Agricola, Georgius, De re metallica, 1912/1950

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    <archimedes>
      <text>
        <body>
          <chap>
            <pb pagenum="240"/>
            <p type="main">
              <s>If the whole space of the furnace covered by the muffle is not filled with
                <lb/>
              scorifiers, cupels are put in the empty space, in order that they may become
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              warmed in the meantime. </s>
              <s>Sometimes, however, it is filled with scorifiers,
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              when we are assaying many different ores, or many portions of one ore at the
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              same time. </s>
              <s>Although the cupels are usually dried in one hour, yet smaller
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              ones are done more quickly, and the larger ones more slowly. </s>
              <s>Unless the
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              cupels are heated before the metal mixed with lead is placed in them, they </s>
            </p>
            <figure number="134"/>
            <p type="caption">
              <s>A—CLAWS OF THE TONGS. B—IRON, GIVING FORM OF AN EGG. C—OPENING.
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              frequently break, and the lead always sputters and sometimes leaps out of them;
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              if the cupel is broken or the lead leaps out of it, it is necessary to assay
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              another portion of ore; but if the lead only sputters, then the cupels should
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              be covered with broad thin pieces of glowing charcoal, and when the lead
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              strikes these, it falls back again, and thus the mixture is slowly exhaled.
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              </s>
              <s>Further, if in the cupellation the lead which is in the mixture is not con­
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              sumed, but remains fixed and set, and is covered by a kind of skin, this is a
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              sign that it has not been heated by a sufficiently hot fire; put into the
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              mixture, therefore, a dry pine stick, or a twig of a similar tree, and hold it
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              in the hand in order that it can be drawn away when it has been heated.
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              </s>
              <s>Then take care that the heat is sufficient and equal; if the heat has not
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              passed all round the charge, as it should when everything is done rightly,
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              but causes it to have a lengthened shape, so that it appears to have a tail,
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              this is a sign that the heat is deficient where the tail lies. </s>
              <s>Then in order
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              that the cupel may be equally heated by the fire, turn it around with a small
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              iron hook, whose handle is likewise made of iron and is a foot and a half long.</s>
            </p>
            <figure number="135"/>
            <p type="caption">
              <s>SMALL IRON HOOK.</s>
            </p>
            <p type="main">
              <s>Next, if the mixture has not enough lead, add as much of it as is required
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              with the iron tongs, or with the brass ladle to which is fastened a very long
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              handle. </s>
              <s>In order that the charge may not be cooled, warm the lead beforehand. </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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