i9°5-] 



HALL AND SMITH— COLUMB1UM. 185 



4. Treatment of the hydrates with cold, fairly concentrated sul- 

 phuric acid, in which the titanium hydrate should dissolve and 

 leave the columbium. 



All of these methods were tried in the endeavor to obtain suf- 

 ficient titanium from the columbium to identify it and prepare some 

 of its derivatives, e. g., the potassium double fluoride. In order to 

 try out method " 1 " the remainder of the residues (page 180) — 

 2 to 3 kilos — was crystallized twice from hydrofluoric acid, thus 

 getting potassium columbium fluoride (K 2 CbF 7 ). The mother 

 liquors were united. They equaled 600 c.c. They were neu- 

 tralized with dilute ammonium hydroxide ; the precipitated hydrate 

 filtered out and the filtrate made alkaline with a large excess of 

 ammonium hydroxide, which gave a further precipitate. This last 

 hydrate was filtered out and dissolved in hydrofluoric acid. Potas- 

 sium carbonate was added and the solution evaporated to dryness 

 on a water bath, the residue taken up in water and crystallized. 

 The crystals obtained were short stubby needles. They were evi- 

 dently not potassium columbium oxyfluoride (K 2 CbOF.). Their 

 quantity was too small to recrystallize, but they were analyzed : 



0.4672 gram of sample gave 0.1740 gram of oxide = 37.6 percent. 

 " " " " " 0.3050 gram of K 2 S0 4 = 65.3 per cent. 



The sp. gr. of the oxide was found to be 5.2, although too little of 

 it was at hand for accurate work. The determination of the 

 titanium in the oxide colorimetrically gave 0.0106 gram of 

 Ti0 2 = 6.1 percent. 



The salt originally taken showed 0.62 percent, of its oxide to be 

 Ti0 2 by the colorimetric determination, while the double fluoride 

 of potassium and columbium obtained showed a Ti0 2 content 

 equal to .25 per cent, of its oxide. Hence it would seem that by 

 method " 1 " the titanium or oxide with lower sp. gr. and molecu- 

 lar weight did concentrate in the mother liquors. 



Crystals 2 and 3 (page 182) were combined. Their total weight 

 was about one kilo. This, in portions of 100 grams at a time, was 

 dissolved in about 2 liters of water and fractionally precipitated 

 with ammonium hydroxide, using dilute alkali and working in the 

 cold with constant stirring. The alkali was added until the solution 

 was barely acid to litmus, the precipitate formed was filtered off and 

 the filtrate made alkaline with an excess of the precipitant. This 



