I. On artificial temporary colour-blindness, with an examination of the colour sensations of 109 persons

Abstract
By artificial colour-blindness I mean the extreme forms of that altered condition of the eye, described two centuries ago by De la Hire, and probably familiar to most people, which can be produced by looking at the sky for some minutes through a piece of coloured glass. It is possible, apparently without serious risk of injuring the eyesight, by exposing the eye to the action of a more intense monochromatic light, to induce a condition of complete blindness to one or more of the primary colours, lasting some three or four minutes, and enabling the observer to experience in his own person the sensations of the colour-blind.