1The fine
concentrates and fine tin-stone are washed again on this canvas
strake. By this method, the canvas lasts longer because it remains fixed,
and nearly double the work is done by one washer as quickly as can be done
by two washers by the other method.
strake. By this method, the canvas lasts longer because it remains fixed,
and nearly double the work is done by one washer as quickly as can be done
by two washers by the other method.
The jigging sieve has recently come into use by miners.
The
metalliferous material is thrown into it and sifted in a tub nearly full of water.
The sieve is shaken up and down, and by this movement all the material
below the size of a pea passes through into the tub, and the rest remains on the
bottom of the sieve. This residue is of two kinds, the metallic particles,
which occupy the lower place, and the particles of rock and earth, which
take the higher place, because the heavy substance always settles, and the
light is borne upward by the force of the water. This light material is taken
away with a limp, which is a thin tablet of wood almost semicircular in
shape, three-quarters of a foot long, and half a foot wide. Before the
lighter portion is taken away the contents of the sieve are generally divided
crosswise with a limp, to enable the water to penetrate into it more quickly.
Afterward fresh material is again thrown into the sieve and shaken up and
down, and when a great quantity of metallic particles have settled in the sieve,
they are taken out and put into a tray close by. But since there fall into
the tub with the mud, not only particles of gold or silver, but also of sand,
pyrites, cadmia, galena, quartz, and other substances, and since the
water cannot separate these from the metallic particles because they are all
heavy, this muddy mixture is washed a second time, and the part which is
useless is thrown away. To prevent the sieve passing this sand again too
quickly, the washer lays small stones or gravel in the bottom of the sieve.
However, if the sieve is not shaken straight up and down, but is tilted to one
side, the small stones or broken ore move from one part to another, and the
metallic material again falls into the tub, and the operation is frustrated.
The miners of our country have made an even finer sieve, which does not
fail even with unskilled washers; in washing with this sieve they have no
need for the bottom to be strewn with small stones. By this method the mud
settles in the tub with the very fine metallic particles, and the larger sizes of
metal remain in the sieve and are covered with the valueless sand, and this
is taken away with a limp. The concentrates which have been collected
are smelted together with other things. The mud mixed with the very fine
metallic particles is washed for a third time and in the finest sieve, whose
bottom is woven of hair. If the ore is rich in metal, all the material which
has been removed by the limp is washed on the canvas strakes, or if the ore
is poor it is thrown away.
metalliferous material is thrown into it and sifted in a tub nearly full of water.
The sieve is shaken up and down, and by this movement all the material
below the size of a pea passes through into the tub, and the rest remains on the
bottom of the sieve. This residue is of two kinds, the metallic particles,
which occupy the lower place, and the particles of rock and earth, which
take the higher place, because the heavy substance always settles, and the
light is borne upward by the force of the water. This light material is taken
away with a limp, which is a thin tablet of wood almost semicircular in
shape, three-quarters of a foot long, and half a foot wide. Before the
lighter portion is taken away the contents of the sieve are generally divided
crosswise with a limp, to enable the water to penetrate into it more quickly.
Afterward fresh material is again thrown into the sieve and shaken up and
down, and when a great quantity of metallic particles have settled in the sieve,
they are taken out and put into a tray close by. But since there fall into
the tub with the mud, not only particles of gold or silver, but also of sand,
pyrites, cadmia, galena, quartz, and other substances, and since the
water cannot separate these from the metallic particles because they are all
heavy, this muddy mixture is washed a second time, and the part which is
useless is thrown away. To prevent the sieve passing this sand again too
quickly, the washer lays small stones or gravel in the bottom of the sieve.
However, if the sieve is not shaken straight up and down, but is tilted to one
side, the small stones or broken ore move from one part to another, and the
metallic material again falls into the tub, and the operation is frustrated.
The miners of our country have made an even finer sieve, which does not
fail even with unskilled washers; in washing with this sieve they have no
need for the bottom to be strewn with small stones. By this method the mud
settles in the tub with the very fine metallic particles, and the larger sizes of
metal remain in the sieve and are covered with the valueless sand, and this
is taken away with a limp. The concentrates which have been collected
are smelted together with other things. The mud mixed with the very fine
metallic particles is washed for a third time and in the finest sieve, whose
bottom is woven of hair. If the ore is rich in metal, all the material which
has been removed by the limp is washed on the canvas strakes, or if the ore
is poor it is thrown away.
I have explained the methods of washing which are used in common for
the ores of many metals. I now come to another method of crushing ore,
for I ought to speak of this before describing those methods of washing which
are peculiar to ores of particular metals.
the ores of many metals. I now come to another method of crushing ore,
for I ought to speak of this before describing those methods of washing which
are peculiar to ores of particular metals.
In the year 1512, George, the illustrious Duke of Saxony14, gave the over