Ch. XIII. S O U T FI A M E R I C A. 1 5 5 



one that the metal in fufion by changing its fituatioHj 

 mull be expofed to the cold air, and, confcquently, 

 foon condenfe. The fecond that the pores of the 

 earth being extremely minute, particularly in a fandy 

 ibil, the filver lliould rather be found in filaments, or 

 fine ramifications, than in large lumps or pieces, as is 

 really the cafe. To both thcfe obje^ions I fnall en- 

 deavour to give a brief but fadsfadory anfwer. 



Before the filver begins to run from the place 

 where it was melted, the fubterraneous fire had per- 

 vaded the pores of the earth, which by the dilatation of 

 the body of air inclofed in them, became diflended ; 

 the metal immediately follows, and finding a channel 

 'lufficiently capacious for introducing itfelf, farther 

 compreffes the particles of the earth contiguous to thole 

 it abrades, and, confequently, continues its courfe 

 without ob{lTU(!lion. The fubterraneous fire which 

 preceded the fufion, cpmmunicates to the earth a de- 

 gree of heat fufficient to expel the cold air<, fo that 

 the metal runs through it, till by degrees^ the heat is 

 abated, and the metal becomes fixed. Another cir^ 

 cumllance which contributes to prolong the heat, is, 

 there being often no fpiracle to thefe paffagss, whence 

 the earth through which the m.etal flows, does not 

 foon emit the firft heat it contracted from the fubterr 

 raneous fi.re ; confequently the metal will not be fixed 

 till at a confiderable diilance from, the place of liquida- 

 tion ; but the firft particles of the metal being checked 

 by the cold they have gradually contraded, thofe 

 which follow flow to the fa^ne place, and there forms 

 a concreted mafs, or mixed body of filver and fcoria, 

 brought with it from the original mine. It now re- 

 mains that we examine Vv^hether what is adlually ob- 

 lerve4 in thefe lumps of filver, agrees with what has 

 been advanced, in order to determine whether this 

 opinion have a probable foundation. 



These papas, or lumps of filver, are of a diflferent 

 compofition from thofe found in the mines, having 



ail 



