Thermit was discovered by Dr. Hans Goldschmidt of Essen, Germany, in 1895, while trying to reduce chromium and manganese.
Soc., 1899, 55, p. 213), the mean value obtained being 52.06; and also by C. Meinecke, who estimated the amount of silver, chromium and oxygen in silver chromate, the amount of oxygen in potassium bichromate, and the amount of oxygen and chromium in ammonium bichromate (Ann., 1891, 261, p. 339), the mean value obtained being 51 99.
Goldschmidt (Annalen, 1898, 301, p. 19) in which the oxide is reduced by metallic aluminium; and if care is taken to have excess of the sesquioxide of chromium present, the metal is obtained quite free from aluminium.
Oxide of chromium and chrome iron ore have been proposed as refractory crucible materials.
The sesquioxide, Cr 2 0 3, occurs native, and can be artificially obtained in several different ways, e.g., by igniting the corresponding hydroxide, or chromium trioxide, or ammonium bichromate, or by passing the vapours of chromium oxychloride through a red-hot tube, or by ignition of mercurous chromate.
Chromium forms three series of compounds, namely the chromous salts corresponding to CrO, chromous oxide, chromic salts, corresponding to Cr203, chromium sesquioxide, and the chromates corresponding to Cr0,, chromium trioxide or chromic anhydride.
In New South Wales chromium is found in the northern portion of the state, in the Clarence and Tamworth districts and also near Gundagai.
Phenanthrenequinone).Alizarin black,C l oH 4 (OH) 2 0 2 NaHS03, the sodium bisulphite compound of 7.8 dioxy-anaphthoquinone, is a dyestuff used for printing on cotton in the presence of a chromium mordant The naphthoquinone is prepared by the action of zinc and concentrated sulphuric acid on a-dinitronaphthalene.
Carbides of chromium are known; when the metal is heated in an electric furnace with excess of carbon, crystalline, C2Cr 3, is formed; this scratches quartz and topaz, and the crystals are very resistant to the action of acids; CCr 4 has also been described (H.
In the amorphous state it is a dull green, almost infusible powder, but as obtained from chromium oxychloride it is deposited in the form of dark green hexagonal crystals of specific gravity 5 2.