ULLOA*S VOYAGE TO SOUTH AMERICA. 6^27 



XII. The province of CarangavS begins feventy leagues weft from the city of Plata, 

 and extends above fifty leagues. The climate of this jurifdidtion is fo cold, that the 

 only efculent vegetables here are the papa, quinoa, and canagua ; but it abounds in cat- 

 tle. Here are a^ great number of filver-mines conftantly worked ; among which that 

 named Turco is very remarkable for a fort of ore termed by miners machacado ; the 

 fibres of the filver forming an admirable intertexture with the ftone in which they are 

 contained. Mines of this kind are generally the richeft. Befides this there are others 

 in this jurifdiclion, which, if not richer, are equally remarkable ; and thefe are found in 

 the barren fandy deferts extending towards the coaft of the South Sea. And here, only 

 by digging in the fands, are found detached lumps of filver, not mixed with any ore or 

 ftone than what adheres in fome parts to the metal. Thefe lumps are called papas, 

 being taken out of the ground, in the fame manner as that root. It is doubtlefs very 

 difficult to account for the formation of thefe mafles of filver in a barren and moveable 

 fand, remote from iny ore or mine. Two conjectures may, however, be offered. The 

 firft by admitting the continual reproduction of metals, of which there are indeed 

 here fo many evident proofs ; as the matrices of gold and filver, met with in many parts 

 of this kingdom. Nay, the very mines themfelves, after being long forfaken, have 

 again been worked with great advantage ; but the ikeletons of Indians found in old 

 mines, and covered with fibres of filver, and the inward parts alfo full of the fame 

 metal, feem to put the matter beyond difpute. If this be admitted, it is natural to con- 

 clude, that the primordial matter of filver is firft fluid, and when it has acquired a cer- 

 tain degree of perfection, fome parts of it are filtrated through the pores of the fand, 

 ftill ftopping in a place proper for completing the fixation ; they there form a folid con- 

 geries of filver ; and being joined with thofe earthy particles they collected in their 

 courfe to the place where they were abforbed by the pores of the fand, confolidated 

 with the filver. 



Though this conjecture be not deftitute of probability, yet I am more inclined to 

 embrace the fecond, as it is, in my opinion, more fimple and natural. Subterraneous 

 fires being very common in thefe parts of America, as I have already obferved in fpeak- 

 ing of the earthquakes, their aCtivity is doubtlefs fo ftrong as to melt any metals depo- 

 fited near the places where they begin ; and to communicate to them a heat fufficient 

 for keeping them a long time in a ftate of fufion ; and hence a portion of filver thus 

 melted neceflarily fpreads, and introduces itfelf through the larger pores of the earth, 

 and continues to expand itfelf, till, being beyond the reach of heat, it fixes, and re-af- 

 fumes its former confiftency, together with other heterogeneous fubftances collected in 

 its paflage. To this hypothefis, two objections may be offered ; one, that the metal in 

 fufion, by changing its fituation, muft be expofed to the cold air, and confequently foon 

 condenfe. The fecond, that the pores of the earth being extremely minute, particularly 

 in a fandy foil, the filver fliould rather be found in filaments, or fine ramifications, than 

 in large lumps or pieces, as is really the cafe. To both thefe objections I fliall endea- 

 vour to give a brief but fatisfaCtory anfwer. 



Before the filver begins to run from the place where it was melted, the fubterraneous 

 fire had pervaded the pores of the earth, which by the dilatation of thet)ody of air en- 

 clofed in them, became diftended ; the metal immediately follows, and finding a chan- 

 nel fufficiently capacious for introducing itfelf, farther comprefles the particles of the 

 earth contiguous to thofe it abrades, and, confequently, continues its courfe without 

 obftruCtion. The fubterraneous fire which preceded the fufion, communicates to the 

 earth a degree 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 circumftance 



4L 2 which. 



