electrolysis on other metals, forming a hard, brilliant, non-tarnishing coating.
Nickelic Oxide. Ni2O3. Syn. Sesquioxide of nickel, Peroxide of nickel. Prep. By passing chlorine through water holding the hydrate in suspension; or by mixing a salt of nickel with bleaching powder. An insoluble, black powder, which is decomposed by heat.
Nick′elous Ace′tate. Ni(C2H3O2)2. Syn. Nickelii acetas, L. Prep. By neutralising acetic acid with nickelous carbonate, and gently concentrating by evaporation, so that crystals may form. Small green crystals, soluble in 6 parts of water.
Nickelous Car′bonate. NiCO3 Syn. Nickelii carbonas, L. Prep. This salt may be obtained in the manner described above in connection with the preparation of metallic nickel, or by simply adding carbonate of sodium to a solution of nickelous chloride of sulphate, but in this case some hydrate is precipitated along with it. The following is another formula which produces a nearly pure carbonate, but one which may still contain a little cobalt, the entire separation of which is a matter of extreme difficulty, and can best be effected in the manner recommended by Rose, described above:—
The mineral (crude speiss or kupfernickel) is broken into small fragments, mixed with from one fourth to one half its weight of iron filings, and the whole dissolved in aqua regia; the solution is gently evaporated to dryness, the residue treated with boiling water, and the insoluble ferrous arseniate removed by filtration; the liquid is next acidulated with hydrochloric acid, treated with sulphuretted hydrogen, in excess, to precipitate the copper, and, after filtration, is boiled with a little nitric acid, to bring back the iron into ferric salts; to the cold and largely diluted liquid a solution of bicarbonate of sodium is gradually added, and the ferric oxide separated by filtration; lastly, the filtered solution is boiled with carbonate of sodium in excess, and the pale green precipitate of carbonate collected, washed, and dried.
Uses, &c. It is freely soluble in the acids, and is chiefly employed to prepare the salts and other compounds of nickel.
Nickelous Chlo′′ride. NiCl2. Syn. Nickelii chloridum, L. Prep. From nickelous carbonate and hydrochloric acid, as the acetate. Small green crystals, of the formula NiCl2,9Aq., which are rendered yellow and anhydrous by heat, unless they contain cobalt, when the salt retains a tint of green.
Double Chlorides. Nickelous chloride unites with the chlorides of ammonium, potassium, and sodium, to form pale green crystallisable salts, which have been used for depositing nickel in iron, lead, copper, &c.
Nickelous Hy′drate. Ni(HO)2. By precipitating a soluble salt of nickel with caustic potassa. Hydrated. An ash-gray powder, freely soluble in acids, forming the ordinary salts of nickel.
Nickelous Ox′alate. NiC2O4. Syn. Nickelii oxalas, L. Prep. By adding a strong solution of oxalic acid to a like solution of nickelous sulphate, and collecting the pale bluish-green precipitate which forms after a time. Used to prepare both metallic nickel and its oxide.