ferric oxide

1. Chem.: Fe2O3, peroxide of iron, sesquioxide of iron, red oxide of iron, rouge, colcothar. It occurs in nature, as red hæmatite, specular iron ore, and is obtained by heating, FeSO4, ferrous sulphate in the preparation of sulphuric acid. It is a red powder, nearly insoluble in acids; it is used as a pigment, and to give an orange or purple color to gla and porcelain, according to temperature. Ferric oxide is not magnetic, and is unaltered by heat. It is used to polish gla , and then finely divided by jewelers under the name of rouge. The hydrated sesquioxide is obtained in a bulky brown precipitate by precipitating ferric chloride by ammonia; soda or potash must not be used, as the oxide retains a large quantity of these substances. The hydrate occurs native, as brown hæmatite. Hydrated ferric oxide is soluble in acids forming ferric salts; these solutions di olve exce of the oxide, which is afterward precipitated as a basic salt. The hydrated oxide is used to remove H S from coalgas, and as a mordant in dyeing. It is reduced by organic matter, but is reoxidized in the air. Ferric oxide unites with ferrous oxide to form magnetic oxide of iron, Fe2O3 FeO, or Fe3O4. [MAGNETIC IRON OXIDE.] 2. Pharm .: Ferri peroxidum hydratum , hydrated peroxide of iron. Obtained by drying the moist peroxide of iron at 212 F., and then reducing it to powder. It is used in the preparation of Emplas trum ferri , chalybeate laster. Ferric oxide is a non-irritating preparation of iron: it is given internally in cases of neuralgia. Ferri peroridum humidum , moist peroxide of iron. Obtained by precipitating persulphates of iron with soda, collecting on a a calico filter, and keeping in a covered ve el; it contains about 86 per cent. of uncombined water. It is used as an antidote in cases of arsenical poisoning: it converts the arsenious acid into insoluble arsenate of iron.