GERMANIUM (symbol Ge, atomic weight 72.5); one of the metallic elements included in the same natural family as carbon, silicon, tin and lead.
Two oxides of germanium are known, the dioxide, GeO2, being obtained by roasting the sulphide and treatment with nitric acid.
By heating the metal with chlorine, germanic chloride, GeCl4, is obtained as a colourless fuming liquid boiling at 86-87° C., it is decomposed by water forming a hydrated germanium dioxide.
Germanium dichloride, GeCl2, and germanium chloroform, GeHCl3, have also been described.
Germanium compounds on fusion with alkaline carbonates and sulphur form salts known as thiogermanates.
If excess of a mineral acid be added to a solution of an alkaline thiogermanate a white precipitate of germanium disulphide, GeS2, is obtained.
Alkyl compounds of germanium such as germanium tetra-ethyl, Ge(C2H5)4, a liquid boiling at C., have been obtained.
The germanium salts are most readily recognized by the white precipitate of the disulphide, formed in acid solutions, on passing sulphuretted hydrogen.
Other elements predicted and characterized by Mendeleeff which have been since realized are gallium, discovered in 1875, and germanium, discovered in 1885 by Clemens Winkler.
Nilson and Pettersson's observations on beryllium and germanium have shown that the atomic heats of these metals increase with rise of temperature, finally becoming constant with a value 5.6.
C. Winkler decided the atomic weight of germanium by similar reasoning.
At the same time, however, it forms a number of compounds in which it is most decidedly tetravalent; and thus it shows relations to carbon, silicon, germanium and tin.
These three he called ekaboron, ekaaluminium, and ekasilicon; and his prophecy was completely vindicated within fifteen years by the discovery of gallium in 1871, scandium in 1879, and germanium in 1886.
Other pairs of isomorphous argentiferous minerals are: the cubic polybasite, 9Ag2S Sb2S3, and pearceite, 9Ag2S As2S3; and the germanium minerals argyrodite, 4Ag 2 S GeS2, and canfieldite, 4Ag 2 S (Sn, Ge) S2.