Agricola, Georgius, De re metallica, 1912/1950

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              <s>
                <pb pagenum="xiii"/>
              their clarity is as crystal to mud in comparison with those of his predecessors—
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              and of most of his successors for over two hundred years. </s>
              <s>As an indication of
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              his grasp of some of the wider aspects of geological phenomena we reproduce,
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              in Appendix A, a passage from
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              De Ortu et Causís,
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              which we believe to be the
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              first adequate declaration of the part played by erosion in mountain sculpture.
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              </s>
              <s>But of all of Agricola's theoretical views those are of the greatest interest which
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              relate to the origin of ore deposits, for in these matters he had the greatest
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              opportunities of observation and the most experience. </s>
              <s>We have on page 108
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              reproduced and discussed his theory at considerable length, but we may repeat
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              here, that in his propositions as to the circulation of ground waters, that ore
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              channels are a subsequent creation to the contained rocks, and that they
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              were filled by deposition from circulating solutions, he enunciated the founda­
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              tions of our modern theory, and in so doing took a step in advance greater than
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              that of any single subsequent authority. </s>
              <s>In his contention that ore channels
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              were created by erosion of subterranean waters he was wrong, except for
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              special cases, and it was not until two centuries later that a further step in
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              advance was taken by the recognition by Van Oppel of the part played by
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              fissuring in these phenomena. </s>
              <s>Nor was it until about the same time that the
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              filling of ore channels in the main by deposition from solutions was generally
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              accepted. </s>
              <s>While Werner, two hundred and fifty years after Agricola, is
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              generally revered as the inspirer of the modern theory by those whose reading
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              has taken them no farther back, we have no hesitation in asserting that of the
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              propositions of each author, Agricola's were very much more nearly in
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              accord with modern views. </s>
              <s>Moreover, the main result of the new ideas
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              brought forward by Werner was to stop the march of progress for half a
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              century, instead of speeding it forward as did those of Agricola.</s>
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              <s>In mineralogy Agricola made the first attempt at systematic treatment
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              of the subject. </s>
              <s>His system could not be otherwise than wrongly based,
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              as he could scarcely see forward two or three centuries to the atomic theory
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              and our vast fund of chemical knowledge. </s>
              <s>However, based as it is upon
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              such properties as solubility and homogeneity, and upon external character­
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              istics such as colour, hardness, &c., it makes a most creditable advance
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              upon Theophrastus, Dioscorides, and Albertus Magnus—his only predecessors.
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              </s>
              <s>He is the first to assert that bismuth and antimony are true primary metals;
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              and to some sixty actual mineral species described previous to his time he
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              added some twenty more, and laments that there are scores unnamed.</s>
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              <s>As to Agricola's contribution to the sciences of mining and metal­
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              lurgy,
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              De Re Metallíca
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              speaks for itself. </s>
              <s>While he describes, for the first
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              time, scores of methods and processes, no one would contend that they
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              were discoveries or inventions of his own. </s>
              <s>They represent the accumulation
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              of generations of experience and knowledge; but by him they were, for the
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              first time, to receive detailed and intelligent exposition. </s>
              <s>Until Schlüter's
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              work nearly two centuries later, it was not excelled. </s>
              <s>There is no measure by
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              which we may gauge the value of such a work to the men who followed in
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              this profession during centuries, nor the benefits enjoyed by humanity
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              through them.</s>
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