| es 
of metallic copper, in a state of fine division, 
with 80 parts of the peroxide, and heating the 
mixture to redness in a close vessel; or by boil- 
ing a solution of the acetate of copper with sugar, 
when the peroxide is gradually deoxidized, and 
subsides as a red powder. It consists of one 
atom, or proportional, of copper, 64, and one of 
oxygen, 8,==72. The sulphuric, muriatic, and 
probably several other acids, form with it salts, 
which, for the most part, are colourless. On ex- 
posure to the air, they attract oxygen, and are 
rapidly converted into per-salts. The peroxide 
of copper is also found native, and may be pre- 
pared artificially by calcining metallic copper, by 
precipitation from the per-salts of copper, by 
means of pure potash, or by heating the nitrate 
of copper to redness. It is composed of one atom 
of copper, 64, and two of oxygen, 16,==80. It va- 
ries in colour from a dark-brown to a bluish- 
black, is insoluble in water, and does not affect 
the vegetable blue colours. It undergoes no 
change by heat alone, but is readily reduced to 
the metallic state by heat and combustible mat- 
ter. It combines with nearly all the acids, and 
most of its salts have a green or blue tint. It is 
soluble, likewise, in ammonia, forming with it a 
deep blue solution—a property by which the per- 
oxide of copper is distinguishable from all other 
substances. Metallic copper is oxidated and dis- 
solved by the greater number of the acids, and 
forms with them, in general, soluble and crystal- 
lizable salts. Sulphuric acid, either concentrated 
or diluted, oxidates it, and combines with the 
peroxide, especially when assisted by heat. The 
solution is of a blue colour, and, when evaporated, 
affords crystals in the form of rhomboidal prisms. 
This salt is the due vitriol of commerce, and is 
usually obtained, either by evaporation of the 
solution of it, formed by the infiltration of water 
through copper mines, or by exposure of sul- 
phuret of copper to the action of air and humi- 
dity, until the sulphur is converted into sulphu- 
ric acid, and the metal is oxidated and combined 
with it. Nitric acid acts on copper with great 
energy, the metal attracting a portion of its 
oxygen, nitric oxide gas being disengaged, and 
the oxide combining with the remaining acid. 
The solution, when evaporated, affords prismatic 
crystals, of a deep green colour, deliquescent, and 
easily soluble in water. From the facility with 
which it parts with oxygen, it acts with energy 
on several substances. Thus it detonates when 
struck with phosphorus, and it burns several of 
the metals. If wrapped in tinfoil, the tin is oxi- 
dated with such rapidity as to be attended with 
inflammation. Muriatic acid dissolves copper 
slowly, when the air is admitted: if it is excluded, 
the action is very inconsiderable, unless heat is 
applied. The solution is of a fine green colour, 
and, by evaporation, slender prismatic crystals 
are obtained, which are diliquescent, and very so- 
luble in water. The combinations of peroxide of 
a 
COPPER. 
861 
acids, are effected by adding to a solution of ni- 
trate or sulphate of copper a solution of a neutral 
salt, containing the acid with which the copper 
is designed to be combined. Copper is slowly 
oxidated by a number of weaker acids, as by some 
vegetable juices, when acted on by them with the 
admission of air. Acetic acid, or vinegar, in par- 
ticular, forms an important compound with the | 
oxide of copper. ‘To obtain it, copper plates are 
exposed to the fumes of vinegar. A crust is soon 
formed of a green colour, which is the verdigris 
of commerce. 
All the salts of copper are decomposed by the 
alkalies and earths. Potash, soda, and the alka- 
line earths, throw down precipitates, which are 
of various shades of green or blue, according to 
the quantity of alkali added, the colour being 
green if a small quantity is added, and becoming 
blue from a larger quantity. ‘These precipitates 
are sub-salts, the alkali attracting the greater 
portion of the acid, but the oxide precipitated 
still retaining a portion of the acid combined 
with it. The action of ammonia upon the salts 
of copper is more remarkable. It first abstracts 
a portion of the acid, and throws down a green 
or blue precipitate, which is a sub-salt; but, 
when added in larger quantity, it redissolves this 
precipitate, and forms a transparent solution of 
a very deep-blue colour, which, when evaporated, 
affords fine blue crystals. A triple compound, 
used in medicine under the name of ammonzuret 
of copper, is prepared by triturating together two 
parts of sulphate of copper with one part of car- 
bonate of ammonia, the mass becoming soft from 
the mutual action of the two salts, the carbonic 
acid being disengaged with effervescence, and 
the triple compound of sulphuric acid, oxide of 
copper, and ammonia, being obtained of a deep 
violet-blue colour. Copper is precipitated in its 
metallic state, from its saline solutions, by zinc 
and iron; either of these metals attracting the 
oxygen which serves as the medium of its union 
with the acid of the solution. Its oxide is pre- 
cipitated by albumen, and the precipitate is al- 
most inert; hence the whites of eggs have been 
recommended as an antidote to the poisonous 
salts of copper.—The best mode of detecting cop- 
per, when suspected to be present in mixed fluids, 
is by sulphuretted hydrogen. The sulphuret, 
after being collected, should be placed on a piece 
of porcelain, and digested in a few drops of nitric 
acid. A sulphate of copper is formed, which, 
when evaporated to dryness, strikes the charac- 
teristic deep blue, on the addition of a drop of 
ammonia.—Oopper and sulphur unite by fusion, 
the combination being attended with the evolu- 
tion of heat and light. A bi-sulphuret of copper 
also exists in copper pyrites. Copper combines 
with a great number of the metals by fusion. It 
communicates: hardness to gold and silver, with- 
out much impairing their ductility, or debasing 
their colour, when in small proportion; hence it 
copper with phosphoric, carbonic, and other | is employed in the standard alloys of these metals, 
