Abstract
THE more of chemistry and physics the photographer knows the better is he able to understand his work, to overcome difficulties, and to meet new contingencies. It is impossible to set forth the main facts of chemistry in so small a volume as this, even if the matter is restricted to those subjects that have an immediate bearing on photography; but it is possible to do something useful in this direction even within so few pages. The author commences with burettes and pipettes, and goes on, rather unnecessarily, to gallipots and jampots. We do not think that such expressions as “The iron, as it were, says to the silver, ‘You've got my NO3; drop it!’ And the silver has to drop it,” assist in representing the subject clearly, and in this case the description would appear to give an incorrect impression. From about the middle of the book the chenistry almost disappears in favour of practical and empirical formulæ, with short instructions for various photographic operations. Some of the author's statements are open to criticism. We read, on p. 62, that “all chemical reactions are reversible.” That as, when a photographic plate is exposed to light “there is no outlet for the products of decomposition-the excess of bromide or other halogen set free on reduction in this case-a state of equilibrium is reached at a certain point. If decomposition is carried beyond this point, reversal sets in, which may go the whole way until the original compounds are re-formed.” At p. 86 we read that carbon tissue is thin, and at p. 94, in the five and a half lines devoted to Dr. Smith's “Uto” paper, that “it is rendered colour sensitive by means of anethol.” Other misleading or unpractical statements might be quoted. A photographer who wishes to know something about combining proportions, the general properties of acids and alkalies, and a few other elementary chemical matters, will probably find what he wants here, with a good many items of miscellaneous information added.
Chemistry for Photographers.
By Chas. F. Townsend. Fifth edition, revised. Pp. 129. (London: George Routledge and Sons, Ltd.; Dawbarn and Ward, Ltd., n.d.). Price 1s. net.
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Chemistry for Photographers . Nature 84, 327 (1910). https://doi.org/10.1038/084327b0
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DOI: https://doi.org/10.1038/084327b0