352 Browning and TJhler — Gallium-Indium Alloy. 



strongly acid with hydrochloric acid and precipitating as the 

 ferrocyanide.* 



Gallium may be precipitated electrolytically by passing a 

 current through an alkaline solution containing the element. f 

 By this method gallium may be separated from indium, as our 

 experiments have shown, practically no spectrographs evi- 

 dence of indium being found in the product. 



A fractional crystallization of the ammonium-gallium and 

 the ammonium-indium alums has resulted after six crystalliza- 

 tions in a marked separation, the ammonium-gallium, at the 

 less soluble end of the series, giving no flame test for indium, 

 while the ammonium-indium alum, at the more soluble end, 

 gave abundant evidence of indium in the flame. This method 

 will be studied more in detail with the substitution of other 

 alkalies for ammonium. The fact that gallium and indium are 

 alum-forming elements makes this method promising for the 

 removal of the non alum-forming elements which may be 

 associated with them, and this possibility also will be further 

 investigated. 



The results obtained by purely physical processes will now 

 be presented. Since no data on the boiling point of gallium 

 could be found the following experiments were performed. 

 A transparent silica tube, of internal diameter O7 om and about 

 30 cm long, was first sealed off round at one end by fusion in 

 an oxygen-illuminating gas flame. After introducing about 

 0*4 cm 3 of the alloy, the tube was joined by sealing-wax to a 

 long glass tube which led to a Gaede rotary mercury pump. 

 The fused end of the tube where the alloy was situated was 

 heated red hot for three hours with an ordinary blast flame 

 while the pump was kept in action and the sealing wax was 

 cooled by running water. The silica tube was nearly horizon- 

 tal and the pressure in the glass tube was less than 0'0005 mm . 

 This process removed all the zinc and other elements of rela- 

 tively low boiling points but the gallium-indium alloy showed 

 no signs of boiling. A bulb made from a silica test-tube was 

 then fused to the end of a new quartz tube and the liquid 

 globule which had not distilled in the previous heating was 

 dropped into the bulb. While the pump and ordinary blast 

 flame were kept going the bulb was also heated very cautiously 

 with an oxygen-illuminating gas flame. The alloy then disin- 

 tegrated with violence, shooting very fine particles of the 

 liquid and a gray powder for a distance of 15 cm along the axis 

 of the tube. Even when the silica bulb was dazzling white 

 and began to cave in there remained a globule of metal which 



*Corapt. rend., xciv, 1228, 1439. 



f Schucht. Chem. Ztg. (1880), 292 ; Erlich, ibid. (1885), 78 ; Kunert, ibid. 

 (1885), 1826. 



