KJSW MINERAL. J ^3Q 



It is probable, that in this instance part of the su'bstance 

 pFCcipitable by the potash was driven off by the high degree of 

 Jheat to which it was exposed : and this would account for the 

 difference in the proportions oi this analysis from those of th«. 

 preceding, 



IV. grs. 



Quantity taken 33. 



Sulphur separated during solution in nitric acid 1.5. 



Ditto in sulph, of baryt, grs. 19 2.7. 



Potash precipitate at 300 Fahr • • . • g. 



33.2, 



Proportion of sulphur about- 

 ' ■ of precipitate • • • 



In this last analysis, the precipitate by potash was after- 

 wards thrown into distilled water, and dissolved, as far as coukl 

 be, by potash ; a dirty-coloured flocculent substance, which 

 remained undissolved, was caught on -a filter : this was readily- 

 dissolved by muriatic acid, and gave a deep blue colour on the 

 addition of prussiate of potash; but the prussiate of iron thus 

 obtained was too small in quantity to afford a satisfactory exa- 

 mination. 



The filtered potash solution was exposed to the action of the 

 galvanic apparatus, and at different times Oy^ grains of a me- 

 tallic substance were recovered from it, which resembled zinc 

 closely in colour, and more closely in its property of burning 

 with a blue flame when thrown on ignited iron, and leaving a 

 white oxide on the surface of the iron. 



But 5j% grains of metallic zinc equal 7-rJo of oxide : there- 

 fore 9 grains of the precipitate having been dissolved in the 

 potash, there remained 1-fV^ grains unrecovered (including, 

 that is, the small proportion of iron which had been separated 

 by filtration). The potash solution was now neutralized by 

 nitric acid, and in this manner ^Vo gi'ains of the original pre- 

 cipitate were recovered ; which being added to the TrsTS sepa- 

 rated by the galvanic apparatus, leaves only y^-^ of the original 

 9 grains unaccounted for. 



The grains 5~ of metallic zinc obtained in the above man- 

 ner, when tlissolved, in part, in diluted sulphuric acid, gave a 

 jjcrfcctly white precipitate with prussiate of potash. 



T2 Bjr 



