Germanium sulfide, precipitated

Extraction. — Germanium ores may be decomposed in a number of ways. (1) The mixed sulfides may be dissolved in strong sulfuric acid and evaporated to dryness. If the sulfates are taken up with water and treated with sodium sulfide, both zinc and germanium are precipitated. The former may be dissolved in sulfuric acid (15 100) while the germanium sulfide remains in solid form. (2) A more satisfactory separation is usually accomplished by suspending the oxides in 1 2 HC1 and saturating with H2S. Filter, wash with dilute HC1, and... 

Separation. — From most of the metals, germanium may be separated by the formation of the sulfo-salts with ammonium sulfide. It may be separated from arsenic, antimony, and tin by exactly neutralizing the sulfo-salts with sulfuric acid and filtering after 12 hours. Evaporate to small bulk, add ammonia, ammonium sulfate, and sulfuric acid and saturate with H. GeS2 precipitates while the other metals remain in solution. 

The other germanium dihalides are less stable and less well studied, but salts of the ion GeClj" are well known.53 The sulfide, GeS, and a yellow amphoteric hydroxide, Ge(OH)2, are known the latter is precipitated by base from GeIV solutions in H2S04 that have been reduced by zinc. 

When this test is performed, it is essential that the acid strength be not less than that stated or germanium (II) sulfide may precipitate. The formation of an orange-colored precipitate on standing is indicative not of incomplete reduction but rather of partial atmospheric oxidation of the material in solution. 

Unlike germanium(IV) sulfide, which may be precipitated by means of hydrogen sulfide only from solutions that are more acid than 6 N, germanium(II) sulfide may be obtained only from weakly acid or alkaline solutions and redissolves if the acidity is increased. When dry, ger-manium(II) sulfide is stable in air. 

Not all the (Il)iodide wiU separate from the concentrated hydriodic acid solution. The germanium in the filtrate is recovered by diluting it and precipitating germanium(II) sulfide. 

The sublimed germaniun(II) sulfide, recovered from germanite, is usually not pure but contains lead and arsenic sulfides. These are eliminated during the process of preparing the (Il)iodide and need not be removed previously. After oxidation of the residues left in the reaction flask, however, it is convenient to precipitate these elements by hydrogen sulfide from a dilute acid solution (0.2 N) before recovery of the germanium as the (IV)sulfide that is precipitated from a 6 iV acid solution. ... 

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