332 Experiments and Obfir-vations 



infigni (leant quantity of fulphate of barytes was obtained. 

 The furplus of barytic nitrate was removed by fulphate or 

 potafh. I next completely edulcorated the mafs which re- 

 mained infolublc after the action of the muriatic and nitric 

 acids; and, adding the water of edulcoration to the muriatic 

 and nitric liquors, evaporated the whole for filica. I then 

 fubmitted the mafs, undiiTolved by the acids and the water, 

 to the treatment with potato, muriatic acid, and evaporation, 

 which was, in the iirft in(tance, applied to the (tone from 

 Benares. The fir if precipitation was, as in that analyfis, alio 

 effected with carbonate of potam ; but, inilcad of endeavour- 

 ing immediatelv to extract alumina, I ignited the precipitate, 

 that the aktmina or filica remaining might be rendered in- 

 fallible. After the ignition, I Separated the oxide of iron 

 with very concentrate muriatic acid ; and the earths, which 

 were left perfectly white, f heated with potaih, until they 

 were again capable oHjeing taken up by the fame acid. The 

 folution fo made was (lowly evaporated ; and, as very nearly 

 every thing was depoiited during the evaporation, I conclude 

 all was filica. The proportions refulling from this iingle ana- 

 lyfis, without the weight of fulphur contained in the pyrites 

 irregularly difieminated through the whole, were, 



Silica ----- ;o 

 Magnefia - - - 34 



Oxide of iron - - - - 53 

 Oxide of nickel - 3 



Examination of the Stone from. Yorlflnre. 



The mechanical feparation of the fubftanccs in this none 

 beine: as difficult as in the preceding cafe, I was necefTarily 

 fatisfled with fubmitting it to the fame treatment. I col- 

 lected, however, 34 grains of malleable particles; which, by 

 the procefs already more than once mentioned, left four grains 

 of earthy matter; and, by yielding 37^ of oxide of iron, in- 

 dicated about four grains of nickel. 



150 grains of the earthy part of the ftone were, by analyfis, 

 refolved into. 



Silica ...'-. 75 

 Magnefia - - - " 37 



Oxide of iron 48 



Oxide of nickel - 2 



162, 



Examination 



