A cuproso-cupric sulphite, Cu2S03, CuSO 3, 2H 2 0, is obtained by mixing solutions of cupric sulphate and acid sodium sulphite.
A neutral solution of an arsenite gives a yellow precipitate of silver arsenite, Ag3AsO3, with silver nitrate solution, and a yellowish-green precipitate (Scheele's green) of cupric hydrogen arsenite, CuHAsO3, with copper sulphate solution.
After having previously roasted the tube and copper oxide, and reduced the copper spiral a, the weighed calcium chloride tube and potash bulbs are put in position, the boat containing the substance is inserted (in the case of a difficultly combustible substance it is desirable to mix it with cupric oxide or lead chromate), the copper spiral (d) replaced, and the air and oxygen supply connected up. The apparatus is then tested for leaks.
Among the analytical methods worked up by him the best known is that for the estimation of sugars by "Fehling's solution," which consists of a solution of cupric sulphate mixed with alkali and potassium-sodium tartrate (Rochelle salt).
Another mode of separating the two acids is to convert them into calcium salts, which are then treated with a perfectly neutral solution of cupric chloride, soluble cupric citrate and calcium chloride being formed, while cupric tartrate remains undissolved.
Copper arsenate is similar to cupric phosphate, and the resemblance is to be observed in the naturally occurring copper arsenates, which are generally isomorphous with the corresponding phosphates.
Copper dioxide, CuO 2 H 2 O, is obtained as a yellowish-brown powder, by treating cupric hydrate with hydrogen peroxide.
Copper sulphate is readily soluble in water, but insoluble in alcohol; it dissolves in hydrochloric acid with a considerable fall in temperature, cupric chloride being formed.
Copper sulphide may be converted either into the sulphate, which is soluble in water; the oxide, soluble in sulphuric or hydrochloric acid; cupric chloride, soluble in water; or cuprous chloride, which is soluble in solutions of metallic chlorides.
Cu2S5, Cu 2 S 6, Cu4S5, Cu 2 S 3, have been described; they are all unstable, decomposing into cupric sulphide and sulphur.
Cupric chloride Obtained either by dissolving cupric chloride Obtained either by dissolving cupric oxide in hydrochloric acid or by the action of chlorine on copper.
Cupric chloride, CuC1 2, is obtained by burning copper in an excess of chlorine, or by heating the hydrated chloride, obtained by dissolving the metal or cupric oxide in an excess of hydrochloric acid.
Cupric fluoride, CuF 2, is obtained by dissolving cupric oxide in hydrofluoric acid.
Cupric hydroxide, Cu(OH) 2, is obtained as a greenish-blue flocculent precipitate by mixing cold solutions of potash and a cupric salt.
Cupric iodide is only known in combination, as in Cu12, 4NH 31 H 2 O, which is obtained by exposing Cu 2 I 2, 4NH 3 to moist air.
Cupric nitrate, Cu(NO 3) 2, is obtained by dissolving the metal or oxide in nitric acid.
Cupric oxide, CuO, occurs in nature as the mineral melaconite (q.v.), and can be obtained as a hygroscopic black powder by the gentle ignition of copper nitrate, carbonate or hydroxide; also by heating the hydroxide.
Cupric sulphate is obtained commercially by the I 91,000 96,000 1 35, 000 218,400 291,000 900,000 oxidation of sulphuretted copper ores (see above, Metallurgy; wet methods), or by dissolving cupric oxide in sulphuric acid.
Cupric sulphate or " Blue Vitriol," CuSO 4, is one of the most important salts of copper.
Cuprous iodide, Cu 2 l 21 is obtained as a white powder, which suffers little alteration on exposure, by the direct union of its components or by mixing solutions of cuprous chloride in hydrochloric acid and potassium iodide; or, with liberation of iodine, by adding potassium iodide to a cupric salt.
Cuprous oxide corresponds to the series of cuprous salts, which are mostly white in colour, insoluble in water, and readily oxidized to cupric salts.
Cuprous oxide is reduced by hydrogen, carbon monoxide, charcoal, or iron, to the metal; it dissolves in hydrochloric acid forming cuprous chloride, and in other mineral acids to form cupric salts, with the separation of copper.
Ferrous chloride decomposes the copper oxide and carbonate with the formation of cuprous and cupric chlorides (which remain in solution), and the precipitation of ferrous oxide, carbon dioxide being simultaneously liberated from the carbonate.
It decomposes when heated to 900; with water it gives nitric oxide and cupric nitrate and nitrite.
It is also obtained by burning the metal in chlorine, by heating copper and cupric oxide with hydrochloric acid, or copper and cupric chloride with hydrochloric acid.
It precipitates platinum, gold and silver from solutions of their salts, and also reduces mercuric, cupric and ferric salts.
It reduces many metallic oxides, such as lead monoxide and cupric oxide, and decomposes water at a red heat.
Merrill, it decomposes when heated, and gives cupric hydride, CuH 21 as a reddish-brown spongy mass, which turns to a chocolate colour on exposure.
Normal cupric carbonate, CuCO 3, has not been definitely obtained, basic hydrated forms being formed when an alkaline carbonate is added to a cupric salt.
Oils which contain sulphur-compounds are subjected to a special process of refining in which cupric oxide or litharge is employed as a desulphurizing agent.
Scheele's green is a basic copper arsenite; Schweinfurt green, an aceto-arsenite; and Casselmann's green a compound of cupric sulphate with potassium or sodium acetate.
The bulk of the copper is thus transformed into cupric chloride, little cuprous chloride being obtained.
The most important are cuprous oxide, Cu 2 0, and cupric oxide, CuO, both of Oxides which give rise to well-defined series of salts.
The only substance which possesses sufficiently strong catalytic properties for the reaction is cupric chloride.
The oxychloride Cu 3 0 2 C1 2.4H 2 O is obtained as a pale blue precipitate when potash is added to an excess of cupric chloride.
The phosphide obtained by heating cupric phosphate, Cu 2 H 2 P 2 O 81 in hydrogen, when mixed with potassium and cuprous sulphides or levigated coke, constitutes " Abel's fuse," which is used as a primer.
The precipitation of the copper from the solution, in which it is present as sulphate, or as cuprous and cupric chlorides, is generally effected by metallic iron.
The rationale of the process is that the sulphite hardly acts upon the dissolved oxide of silver, but it reduces some of the cupric oxide to cuprous oxide, which reduces its equivalent of silver oxide to silver and reforming cupric oxide which passes through the same cycle.
The salts derived from cupric oxide are generally white when anhydrous, but blue or green when hydrated.
This is imperfectly accomplished, in the wet way, by cupric and cuprous chloride solutions, but completely so, in the dry way, by roasting with salt (chloridizing roasting).
This salt, insoluble in water but soluble in brine, also acts upon argentite (Ag 2 S-+-Cu 2 C1 2 =2AgC1±-CuS±-Cu) and pyrargyrite (2Ag 3 SbS 3 -I-Cu 2 C12 = 2AgC1 +Ag 2 S +2Ag +2CuS +Sb2S3), and would give with silver sulphide in the presence of quicksilver, the Patioreaction; metallic silver, cupric sulphide, and mercurous chloride (2Ag 2 S+Cu 2 C1 2 +2Hg=4Ag+2CuS+Hg 2 C1 2), but the iron decomposes the quicksilver salt, setting free the quicksilver.
Thus cupric chloride dissolves in much water with an evolution of heat, but when the solution is nearly saturated, it is cooled by taking up more of the solid.
When salt and copper sulphate are added to the charge, they form sodium sulphate and cupric chloride, both of which are readily soluble in water.