Useful Knowledge: Volume 1. Minerals: Or, a familiar account of the various productions of natureBingley, William
History
Useful Knowledge: Volume 1. Minerals: Or, a familiar account of the various productions of nature
Bingley, William
Commercial products; Geology, Economic; Natural history
This metal ranks next in value to gold. Like gold, it is coined into
money, and is manufactured into various kinds of utensils, such as
goblets, vases, spoons, and dishes, which have the general appellation
of _silver plate_. For all these purposes it is alloyed with copper,
which does not affect its whiteness, and is not easily detected, unless
it be in too great proportion: the intention of this is to render it
harder than it would otherwise be, and thereby the better to adapt it to
receive fine and sharp impressions on being cast. Our _standard silver_
is composed of somewhat more than 12¼ parts of pure metal and one part
of copper; and the metal of this standard is used, both for silver
plate, and in the coinage. The mark or stamp which is given to it at
Goldsmiths’ Hall is similar to that which has been explained for
sterling gold.
After platina (226) and gold (227), silver is considered the most
unchangeable of all metals. The air does not easily act upon its surface
in such manner as to injure it; but, when long exposed to the
atmosphere, especially in frequented or smoky places, it acquires a
covering or rust of dark brown colour, which, on examination, is found
to be what chemists denominate _sulphuret of silver_. The fumes of
sulphur and other inflammable substances blacken silver. Various powders
have been contrived with a view to restore to plate its original lustre;
but these should be used with caution, as some of them are very
injurious.
Silver is nearly as ductile as gold. It may be beaten into leaves so
thin that a single grain in weight will cover a space of more than
fifty─one inches; and it may be drawn into wire much finer than a human
hair, indeed so fine that a single grain of silver has, in this form,
been extended nearly to the length of 400 feet. It is this wire gilded
that has the name of gold wire; and what is denominated _gold lace_
(227) is but flatted silver thread gilt, twisted round silk, and woven.
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