COPPER. 
fall off by the sudden contraetion of the 
heated copper. This may be repeated till 
the whole is converted into this oxide. The 
copper in this state is in the highest degree 
of oxidation. The component parts of this 
oxide are, 
Oxygen 25 
Copper T'o 
100 
There are, however, different oxides ; 
copper combines with a smaller proportion 
of oxygen, forming an oxide of an orange 
colour. This is the oxide of copper with 
the smaller proportion of oxygen. The 
component parts of this oxide, according to 
Mr. Chenevix, are. 
Oxygen 11.5 
Copper 88.5 
100.0 
This oxide changes colour the moment it 
is exposed to the air, by the absorption of 
oxygen, for which it has a very strong affi- 
nity. There is no action between azote, 
hydrogen, or carbon, and copper. Phos- 
phorus readily combines with copper, and 
forms with it a phosphuret, which is pre- 
pared by fusing equal parts of copper and 
phosphoric gas, with ith of the whole of 
charcoal in powder. Copper combines 
with sulphur by different processes. If 
sulphur in powder and filings of copper are 
mixed together, and formed into a paste 
with a little water, when they are exposed 
to the air, the mass swells up, becomes hot, 
and is converted into a brown matter, which 
effloresces slowly in the air, and is converted 
into sulphate of copper. 
Copper combined with sulphur is one of 
the most common ores of this metal. Ac- 
cording to the experiments of Proust, the 
natural production, known by the name of 
copper pyrites, is a sulphuret of copper, 
combined with an additional portion of sul- 
phur. It is distinguished by its brittleness, 
metallic lustre, and yellow colour. 
The alloys of copper (that' is, those in 
which this metal predominates) are more 
numerous and more important in the arts 
than those of any other metal. Many of 
them are perfectly well known, and have 
been in use from very ancient times ; of ma- 
ny the exact composition, and particularly 
the mode of preparing, are kept as secret 
as possible ; for even when the precise eom- 
position of an alloy is found by chemical 
analysis, it may often be extremely difficult 
to produce a mixture by common methods, 
which shall have exactly the same shade of 
colour, the same malleability, texture, sus- 
ceptibility of polish, or some other excel- 
lence, which, perhaps, a mere accident has 
discovered to tlie possessor. 
Tlie principal objects of alloying copper 
appears to be to render it less liable to 
tarnish, and especially to be acted on by 
common animal or vegetable substances, 
to make it more fusible, and harder, and 
able to take a higher polish, and to alter its 
colour either to a golden yellow or silvery 
white. All these objects are attainable 
by different alloys. Copper alloyed with 
gold, silver, and platina, is seldom, if ever, 
used in the proportions in which it would 
be reckoned as alloy of copper, being much 
too costly for any purpose of manufacture ; 
with this exception, however, that a very 
small portion of silver much improves the 
composition of the alloy of copper and tin, 
when used as bell-metal or speculum-metal. 
Copper is used largely as an alloy of gold 
and silver, and it is often plated w'ith one or 
the other. 
Tutenag is a white alloy of copper, zinc, 
and iron, according to Keir, which is very 
hard, tough, and sufficiently ductile to be 
wrought into various articles of furniture, 
such as candlesticks. See. which take a high 
polish, and when made of the better sort of 
tutenag are hardly distinguishable from 
silver. The inferior kinds are still white, 
but with a brassy yellow. The Chinese 
petong is another tine, white, malleable al- 
loy of copper, the composition of which is 
not exactly known, but it contains a small 
portion of silver. Copper unites with lead 
very intimately by fusion, but when a mass 
of this alloy is exposed to a heat less than 
that at which the whole melts, the lead alone 
sweats out, leaving almost all the copper in 
a porous or honey-combed state. When the 
copper holds a small portion of silver, the 
lead carries the latter out with it, and this 
is the principle of the old process of eliqua- 
tion, formerly much used in the extracting 
of silver from copper ores. Copper, with 
about a fourth of its weight of lead, forms 
pot-metal, used by the ancients for their 
coins. 
Copper nearly saturated with zinc, forms 
brass, the most important of all the alloys 
of this metal. See Brass. With a much 
less proportion of zinc the colour of the al- 
loy approaches very nearly to that of gold, 
and the malleability increases. Mixtures 
chiefly of these two metals are used to form 
