37 
Copper . 
previously roasted. But at Fahlun and many places in 
Germany, the ore is roasted in the open air, upon a level- 
led platform of earth about 14 feet long by 7 feet 6 inches 
broad. The bottom is well covered with billets, on which 
the ore is laid and heaped up to the height of about 5 feet 
6 inches. The more sulphurous and pyritical pieces are 
in the middle* the richer on the outside. The sides are 
covered with the dust of the ore sufficiently thick to re- 
tain the heat. Holes are made at the top for the sulphur 
and fume to escape. The fire is gradually kept up for a 
month or more. The mass is then opened, and the ore 
carried to the furnaces for smelting the copper into a matt, 
which is afterwards carried to the refining furnace. 
Of these furnaces, both Schlatter and Jars give plates, 
(Schlatter plate 32, Jars vol. 3. plate 3). The smelting 
furnace at Fahlun, is made thus: upon an arch open at 
each end, surrounded by masonry (the arch being prefer- 
red to avoid the quantity of moisture which solid mason- 
ry would furnish) a platform of brasque, a composition, 
half clay and half sand, is laid and well beaten ; four or 
five feet square. On this another composition is well 
beaten of equal parts of clay and charcoal dust. This is 
hollowed out to 15 inches deep, leaving the two layers 
of brasque at least six inches thick. At this level of 15 
inches from the bottom is placed the nose of the tuyere. 
The bottom has a gentle inclination to allow the melted 
matter to run and gather to one end. The furnace is a- 
bout 3 feet by 3 feet 6 inches and about 4 feet 8 inches 
high. It is well dried by being gradually heated. It is 
charged with charcoal and ore. The front is made up 
with fire stone or clay, and the furnace tapped as occasion 
requires. 
At Fahlun, sometimes the ore is roasted in furnaces ap- 
propriated to this purpose, where it receives seven or 
eight firings. 
