Germanous Sulphide, GeS

Germanous Sulphide, GeS, the best characterised germanous compound, may be prepared in the dry or wet way. In the dry way it is produced by heating a mixture of the disulphide and metallic germanium in a current of carbon dioxide, or by igniting the disulphide in a stream of hydrogen. In the latter case reduction may proceed as far as the metal. In the wet way the sulphide is obtained by precipitating a germanous solution with hydrogen sulphide. Precipitated, amorphous germanous sulphide is brownish red, but when this compound is prepared in the dry way it is obtained in thin greyish black, metallic-looking plates, which are rhombic or monoclinic and appear red by transmitted light; it melts to a dark-coloured liquid and can be vaporised without decomposition, the vapour density at 1100° C. being 3.54 (air = 1) or 51.0 (H = 1), theory for GeS requiring 3.60 (air = 1) or 51.8 (H = 1). This sulphide is slightly soluble in water, and dissolves in concentrated hydrochloric acid, forming a solution from which it is reprecipitated by hydrogen sulphide, thus:

GeS + 2HCl ⇔ GeCl₂ + H₂S.

It also dissolves in alkalis and is precipitated again by acid; with yellow ammonium sulphide it forms a thio-salt of GeS₂. Thus GeS resembles SnS in chemical properties, though it is probably more acidic than the latter sulphide. When the precipitated sulphide is washed it shows a tendency to pass into the colloidal state.