Agricola, Georgius, De re metallica, 1912/1950
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              These pieces of metal are afterward heated in iron basins and smelted in the
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              cupellation furnace by the smelters.</s>
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              <s>Although the miners, in the shafts or tunnels, have sorted over the
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              material which they mine, still the ore which has been broken down and carried
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              out must be broken into pieces by a hammer or minutely crushed, so that
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              the more valuable and better parts can be distinguished from the inferior and
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              worthless portions. </s>
              <s>This is of the greatest importance in smelting ore, for
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              if the ore is smelted without this separation, the valuable part frequently
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              receives great damage before the worthless part melts in the fire, or else the
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              one consumes the other; this latter difficulty can, however, be partly
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              avoided by the exercise of care and partly by the use of fluxes. </s>
              <s>Now, if a
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              vein is of poor quality, the better portions which have been broken down and
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              carried out should be thrown together in one place, and the inferior portion
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              and the rock thrown away. </s>
              <s>The sorters place a hard broad stone on a table;
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              the tables are generally four feet square and made of joined planks, and to
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              the edge of the sides and back are fixed upright planks, which rise about a
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              foot from the table; the front, where the sorter sits, is left open. </s>
              <s>The </s>
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              <s>A—TABLES. B—UPRIGHT PLANKS. C—HAMMER. D—QUADRANGULAR HAMMER.
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              E—DEEPER VESSEL. F—SHALLOWER VESSEL. G—IRON ROD.</s>
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