COP 
CO V 
COP 
^•converted into protoxide. The oxides of 
copper ere easily reduced to the metallic 
state when heated with charcoal, oils, or 
other fatty bodies; and even with some of 
the metals, especially zinc. 
3. When copper is, dissolved in nitric acid, 
and a sufficient quantity of potash is added to 
the solution, a blue powder falls to the bot- 
tom, which was formerly considered as a pe- 
culiar oxyd of copper, and accordingly call- 
ed blue oxyd of copper. But Mr. Proust 
has shown "that it is nothing else than the 
black oxyd combined with water ; and lias 
therefore called it hydrat of copper. When 
distilled, 100 parts of it yield 25 parts of 
water, and there remain behind 75 parts of 
black oxyd. When this blue powder is ex- 
posed moist to the atmosphere, it gradually 
becomes green. This was formerly supposed 
to be owing to the absorption of oxygen; 
accordingly' the green powder was called 
green oxyd of copper. But Mr. Proust has 
shewn that this change is not owing to the 
absorption of oxygen, but to the combination 
of the black oxyd of copper with carbonic 
acid. 
Copper has never been combined with car- 
bon nor hydrogen; but it combines readily 
with sulphur and phosphorus, and forms with 
them compounds called sulphuret and phos- 
plmret of copper. 
When equal parts of sulphur and copper 
are stratified alternately in a crucible, they 
melt, and combine at a red heat. Sulphuret 
of copper thus obtained is a brittle mass, 
of a black or very deep bind grey colour, 
much more fusible than copper ; and com- 
posed, according to the experiments of Mr. 
Proust, of 78 parts of copper, and 22 of sul- 
phur. The same compound may be formed 
by mixing copper filings and sulphur toge- 
ther, and making them into a paste with wa- 
ter, or even by merely mixing them toge- 
ther without any water, and allowing them to 
remain a sufficient time exposed to the air. 
Eight parts by weight of copper filings, 
mixed with three parts of flowers of sulphur, 
are put into a glass receiver, and placed upon 
burning coals : the mixture first melts, then a 
kind of explosion takes place ; it becomes 
red-hot, and, when taken from the fire, con- 
tinues to glow for some time like a live coal. 
If we now examine it, we find it converted 
into sulphuret of copper. This experiment 
has exc.ted great attention, and has been 
very often repeated ; because it is the only 
instance known of apparent combustion with- 
out the presence of oxygen. Mr. Proust has 
shewn that tire sulphuret of copper is capable 
of combining with an additional dose of sul- 
phur, and of forming a new compound which 
may be called supersulphuret of copper. It 
is brittle, has a yellow colour, and a me- 
tallic lustre ; and is found native abundantly, 
being well known to mineralogists by the' 
name of copper pyrites. 
M. Pelletier formed phosphuret of cop- 
per by melting together 16 parts of copper, 
16 parts of phosphoric glass, and one part of 
charcoal. Margraf was the first person who 
formed this phosphuret. His method was to 
distil phosphorus and oxyd of copper toge- 
ther. It is formed most easily by projecting 
phosphorus into red-hot copper. It is of a 
white colour ; and, according to Pelletier, is 
composed of 20 parts of phosphorus and 80 
of copper. This phosphuret is harder than 
Vol. 1. 
iron : it is not ductile, and yet cannot easily 
be pulverized. Its specific gravity is 7'. 1220. 
It crystallizes in four-sided prisms. It is 
much more fusible than copper. When ex- 
posed to the air it loses its lustre, becomes 
black, falls to pieces, the copper is oxydated, 
and the phosphorus converted into phospho- 
ric acid. When heated sufficiently the phos- 
phorus burns, and leaves the copper under 
the form of black scoriae. 
Copper is not capable of combining with 
azote. Muriatic acid gas readily converts 
it into an oxyd, with which it enters into 
combination. 
Copper is capable of combining with most 
of the metals ; and some o£ its alloys are of 
very great utility. 
The alloy of gold and copper is easily 
formed by melting the two metals together. 
This alloy is much used, because copper has 
the property of increasing the hardness of 
gold without injuring its colour. Muschen- 
broeck has ascertained that the hardness of 
this alloy is a maximum when it is composed 
of seven parts of gold and one of copper. 
The gold coin both in Britain and France is 
an alloy, containing eleven parts of gold and 
one of copper. Its specific gravity is consi- 
derably above the mean ; consequently the 
density of the metals is increased by alloying 
them together. It ought to be 17.153, but 
it actually is 17.486 ; so that the density is 
increased one-forty-eighth part. This alloy 
being more fusible than gold, is employed as 
a solder to join pieces of that metal toge- 
ther. 
