Note on a tentative hypothesis of the latent image. II

Abstract

1. (1) Based on the theoretical conclusions of Wightman and Quirk in their investigations on the action of hydrogen peroxide on high-speed plates, and of Clark's experiments on the action of oxidizers on sensitivity and latent image, which indicate that the sensitizing speck of high-speed photographic emulsions, as well as the latent image, probably consists of both silver and silver sulphide, a probable elementary photo-electric cell on the surface of the silver halide grains can be pictured. 2. (2) A proposed mechanism of the action of this cell in producing sensitivity is described. 3. (3) Assuming that optical sensitizing is due to an increase of the photo-conductivity for longer wave-lengths, a possible mechanism is given of how either certain dyes, or silver, or silver sulphide could act as an optical sensitizer to increase the sensitivity of silver halide for wave-lengths longer than the blue. This mechanism is based upon the assumption that dye specks, or finely divided silver, or silver sulphide, lying in the field of the photo-electric cell, Ag|AgBr|Ag 2S, increases its photo-conductivity above that of such a cell without one of these substances present. to wave-lengths longer than the blue. The range and intensity of the color senstivity is dependent not only upon the absorption of light of given wave-lengths, but also upon the size and distribution of the specks of impurity.