Hess and Wells — Occurrence of Struverite. 439 



no titanium chloride or sulphur chloride condensed in the hard 

 glass tube at a temperature of ^0-80°. In fact a considerable 

 number of wash bottles were required to collect all the vapors 

 of titanium chloride, owing to the heat generated by the 

 reactions which occurred with the water of the wash bottles. 

 Unfortunately, however, a little of the columbium and tanta- 

 lum chlorides passed over with the titanium, a difficulty which 

 no style of condensing chamber seemed to wholly prevent. To 

 decrease this loss as much as possible the condensing tube was 

 inclined slightly so as to force the gases upward. The titanium 

 oxide, after collection, was treated a second time to recover the 

 small fraction of tantalum and columbium which was carried 

 over the first time. By such a repetition it was possible to 

 separate nearly all the tantalum and columbium from the 

 titanium. The sublimed columbium and tantalum chlorides 

 are best washed out with concentrated hydrochloric acid and 

 after nearly neutralizing with ammonia precipitated by boiling 

 with sulphur dioxide. The oxides thus precipitated do not run 

 through the filter. A slight residue, partly sulphate, forms in 

 the boat, which is with difficulty converted into chloride. It 

 is possible that the use of carbon tetrachloride vapor might 

 be a better agent for converting the oxides of columbium, 

 tantalum and titanium into chlorides than sulphur mono- 

 chloride.* 



In analyzing the mineral it was found simpler to treat it 

 directly in chlorine than to remove the tin and iron first. In 

 this way three portions resulted, — a slight residue in the boat, 

 a sublimate containing most of the tantalum, columbium and 

 iron, and a dissolved portion containing titanium and tin. The 

 titanium portion was nearly neutralized and precipitated by 

 boiling with sulphur dioxide, leaving tin in solution. After 

 ignition this precipitate was treated again in chlorine to obtain 

 the little columbium and tantalum which escaped the first time. 

 The columbium and tantalum oxides were precipitated together 

 by sulphur dioxide, ignited and weighed. 



The tantalum and columbium oxides, finally freed from 

 titanium, were next subjected to the method of Metzger and 

 Taylor for determining columbium in which the columbium 

 sulphate is reduced in a zinc reductor and titrated with 

 KMn0 4 .f Metzger and Taylor found that on the average 

 1 grm. KMn0 4 was equivalent to 2-232 grm. Cb 2 B . As in a 

 blank experiment 1 grm. KMn0 4 was found equivalent to 2*4:58 

 grm. Cb 2 6 , the average 2*34 was used in computing the Cb. 

 The results obtained by these methods were : 



*A. Dernarcay, Compt. rend., civ, 111-13. 



+ Columbia School Mines Quart., xxx, 323-24, 1909. 



