182 Bradley — Composition of the Mineral Warwickite. 



the main precipitate before igniting. A trace of iron was also 

 precipitated at this point, and this together with a mere trace 

 retained by the main titanium precipitate was recovered by 

 fusing the Ti0 2 with acid potassium sulphate and a volumetric 

 determination for iron was made in the usual way with 

 KMn0 4 . The filtrate from the titanium precipitation con- 

 taining the iron in the ferrous state was treated with nitric 

 acid to oxidize the iron, and hydrochloric acid added to form 

 enough ammonium chloride to keep the magnesium in solution, 

 when ammonium hydroxide was added to precipitate the iron, 

 etc. Double precipitations of the hydroxides were made and 

 the weight of the mixed oxides obtained. The oxides were 

 then fused with acid potassium sulphate, and the total iron 

 determined as usual by titration with KMn0 4 . Traces of 

 titanium retained by the precipitate of ferric hydroxide were 

 determined where present by the colorimetric method and 

 corrections for both iron and titanium were made. The 

 amount of the alumina present was as usual arrived at by 

 difference. The filtrate from the ammonium hydroxide pre- 

 cipitation served for the determination of magnesium, which 

 was precipitated as ammonium magnesium phosphate. This 

 was then dissolved, reprecipitated and filtered on a Gooch 

 crucible and finally weighed as magnesium pyrophosphate. 

 The determination of ferrous iron was made by dissolving the 

 mineral in a mixture of hydrofluoric and sulphuric acids, and 

 finally titrating with KMn0 4 , the modifications of Pratt* 

 being used throughout the above operation. 

 The results of the analysis follow : — 



I II Average Eatios 



B 2 3 ___. 



21-21 



2136 



21-29 



•304 





•304 



Ti0 2 .... 



25-06 



24-66 



24-86 



•310 



l 



•3328 



Si0 2 .... 



1-45 



1-32 



1-39 



•0228 



MgO .... 

 FeO .... 



35-41 

 9-11 



36-01 

 9-20 



35-71 

 9-15 



•884 

 •127 



1 

 I 



1-011 



Fe 2 3 ... 



4-77 



4-76 



4-76 



•0297 







A1 2 3 ... 



2-95 



2-87 



2-91 



•0284 







99-96 100-18 100-07 



The amounts of sesquioxides found are comparatively small 

 and the ratios obtained from them have no rational relation to 

 those obtained from the percentages of the other constituents. 

 Disregarding the Fe 2 3 and A1 2 3 for the present, it will be 

 seen that the other constituents yield, 



B 2 3 : Ti0 2 : (Mg, Fe)0 = 1 : 1-094: 3-325. 



* This Journal (3), xlviii, 149, 1894. 



