This kind of earth having first been dug up in such quantity as would
make three hundred wheelbarrow loads, is thrown into two tanks; then the
water is turned into them, and if it (the earth) contains vitriol it must be
diluted with urine. The workmen must many times a day stir the
ore with long, thick sticks in order that the water and urine may be
mixed with it; then the plugs having been taken out of both tanks, the
solution is drawn off into a trough, which is carved out of one or two trees.
If the locality is supplied with an abundance of such ore, it should not
immediately be thrown into the tanks, but first conveyed into open spaces
and heaped up, for the longer it is exposed to the air and the rain, the better it
is; after some months, during which the ore has been heaped up in open
spaces into mounds, there are generated veinlets of far better quality than
the ore. Then it is conveyed into six or more tanks, nine feet in length
and breadth and five in depth, and afterward water is drawn into them
of similar solution. After this, when the water has absorbed the alum, the
plugs are pulled out, and the solution escapes into a round reservoir forty
feet wide and three feet deep. Then the ore is thrown out of the tanks
into other tanks, and water again being run into the latter and the urine
added and stirred by means of poles, the plugs are withdrawn and
the solution is run off into the same reservoir. A few days afterward,
the reservoirs containing the solution are emptied through a small launder,
and run into rectangular lead caldrons; it is boiled in them until the
make three hundred wheelbarrow loads, is thrown into two tanks; then the
water is turned into them, and if it (the earth) contains vitriol it must be
diluted with urine. The workmen must many times a day stir the
ore with long, thick sticks in order that the water and urine may be
mixed with it; then the plugs having been taken out of both tanks, the
solution is drawn off into a trough, which is carved out of one or two trees.
If the locality is supplied with an abundance of such ore, it should not
immediately be thrown into the tanks, but first conveyed into open spaces
and heaped up, for the longer it is exposed to the air and the rain, the better it
is; after some months, during which the ore has been heaped up in open
spaces into mounds, there are generated veinlets of far better quality than
the ore. Then it is conveyed into six or more tanks, nine feet in length
and breadth and five in depth, and afterward water is drawn into them
of similar solution. After this, when the water has absorbed the alum, the
plugs are pulled out, and the solution escapes into a round reservoir forty
feet wide and three feet deep. Then the ore is thrown out of the tanks
into other tanks, and water again being run into the latter and the urine
added and stirred by means of poles, the plugs are withdrawn and
the solution is run off into the same reservoir. A few days afterward,
the reservoirs containing the solution are emptied through a small launder,
and run into rectangular lead caldrons; it is boiled in them until the
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