X. On the photo-electric discharge from metallic surfaces in different gases

Abstract

Abstract The experiments described in this paper were designed with a view to studying as systematically as possible the dependence of the magnitude of the photo-electric current from a metal surface illuminated by ultra-violet light—or Hallwachs effect, as it is called, after the name of its discoverer, by continental physicists—on the pressure and nature of the gas in which the illuminated surface is enclosed. Very few experiments appear to have been made on the comparison of photo-electric currents in different gases, and the experiments hitherto carried out on the photo­-electric effect in gases at pressures other than atmospheric have been made principally to test special points in theory; such as those made by Townsend (‘Phil. Mag.,’ 6th series, vol. 3, p. 557, 1902) in support of the theory of the genesis of ions by collision.