The electrical condition of hot surfaces during the adsorption of gases. Part IV.—carbon and copper surfaces at temperatures up to 850° C

Abstract

In continuation of the investigation of which an account has been given in Parts I, II and III of this series we have now completed an examination of the electrical condition of hot carbon and copper surfaces. Those previously investigated consisted of gold, silver, nickel and platinum. Carbon and copper were chosen for the experiments to be described below because of their chemical reactivity, and the former especially as a non-metal. Experimental . The apparatus and the experimental method and procedure followed have been previously described in detail. The copper surface consisted of a 6 cm. by 10 cm. sheet of 22 S. W. G. electrolytic copper connected to the electrometer switch by a copper wire welded on to the sheet. A coreless arc carbon rod, 1⋅2 cm. diameter and 25 cm. long, supplied by the General Electric Company, served as the carbon surface. The rod was sealing-waxed into the vertical vessel (Part I, fig. 1) and the protruding portion coated with sealing-wax in order to render the apparatus vacuum tight. The electrometer lead was soldered to a brass terminal screwed into the end of the carbon rod. Both surfaces were cleaned by washing with light petroleum spirit.