32 The feveral SPECIES 



may, 'tis true, be famples, not perfectly coming 

 up to any of the abovementioned three colours ; 

 one yellow may happen to be higher than an- 

 other, nay, needs mult, as not agreeing in their 

 contents, namely copper, to which the yellownefs 

 is moftly owing. The fame holds of the yellowifh, 

 wherein often there is no arfenic at all, often very 

 little, and often a great deal ; now the arfenic 

 lowering or bringing down the yellow, 'tis not 

 pofTible to fix this colour to an indivifible point. 

 The white alone is the mod conftant colour, as 

 being owing to the arfenic -, having obferved that 

 where it is lodged in the proportion, it bears in 

 the arfenic pyrites ', not only the fulphur, which 

 might fomewhat alter the colour, muft be entirely 

 excluded, but the copper alio. But thefe dif- 

 ferences in colour are fo very minute, as fcarcely 

 to be diftinguifhable - 9 the three, that have been 

 affigned, being to many difficult enough to dif- 

 cern with exactnefs. 



The white pyrites is in effence or nature only 



the poifon-pyrites^ the arfenic-py rites, the mifspickel 



and mifspilt of Friberg, and in external appearance 



not eafily diftinguifha,)le from the white-goldifh 



ore, the fmalt-cobald, efpecially the latter, though 



darker, internally differing much among them- 



felves. The genuine fmak-cobald agrees, 'tis true, 



in its volatile portion, namely, the arfetiic, with 



the arfenk-pyrites, but in its fixed portion widely 



differs ; feeing the true cobald fmelts to a beautiful 



blue glafs, which xhtarfenic-pyrites, on the fcore'of 



its iron refufes, Cobalds are of two principal 



forts, i. That yielding the fineft fmalt, and 



appearing of the darkeft grey, fo as to be eafily 



diftinguifhable among the mifspickels. 2. A fort 



fomewhat brighter, found alfo among the other, 



in luflre almoit vying with the arfenic-pyrites, only 



•a ftnall matter darker than it j and yielding by far 



not 



