of the Pyrites. 21 



pyrites and copper-ores, which tho* with us not 

 work'd for, yet contain fulphur. Tho' arfenic-py- 

 rites, in its metallic contents, efpecially iron, coin- 

 cides with the other, yet in its volatile part 

 it differs greatly. And tho' fulphur and arfenic are 

 often found together in pyrites , yet there are fome 

 without any arfenic at all •> and again, not a few 

 that contain no fulphur, but only a pure arfenic. 

 Further, tho' fulphur and arfenic readily unite, yet 

 are they never produced the one from the other. So 

 that this divifion, in preference to the others, par- 

 ticularly the foregoing, may be permitted as taken 

 not fo much from the different matters for which 

 this fort is worked, as from their different principles, 

 and feems to have fome foundation in nature. At 

 Friberg tho' we ufe not the term arfenic -pyrites, yet 

 we denote the fame thing by mifspickel or white-py- 

 rites. 'Tis here to be obferved, that the black 

 arfenic- pyrites or fly-ficne, is not properly of this 

 clafs, as being entirely fugitive, without leaving 

 any fixed earth behind, and confequently having 

 one part only of the effence, and not the other 

 fixed, metallic principle of a. pyrites. 



The appellation fandarach-pyrites, has intro- 

 duced numerous miftakes : fandarach is only a 

 fulphurated arfenic, or an arfenic tinged yellow 

 with fulphur, not having its own peculiar pyrites^ 

 contradiftinguifhed from the arfenic-pyrites, as one 

 might be led to imagine : feeing it confifls of the 

 very fame parts peculiar to the pyrites itfelf ; only 

 that thefe are feldom lodged together in a' due 

 proportion, to fit them to be worked for fandarach, 

 without making fome additions. In moft fulphur- 

 pyrites there is at laft procured a fmall quantity of 

 fandarach 'as moft of them hold fome arfenic) and 

 but a little ; and that either in the courfe of 

 purifying the crude fulphur, as is obfervable from 

 tht beautiful tranfparenr, ruby-red fublimate, and 



orange- 



