of Baryta or Sironita when in union with Lime. 405 



phcite of strontia from a solution of the earths in nitric acid, 

 and after washing it with repeated affusions of boiling water 

 to determine its weight. This mode of analysis appears to me, 

 with much deference to so high an authority, to be much more 

 exceptionable than any that has yet been proposed. I have 

 in vain endeavoured to throw down sulphate of strontia in this 

 manner, although present to the amount of 5 per cent ; for 

 when the solution was made so dilute that no precipitate at 

 fii'st appeared on the addition of sulphate of soda, a volu- 

 minous deposit of crystallized sulphate of lime slowly formed, 

 without any previous precipitation of sulphate of strontia. 

 Nor will boiling water effect a separation of the sulphates 

 of lime and strontia, as it is nearly impossible to wash away 

 any considerable quantity of the former sulphate by means of 

 that liquid, while the latter is at the same time sensibly soluble 

 in it. It is possible, however, that there may be some circum- 

 stance on which the success of this experiment depends, of 

 which I have not been aware ; for Mr. Brande obtained by 

 this means a precipitate which upon examination proved to be 

 pure sulphate of strontia, and the weight of which corresponded 

 exactly with the oi-iginal quantity of carbonate of strontia that 

 he employed. It will certainly be less liable to objection in 

 the case of baryta; but it appears to me very doubtful whether 

 it will effect a complete separation, or distinguish a small quan- 

 tity, even of that earth. 



The following method, which is merely an extension of that 

 proposed by Bucholz, will be found not less sensible in its in- 

 dications, while it is at the same time more easy of execution, 

 and more certain in its results, than the process of Stromeyer. 

 Dissolve the carbonates of lime and baryta or strontia in 

 nitric acid, evaporate the solution to dryness, and decompose 

 the nitrates by heat; to the dry mass add boiling water (pure 

 in the case of baryta, but saturated in the cold with sulphate 

 of strontia in the case of that earth), and boil it for a few mi- 

 nutes, keeping the crucible at the same time loosely covered 

 with its lid. Throw the whole on a covered filter; and to 

 the liquid which passes through add suli)huric acid or a so- 

 luble sulphate: a white powder will precipitate if either ba- 

 ryta or strontia be present ; but if not, the liquid will retain 

 its transparency. 



I decomposed in this manner 99*75 grains of nitrate of lime 

 and ''ZS grain of nitrate of baryta ; a white precipitate immedi- 

 ately appeared on the addition of sulphuric acid to the filtered 

 licjuid. A similar experiment made witii e(]uul i)roportions of 

 the nitrates of lime and strontia was attended with the same 

 result; the precipitate, however, did not a})|)ear quite so soon 

 as before. Hence it ap[)ears, that ji'-jc/'^'' \*^^^ ^^ least of ba- 



jyta 



