Intelligence and Miscellaneous Articles. 319 



Thomas, who has been anxious to contribute, with generous liber- 

 ality, to the success of a research of pure science. M. Thomas has 

 kindly had treated according to oar directions 4300 kilograms of 

 Bensberg blende, that ore being the richest known. 

 The course adopted was as follows : — 



1. The blende, pulverized, is roasted in one of the bays of a 

 Perret oven kept at a sufficiently high temperature by the simul- 

 taneous combustion of pyrites in the other bays. The gallium re- 

 mains fixed, while the greater part of the indium appears to be 

 volatilized. 



2. The product of the roasting is treated with a quantity of sul- 

 phuric acid sufficient to dissolve nearly all the zinc, leaving never- 

 theless in the mass enough subsulphate to cause the filtered solution 

 to become cloudy on the addition of cold water. Thus, on the one 

 hand, commercial sulphate of zinc is obtained, and, on the other, a 

 residue containing gallium. 



3. This residue is again taken up by excess of sulphuric acid. 

 After reduction of the persalt of iron by metallic zinc, the filtered 

 liquor is precipitated by carbonate of soda (fractionating and fol- 

 lowing the course of the operation with the spectroscope). The pre- 

 cipitates are again taken up by sulphuric acid ; then a second reduc- 

 tion is effected with zinc, and a fractionation with carbonate of soda. 



At the Javel works all the gallium of the 4300 kilograms of blende 

 was thus concentrated into a mass weighing (still wet) about 100 

 kilograms. This product was remitted to us by M. Thomas. At 

 this point, indeed, the treatment ceased to be on the large scale, 

 and could be pursued in a laboratory. 



4. To remove the iron, which, through reoxidation, in tolerably 

 large quantity escaped the preceding purifications, the reductions 

 by zinc and the fractionations by carbonate of soda are repeated 

 several times. 



5. The galliferous precipitates are again taken up by sulphuric 

 acid ; most of the excess of acid is eliminated by evaporation ; and 

 the residue is boiled with a large quantity of water. The filter 

 separates a deposit containing some titanic acid. 



6. After purifying by sulphuretted hydrogen, to the very acid 

 liquor, still sufficiently charged with zinc, acetate of ammonia is 

 added, and it is again treated with hydrosulphuric gas : sulphide 

 of zinc is precipitated, carrying with it some gallium, which is thus 

 separated from the alumina. The additions of sulphate of zinc, 

 acetate of ammonia, and the currents of hydrosulphuric acid are 

 repeated as long as the sulphide gives the gallium-lines. 



7. The sulphuric solution of the galliferous sulphides of zinc is 

 carefully fractionated with carbonate of soda. Spectral examination 

 assisting, a pretty accurate separation of the zinc is accomplished. 



8. After fresh treatment with sulphuric acid in the precise propor- 

 tion necessary, we separate by sulphuretted hydrogen a little cadmium , 

 lead, indium, zinc, &c, then raise to ebullition the liquor diluted 

 with much water. By filtering it while hot we collect a consider- 

 able amount of subsalt of gallium, which is immediately washed with 

 boiling water ; for with cold it would redis solve in its mother-liquor. 



9. The basic salt is readily attacked by potass, which leaves in the 



