Abstract
DR. OLAT BLOCK, chief chemist of Messrs. Ilford Limited, delivered the twenty-ninth annual May Lecture before the Institute of Metals on May 10. Dr. Bloch pointed out that the photographic emulsion consists of a finely divided suspension of one or more of the halides of silver in gelatin. There are two broad theories of development, one of which suggests that the process consists in the deposition of silver upon the latent image from the developer which has first become supersaturated, whilst the second postulates increased adsorption at the points constituting the latent image with consequent increase of developer activity in these regions. As to the latent image, we are still without definite proof of its nature. Silver bromide crystals become much more sensitive by the inclusion in them of a small amount of iodide, but the great advance which has been made in emulsion-making technique is largely due to the employment of dye-sensitizers. The second part of the lecture dealt with the applications of photography to industry. By means of the photographic emulsion our powers of observation extend far beyond the limits originally set by the senses, and. further, the grains of the emulsion are rendered developable by the passage of the fast moving particles ejected from disintegrating atoms. Investigations into the nature of cosmic rays are also being actively carried on by the aid of the photographic emulsion. For this work special emulsions have to be prepared, but all are members of a large emulsion family who serve mankind in the making of illustrations for books, in survey work, in photomicrography and photo-telegraphy, for ordinary picture making and record work, and in nearly every field of research.
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Photography in Science and Industry. Nature 143, 817 (1939). https://doi.org/10.1038/143817a0
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DOI: https://doi.org/10.1038/143817a0