Abstract
IT is clearly desirable, whether one looks forward to the use of goniometric methods as an everyday means of identification or not, that a research worker in one laboratory should issue the results of his study in exactly the same form as an independent worker in another. But in the anorthic system, the odds against an identical treatment, even in relatively simple cases, are at least fifty to one. Yet it requires only a little care in the choice of the simplest possible indices, aided by a few rules and conventions no more unreasonable or difficult to remember than the convention that the axial angle β of a monoclinic crystal is the obtuse angle, and the odds may be reversed. The necessary rules, and the method of their application, Dr. Barker has set forth clearly. Once given the uniformity of description which would be consequent on a universal adoption of this system, the preparation of determinative tables of crystals, classified by their angles and symmetry, is relatively simple, and a specimen of such a table is given, covering some hundred substances. That such tables are of practical value is shown by Dr. Barker?s successful identification of nine substances chosen from this hundred, by their aid alone. It is perhaps not too much to suggest that it is the duty of every crystallographer to study and adopt the proposed conventions—or to put forward better ones instead.
Systematic Crystallography: an Essay on Crystal Description, Classification and Identification.
By T. V. Barker. Pp. xi + 115. (London: Thomas Murby and Co., 1930.) 7s. 6d. net.
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[Book Review]. Nature 127, 624 (1931). https://doi.org/10.1038/127624b0
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DOI: https://doi.org/10.1038/127624b0