Agricola, Georgius, De re metallica, 1912/1950

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    <archimedes>
      <text>
        <body>
          <chap>
            <p type="caption">
              <s>
                <pb pagenum="310"/>
              The fine concentrates and fine tin-stone are washed again on this canvas
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              strake. </s>
              <s>By this method, the canvas lasts longer because it remains fixed,
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              and nearly double the work is done by one washer as quickly as can be done
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              by two washers by the other method.</s>
            </p>
            <p type="main">
              <s>The jigging sieve has recently come into use by miners. </s>
              <s>The
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              metalliferous material is thrown into it and sifted in a tub nearly full of water.
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              </s>
              <s>The sieve is shaken up and down, and by this movement all the material
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              below the size of a pea passes through into the tub, and the rest remains on the
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              bottom of the sieve. </s>
              <s>This residue is of two kinds, the metallic particles,
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              which occupy the lower place, and the particles of rock and earth, which
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              take the higher place, because the heavy substance always settles, and the
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              light is borne upward by the force of the water. </s>
              <s>This light material is taken
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              away with a limp, which is a thin tablet of wood almost semicircular in
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              shape, three-quarters of a foot long, and half a foot wide. </s>
              <s>Before the
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              lighter portion is taken away the contents of the sieve are generally divided
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              crosswise with a limp, to enable the water to penetrate into it more quickly.
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              </s>
              <s>Afterward fresh material is again thrown into the sieve and shaken up and
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              down, and when a great quantity of metallic particles have settled in the sieve,
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              they are taken out and put into a tray close by. </s>
              <s>But since there fall into
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              the tub with the mud, not only particles of gold or silver, but also of sand,
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              pyrites,
                <emph type="italics"/>
              cadmia,
                <emph.end type="italics"/>
              galena, quartz, and other substances, and since the
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              water cannot separate these from the metallic particles because they are all
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              heavy, this muddy mixture is washed a second time, and the part which is
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              useless is thrown away. </s>
              <s>To prevent the sieve passing this sand again too
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              quickly, the washer lays small stones or gravel in the bottom of the sieve.
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              </s>
              <s>However, if the sieve is not shaken straight up and down, but is tilted to one
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              side, the small stones or broken ore move from one part to another, and the
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              metallic material again falls into the tub, and the operation is frustrated.
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              </s>
              <s>The miners of our country have made an even finer sieve, which does not
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              fail even with unskilled washers; in washing with this sieve they have no
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              need for the bottom to be strewn with small stones. </s>
              <s>By this method the mud
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              settles in the tub with the very fine metallic particles, and the larger sizes of
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              metal remain in the sieve and are covered with the valueless sand, and this
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              is taken away with a limp. </s>
              <s>The concentrates which have been collected
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              are smelted together with other things. </s>
              <s>The mud mixed with the very fine
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              metallic particles is washed for a third time and in the finest sieve, whose
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              bottom is woven of hair. </s>
              <s>If the ore is rich in metal, all the material which
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              has been removed by the limp is washed on the canvas strakes, or if the ore
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              is poor it is thrown away.</s>
            </p>
            <p type="main">
              <s>I have explained the methods of washing which are used in common for
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              the ores of many metals. </s>
              <s>I now come to another method of crushing ore,
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              for I ought to speak of this before describing those methods of washing which
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              are peculiar to ores of particular metals.</s>
            </p>
            <p type="main">
              <s>In the year 1512, George, the illustrious Duke of Saxony
                <emph type="sup"/>
              14
                <emph.end type="sup"/>
              , gave the over­</s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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