IX. The action of light on selenium

Abstract

This paper contains an account of a series of experiments which have been carried on by the authors during the last year and a half, and which have had for their object the investigation of the electrical behaviour of selenium, especially as regards its sensitiveness to light. Early in the year 1873 it was discovered by Mr. Willoughby Smith that when an electrical current was passing through a bar of crystalline selenium, its resistance was less when the bar was exposed to the action of light than it was when the bar was kept in the dark.