174 Intelligence and Miscellaneous Articles. 



clean that one of the precipitates may give the lines of gallium 

 brighter than those of zinc, while the following one shows a feeble 

 image of the line Gaa417 and a bright spectrum of zinc. 



(21) If acetic acid be added to an ammoniacal solution of sul- 

 phates or chlorides of gallium and zinc, almost the whole of the gal- 

 lium separates in the form of a gelatinous ilocculent white precipi- 

 tate, which is not redissolved by boiling with a considerable excess 

 ofC 2 H 4 2 . 



I now examine certain reactions of pure salts of gallium. 



1. The electric spectrum of slightly concentrated chloride of gal- 

 lium is very brilliant. The line 417 is much brighter than the line 

 404. I have not observed any other line attributable to gallium ; 

 there is certainly not any of notable intensity, at least under the 

 physical conditions of my operations. The colour of the spark 

 bursting on chloride of gallium is a beautiful light violet. 



2. In the gas-flame I obtained only the line Gaa4l7; and it 

 was very faint and fugitive, even with a salt that gave a brilliant 

 electric spectrum. 



3. The chloride and the sulphate of gallium are precipitated by 

 NH 3 ; but the precipitate is in great part redissolved in an excess 

 of NH 3 . Taking up by HC1 the portion not dissolved by NH 3 , 

 and recommencing the operation, all the gallium is promptly ob- 

 tained as ammoniacal solution. 



4. An ammoniacal solution of sulphate or chloride of gallium is 

 precipitated, with or without heating, by an excess of acetic acid 

 (specimen 2). That precipitation may cease, the liquor must be 

 extremely dilute. 



5. The chloride and sulphate of gallium are not precipitated in 

 the cold by acid acetate of ammonia ; but the reaction takes place 

 on heating. 



6. Sulphate of gallium, evaporated and dried till the white sul- 

 phuric vapours nearly cease to be evolved, does not lose its solubility 

 in water. 



7. Sulphate of gallium is soluble in alcohol of 60 per cent. 



8. I have obtained a salt which I confidently believe to be am- 

 monio-gallic alum*. lor want of a sufficient quantity, I have not 

 been able to analyze it, nor to measure the angles ; but its charac- 

 ters appear sufficiently well marked to convince me, reserving ulte- 

 rior verification. The following facts refer to the small crystals of 

 specimen 3. 



9. Gallium-alum is soluble in cold water ; but if it be heated, 

 the salt is decomposed and the liquor becomes very thick. 



10. This alum is not decomposed by hot water with the addition 

 of acetic acid. 



11. The alum readily crystallizes in cubes and octahedrons, pre- 

 senting exactly the aspect of common alum ; its solution, too, eva- 

 porated under the microscope, pursues the characteristic course 

 of the known alums. 



* There cannot have been present any other alkali than NH 3 and traces 

 of Na. 



