Photo-conductance phenomena in the silver halides, and the latent photographic image.―Introduction and Part I

Abstract

In studying the mechanism of the photographic process the question naturally arises as to the part played by the silver halides, which form the basis of practically all photographic emulsions. It becomes important to determine whether, or not, the photographic mechanism can be linked up with one or more particular characteristics of these silver salts. Especially is this so in view of the fact that some investigators have developed theories in which the silver halides play no direct part in the photo-reaction taking place on exposure. They have assumed that the absorption of the active light and the resulting process occurs in other light sensitive substances associated with the silver halides in the emulsions, and that the function of the silver halide is merely to act as a source from which metallic silver is produced by the process of development. Weigert especially supports this idea at the present time. It seems to us, however, that the evidence which now exists is not only strongly against this view, but is in favour of the idea that the primary photographic process is intimately concerned with the absorption of light by the silver halides themselves, and may indeed be identified with certain of their characteristic properties.