Abstract
I LATELY received, through the Home Office at Washington, a “Report on the Geology of the Henry Mountains,” by G. K. Gilbert, being a portion of the “Geography and Geology of the Rocky Mountains.” With the merits or demerits of this paper I am not concerned. I am not prepared, however, to pass in silence and without protest the following paragraphs, which I find at p. 76:—“Bischof attempted, by melting eruptive rocks in clay crucibles, to obtain their ratios of expansion and contraction, but his method involved so many sources of error that his results have been generally distrusted. He concluded that the contraction, in passing from the molten to the crystalline state, is greater in acidic than in basic rocks. Delesse, by an extended series of experiments in which crystalline rocks were melted and afterwards cooled to glasses, showed that acidic rocks increase in volume from 9 to 11 per cent. in passing from the crystalline state to the vitreous, while basic increase only 6 to 9 per cent. Mallet concluded, from some experiments of his own, that the contraction of rocks in cooling from the molten condition is never more than 6 per cent., and that it is greater with basic than with acidic rocks; but considering that the substances which he treated were artificial and not natural products, that his methods were not uniform, and that he ignored the distinction between the vitreous and the crystalline, of which Delesse had demonstrated the importance, no weight can be given to his results.”
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MALLET, R. “Geology of the Henry Mountains”. Nature 22, 266 (1880). https://doi.org/10.1038/022266c0
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DOI: https://doi.org/10.1038/022266c0
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