Abstract
(1) Mr. S. J. Johnstone'S monograph on sources of potash is the most useful summary that has been produced since that written by Messrs. H. S. Gale and W. B. Hicks for the Geological Survey of the United States (“Potash in 1917,” published 1919). It has no index, but ends with an excellent bibliography, arranged in the sequence of references to the papers in the text. The author deals with all commercial sources of potash, including (p. 112) the product styled Karroo ash, a residue from the ignition of the sheep-dung used as fuel in the Karroo region of S. Africa. The attention now given to alunite is well reflected in the summaries on pp. 51 to 60. The methods of treatment are described, and it may be remembered that a research by W. T. Schaller, the mineralogist, led to the suggestion of the simultaneous extraction from alunite of potash and alumina for commercial purposes. The nomenclature in the analyses of products from the Alsatian mines on p. 12 does not agree with that adopted elsewhere in the text, and the use of “kainite,” here and on p. 5, as a synonym for “sylvinite” is an obvious error. “Sylvinite” is, of course, a trade-name for a mixture of sylvine and rock-salt. It is surely time that “muriate of potash,” as a name for a substance containing no potash, disappeared. On p. 5 the potassium-content of various products is given, calculated as potash, and the German and other salts are quoted as yielding 100 per cent. We believe that 12-4 per cent, was the official figure adopted by the German Potash Syndicate in 1921. The account of the occurrences of the ordinary soluble potassium salts seems the least satisfactory part of the present memoir. What, for instance, is meant (p. n) by “the amount of potash averages 30 per cent, of potassium chloride” in the description of an Alsatian deposit?
(1) Potash.
By Sydney J. Johnstone. New edition revised and enlarged. (Imperial Institute. Monographs on Mineral Resources, with special reference to the British Empire.) Pp. x + 122. (London: John Murray, 1922.) 6s. net.
(2) Oil Shales.
By Dr. H. B. Cronshaw. {Ibid. ) Pp. x + 80. (London: John Murray, 1921.) 5s. net.
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C., G. (1) Potash (2) Oil Shales. Nature 110, 307 (1922). https://doi.org/10.1038/110307a0
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DOI: https://doi.org/10.1038/110307a0
