d//& Pyrites, 6* 



Friberg, at the Tfcherper and at Tfchopau, in 

 colour ibmetimes approaching the rare white- grey, 

 and often to the extremely beautiful green lead- 

 ore : and therefore this leady earth, which is fome- 

 thin^ very uncommon, and hitherto only found 

 in formal veins at the due depth of ores, is to 

 be confidered as an earth, already peculiarly pre- 

 pared for particular metals, nay almoft as a lead- 

 ore : befides, we may conclude from the vein, 

 which has its felvages entire and clofe, and from 

 the extraordinary lead-yield, often amounting to 

 20 pounds the quintal, the vein was formerly an 

 open fifiure, and this leady clay, as a fluid gur, de- 

 rived from a lead-ore, weathered and reduced to 

 earth. Nay the univerfal, upper fatty layer of 

 earth comes near to the conftitution of iron, fo 

 that thefe particles of it fwallowed up by plants, 

 lofe not their fiends for metal, but according to 

 M. Lemery's experience, are reducible to a genuine 

 iron, as will plainly appear by the magnet. 



Converfely it alfo holds, that all metals are 

 again reducible to earth, yet none more fo than 

 iron, as it ufually falls entirely to ruft, ochre and 

 earth by the bare moifture of the air ; whereas for 

 the corrofion of copper a longer time is re- 

 quifite •, and for lead and tin fcarce the longed 

 term fufficient : the nobler metals, as fine gold 

 and fine filver, neither air nor time feetii capable 

 of affecting in the leaft. No other metal is af- 

 fected fo foon as iron with the weakeft depart* 

 waters^ which fcarce touch other metals ; nor are 

 any fo eafily reducible to the form of earth, as 

 iron. This may be proved by employing the fame 

 additions for the metallifation of metallic earths, 

 and cakes. To which may be added, that no metal 

 fo readily becomes verifiable, or is brought to the 

 higheit degree of a perfect earth. Whence the 

 pyrites is indifpenfably necefiary in the bufinefs of 



fmelting, 



