8 4 CHEMICAL ANALYSIS 



time with a frefh portion of fulphuric acid ; and afterwards 

 boiled with water, filtered and warned, exactly in the fame man- 

 ner as before. The undiffolved part of the ftone was now al- 

 moft white. 



The filtered folutions being mixed together, were evaporated 

 to drynefs ; and the faline mafs which remained was heated red 

 hot for one hour in a clean and new Heflian crucible. When 

 cold the mafs was of a brick red colour. Having powdered it 

 well, I boiled it in water, poured the whole on a filter, and 

 warned the reddifh matter carefully. This filtered liquor, in 

 which all the foda, feparated from the bafalt by the fulphuric 

 acid, was diflblved in the ftate of fulphate of foda, could contain 

 only a fmall quantity of earthy matter ; for the greater part of 

 the fulphate of argil, and of iron, formed by the firft part of 

 the procefs, muft have been decompofed by the red heat, to 

 which the mafs was afterwards expofed. Accordingly, the fo- 

 lution being treated with carbonate of ammonia, only a fmall 

 quantity of a precipitate was thrown down, which was careful- 

 ly feparated. The folution was then evaporated to drynefs. A 

 faline mafs remained, confiding, in part, of fulphate of ammo- 

 nia ; to feparate which the whole was expofed to heat in a fmall 

 crucible, and when it ceafed to emit fumes, the heat was increa- 

 fed to rednefs. A fixed white fait was left, which weighed 25 

 grains. 



This fait I redifTolved in water, added fome carbonate of am- 

 monia, and heated the mixture till it boiled. A fmall quantity 

 of an earthy precipitate was again thrown down, which being 

 feparated by filtration, the folution was evaporated to drynefs, 

 and the fait which remained heated red hot a fecond time. By 

 thefe fucceffive operations, all the earthy matter, at firft difTol- 

 ved, was feparated. The fait now weighed 23 grains, andhad 

 all the properties of fulphate of foda. Thefe properties were 

 the following •. 



1, It 



