Ferrous selenide

Aluminium and magnesium selenides are very similar light brown powders, unstable in air. Zinc and iron (ferrous) selenides are more stable in air, the zinc compound being citron-yellow and the iron compound black and metallic in appearance.8 The latter becomes brown in air owing to oxidation. Ferric selenide is difficult to obtain pure. Cadmium selenide, which is dark brown, is very stable in colour and is used as a pigment. With thallium, selenium is said to form three distinct compounds,9 but analyses of these compounds have led to discordant results. The selenides of aluminium, chromium and uranium cannot be prepared in the wet way. Nickel selenide, unlike the sulphide, shows no tendency to form a colloidal solution. 

Carbon Sulphidoselenide, CSSe, may be prepared by the action of carbon disulphide vapour on ferrous selenide at 650° C. The product, on fractional distillation through a 50-inch head-filled glass column, yields a deep yellow liquid as residue, which on repeated fractionation through the same column yields a middle fraction of the pure sulphidoselenide. It is obtained as a yellow oil of boiling-point 88-90° to 83-95° C. at 749-2 mm., and having a surface tension y =40-44 dynes/cm. at 20° C. 

When iron and selenium are heated together to a high temperature, combination takes place, but the product usually contains more selenium than corresponds to the monoselenide or ferrous selenide, FeSe. By heating the product m hydrogen, however, the monoselenide results,7 8 further reduction to a sub-selenide not taking place, although the selenides of nickel and cobalt are reduced to sub-selenides under like conditions. 

Ferrous selenide was first obtained by Divers and Shimidzu 9 by heating a mixture of wrought-iron filings and selenium in a graphite pot. When the mixture had grown hot, a considerable portion of the selenium had volatilised and a further portion was added which combined with the iron with very little loss, causing vivid ignition and complete liquefaction. The product thus obtained closely resembles iron sulphide. It is not very sensitive to acids, but when warmed with... 

OTHER COMMENTS prepared by heating selenium and hydrogen in a sealed tube at 440°C, by passing a mixture of hydrogen and selenium vapor over pumice stone at 440°C, or by warming potassium or ferrous selenide with hydrochloric acid. 

Cadmium sulfo-selenide ferrous oxide None 2 7 19 - -... 

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