Cíi.XIIÍ. SOUTH AMERICA. 1^^^ 



one that the metal in fusion by chano;ing its situation 

 must be exposed to the cold air, and eonsequentb 

 sooii condense. The second that the pores of the eartu 

 being extremely minute, particularly in a sandy soil, 

 the silver should raiher be found in filaments, or fine 

 ramifications, than in lar2;e lumps or pieces, as is re- 

 ally the case. To both these objections I shall endea- 

 vour to ivive a brief but satisfactory answer. 



Before the silver begins to run from the place 

 where it wa^ melted, the subterraneous fire had per- 

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

 the body of air enclosed in them, became distended ; 

 the metal immediately fojlows, and finding a channel 

 sufficiently capacious for introducing itself, farther 

 compresses the particles of th<* earth contiguous to 

 those tt abrades, and consequently, continues its course 

 without obstruction. The subierraneous fire which 

 preceded the fusion, comnumicates to tlie eaith a de- 

 gree of heat suiiicient to expel the cold ahv, so that 

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

 abated, and the metal becomes fixed. Another cir^ 

 cumstance which contributes to prolong tlie heat is, 

 there being often no spiracle to these passages, whence 

 the earth ihrou^h which the metal flows, does not 

 soon emit the first heat it contracted from the subte r- 

 xaneous fire ; consequently the metal will not be fixed 

 till at a considerable distance from the pl;ice of liqui- 

 dation : but the first particles of the metal being cb'^ck- 

 ■ed b) the cold they have gradually conti acted, tli¿->se 

 which follow flow to the same plate, and there form 

 a concreted mass, or mixed body of silver and scoria, 

 brouglit with it from t!ie original mine. It now re- 

 mains that we exainine whetlicr what is actually ob- 

 ser\ed in these lumps of silver, agiees wii h what has 

 been advanced, morder to determine whether this 

 opiiuon have a probable foundation. 



These papas or hnnps of silver, are of a diflerent 

 composition irom those fouiid in the mines, having 



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