Browning and Porter — Gallium. 22t 



Art. XYIJ.— 6^n the Qualitative Separation and Detection of 

 Gallium ; by Philip E. Bkowning and Lyman E. Porter. 



[Contribution from the Kent Chemical Laboratory of Yale Univ. — ccxci.] 



- Gallium, discovered in 1875 by Lecoq de Boisbaudran," is 

 found in nature most closely associated with the elements 

 aluminium, iron, manganese, zinc, lead, and indium.f 



Analytically it falls into the aluminium group. It may be 

 separated from the bases giving sulphides in acid solution by 

 hydrogen sulphide; from nickel, cobalt, zinc, manganese, the 

 alkali earths, and the alkalies by ammonium hydroxide in the 

 presence of ammonium chloride; and from iron, titanium, 

 thallic thallium, uranium, indium, and the rare earths by 

 sodium hydroxide in excess, in which reagent the hydroxide of 

 gallium is soluble.. In the ordinary course of analysis it 

 appears in the group containing aluminium, beryllium, chro- 

 mium, and vanadium. From the last mentioned two elements 

 it may be, separated by ammonium hydroxide after their oxida- 

 tion to the acidic condition. 



This narrows the problem of separation down to the separa- 

 tion from aluminium and beryllium ; and the practical absence 

 of beryllium from products containing gallium leaves the most 

 important separation, that from aluminium. 



Lecoq de Eoisbaudran, in a series of articles published soon 

 after the announcement of his discovery, :j: suggested many 

 methods of separation from the other elements, and recom- 

 mended especially for the separation from aluminium the use 

 as a precipitant§ of potassium ferrocyanide in the presence of 

 strong hydrochloric acid to about one-third of the volume of 

 the solution. 



In previous papers|| one of us has shown that silver, lead, 

 zinc, copper, and indium have been successfully separated from 

 gallium by various applications and modifications of known 

 methods. The object of this paper is to give the results of 

 some work upon the application of potassium ferrocyanide to 

 the separation of gallium from aluminium and beryllium, and 

 to describe the outcome of experiments upon the delicacy of 

 the test for gallium by the ferrocyanide method, upon the 



* Gompt. rend. (Paris), Ixxxi, 493. 



f Bonlanger and Bardet, Compt. rend. (Paris), clvii, 718 ; Hartley & Ram- 

 age, Jour. London Chem. Soc, 1897. 533, 547; Hillebrand and Schnerrer, 

 Ind. Eng. Chem., viii, 225. 



tGomp. rend. (Paris), xciv, 1154, 1228, 1439, 1628; xcv, 157, 410, 503, 

 1192, 1332 ; xcvi, 152, 1696, 1838 ; xcvii,.142, 295, 522, 623, 730, 1463. 



§ Comp. rend. (Paris), xcix, 526. 



If Browning and Uhler, this Journal, xli, 351, Apr. 1916 ; Uhler and Brown- 

 ing, ibid., xlii, 389, Nov. 1916. 



