Galena and other lead ores are abundant in veins in the limestone, but they are now only worked on a large scale at Mill Close, near Winster; calamine, zinc blende, barytes, calcite and fluor-spar are common. [Please select]
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, Chemical Investigation of Fluor Acid, with a View to the Earth which it Yields, by Mr. [Please select]
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Fluor spar, and some other substances, when raised to a temperature still under redness, emit light. [Please select]
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The diamond shines for a time in the dark after it has been exposed to the sun; so do pieces of quartz when rubbed together, and powdered fluor-spar when heated shines with considerable brilliancy. [Please select]
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In these cases what we have is either a conversion of heat rays into light rays (as in the powdered fluor-spar), or the absorption and giving out again of sun-rays. [Please select]
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