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Chemical Examination of Isopyre, By Edward Turner, 

 M. D., F. R. S. E., Lecturer on Chemistry, Edinburgh. Com- 

 municated by the Author. 



-Defore the blowpipe the isopyre fuses without the disen- 

 gagement of any gaseous matter ; and melted with salt of phos- 

 phorus, it gives evident indications of the presence of silica. 

 On reducing it to powder, and exposing a portion of it on pla- 

 tinum wire to the blowpipe flame, a rich green tint appears. 

 Acids act upon it with difficulty ; but it is easily and completely 

 decomposed by an alkaline carbonate. Heated to redness it 

 does not give off water, nor suffer any loss in weight. 



Having ascertained by preliminary trials that the isopyre con- 

 sists of silica, alumina, oxide of iron, lime, and a little copper, 

 without either manganese or magnesia, I proceeded in the follow- 

 ing manner to the analysis, in which I was assisted by my friend 

 Mr Copland. Of the isopyre in fine ^powder 20.625 grains 

 were mixed with 80 grains of the carbonate of soda, and ex- 

 posed during half an hour to a red heat. The mass, which had 

 acquired a yellowish tint, and contracted considerably, was dis- 

 solved by dilute muriatic acid. The solution was evaporated 

 very slowly to perfect dryness, and the silica separated in the 

 usual manner. After exposure to a red heat, it weighed 9-71 

 grains, equivalent to 47.09 per cent. The silica proved on ex- 

 amination to be quite pure. 



From the solution, thus freed from silica, the copper was pre- 

 cipitated by sulphuretted hydrogen. The sulphuret of copper 

 was then dissolved in nitromuriatic acid, the excess of acid ex- 

 pelled by evaporation, and the peroxide of copper precipitated 

 by pure potash. The oxide of copper, after being heated to 

 redness, weighed 0.40, amounting to 1.94 per cent. 



After separating the copper, the solution was heated with 

 nitric acid, in order to convert the iron into peroxide, and the 

 iron and alumina were then thrown down by a very slight ex- 

 cess of pure ammonia. The peroxide of iron and alumina were 

 then separated as usual by pure potash, and deprived of water 

 by heat. The former amounted to 4.14 grains, or 20.07 per 

 cent., and the latter to 2.87 grains, or 13.91 per cent. 



