The metal is chiefly used, as the oxide, for colouring glass and porcelain.
Metallic cobalt may be obtained by reduction of the oxide or chloride in a current of hydrogen at a red heat, or by heating the oxalate, under a layer of powdered glass.
As prepared by the reduction of the oxide it is a grey powder.
Cobalt burns in nitric oxide at 150° C. giving the monoxide.
Cobalt monoxide, CoO, is prepared by heating the hydroxide or carbonate in a current of air, or by heating the oxide C0304 in a current of carbon dioxide.
It is a brown coloured powder which is stable in air, but gives a higher oxide when heated.
Heated at 190-300° in a current of hydrogen it gives the oxide C0304, while at higher temperatures the monoxide is formed, and ultimately cobalt is obtained.
The cobaltous salts are formed when the metal, cobaltous oxide, hydroxide or carbonate, are dissolved in acids, or, in the case of the insoluble salts, by precipitation.
The most common of these sulphides is cobaltous sulphide, CoS, which occurs naturally as syepoorite, and can be artificially prepared by heating cobaltous oxide with sulphur, or by fusing anhydrous cobalt sulphate with barium sulphide and common salt.
Cobaltous sulphate, CoSO 4.7H 2 O, is found naturally as the mineral bieberite, and is formed when cobalt, cobaltous oxide or carbonate are dissolved in dilute sulphuric acid.
For the quantitative determination of cobalt, it is either weighed as the oxide, C0304, obtained by ignition of the precipitated monoxide, or it is reduced in a current of hydrogen and weighed as metal.
If an air-tight receptacle is not available, a small percentage of powdered carbon is added to the zinc-dust, to prevent increase in the amount of oxide, which, if present in excess, tends to make the deposit dull.
(For the significance of this fact see Radioactivity.) The richest known source is thorianite, which consists mainly of thorium oxide, and contains 9.5 cc. of helium per gram.
It may be prepared by boiling a-dichlorpropionic acid with silver oxide; by the hydrolysis of acetyl cyanide with hydrochloric acid (J.
Phys., 1895, 6, p. 296) heats three parts of the oxide with one part of magnesium powder.
The dark product obtained is washed with water, hydrochloric acid and hydrofluoric acid, and finally calcined again with the oxide or with borax, being protected from air during the operation by a layer of charcoal.
It reduces many metallic oxides, such as lead monoxide and cupric oxide, and decomposes water at a red heat.
Boron trioxide B203 is the only known oxide of boron; and may be prepared by heating amorphous boron in oxygen, or better, by strongly igniting boric acid.
It is not volatile below a white heat, and consequently, if heated with salts of more volatile acids, it expels the acid forming oxide from such salts; for example, if potassium sulphate be heated with boron trioxide, sulphur trioxide is liberated and potassium borate formed.
Claus, Ber., 1873, 6, p. 723); by passing aniline vapour over lead oxide, or by the oxidation of dihydrophenazine, which is prepared by heating pyrocatechin with orthophenylene diamine (C. Ris, Ber., 1886, 19, p. 2206).
Zinc ores, in the several varieties of carbonates, silicates, oxide, sulphide and sulphate of zinc, have been found in several of the Australian states, but have attracted little attention except in New South Wales, where special efforts are being made successfully to produce a high-grade zinc concentrate from the sulphide ores.
The oxide is a black or brown powder according as it is prepared from the exalate or sulphate, and when pure it is non-fluorescent, but mixed with gadolinia or alumina it possesses this property.
Simultaneously Hermann, a German chemical manufacturer, discovered the new metal in a specimen of zinc oxide which had been thought to contain arsenic, since it gave a yellow precipitate, in acid solution, on the addition of sulphuretted hydrogen.
The metal is quite permanent in dry air, but in moist air it becomes coated with a superficial layer of the oxide; it burns on heating to redness, forming a brown coloured oxide; and is readily soluble in mineral acids with formation of the corresponding salts.
Cadmium vapour decomposes water at a red heat, with liberation of hydrogen, and formation of the oxide of the metal.
Half a century later, nitrous oxide came into use as an anesthetic.