Photographic Theory


IN the course of photographic investigations at the Royal Observatory, Edinburgh, it has been found by Mr. E. A. Baker that the initial stages of the photographic action, including the deviations from the reciprocity law, are calculable and well represented by assuming that the developable product is formed in two stages, each requiring one quantum; and that the product of the first stage returns in the absence of further stimulus to its original sensitive state, according to the usual law governing the progress of a mono-molecular change. In the case of process plates, where the grains are small and nearly uniform in size, the experimental results agree so closely with those deduced on this theory as to warrant the belief that the departures from it with fast emulsions, where not due to the reversal action, are to be accounted for by the diversity of grain size. The results of these investigations will be submitted to the Royal Society of Edinburgh during the coming session.

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

SAMPSON, R. Photographic Theory. Nature 118, 374 (1926).

Download citation


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.