CELESTINE AND BARYTO CELESTINE OF CLIFTON. 29^ 



baryto-calcite BaCOs, CaCOs, etc. At the same time, however, 

 dolomite, and probably other minerals of a similar kind often 

 occur, in which their constituents are present in indefinite propor- 

 tions. Thus the dolomite of this neighbourhood contains very 

 much less magnesium carbonate than is required for the formula 

 CaMg (003)2. The quantitative separation of barium and 

 strontium being however attended with difficulty, I have abandoned 

 the direct process of estimating them separately, and have resorted 

 instead to an indirect method of estimation. This method consists 

 in converting the sulphates into carbonates by fusing the mineral 

 with carbonate of sodium ; dissolving oat the resulting sulphate of 

 sodium, and after washing the insoluble carbonates of the two metals, 

 collecting them on a weighed filter and ascertaining their weight. 

 The carbonic acid which they contain is then determined by 

 treating them with an acid, and weighing the evolved carbonic 

 acid in the ordinary manner. From the weight of the two 

 carbonates and the weight of the carbonic acid which they 

 contain, the proportions of barium and strontium may be calculated. 



The analyses were as follows : — 



i'33o5 g^'Jfi^s. of the mineral gave i.i 13S of carbonates and 

 .269 of carbonic acid = Barium, 48.5 per cent-, and 

 Strontium, 12.4 per cent. 



.7287 grms. of the mineral gave .6075 of carbonates and 

 .147 of carbonic acid = Barium, 44.0 per cent., and 

 and Strontium, 11.8 per cent. 



The formula 2 BaSOj, SrS04, would require — 

 Barium ... 42.2 7o 



Strontium ... 13.2 



O I 



These numbers approximate to each other but are scarcely 

 sufficiently near, even allowing for errors of experiment, for the 

 assumption that the mineral is a definite compound in molecular 

 proportions of the two sulphates, and it must thus be regarded as an 



