in the Pyrites. 141 



fhewn above, chap. III. There are fo many py- 

 rits containing copper, that fcarce one in a hun- 

 dred is without it, or that confift entirely of iron. 

 A pyrites, that, preferably to another, yields gold, 

 mufi always pofTcfs iron or copper, or both, for its 

 ground-earth. And 1 have remarked, that fuch 

 pyrit* are ever coppery, nay the very richeft cop- 

 per ores ; and, in the other cafe, ever purely ar- 

 fenical, or the white pyrites. Now, in the laft 

 place, whether it was an actual gold-pyrites, or no, 

 we are to underftand, that pyrites breaking in fif- 

 fures and veins, is feldom without fome little cop- 

 per. So that our author might have faved himfelf 

 many uneafy reflections about the caufes, whence his 

 copper might arife -, and alfo have fpared himfelf 

 the trouble of imagining a metallic fulpbur fpir it ; as 

 he needed only to have put the alternative ; either 

 the copper is along with the fulpbur educed bodily 

 out of the pyrites in form of the mod fubtil earth ; 

 or generated, as a new production, out df the fuU 

 phur, or its peculiar earth, with the addition of 

 linfeed oil, or its fatty earth ; alfo for a certainty, 

 with the addition of the material, fatty particles of 

 the fire. 



It is, however, probable, the above copper was 

 not generated but educed : for, in the firft place, 

 the volatility, or at lean:, the volatilifation of all 

 imperfect metals in general, is a plain cafe. (2.) 

 We have a peculiar inflmce in iron, which is moil 

 proximately allied to copper. {%.) The fulpbur, 

 which mult here ferve as the vehicle, adheres longer 

 and clofer to the copp-r than to the iron. (4 ) The 

 volatility of copper afifayers experience but too 

 often, upon too brifkly roafting its ore ; when 

 they remarkably educe a lefs quantity of copper, 

 than when together with care and time they employ 

 a gentler tire. 



Now 