Platinum may be alloyed with copper by 
fusion, but a strong heat is necessary. The 
alloy is ductile, hard, takes a fine polish, and 
is not liable to tarnish. This alloy has been 
employed with advantage for composing the 
mirrors of reflecting telescopes. 
Silver is easily alloyed with copper by fu- 
sion. This alloy is harder and more so- 
norous than silver, and yet the density of the 
metals is diminished. Thus when 137 parts 
of silver and 7 of copper are alloyed toge- 
ther, the specific gravity ought to be 10.3016, 
but it actually is 10.1752; consequently the 
bulk of the two metals is increased by alloy- 
ing them together about sV part. Y\ hen the 
proportion of copper is small the colour of 
the silver is not altered. The silver coin of 
tliis country is composed of 1 part of copper 
and 15 of silver ; that of France of 7 parts of 
copper and 137 of silver, or 1 part copper 
and 19.57 silver. The French silver coin 
therefore is purer than the British. 
The amalgam of copper cannot be formed 
by simply mixing that metal with mercury, 
nor even by the application of heat ; be- 
cause the heat necessary to melt copper sub- 
limes mercury. It may be obtained by tri- 
turating mercury with common salt and ver- 
digris, or by keeping plates of copper in a 
solution of mercury and nitric acid. The 
amalgam is at first soft, and will take any 
impression ; but it soon becomes hard when 
exposed to the air. 
The affinities of copper and its oxyds are 
exhibited by Bergman in the following or- 
der : 
Copper. Oxyd of Copper. 
Gold, 
Silver, 
Arsenic, 
Oxalic acid, 
Tartaric, 
Muriatic, 
3 I 
43’i 
Copper. 
Oxyd of Copper, 
Iron, 
Manganese, 
Zinc, 
Antimony, 
Platinum, 
Tin, 
Fead, 
N ickel. 
Bismuth, 
Cobalt, 
Mercury, 
Sulphur, 
Phosphorus. 
Sulphuric acid, 
Saclactic, 
Is 1 , trie. 
Arsenic, 
Phosphoric, 
Succinic, 
Fluoric, 
Citric, 
Lactic, 
Acetic, 
Bovacic, 
Prussic, 
Carbonic. 
Copper is not unfrequently found native 
and malleable, sometimes in small and slen- 
der fibres, and sometimes in little globular 
and irregular masses. However, it is most 
frequently found in the state of ore, some- 
times blended with the strata of stones, where 
it discovers itself in blue or green efflores- 
cences. The green and blue ochres also are 
a sort of ores of copper, and the pyritae and 
marcasites frequently contain large quantities 
of this metal. There is also a rich kind of 
copper ore of a reddish-grey colour ; and 
another of a dusky-purple or blackish co- 
lour. But besides all these there are two 
other appearances of copper ore, known by 
the names of lapis lazuli, and. the turcois or 
turquoise. 
In Germany and Sweden there are very 
good mines of copper ore ; and we have 
some in England, particularly in Cornwall, 
not inferior to the finest Swedish. 
In order to discover whether the pyrites 
contains any copper, let it be roasted in an 
open fire, and a solution made by pouring 
upon it a quantity of warm water : into tins 
solution let iron plates, perfectly clean and 
free from grease, be immersed ; and if the 
pyrites contains any copper it will stick to 
these iron plates, in form of a flue yellow 
powder. 
As to the method of obtaining copper from 
the ore, this last being previously washed 
and powdered, is smelted by means of a black 
flux ; and the metal is found at the bottom of 
the vessel when cold, in the form of a solid 
and malleable mass; which may be farther 
refined by repeating the operation. See Mi- 
neralogy. 
COPPERAS, a name given to the mar- 
tial or sulphate of green vitriol. See Iron, 
COPULA, in logic, the verb that con- 
nects any two terms in an affirmative or ne- 
gative: as, “ Riches make a man happy;” 
where make is the copula : “ No weakness 
is anv virtue ;” where is is the copula. 
COPULATIVE propositions, in logic, 
those where the subject and predicate are so 
linked together by copulative conjunctions, 
that they may be all severally affirmed or 
denied one of another. Example, “ Riches 
and honours are apt to elate the mind, and in- 
crease the number of our desires.” 
COPY, in a legal sense, is the transcript 
of an original writing ; as the copy of a pa- 
tent, of a charter, deed, &c. but a clause out 
of either cannot be given in evidence to prove 
the original, as it must be absolutely a true 
office-copy of the whole. 
COPYHOLD, a tenure for which the 
tenant has nothing to shew but the copy of 
the rolls made by the steward, as ho enrols 
