Agricola, Georgius, De re metallica, 1912/1950

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              <s>
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              in the bottoms of the sieves, if they contain any metal the miners put them
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              under the stamps. </s>
              <s>The larger pieces of broken rock are not separated from
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              the smaller by this method until the men and boys, with five-toothed rakes,
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              have separated them from the rock fragments, the little stones, the
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              coarse and the fine sand and earth, which have been thrown on to the dumps.</s>
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            <p type="main">
              <s>At Neusohl, in the Carpathians, there are mines where the veins of copper
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              lie in the ridges and peaks of the mountains, and in order to save expense
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              being incurred by a long and difficult transport, along a rough and sometimes
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              very precipitous road, one workman sorts over the dumps which have been
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              thrown out from the mines, and another carries in a wheelbarrow the earth,
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              fine and coarse sand, little stones, broken rock, and even the poorer ore, and
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              overturns the barrow into a long open chute fixed to a steep rock. </s>
              <s>This
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              chute is held apart by small cleats, and the material slides down a distance of
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              about one hundred and fifty feet into a short box, whose bottom is made of a
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              thick copper plate, full of holes. </s>
              <s>This box has two handles by which it is
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              shaken to and fro, and at the top there are two bales made of hazel sticks,
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              in which is fixed the iron hook of a rope hung from the branch of a tree or
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              from a wooden beam which projects from an upright post. </s>
              <s>From time to
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              time a sifter pulls this box and thrusts it violently against the tree or post,
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              by which means the small particles passing through its holes descend down
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              another chute into another short box, in whose bottom there are smaller
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              holes. </s>
              <s>A second sifter, in like manner, thrusts this box violently against a
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              tree or post, and a second time the smaller particles are received into a third
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              chute, and slide down into a third box, whose bottom has still smaller holes.
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              </s>
              <s>A third sifter, in like manner, thrusts this box violently against a tree or post,
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              and for the third time the tiny particles fall through the holes upon a table.
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              </s>
              <s>While the workman is bringing in the barrow, another load which has been
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              sorted from the dump, each sifter withdraws the hooks from his bale
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              and carries away his own box and overturns it, heaping up the broken rock
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              or sand which remains in the bottom of it. </s>
              <s>As for the tiny particles which
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              have slid down upon the table, the first washer—for there are as many
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              washers as sifters—sweeps them off and in a tub nearly full of water, washes
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              them through a sieve whose holes are smaller than the holes of the third box.
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              </s>
              <s>When this tub has been filled with the material which has passed through
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              the sieve, he draws out the plug to let the water run away; then he removes
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              with a shovel that which has settled in the tub and throws it upon the table
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              of a second washer, who washes it in a sieve with smaller holes. </s>
              <s>The sedi­
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              ment which has this time settled in his tub, he takes out and throws on the
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              table of a third washer, who washes it in a sieve with the smallest holes.
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              </s>
              <s>The copper concentrates which have settled in the last tub are taken out and
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              smelted; the sediment which each washer has removed with a limp is
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              washed on a canvas strake. </s>
              <s>The sifters at Altenberg, in the tin mines of
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              the mountains bordering on Bohemia, use such boxes as I have described,
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              hung from wooden beams. </s>
              <s>These, however, are a little larger and open in
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              the front, through which opening the broken rock which has not gone through
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              the sieve can be shaken out immediately by thrusting the sieve against its post.</s>
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          </chap>
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