharge-tube is apparent at once. Moreover, the phenomena of electrolysis show that the two electricities are attached to certain substances — the positive one to the metallic atoms, the negative one to the other part of the electrolyte.

Lecture held on Oct. 26 1920 at the meeting of the section for electrical engineering of the K. Inst. v. Ing. In the lecture, actually delivered, the mathematical developments and a few other parts of the following were omitted. De Ingenieur. 36, 212, 1921.