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IN A LEAD MINE. MINERS ABOUT TO ASCEND. FROM A TRANSPARENCY IN THE DIVISION OF MINERAL TECHNOLOGY, UNITED STATES NATIONAL MUSEUM.

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THE CONCENTRATION OF LEAD ORES. SEPARATING THE LEAD MINERALS FROM THEIR NATURAL ASSOCIATES. FROM A TRANS-
PARENCY IN THE DIVISION OF MINERAL TECHNOLOGY, UNITED STATES NATIONAL MUSEUM.

Smithsonian Report, 1921.-Mitman.

PLATE 4.

THE SMELTING OF LEAD ORES.

THE SCOTCH HEARTH, WHERE THE LEAD IS EXTRACTED FROM THE ORE.
IN THE DIVISION OF MINERAL TECHNOLOGY, UNITED STATES NATIONAL MUSEUM.

FROM A TRANSPARENCY

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THE REFINING OF LEAD. REMOVING SILVER BY THE AID OF ZINC. FROM A TRANSPARENCY IN THE DIVISION OF MINERAL TECHNOLOGY, UNITED STATES NATIONAL MUSEUM.

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SOME IMPORTANT PROPERTIES OF LEAD. PHOTOGRAPH OF A GROUP OF OBJECTS IN THE LEAD EXHIBIT, DIVISION OF MINERAL TECHNOLOGY, UNITED STATES NATIONAL MUSEUM.

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