4 A SYSTEM OF 



fubjeft to the fame alterations, and we likewifc 

 outlive the greater!: part of them, therefore we 

 treat them with more eafe and conveniency ; 

 whereas the changes which the mineral kingdom 

 undergoes, are hidden to us, and require many 

 centuries to compleat them. 



I cannot fuppole the mineral bodies to be pro- 

 duced by feeds, for want of proof; and I do not 

 know why the metals fliould have any preference 

 in that refpect. Native or virgin copper and 

 filver are produced in the fame manner as the 

 ftaladlites. The water carries along with it the 

 invifible particles of lime, copper, or filver, and 

 depofits them upon other fubjecls, either by 

 means of an attractive power in thefe, or by fome 

 alteration in itfelf, occafioned by its motion. The 

 precipitated particles are, at the beginning, very 

 eafily feparated ; but in procefs of time they co- 

 here very firmly, as is evidently feen in the na- 

 tive precipitated or Ziment-copper *, which, after 

 it has been fome time taken out of the water, is 

 partly malleable. The figure which native gold 

 and filver have in their rocks or beds, does not 

 prove any more than do the metallic iron's or cop- 

 per's accreting into a mofs-like form in the poor 

 or rich roafted ores or reguli at the furnaces ; it 

 gives us rather an idea, how thofe accidents hap- 

 pen, merely by the fhrinkingand the fudden cool- 

 ing of their furfaces : and we can then alio beaki 

 to conceive iomething of the reafon why cryftals 

 are found in a pebble form, or in loofe nodules, as 

 the -petrified melons of Mount Cartnel, and the Ita- 

 lian iron ores, in form of balls, &c. without 

 wanting to have recourfe to the fuppofition of a 



* Called ZIment-coppfr from its being firft noticed in a 

 vitriolic water called zimtnr, ac Herrengrund in Hungary. 

 L>. C. 



melting 



