480 Intelligence and Miscellaneous Articles. 



by the zinc a current of sulphuretted hydrogen is passed ; it is 

 filtered, the sulphuretted hydrogen expelled; and finally carbonate 

 of soda is added fractionally until the line Ga a 417 ceases to be 

 visible with the chlorhydric solution of the precipitate. 



3. The oxides (or subsalts) are again taken up by sulphuric acid ; 

 the solution is cautiously evaporated until no more white sulphuric 

 fumes (or scarcely any) are liberated. It is allowed to cool, then 

 agitated with water, which dissolves the mass after a time varying 

 from a few hours to two days. The solution of the nearly neutral 

 sulphate is diluted with water and heated to ebullition, and the 

 subsalt of gallium separated by nitration hot. 



4. This basic salt is dissolved in a little sulphuric acid ; and a 

 slight excess of caustic potass is added, so as not to separate the 

 gallium but to throw down the iron. Filtration follows, and then 

 the passage of a prolonged current of carbonic acid gas, which 

 precipitates the oxide of gallium. 



5. This oxide is redissolved by the smallest possible quantity of 

 sulphuric acid ; a small excess of slightly acid acetate of ammonia 

 is added, and then sulphuretted hydrogen is passed into the solution. 

 Under these conditions gallium is not precipitated. 



6. The acetic liquid is filtered, diluted with water, and brought 

 to ebullition ; the largest portion of the gallium is precipitated. It 

 is filtered while hot. The mother-liquor, concentrated and boiled 

 with aqua regia (in order to break up the salts of ammonia), is put 

 with the other gallium-residues. 



7. The precipitate formed by the hot acetic liquor is redissolved 

 by sulphuric acid; we add a slight excess of caustic potass, and 

 filter. 



8. The potassic solution is electrolyzed. The metallic gallium is 

 readily detached from the plate of platinum by squeezing this be- 

 tween the fingers under tepid water. 



9. The metal is kept for about half an hour, at a temperature of 

 60° or 70° C, in nitric acid (quite free from chlorine) diluted with 

 its volume of water ; after washing, it may be considered pure. 



The various galliferous residues from the manipulations nos. 2 

 to 9 are mixed, and treated first with fractional parts of carbonate 

 of soda, to separate the greater portion of the zinc, aluminium, &c, 

 and then with potass to remove the iron. The product is joined 

 to that of operation no. 2. When we arrive at a residue contain- 

 ing but little gallium and much iron, the simplest way is to treat 

 it with zinc, heating it and excluding the air ; the greater part of 

 the iron will remain in solution. — Comptes Renclus de lAcademie 

 des Sciences, tome lxxxiii. pp. 636-638. 



