Abstract
THE introduction of the various forms of rectifier photo-electric cell has certainly simplified many problems in the use of instruments such as colorimeters (chemical type), densitometers and the like, since currents of the order of 100 microamperes can be attained without very intense light, the cell acting, when suitably illuminated, as a primary source of direct current without the use of batteries. Many such applications have now been developed. A convenient instrument of this type has been recently designed by Messrs. Imperial Chemical Industries, Ltd., and put on the market by Messrs. Baird and Tatlock (London), Ltd., for the testing of the clarity of gelatine and other aqueous solutions. It is well made and easy to operate, and should be found of great assistance in saving time in such tests as well as in giving much better accuracy than visual comparisons. No doubt more or less empirical scales would have to be established for particular types of product, and in instruments of this kind (as indeed in visual photometry) it will be important to avoid confusion between scattering and direct absorption of light.
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A Clarity Tester for Gelatine. Nature 137, 862 (1936). https://doi.org/10.1038/137862a0
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DOI: https://doi.org/10.1038/137862a0