Agricola, Georgius, De re metallica, 1912/1950

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    <archimedes>
      <text>
        <body>
          <chap>
            <p type="main">
              <s>
                <pb pagenum="241"/>
              But it is better at first to add as much lead as is required to the ore which
                <lb/>
              needs melting, rather than afterward when the melting has been half finished,
                <lb/>
              that the whole quantity may not vanish in fumes, but part of it remain
                <lb/>
              fast. </s>
              <s>When the heat of the fire has nearly consumed the lead, then is the
                <lb/>
              time when the gold and silver gleam in their varied colours, and when all the
                <lb/>
              lead has been consumed the gold or silver settles in the cupel. </s>
              <s>Then as
                <lb/>
              soon as possible remove the cupel out of the furnace, and take the button out
                <lb/>
              of it while it is still warm, in order that it does not adhere to the ashes. </s>
              <s>This
                <lb/>
              generally happens if the button is already cold when it is taken out. </s>
              <s>If the
                <lb/>
              ashes do adhere to it, do not scrape it with a knife, lest some of it be lost and
                <lb/>
              the assay be erroneous, but squeeze it with the iron tongs, so that the ashes
                <lb/>
              drop off through the pressure. </s>
              <s>Finally, it is of advantage to make two or
                <lb/>
              three assays of the same ore at the same time, in order that if by chance
                <lb/>
              one is not successful, the second, or in any event the third, may be certain.</s>
            </p>
            <p type="main">
              <s>While the assayer is assaying the ore, in order to prevent the great heat
                <lb/>
              of the fire from injuring his eyes, it will be useful for him always to have
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              ready a thin wooden tablet, two palms wide, with a handle by which it may
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              be held, and with a slit down the middle in order that he may look through
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              it as through a crack, since it is necessary for him to look frequently within
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              and carefully to consider everything.</s>
            </p>
            <figure number="136"/>
            <p type="caption">
              <s>A—HANDLE OF TABLET. B—ITS CRACK.</s>
            </p>
            <p type="main">
              <s>Now the lead which has absorbed the silver from a metallic ore is con­
                <lb/>
              sumed in the cupel by the heat in the space of three quarters of an hour. </s>
              <s>When
                <lb/>
              the assays are completed the muffle is taken out of the furnace, and the
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              ashes removed with an iron shovel, not only from the brick and iron furnaces,
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              but also from the earthen one, so that the furnace need not be removed from
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              its foundation.</s>
            </p>
            <p type="main">
              <s>From ore placed in the triangular crucible a button is melted out, from
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              which metal is afterward made. </s>
              <s>First of all, glowing charcoal is put into
                <lb/>
              the iron hoop, then is put in the triangular crucible, which contains the ore
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              together with those things which can liquefy it and purge it of its dross;
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              then the fire is blown with the double bellows, and the ore is heated until
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              the button settles in the bottom of the crucible. </s>
              <s>We have explained that
                <lb/>
              there are two methods of assaying ore,—one, by which the lead is mixed </s>
            </p>
          </chap>
        </body>
      </text>
    </archimedes>
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