Three characteristic oxides of cobalt are known, the monoxide, CoO, the sesquioxide, C0203, and tricobalt tetroxide, C0304; besides these there are probably oxides of composition Co02, Co 8 0 9, C0607 and C0405.
Tricobalt tetroxide, C0304, is produced when the other oxides, or the nitrate, are heated in air.
Pure ruthenium tetroxide distils over.
Red lead or triplumbic tetroxide, Pb304, is a scarlet crystalline powder of specific gravity 8.6-9.1, obtained by roasting very finely divided pure massicot or lead carbonate; the brightness of the colour depends in a great measure on the roasting.
Three oxides of columbium are certainly known, namely the dioxide, Cb202, the tetroxide, Cb 2 0 4, and the pentoxide, Cb 2 0 5, whilst a fourth oxide, columbium trioxide, Cb203, has been described by E.
Tetroxide, Cb204, is obtained as a black powder when the pentoxide is heated to a high temperature in a current of hydrogen.
Bismuth tetroxide, Bi 2 O 4, sometimes termed bismuth bismuthate, is obtained by melting bismuth trioxide with potash, or by igniting bismuth trioxide with potash and potassium chlorate.
It is also formed by oxidizing bismuth trioxide suspended in caustic potash with chlorine, the pentoxide being formed simultaneously; oxidation and potassium ferricyanide simply gives the tetroxide (Hauser and Vanino, Zeit.
An alternative method consisted in passing an electric current through a filament of the tetroxide in a vacuum.
Tantalum tetroxide, Ta 2 0 4, is a porous dark grey mass harder than glass, and is obtained by reducing the pentoxide with magnesium.
The tetroxide, 0s04, can be easily reduced to the metal by dissolving it in hydrochloric acid and adding zinc, mercury, or an alkaline formate to the liquid, or by passing its vapour, mixed with carbon dioxide and monoxide, through a red-hot porcelain tube.
The dioxide, 0s0 2, is formed when potassium osmichloride is heated with sodium carbonate in a current of carbon dioxide, or by electrolysis of a solution of the tetroxide in the presence of alkali.
Potassium osmiate, K 2 0sO 4 2H 2 0, formed when an alkaline solution of the tetroxide is decomposed by alcohol, or by potassium nitrite, crystallizes in red octahedra.
The tetroxide, 0s04, is formed when osmium compounds are heated in air, or with aqua regia, or fused with caustic alkali and nitre.
Potassium osmichloride, K 2 OsC1 6, is formed when a mixture of osmium and potassium chloride is heated in a current of chlorine, or on adding potassium chloride and alcohol to a solution of the tetroxide in hydrochloric acid.
Iodine has no action on osmium, but on warming the tetroxide with a mixture of potassium iodide and hydrochloric acid a deep emerald green colour is produced, due to the formation of a compound 0s12.2H1; this reaction is a delicate test for osmium (E.
Trimanganese tetroxide, Mn304, is produced more or less pure when the other oxides are heated.
Antimony may be estimated quantitatively by conversion into the sulphide; the precipitate obtained is dried at too° C. and heated in a current of carbon dioxide, or it may be converted into the tetroxide by nitric acid.
There are three known oxides of antimony, the trioxide Sb406 which is capable of combining with both acids and bases to form salts, the tetroxide Sb204 and the pentoxide Sb205.
The corresponding hydroxide, orthoantimonious acid, Sb(OH) 31 can be obtained in a somewhat impure form by precipitating tartar emetic with dilute sulphuric acid; or bet::er by decomposing antimonyl tartaric acid with sulphuric acid and drying the precipitated white powder at too° C. Antimony tetroxide is formed by strongly heating either the trioxide or pentoxide.
Antimony trichloride ("Butter of Antimony"), SbCl 31 is obtained by burning the metal in chlorine; by distilling antimony with excess of mercuric chloride; and by fractional distillation of antimony tetroxide or trisulphide in hydrochloric acid solution.
On precipitating antimony trichloride or tartar emetic in acid solution with sulphuretted hydrogen, an orange-red precipitate of the hydrated sulphide is obtained, which turns black on being heated to 200° C The trisulphide heated in a current of hydrogen is reduced to the metallic state; it burns in air forming the tetroxide, and is soluble in concentrated hydrochloric acid, in solutions of the caustic alkalis, and in alkaline sulphides.
It is comparatively stable up to 200°, but when heated in a sealed tube to 440° it gives phosphorus and the tetroxide P204.
Phosphorus tetroxide, P204, was obtained by Thorpe and Tutton by heating the product of the limited combustion of phosphorus in vacuo as a sublimate of transparent, highly lustrous, orthorhombic crystals.
The tetroxide, V204, results when the pentoxide is heated with dry oxalic acid and the resulting mixture of the triand pentoxide is warmed in the absence of air, or when the pentoxide is reduced by sulphur dioxide.