Abstract
Early Copper EXPERIMENTS in smelting copper from ores have been carried out by H. H. Coghlan with the view of throwing light on the supposed accidental discovery of copper smelting by primitive man (Man, July 1939). Primitive conditions were simulated so far as possible, to show whether copper could be produced in a ‘hole in the ground’ or camp fire. The green carbonate malachite was selected as the most probable material from which the earliest smelted copper was produced. A cone of charcoal was built up in a hole in the ground about three feet in diameter, and surrounded by a ring of stones. The ore was well embedded in the centre of the cone. A bright red heat was obtained, which could not have been increased without a forced draught. The fire was kept at full heat for some hours, and then allowed to die down slowly. The malachite had only been reduced to black oxide of copper, and no metallic copper was produced. Failure is attributed to excess of air, and later experiments proved that low temperature was not the cause of failure. The theory of accidental discovery precludes the use of bellows to produce a forced draught, as this is a method which belongs to a sophisticated copper-smelting technique. An alternative theory is put forward that accidental discovery may have resulted from the employment of a pottery kiln, especially in view of the fact that the use of pottery preceded the discovery of copper. A test was made in a simple kiln, such as that which had been in use at Erosd in the Alt Valley, where the baking chamber was simply a dome of brick or burnt clay. The kiln following this model was covered with charcoal, and the fire kept at a good red heat for some hours. Metallic copper was produced, at first as sponge copper, and afterwards with a closer packing, as a compact and close-grained bead. The malachite may have been introduced into the primitive pottery kiln by accident or in the form of a paint or slip, or made up as a glaze.
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Research Items. Nature 144, 484–485 (1939). https://doi.org/10.1038/144484a0
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DOI: https://doi.org/10.1038/144484a0