i9°5-J 



HALL AND SMITH— COLUMBIUM. 191 



dissolved in hydrofluoric acid and potassium carbonate added to 

 change it to the potassium double fluoride. 

 Analysis of the crystals obtained : 



0.1S93 gram of sample gave 0.0642 gram of Ti0 2 and 

 o. 1366 gram of K 2 S0 4 



Calculated. Found. 



Oxide 33.33 33.91 



K 2 S0 4 72.50 72.16 



The determination of the Ti0 2 colorimetrically gave .0636 gram. 

 The salt was undoubtedly potassium titanium fluoride, proving 

 conclusively the presence of titanium in columbite. 



Behavior of Solutions of the Double Fluorides of Colum- 

 bium and of titanium with a variety of bases. 



Excess of sodium hydroxide was found to precipitate titanium 

 completely from a solution of potassium titanium fluoride, while 

 with potassium columbium oxyfluoride it gave a precipitate soluble 

 in slight excess but again insoluble and separating in a crystalline 

 form from a large excess of the sodium hydroxide. The precipi- 

 tate formed in the case of the titanium was insoluble in water, 

 while in the case of columbium the crystalline deposit was com- 

 pletely soluble in hot water. It was hoped that this difference of 

 behavior might afford a means of separating these two elements. 

 To test this experiments were tried as follows : 



1. 0.9600 gram of K 2 CbOF. -f H 2 0, containing 0.4272 gram 

 ofCb 2 0., and 1. 1600 gram K 2 TiF 6 , containing 0.3753 gramofTi0 2 , 

 were dissolved in 200 c.c. water, brought to boiling and an excess 

 of sodium hydroxide added. The precipitate which formed was 

 partly crystalline and partly flocculent. The solution was allowed 

 to stand over night. The precipitate was filtered out, drained, and 

 washed back into a platinum dish. It was covered with 200 c.c. 

 of water, brought to boiling, filtered hot, and washed with hot 

 water. The filtrate which should contain most of the columbium 

 and none of the titanium was brought to boiling and sulphuric 

 acid and ammonium hydroxide added. The hydrate obtained was 

 ignited to oxide and weighed 0.1640 gram. It was found to con- 

 tain .0117 gram of Ti0 2 . The titanium content was determined 

 colorimetrically by fusing with potassium acid sulphate, dissolving 



