Letter | Published:

Optical Reflections From Coal

Naturevolume 150page690 (1942) | Download Citation



THE classification of the petrological constituents of coals developed in Great Britain by Dr. Marie C. Stopes and published in a revised version in 19351 has been widely adopted as a basis for further research in many directions. Much more attention appears, however, to have been given to petrological and chemical than to physical properties. Many workers give density determinations and C. Mahadevan has made an X-ray diffraction study of coals2. In general, measurements for the coal properties selected have cut across the Stopes classification when they have been determined for vitrain, clarain, durain and fusain. Typical results taken from Hoffmann's paper3 are given in showing the maximum variations in samples taken from different seams in the same coalfield, and the overlap between the constituents.

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  1. 1

    Fuel, 14, 4–13 (1935).

  2. 2

    Fuel, 14, 231–241 (1935).

  3. 3

    Fuel, 8, 525 (1929).

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  1. Physics Department, Chelsea Polytechnic, London, S. W. 3.

    • C. G. CANNON
    •  & W. H. GEORGE


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