Popular Technology; or, Professions and Trades. Vol. 2 (of 2)Hazen, Edward
History
Popular Technology; or, Professions and Trades. Vol. 2 (of 2)
Hazen, Edward
Industrial arts; Occupations
3. There are two methods of separating silver from its various ores,
and these are called _smelting_ and _amalgamation_. In the former
method, the ore and a due proportion of lead are heated together; and
the latter, from its great affinity for silver, unites with it, and
separates it from other substances. The two metals are afterwards
separated from each other, by melting them on a cupel, and then
exposing them to a current of atmospheric air, by which the lead is
converted into an oxyde, while the silver remains untouched. This
process is called _cupellation_.
4. In the other method, the first thing done is to roast the ore, to
expel the sulphur and other volatile parts. It is then reduced to an
impalpable powder by machinery; and having been sifted, it is agitated
sixteen or eighteen hours in barrels, with a quantity of quicksilver,
water, and iron, combined in certain proportions. This agitation
causes the several substances composing the _charge_, to unite
according to their respective affinities.
5. The silver and mercury combine, forming an amalgam, which, having
been put into a leather sack, a part of the latter is separated from
the rest by filtration, still leaving six parts of this metal to one
of the silver. The amalgam is next submitted to the action of heat in
a distilling furnace, by which the mercury is sublimated.
6. The value of the silver annually taken from the mines in all parts
of the world, is supposed to be about $20,000,000, of which Mexico and
South America yield the greater part. The several silver mines of
Europe and Asia produce about two millions and a half.
THE SILVERSMITH.
1. The artisan who forms certain articles of gold and silver, is
called indifferently a goldsmith or a silversmith. The former
denomination is most commonly employed in England, and the latter, in
the United States.
2. The most common subjects of manufacture by the silversmith are
cups, goblets, chalices, tankards, spoons, knives, forks, waiters,
bread-trays, tea-pots, coffee-pots, cream-pots, sugar-bowls,
sugar-tongs, and pencil-cases. Many of these articles he sometimes
makes of gold; this is especially the case in Europe, and some parts
of Asia. In the United States, the people are commonly satisfied with
the less expensive metal.
3. A great proportion of the silver used by this mechanic, has been
previously coined into dollars. In working these into different
utensils or vessels, he first melts them in a crucible, and casts the
silver into solid masses by pouring it into iron moulds; and having
forged it on an anvil, he reduces it still further, and to a uniform
thickness, by passing it several times between steel rollers. In
giving additional explanations of the operations of the silversmith,
we will describe the manner in which a plain tea-pot is manufactured.
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