Phenomena of the capillary electroscope

Abstract

In a communication “On the Capillary Electroscope” (“Proc. Roy. Soc.,” vol. 30, p. 32), I have described various details necessary to be attended to in the construction and use of a modified form of that apparatus, and I now give an account of an investigation I have made of the phenomena of the movements of the mercury in such instruments. A research I formerly made, “On the Movements of Liquid Metals and Electrolytes in the Voltaic Circuit" ("Proc. Roy. Soc.,” vol. 10, p. 235), throws additional light upon the subject. Some of the phenomena arising out of this research have, for the sake of convenience, been made the subjects of separate communications. (See “Effects of Electric Currents on the Surface of Mutual Contact of Aqueous Solutions," "Proc. Roy. Soc.,” vol. 30, p. 322, ibid ., vol. 31, p. 250; "Influence of Electric Currents on Diffusion of Liquids;" "Experiments on Electric Osmose;” "Electric Currents caused by Liquid Diffusion and Osmose,” ibid ., vol. 31, p. 253, ibid., vol. 31, p. 296.) Erman, in the year 1809, appears to have been the first to observe the movements of mercury in a conducting solution while under the influence of an electric current. Since that time a large number of investigators have examined the phenomenon and the allied ones of electric osmose, electro-capillary action, electric currents produced by capillarity, the mechanical effect of electric currents upon liquids and upon solid particles suspended in them, &c. Among these are Armstrong, E. Becquerel, Buff, H. Davy, Draper, Du Bois Reymond, Faraday, Heidenhain, Hellwig, Herschel, Hittorf, Jürgensen, Kühne, Lippmann, Logeman, Matteucci, Paalzow, Pfaff, Poggendorff, Porrett, Quincke, Reichert, Reuss, Runge, Sabine, Serullas, Varley, Wheatstone, Wiedemann, and Wright. It is difficult, therefore, to entirely avoid restatement of some of the results arrived at by these investigators. I have examined the movements in relation to a variety of conditions, some of which, however, are unessential and may he eliminated or diminished. The phenomena have been found to he purely physical, except in those cases where the electricity was of too high tension and produced electrolysis, and in those in which the solution acted chemically upon the mercury.