436 Hess and Wells — Occurrence of Struverite. 



late 6*9, the mineral evidently contained a heavier constituent 

 than titanium or iron and the presence of tantalum was thus 

 first suggested. 



While the analysis of this mineral was in progress the paper 

 by Prior and Zambonini appeared* and other suggestive papers 

 upon the analysis of chemically similar minerals have recently 

 been published. A method for analyzing columbite has been 

 published by E. S. Simpson but is not intended to be used when 

 titanium is present, f W. B. Giles has described the opening 

 up of minerals containing columbium and tantalum.^ Weiss 

 and Landecker,§ Iiauser and Finckhjj have worked on the sepa- 

 ration of these elements. 



When it was desired simply to get the mineral into solution, 

 fusion with acid sodium sulphate was employed. The melt 

 was dissolved in 5 or 10 per cent sulphuric acid. 



The colorimetric determination of Ti0 2 gave 45*8 per cent 

 as an average of several experiments and readings, the series 

 being 47"4, 44-2, 464, 45-3, 46-5, 45-3, 43-6, 45-6, and 47*6. 

 All of the precautions mentioned by Merwin^f with regard to 

 the influence of sodium sulphate, etc., were not considered, but 

 about 5 per cent of sulphuric acid was present in the standard 

 and sample compared. 



Since the mineral was not attacked by boiling with dilute 

 sulphuric and hydrofluoric acids, a determination of the state 

 of oxidation of the iron was abandoned. Calculated as ferrous 

 oxide, the amount present was 7*5 per cent. 



By reducing the mineral in hydrogen and dissolving in hydro- 

 chloric acid 0*6 per cent Sn0 2 was obtained. More, however, 

 was obtained by fusing with bisulphate, adding to the solution 

 sodium hydroxide in excess, filtering and adding hydrogen 

 sulphide. This treatment gave 1*09 and 1*14 per cent SnO„ 

 after correcting for platinum and other impurities. The method 

 of attack recommended by Giles** for determining tin was also 

 tried. He states that by fusing a columbite containing tin at 

 a high temperature with potassium carbonate and digesting in 

 warm citric acid, the tin may be brought into solution as well 

 as other constituents except titanium, zirconium and a little 

 silica. From one gram after three fusions there remained 

 only -0475 grm. of insoluble matter consisting of -0351 grm. 

 Fe 2 3 and a little Ti0 2 . From the soluble part, however, 

 there was obtained only 07 per cent SnG 2 by hydrogen sul- 

 phide, which was less than that obtained in the previous way. 

 In a wholly different way as much as 1*7 per cent Sn0 3 was 



* Loc. cit. f Chem. News, xcix, 243, 1909. 



X Chem. News, xcix, 1, 1909. §Zs. anorg. Chem. 64, 65. 

 1 Ber., 1909, 2270. If This Journal (4), xxviii, 119. 



** Chem. News, xcix, 27, 1909. 



