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Nature volume 154, pages 573574 (04 November 1944) | Download Citation



Two complementary papers dealing with cinemicrography were given at a meeting of the Association for Scientific Photography on October 14. Mr. H. Emmett described the apparatus used in one of the I.C.I. research laboratories, consisting of a petrological microscope, above which is supported the cine camera without its lens, while the microscope is also used without the usual eyepiece, but with a viewing attachment to enable the image to be kept under observation while being filmed. Focus on the film is ensured by inserting a piece of ground glass in the gate and balancing this image with the one seen in the viewing eyepiece; careful centring of the light is obviously of first importance. A 9·5 mm. camera was used connected through a belt drive to an electrically controlled gramophone motor which enables exposures to be taken at known intervals. Mr. Emmett showed films illustrating crystal growth, such as the change in crystalline form induced by the presence of impurities, the allotropic change in acicular crystals of ammonium nitrate which can take place on lowering the temperature, and the concentration gradient around a crystal during growth.

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