a, is the melting furnace, with a cylinder bellows behind it; b, c, d, furnaces similar to the preceding, with wooden bellows, such as [fig. 1013]; e, is a furnace for the same purpose, with three tuyères, and a cylinder bellows; f, the large furnace of fusion, also with three tuyères; g, a furnace with seven tuyères, now seldom used; h, low furnaces, like the English slag-hearths (krummofen), employed for working the last mattes; k, slag-hearths for reducing the litharge; m, the area of the liquation; n, p, cupellation furnaces.
x, y, a floor which separates the principal smelting-house into two stories; the materials destined for charging the furnaces being deposited in beds upon the upper floor, to which they are carried by means of two inclined planes, terraced in front of the range of buildings.
Here 89,600 quintals of schlich are annually smelted, which furnish—
| Marketable lead | 20,907 | quintals. |
| Marketable litharge, containing 90 per cent. of lead | 7,555 | |
| Silver, about | 67 | |
| Copper (finally purified in the works of Altenau) | 35 | |
| Total product | 28,564 |
This weight amounts to one twenty-fifth of the weight of ore raised for the service of the establishment. Eight parts of ore furnish, on an average, about one of schlich. The bellows are constructed wholly of wood, without any leather; an improvement made by a bishop of Bamberg, about the year 1620. After receiving different modifications, they were adopted, towards 1730, in almost all the smelting-works of the continent, except in a few places, as Carniola, where local circumstances permitted a water blowing-machine to be erected. These pyramidal shaped bellows, composed of movable wooden boxes, have, however, many imperfections: their size must often be inconveniently large, in order to furnish an adequate stream of air; they do not drive into the furnace all the air which they contain; they require frequent repairs; and, working with great friction, they waste much mechanical power.
[Fig. 1014.] represents such wooden bellows, consisting of two chests or boxes, fitted into each other; the upper or moving one being called the fly, the lower or fixed one, the seat (gite). In the bottom of the gite, there is an orifice furnished with a clack-valve d, opening inwards when the fly is raised, and shutting when it falls. In order that the air included in the capacity of the two chests may have no other outlet than the nose-pipe m, the upper portion of the gite is provided at its four sides with small square slips of wood c, c, c, which are pressed against the sides of the fly by strong springs of iron wire b, b, b, while they are retained upon the gite by means of small square pieces of wood a, a, a, a. The latter a, a, are perforated in the centre, and adjusted upon rectangular stems, called buchettes; they are attached, at their lower ends, to the upright sides of the gite G. P is the driving-shaft of a water-wheel, which, by means of cams or tappets, depresses the fly, while the counterweight Q, [fig. 1013.], raises it again.
[Figs. 1015], [1016], [1017], [1018.] represent the moderately high (demihauts, or half-blast,) furnaces employed in the works of the lower Hartz, near Goslar, for smelting the silvery lead ores extracted from the mine of Rammelsberg. See its section, in [fig. 737.]