Year: 1872

NO. J.-COPPER.


This useful metal has been known from time
almost immemorial. When pure it is Of a red
dish, brown Color Its specific gravity Is SSo,
that is it is nearly nine times as heavy as water.
Both the smell and taste OF this metal are ex-
cessively disagreeable. 1t is very malleabe,
next SO in degree after gold and silver, and can
be beaten out out into extremely thin leaves.
In ductility it ranks after gold, silver, platinum
and iron, while in tenacity it yields only to the
latter. A copper wire one-tenth of an inch in
diameter will sustain weight of 3S5 pounds.
Copper is the most sonorous of oil metals, and
is therefore employed for trumpets and many
other musical Instruments The alloys Of cop
per are numerous and important. 1t forms
part of the gold and silver employed for coin,
plate and innumerable articles, both of utility
and ornament. Brass, however, is the most i'm
portant of the alloys of copper. Brass is pro-
duced by cementing copper plates with caamlne,
an oxide of zinc, mixed with charcoal. The pro-
portions in which the two metals are combined
to form brass vary in different places, from
twelve to twenty five parts of zinc to one hun
dred parts of copper. The compositions known





Prince Ruperts metal, and others, are only va
rieties of brass differing in the proportions of
tha copper and zinc. An alloy Of one part OF
tin with three of copper constitutes bell-metal.
When bell-metal is used for making bells, zinc,
antmony and sometimes silver are added to
improve the sonorousness of the compound.
The famous Corlnthan brass of antiquity was
Ill f oth hot eto al
was said to have been produced accidentally, by
the fusion together of various articles formed OF
these metals during the destruction by fire OF the
city of Corinth by the Romans. Pliny states
that vases made of this brass was considered
more valuable than if made of gold, on account
of the beauty of the metal and its fitness for
chasing and sculpture, or other modes of en-
craving. Swords and cutting Instruments among
the ancients before iron was used for that pur-
pose, were made of copper alloyed with from one
to FIVE per cent of tin A mixture of two parts
copper with one of tin form an extremely hard,
fine, brittle alloy, admitting of an exquisite pol
ish, with lustre nearly equal to that of mer
curry. Il is called speculum metal from its be-
ing employed for the renectors of telescopes and
similar optical purposes. This alloy generally
contains little zinc, arsenic and silver. 1t was
known to the ancients and used by them for
making mirrors. The white copper, pack
fong Of the Chinese, is by some persons, sup
posed to be an alloy of copper, zinc nickel and
iron; the copper being one-half of the whole and
the other metals in about equal proportions
Copper with about one fourth of its weight OF
Io,l 10 al o1s l,utou t, fba
composition of pewter. Many of the Greean
and Roman coins were formed OF an alloy of 100
parts Of copper, 2 of lead and of tin, or, with
larger proportion of the latter metals. The
compositions made in imitation of silver, called
German silver are alloys of copper of various
kinds. Oxides OF copper aye soluble in most
acids, and form salts, some Of which are import
copper. /. Is employed in glass-stanng in
dyeing, and occasionally in surgery. The fine
blue color called verditer is prepared from nj
rate of copper. verdgris is the acetate OF cop
per, and is used in painting and dyeing. 1t is
an active poison. The uses Of copper are almost
numberless. The bottoms of ships arc sheathed
with it to protect the timber from sea-worms and
to facilitate the motion of the vessel by dimin-
shing friction in the water large boilers for
sugar-works and breweries are made of copper,
as are also great variety OF articles too numer
GUS to mention. Whenever copper vessel is
intended for the preparation OF food. the surface
ought to be covered with coating of tin or sill
yer, for copper is so easily corroded or dissolved
by the acid contained in most articles Of food
that highly poisonous salts nTe thus formed,
which would have fatal effects if taken in the
stomach. Accidents are perpetualiy occurring
from using copper vessels, the timing or plating
of which has worn OF. In Sweden the govern
ment does not, for this reason, allow of any
culinary vessel being made Of copper. Another
most important use of copper, for which its
softness and malleability particularly adapt it,
is for engraving on for multiplying copies of any
design, by impressions taken on paper from II
copper plate on which the subject has been cut
n or, as it is called, engraved. The copper for
this purpose must be very pure, free from oil
defects, and well polished in thin plates. Steel
plates are now made use of for the same pur-
pose, from their superior durability. The pro-
cess Of engraving upon them precisely the
same as upon copper, only instead of nitrous
acid u solution of corrosive sublimate or some
other liquid of appropriate kind is used in the
process of etching Copper is found in veins
and beds, in granite. slate. limestone and other
rocks, accompanied by various other ores of the
metal, which are numerous that collection
in Cornwall contains thousand different kinds
One species of copper ore is of fine ornamental
stone called maachite. This is carbonate of
copper, the finest specimens of which come from
Hungary and Siberia. 1t is also found in Aus
tralia.


COBALT.


This metal is of q purple grey color and fbrous
texture. Its specific gravity is S.53 1t oxydizes
at a red heat, in an open vessel The fine blue
mineral called zaifer is an impure oxide of this
metal, containing some SILICA, and is obtained
from the commonest ore of it by roasting, which
process dissipates the arsenic and sulphur con-
tained in it, The color of this oxide is so in
tense that gram OF it will impart full blue to
two hundred and forty grains of glass. Smalt
| or smaltz is vitrous substance, produced by
melting zaffer with silex and potash When
to n fine Oowrar il is known hy the nam a