and Detection of Gallium. 223 



test for the gallium was unmistakable and practically imme- 

 diate. 



A number of reactions were investigated leading to the 

 decomposition of the gallium ferrocjanide and the recovery of 

 the gallium as the hydroxide, such as treatment with bromine 

 and with nitric acid, and fusion with sodium peroxide and with 

 ammonium nitrate. The most satisfactory proved to be fusion 

 with ammonium nitrate, which destroyed the ferrocyanide rad- 

 ical, and subsequent treatment with sodium hydroxide, which 

 precipitated the ferric hydroxide and left the gallium in solu- 

 tion, from which the hydroxide could be readily precipitated 

 by adding ammonium chloride in excess and boiling. 



Gooch and Havens* have shown that iron may be separated 

 from aluminium by saturating solutions containing these ele- 

 ments with hydrochloric acid gas, adding ether and again 

 saturating. The chloride of aluminium is completely precip- 

 itated by this method, and the iron remains in solution. This 

 process was applied successfully to the separation of aluminium 

 from gallium. The presence or absence of gallium may be 

 determined by evaporating the filtrate to dryness on a steam 

 bath and dissolviug the residue in dilute hydrochloric acid. 

 This solution, which is free from aluminium, may be tested for 

 gallium by means of potassium ferrocyanide. The following 

 series of unknown solutions was tested by this method, the 

 aluminium chloride used having been purified by the hydro- 

 chloric acid precipitation : 



Issued Fonnd 



(1) 0-0005 grm. Ga Al absent, Ga present 



(2) O'l grm. Al Al present, Ga absent 



(3) 0-1 grm. Al -f- 0-0005 grm, Ga Al present, Ga present 



(4) Distilled water Al absent, Ga absent 



(5) 0*02 grm. Al ■\- 0*001 grm. Ga Al present, Ga present 



(6) 0-0001 grm. Ga Al absent, Ga present 



During the first trial of this method aluminium nitrate was 

 used in hydrochloric acid solution, and it was found that no 

 Drecipitation took place with potassium ferrocyanide. After 

 treatment with the hydrogen chloride gas and evaporation, 

 however, an indication of gallium was found. This led to an 

 investigation which showed that there was some gallium pres- 

 ent in the aluminium nitrate, but that the nitric acid formed 

 by dissolving it in hydrochloric acid was sufficient to prevent 

 the precipitation of the gallium as the ferrocyanide. In the 

 evaporation process the nitric acid is destroyed and the test 

 becomes very delicate. 



* This Journal, ii, 416, 



