20 ACCOUNT of a MINERAL 



fubtle powder, and is what I have hitherto denominated the ar- 

 tificial carbonate. In diluted muriatic acid, I diflblved 200 

 grains of Strontian mineral, and then added fait of tartar, 

 which had run per deUqnium as long as it occafioned any preci- 

 pitate. By the teft of fulphuric acid, 1 difcovered that the al- 

 kali had feparated the whole of the earth, which was well 

 wafhed, and afterwards dried before a fire, being towards the 

 conclufion of the exficcation brought very near the bars j it 

 weighed 198 grains. This deficit of two grains I afcribe to ac- 

 cidental lofs, as during wafhing, by adhering to the filter, l^c. 

 The artificial carbonate pofTefTes all the chemical qualities of 

 the native, with this difference, that it parts with its acid more 

 readily when urged by heat. 



48. The prufTiate of potafs and of lime did not diflurb the 

 tranfparency of a folution of a pure colourlefs mafs of Stron- 

 tian mineral in nitric acid. Sometimes, however, thefe fub- 

 flances threw down from folutions in the muriatic acid a fpa- 

 ring precipitate of a blue colour, which denotes the exiflence of 

 a minute portion of iron in fome fpecimens. The precipitate 

 is moft abundant when a coloured fpar has been employed ; 

 whence I conclude, that the colour which the fpar occalionally 

 exhibits is adventitious, and is owing to the iron it contains. 



49. With fulphur, Strontites combines into an hepar. Equal 

 weights of calcined Strontian mineral and flowers of fulphur 

 were triturated together, and expofed to heat in a covered cru- 

 cible. The heat was continued till a few minutes after the 

 blue flame had ceafed to appear at the chinks of the cover. 

 The mafs had been in fufion. Being pulverifed, part was 

 thrown into muriatic acid ; an efTervefcence enfued, and the 

 hepatic odour becairie ofFenfive Boiling water was poured on 

 the remaining portion ; a yellow- coloured fluid refulted, which 

 was decompofed by acids, and gave with acetite of lead a very 

 abundant black precipitate. In the humid way likewife a he- 

 par may be formed. On a mixture of equal parts of flowers 



of 



