On the Occurrence of Gallium in Clay-ironstone. 405 



adding a few drops of ammonia; if any precipitate was produced it. 

 was collected and added to the other precipitate. The precipitate in 

 this case was added to ferrocyanide precipitates obtained from the 

 residue W. The paper, after being scraped to remove the residue as 

 far as possible, was burnt in the oxyhydrogen flame. The gallium 

 lines are strong. 



The ferrocyanide precipitates with others rich in gallium were 

 ignited at low redness to decompose the cyanides, and then fused 

 with pure caustic soda. The produce was extracted with water and 

 filtered. 



Residue from Fusion. Dissolved in hydrochloric acid, expelled the 

 excess of acid, added water, reduced the ferric salt, and filtered. 

 Residue remaining contained only a trace of gallium. 



Filtrate. Boiled with an excess of ammonium acetate and filtered 

 off the precipitate. The filtrate was mixed with sodium phosphate and 

 boiled, thus yielding a second precipitate. The filtrate from this was 

 again boiled, and ammonium carbonate added until a third precipitate 

 was produced. Very small portions of these three precipitates were 

 burnt in the oxyhydrogen flame. The first two were rich in gallium, 

 while the third contained only a trace. Ignited the first and second 

 precipitates, heated the residue in a platinum crucible with hydro- 

 chloric and sulphuric acids, expelled the former acid by heating until 

 the white fumes of sulphuric acid were evolved, and then fused the 

 residue with caustic soda. Extracted with water and filtered. After a 

 second fusion the residue was practically free from gallium. The 

 alkaline filtrates were acidified with hydrochloric acid, and the 

 gallium precipitated by boiling with ammonia until the excess ot 

 ammonia was expelled. Filtered and tested the filtrate by repeating 

 the process of boiling with ammonia until no further precipitate 

 resulted. 



The precipitates of gallium hydrate and phosphate, obtained as 

 described, were dissolved in hydrochloric acid and, after adding one- 

 fourth the volume of the solution of strong hydrochloric acid, an 

 excess of potassium ferrocyanide was added. After standing for one 

 day the precipitate was collected, washed, and ignited. It weighed 

 0-0670 gram. 



This residue was dissolved by heating with strong sulphuric acid 

 in a platinum crucible, some water being added, after heating strongly, 

 and then an excess of caustic soda prepared from sodium. The 

 crucible was then heated until the water was expelled, and the residue 

 retained in the fused caustic soda. The process was repeated on the 

 residue which remained after adding water and filtering. The second 

 residue was practically free from gallium. 



The filtrates were collected in a platinum basin, made faintly acid 

 with hydrochloric acid, and saturated with sulphuretted hydrogen. 



