Agricola, Georgius, De re metallica, 1912/1950

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1These pieces of metal are afterward heated in iron basins and smelted in the
cupellation furnace by the smelters.
Although the miners, in the shafts or tunnels, have sorted over the
material which they mine, still the ore which has been broken down and carried
out must be broken into pieces by a hammer or minutely crushed, so that
the more valuable and better parts can be distinguished from the inferior and
worthless portions.
This is of the greatest importance in smelting ore, for
if the ore is smelted without this separation, the valuable part frequently
receives great damage before the worthless part melts in the fire, or else the
one consumes the other; this latter difficulty can, however, be partly
avoided by the exercise of care and partly by the use of fluxes.
Now, if a
vein is of poor quality, the better portions which have been broken down and
carried out should be thrown together in one place, and the inferior portion
and the rock thrown away.
The sorters place a hard broad stone on a table;
the tables are generally four feet square and made of joined planks, and to
the edge of the sides and back are fixed upright planks, which rise about a
foot from the table; the front, where the sorter sits, is left open.
The
144[Figure 144]
A—TABLES. B—UPRIGHT PLANKS. C—HAMMER. D—QUADRANGULAR HAMMER.
E—DEEPER VESSEL. F—SHALLOWER VESSEL. G—IRON ROD.

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