[ 127 ] 

 CHAP. VIII. 



Of the U N M E T A L L I C EARTH in the P Y R I T E S. 



TH AT along with the iron and copper in the 

 pyrites, there is, befides, a fixed fort of 

 earth, which is neither fulphur nor arfenic, neither 

 iron nor copper; in a word, which neither is it- 

 felf, nor can yield, any metal, is a thing deferving 

 a particular confideration, as being one of the pe- 

 culiar principles of the pyrites. Upon this head 

 we fhall briefly only (intending to leave the further 

 difquifition of the fubject to the more minute exa- 

 mination of others) confider thefe four things ; 

 (i.) What we are to underftand by fuch an unme- 

 tattic earth: (2.) Whether fuch an earth is to be 

 obferved in other ores : (3.) Whether fuch can be 

 (hewn actually exifting in pyrites : (4.) What its 

 nature and properties are. 



As to the firft, or what is to be underftood by 

 the unmet allic earth , we muft, firft of all, guard 

 the reader againft a miftake, in which he might 

 be otherwife apt to fall, and caution him, that by 

 no means are we to underftand by it the adhering, 

 interfperfed, quartzy, fpathy matters, and the like 

 earth, rock, or ftone, or any thing that is fepa- 

 rable by the wedge, or diftinguifhable by the 

 naked, or even by the armed, eye ; feeing fome- 

 times in ores there lies interfperfed, like a fand, a 

 fmall- grained, either quartzy or felenitical, fort ©f 

 rock, or ftone, as I have had a fample from the 

 Bannat of Temefwaer, in which an unarmed eye 



could 



