^66 Dr E. Turner's Chemical Examination qflsopyre. 



The lime contained in the ammoniacal sokition was precipita- 

 ted by oxalate of ammonia. The oxalate of lime, decomposed 

 and rendered caustic by heat, yielded 3.19 grains, or 15,43 per 

 cent, of pure lime. 



To ascertain if an alkali is contained in isopyre, 30 grains of 

 the mineral in fine powder were decomposed by 180 grains of 

 the carbonate of baryta, and the earthy and metallic substances 

 removed in the way above mentioned. After expelling the am- 

 moniacal salts by heat, there remained a trace of soda, which was 

 most probably derived from the reagents. 



In order to discover if any acid is contained in isopyre, I de- 

 composed 20 grains of the mineral by carbonate of soda, and 

 removed the soluble parts by distilled water. In the alkaline 

 solution, neutralized by nitric acid, muriate of baryta discovered 

 a trace of sulphuric acid ; but I was unable to detect the pre- 

 sence either of the muriatic, phosphoric, fluoric, or boracic acids. 

 The sulphuric acid is most probably derived from the copper 

 being combined wholly or in part with sulphur ; at least, on 

 digesting isopyre in powder with nitromuriatic acid, the solution 

 was found to contain both a little copper and sulphuric acid. 



According to this analysis, the isopyre is composed in 100 

 parts of 



SiUca, - 47.09 



Alumina, - 13.91 



Peroxide of Iron, 20.07 



Lime, - 15.43 



Peroxide of Copper, 1.94 



98.44 



I forbear to speculate concerning the precise atomic constitu- 

 tion of isopyre, since it is impossible to depend on the purity of 

 a mineral which is both opaque and uncrystallized. With re- 

 spect to the iron, it must in part be in the state of black oxide, 

 as appears both from the colour of the mineral and from its being 

 attracted by the magnet. The copper can scarcely be regarded 

 as an essential constituent ; for, though I have seen no specimen 

 which is free from copper, the quantity of that metal is not con- 

 stant. I found it on one occasion considerably below 1 per cent. 



