Bradley — Composition of the Mineral WarwicMte. 181 



final separation was made by means of barium mercuric iodide 

 with a specific gravity of 3*55. 



Considerable difficulty was caused by the presence of a 

 greenish blue glassy spinel which in the solution closely 

 resembled the grains of warwickite, but by repeated treat- 

 ment with the heavy solution the latter was obtained in a quite 

 pure condition. The material was further purified by the action 

 of an electro-magnet which helped to remove some of the 

 remaining foreign material. Finally by means of a very power- 

 ful glass the few remaining grains of the associated minerals 

 were as far as possible removed. The final sample obtained 

 amounted to a little over two grams and was quite uniform in 

 character. 



The specific gravity, determined by means of the barium 

 mercuric iodide solution and a Westphal balance, was found 

 to be 3 - 342 ; this is practically the same as that given by 

 Brush, viz. : 3*351 for small fragments. 



Owing to the limited amount of material available for 

 analysis it was desirable to determine the main constituents, 

 B 2 3 , Ti0 2 , MgO and total iron in one portion. After 

 repeated fusions of the mineral with sodium carbonate the 

 resulting cake was soaked out and the liquid decanted through 

 a filter, the residue being thoroughly boiled with 25 cc of 

 sodium carbonate solution and transferred to the filter and 

 finally washed with dilute sodium carbonate solution. The 

 filtrate containing the boron was transferred to a distilling 

 bulb and the determination of boron made by distilling with 

 methyl alcohol, the distillate being collected in ammonium 

 hydroxide and finally evaporated over calcium oxide. The 

 residue left in the bulb after distillation contained a trace of 

 titanium which was recovered and added to the main solution 

 previous to the precipitation of the titanium. The residue 

 from the sodium carbonate fusion was brought into solution 

 by prolonged fusion with acid potassium sulphate, and the 

 resulting cake dissolved in cold water to which had been 

 added strong S0 2 water. The solution was then largely 

 diluted and rather strongly acidified with acetic acid ; ' the 

 titanium precipitation being made in the presence of sodium 

 acetate and brought about by boiling the solution from three 

 to five minutes, strong S0 2 water being added before the boil- 

 ing point was reached. The precipitate was then filtered and 

 washed with dilute acetic acid and finally weighed as Ti0 2 . 

 Some of the details of the above briefly outlined method are 

 those recommended by Warren. * 



The filtrate from the precipitation of titanium was concen- 

 trated and a very small precipitate was collected and added to 



* This Journal (4), xxv, 23, 1908. 



Am. Jour. Sci.— Fourth Series, Vol. XXVII, No. 158.— February, 1909. 

 13 



