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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1860 Excerpt: ...is more or less intermingled with the vein-stones, and frequently disseminated through them. The expence of fusing the large quantity of earthy matter, would greatly exceed the value of the metal it contains, has led to the exercise of great skill in mining countries, in contriving mechanical process for effecting the separation as soon as extracted from the mine; when this separation has been properly accomplished, the metallic residue can be profitably smelted for the benefit of the adventurers, and the labouring classes, who dress the ores on the surface of the mining ground. The average yield in Cornwall of pure copper is from 6 to 8 per cent, of the whole mass of ore. Some writers have asserted that the principal mining districts in Cornwall, which we have already described, and the whole county, as well as several other mining counties, have been explored, and have had by far the greater part of the mineral produce extracted from deposits which have been long worked, the principal new discoveries being made upon untried portions of untried veins, or otherwise by simply cutting passages or cross cuts from mines, or in working in a direction which traverses that of the vein upon which they are worked, so as to prove the adjoining ground. We controvert this assumption, and contend that a very considerable portion of the mining ground of Cornwall and Devon is yet untried, and that the increased intelligence and experience of our mining population, will, year by year, for centuries to come, discover new openings for their industry and the development of minerals for the benefit of the commercial community, from mines equally productive as those we have already described. The largest portion of the county of Devon is unexplored, although an eminent mining e...
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