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.
The tetroxide, 0s04, is formed when osmium compounds are heated in air, or with aqua regia, or fused with caustic alkali and nitre.
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.
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.