1through which there flows on to the iron plate so much
water as is necessary
for this washing. Next, a boy throws the metalliferous material on to the
iron plate with an iron shovel and breaks the small lumps, stirring them this
way and that with the same implement. Then the water and sand penetra
ting the holes of the plate, fall into the box, while all the coarse gravel remains
on the plate, and this he throws into a wheelbarrow with the same shovel.
Meantime, a younger boy continually stirs the sand under the plate with a
wooden scrubber nearly as wide as the box, and drives it to the upper end of
the box; the lighter material, as well as a small amount of tin-stone, is
carried by the water down into the underlying trough. The boys carry on
this labour without intermission until they have filled four wheelbarrows
with the coarse and worthless residues, which they carry off and throw away, or
three wheelbarrows if the material is rich in black tin. Then the foreman
has the plank removed which was in front of the iron plate, and on which the
boy stood. The sand, mixed with the tin-stone, is frequently pushed backward
and forward with a scrubber, and the same sand, because it is lighter, takes
the upper place, and is removed as soon as it appears; that which takes the
lower place is turned over with a spade, in order that any that is light
can flow away; when all the tin-stone is heaped together, he shovels it out
of the box and carries it away. While the foreman does this, one boy with
an iron hoe stirs the sand mixed with fine tin-stone, which has run out of the
box and has settled in the trough and pushes it back to the uppermost part
of the trough, and this material, since it contains a very great amount of tin
stone, is thrown on to the plate and washed again. The material which has
settled in the lowest part of the trough is taken out separately and piled in a
heap, and is washed on the ordinary strake; that which has settled in the
pool is washed on the canvas strake. In the summer-time this fruitful
labour is repeated more often, in fact ten or eleven times. The tin-stone
which the foreman removes from the box, is afterward washed in a jigging
sieve, and lastly in a tub, where at length all the sand is separated out.
Finally, any material in which are mixed particles of other metals, can be
washed by all these methods, whether it has been disintegrated from veins or
stringers, or whether it originated from venae dílatatae, or from streams and
rivers.
for this washing. Next, a boy throws the metalliferous material on to the
iron plate with an iron shovel and breaks the small lumps, stirring them this
way and that with the same implement. Then the water and sand penetra
ting the holes of the plate, fall into the box, while all the coarse gravel remains
on the plate, and this he throws into a wheelbarrow with the same shovel.
Meantime, a younger boy continually stirs the sand under the plate with a
wooden scrubber nearly as wide as the box, and drives it to the upper end of
the box; the lighter material, as well as a small amount of tin-stone, is
carried by the water down into the underlying trough. The boys carry on
this labour without intermission until they have filled four wheelbarrows
with the coarse and worthless residues, which they carry off and throw away, or
three wheelbarrows if the material is rich in black tin. Then the foreman
has the plank removed which was in front of the iron plate, and on which the
boy stood. The sand, mixed with the tin-stone, is frequently pushed backward
and forward with a scrubber, and the same sand, because it is lighter, takes
the upper place, and is removed as soon as it appears; that which takes the
lower place is turned over with a spade, in order that any that is light
can flow away; when all the tin-stone is heaped together, he shovels it out
of the box and carries it away. While the foreman does this, one boy with
an iron hoe stirs the sand mixed with fine tin-stone, which has run out of the
box and has settled in the trough and pushes it back to the uppermost part
of the trough, and this material, since it contains a very great amount of tin
stone, is thrown on to the plate and washed again. The material which has
settled in the lowest part of the trough is taken out separately and piled in a
heap, and is washed on the ordinary strake; that which has settled in the
pool is washed on the canvas strake. In the summer-time this fruitful
labour is repeated more often, in fact ten or eleven times. The tin-stone
which the foreman removes from the box, is afterward washed in a jigging
sieve, and lastly in a tub, where at length all the sand is separated out.
Finally, any material in which are mixed particles of other metals, can be
washed by all these methods, whether it has been disintegrated from veins or
stringers, or whether it originated from venae dílatatae, or from streams and
rivers.
The sixth method of washing material of this kind is even more modern
and more useful than the last. Two boxes are constructed, into each of
which water flows through spouts from a cross trough into which it has been
discharged through a pipe or launder. When the material has been agitated
and broken up with iron shovels by two boys, part of it runs down and falls
through the iron plates full of holes, or through the iron grating, and flows
out of the box over a sloping surface into another cross trough, and from
this into a strake seven feet long and two and a half feet wide. Then
the foreman again stirs it with a wooden scrubber that it may become
clean. As for the material which has flowed down with the water and settled
in the third cross trough, or in the launder which leads from it, a third boy
rakes it with a two-toothed rake; in this way the fine tin-stone settles down
and more useful than the last. Two boxes are constructed, into each of
which water flows through spouts from a cross trough into which it has been
discharged through a pipe or launder. When the material has been agitated
and broken up with iron shovels by two boys, part of it runs down and falls
through the iron plates full of holes, or through the iron grating, and flows
out of the box over a sloping surface into another cross trough, and from
this into a strake seven feet long and two and a half feet wide. Then
the foreman again stirs it with a wooden scrubber that it may become
clean. As for the material which has flowed down with the water and settled
in the third cross trough, or in the launder which leads from it, a third boy
rakes it with a two-toothed rake; in this way the fine tin-stone settles down