BARYXrC SALTS DECOMPOSED BY SODA. 6^ 



"be separated from the liquid after it is completely cooled, 

 Washed in the smallest possible quantity of water, and dried 

 quickly by pressing them between several folds of blotting 

 paper, they will be found to be crystals of pure barj'^tes, These pure 

 without any mixture of acetate. Of this I satisfied myself ^'y^^^- 

 in the following^ way, 



1. 1 exposed part of these crystals to the air. After some Converted into 

 days I washed the carbonate thus obtained with pure water, exposure to 

 which then took up nothing, that sulphuric acid, or alkaline Hie air. 

 carbonates or sulphates would throw down. The whole 



of the crystals therefore had been converted into carbonate; 

 which would not have been the case, had they contained any 

 acetate of barytes. 



2. I dissolved two or three grammes of the same crystals Were alkaline. 

 in distilled water. The solution restored the blue colour of 

 reddened litmus paper : consequently it contained an ex- 

 cess of alkali. 



I added a few drops of sulphuric acid to this solution, J^lpli^nc acid 

 J .. r»ii/»i f IT lormed With 



and a precipitate ot sulphate ot barytes was tormed. 1 them sulphate 



tested the liquid again with litmus paper, and I still found of barytes, 

 an excess of alkali. I then gradually added more sulphuric 

 acid, till there was a slight excess of acid in the liquor; 

 filtered it, and found it no longer contained any barytes, but 

 a little free sulphuric acid. This would not have been the 

 case, had^ the crystals contained any acetate of barytes ; for, 

 on this supposition, the moment when the excess of acid 

 began to be sensible by the test paper, only a small portion and no acetous 

 of the acetate would have been decomposed, and acetous ^^^ appeare . 

 acid would have been set free. The filtered liquor there- 

 fore ought to have contained a slight excess of acetous acid, 

 and the undecomposed acetate of barytes : but this was con- 

 tradicted by the experiment. 



3. The mother water of the crystals employed in the pre- The mother 



ceding experiments ought to contain only that small quan- ^f^^\ contain- 

 j^'j. o J 1 • 1 • 1 1 • • 1 . , edonly pure 



tity or pure barytes, which it could retain m solution when barytes and 



cold, in addition to the whole of the acetate of soda em- acetate of soda. 

 ployed. This too the analysis of the mother water demon- 

 strates, if alcohol be poured into it, as Mr. Perpj^res directs. 

 The shining scales that fall down are nothing but crystals 

 of barytes: and examined in the way I have mentioned 



r 2 above. 



