1, The fusion of the schlich (sludge); 2, the roasting of the mattes
under a shed, and their treatment by four successive re-meltings; 3, the
treatment of the resulting black copper; 4, the liquation; 5, the
reliquation (_ressuage_); 6, the refining of the copper; 7, the
cupellation of the silver; 8, the reduction of the litharge into lead.
The 5th and 6th processes are carried on at the smelting works of
Altenau.
The buildings are shown at A, B, C, and the impelling stream of water at
D; the upper figure being the elevation; the lower, the plan of the
works.
[Illustration: 1013]
_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.