in the Pyrites. 99 



We (hall, in the firft place, enquire into the 

 conftituent parts, then into the principles of the 

 pyrites : the former we mall confider in this and 

 the following chapters ; the latter, namely the 

 principles, in a chapter apart. 



In order to treat with propriety of the con- 

 ftituent parts of the pyrites, we muft premife its 

 divifion into fulphur and arfenic -pyrites. By the 

 former I underftand not only that fort which yields 

 fulphur and pure iron, with little or no copper 

 or arfenic, confequently little or no fandarach : 

 but alfo copper -pyrites, nay, rich copper-ores ; by 

 the latter, that white fort, which contains pure arfenic 

 with but very little iron, copper, or other metal, 

 and with little or no fulphur :, the arfenic being in 

 form either of a grey meal, or a footy arfenical 

 fublimate or fly-ftone, and giving, by means of a 

 proper addition of fulphur, fandarach •, this kind 

 of pyrites is at Friberg called mifspickel, but in the 

 Obergeburge, poifon-pyrites. 



In fhort, the former are either more, or en- 

 tirely fulphureous ; the latter more or entirely ar- 

 fenical. Now in the fulphureous, the iron is the 

 principal and largeft part, and of which they all 

 indeed confift •, copper holds the fecond rank, 

 which in fome is none at all, in others in a fmali, 

 in others again in a very rich proportion ; fulphur, 

 the third, and which like the iron, is in all the 

 kinds of the pyrites ; arfenic, the fourth, of which 

 in many there is none, in fome only a very fmall 

 proportion, in others a considerable one, bewray- 

 ing itfelf either in the fulphur flags, or in the fan- 

 darach ; but contained in no one pyrites, where 

 iron and fulphur conftitute the capital parts, fo 

 largely, as without the addition 'of mifspickel to the 



H 2 fulphur- 



