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48 [Doc. 205.
SWEDENBORG’S TRAVELS AND DIARIES.
there is much scoria. Each time two spadefuls and a bucket
of charcoal are thrown in. The pulverized ore is mixed with the
pulverized scoriæ ; these scoriæ usually pass twice through the
furnace, before they are cast aside. The charcoal is moistened
considerably or soaked in water. There is thus a crust formed
on the top by the charcoal, so that the flame does not seem to
burst out anywhere. At first a few buckets of charcoal are put
in, and afterwards the ore is introduced in the usual fashion.
This smelting process is generally carried on in one fur
nace for from eighteen to twenty-four hours ; but in the nar
rower furnaces for upwards of thirty days. The melted tin
flows out continually by the hole in front into the upper re
ceptacle, where it is kept, until so much of it is collected
that it can be drawn off.
Meanwhile the scoria, which continually collect on the melted
metal, are taken out, and placed at the side close by. Thence
they are taken and thrown into a vessel filled with water,
where they are to be reduced to powder. On a table which
stands near they are crushed still further, and then mixed
with pulverized ore, and again introduced into the furnace.
The quality of the smelting process may be seen from the
scoriæ, i. e. whether it is difficult or not, and whether there
is much heterogeneous matter in the ore, or not. For if the
scoriæ are thick and tough, it is a sign that there is much
heterogeneous matter contained in it, and that its fusion or
separation is more difficult, wherefore the fire has to be tempered
and moderated accordingly.
After the tin has been collected in the upper recept
acle, it is let out into the small well, cut out of the rock,
which is placed on or fastened into the ground. This
little well is capacious enough to hold about two and a half
hundred-weight of the metal; so much is obtained within six
hours. Two hours and a quarter, or two hours and a half, are
usually required for obtaining a hundred-weight of tin ; and
this quantity is derived from two hundred-weight of the tin
ore. This hundred-weight is rather heavy; for it weighs 100
pounds at the works ; in Prague 120 pounds, and in Nurem
berg 140 pounds ; the pound being so much heavier near the
works. The hundred-weight is sold for fifty-one florins. About
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