Hess and Wells — Occurrence of Struverite. 437 



obtained in one experiment. The mean of all was 1*3 per 

 cent. 



A few words may be said upon the results of fusing the 

 mineral with sodium carbonate. It was attempted to make a 

 separation of titanium and other bases from tantalum and 

 columbium by such a fusion and extracting the tantalate and 

 columbate with hot water. After two fusions with sodium 

 carbonate in one experiment, the insoluble portion (a) was 

 found to be 83 - 8 per cent, the soluble portion (0) 16 - 5 per cent. 

 But the separation was incomplete, for, after determining in 

 portion (a) 7'8 per cent Fe 2 3 , 42 - 3 per cent Ti0 2 and traces 

 of other constituents, there remained 33 # 3 per cent unac- 

 counted for, which was probably tantalum and columbium 

 oxides, and in portion (0) there was found 4*5 per cent Ti0 2 . 

 In another experiment one gram was fused with sodium 

 carbonate and very thoroughly extracted with hot water. The 

 residue was re-treated. Three such extractions brought 18 

 per cent into solution, but of this a third or 6 per cent of 

 the mineral was Ti0 2 . Hence the columbium and tantalum 

 carried titanium with them into the soluble portions, and it was 

 not possible to extract nearly all the columbium and tantalum 

 by even repeated treatments. 



With respect to this sodium carbonate treatment the experi- 

 ments of Weiss and Landecker demand consideration.* They 

 reasoned that the carrying into solution of titanium by colum- 

 bium must be due to the formation of a compound of the two 

 which they thought could be decomposed by adding a little 

 niter during the sodium carbonate fusion. A trial of their 

 method was made, but it was found that titanium passes into 

 the soluble part with columbium and tantalum just as it does 

 when no niter is used. In their description the method of 

 freeing titanium from columbium and tantalum by hydrogen 

 sulphide is not clear. In view of these facts the sodium 

 carbonate attack was abandoned. f 



Another method of analysis was carried out as follows : 



After a bisulphate fusion, silica, tin, and iron were removed 

 by the use of tartaric acid, ammonia, and hydrogen sulphide. 

 The tartaric acid was destroyed by ignition, the total acid earths 

 dissolved by bisulphate and eventually converted into the 

 double fluorides of potassium. These were separated by the 

 method of Marignac. The weight of crude Ta 2 6 thus obtained 

 was corrected for the Ti0 2 present. The total Ti0 3 had 

 already been determined. Cb 2 6 was computed by difference. 

 Two such experiments gave the results below, in which are 

 collected the data for the other constituents so far determined : 





* Chem. News, ci, 13, 1910. 



f Compare Foote and Langley, this Journal, xxx, 401, 1910. 



Am. Jour. Sci.— Fourth Series, Vol. XXXI. No. 185.— Mat, 1911. 

 30 



