Germanic Oxide, GeO₂

The preparation of germanic oxide from argyrodite has already been described Under the metal. This oxide may also be obtained by burning the metal, by oxidising the sulphide by nitric or sulphuric acid or by roasting, and by decomposing the chloride with water and igniting the product.

Germanium dioxide is a dense white powder, having a density of 4.703 at 18° C.; it can be melted to a clear liquid, but is not volatile at 1025° C. It is somewhat soluble in water, 1 part dissolving in 247.1 parts of water at 20° C. and in 95.3 parts at 100° C.; the solution reacts acid, and from it on evaporation the anhydrous oxide separates in microscopic rhombic crystals. The ignited oxide forms with water an emulsion which becomes clear on heating owing to the formation of a colloidal solution. Germanium dioxide dissolves both in acids and alkalis; in the former case germanic salts appear to be produced in solution, in the latter alkali germanates. Carbon dioxide precipitates colloidal hydrated germanic oxide from alkali solution.4 Neither of the hydroxides GeO(OH)₂ or Ge(OH)₄ is definitely known.