Mining Ordinances of Spain. 149 



San Juan de Lucanas in Peru, and was printed at Lima in 1738, 

 and reprinted at Madrid in 1743 ; where a summary of the dis- 

 covery was likewise printed separately, in the same year, which 

 met with commendation from the pen of Father Feyjoo*. The 

 discovery consists in employing colpa, or copperas ; the goodness 

 of which is tried by reducing it to powder, moistening it with 

 water, and throwing some globules of quicksilver into it. If the 

 quicksilver spreads, or separates into minute particles, the colpa is 

 good ; and the like if the quicksilver, when placed on the colpa, and 

 stirred in a cup or with the finger, assumes a bluish ash colour, or 

 divides. 



* The ore and the colpa being well ground, the latter is to be 

 taken in an equal proportion to the salt used. The mixture is to be 

 stirred, as in the ordinary process of reduction, four times a day, 

 and is afterwards to be charged with about two quintals more of 

 the colpa, and water is to be sprinkled uniformly over it. The 

 quicksilver is then to be stirred in, in such quantity as the nature of 

 the ore may require. After six days an assay is made, the stirring 

 being continued ; and if the ore be too warm, it is allowed to cool, 

 or lime is thrown in ; after which fresh charges of quicksilver are 

 added from time to time. The slime must be washed without 

 throwing in any quicksilver by way of bano^. When the quick- 

 silver is driven off, it will be found that a greater proportion of 

 silver is obtained, and that none of the quicksilver is consumed, 

 except such part as is lost in the stirring, or from other accidental 

 circumstances. This is the method pursued with the cold ores. 



' For the warm ores it is said, that when ground, a basketful of 

 lime is to be thrown uniformly over them. To twenty-five quintals 

 of ore, ten arrobas I of salt are to be added, with a sufficient 

 quantity of water, and the mixture must undergo four stirrings. The 

 next day, the colpa, being first well prepared, is to be added, in the 

 proportion of one half, to the weight of salt used ; and a sufficient 

 quantity of water being added, the mass is to be stirred four times, 

 and as often on the following day. The mass being spread abroad, 

 another arroba of colpa is to be thrown in, distributing it uniformly, 

 and the mixture is to be sprinkled with water. When thus moist- 

 ened, the quicksilver is to be stirred in; and three da\s afler, it 

 must be ascertained, as in the ordinary mode of reduction, whether 

 the montons are cold and require more stirring, or whether they 

 are warm, and demand a further addition of lime.* 



Other methods of reduction are likewise described, which, 

 being in less general use, we pass over. 



When on the subject of boundaries, the author describes, at 



* Cartas eruditas, torn, ii., carta 19. 



f A term applied to a supplementary proportion of quicksilver, usually thrown 

 iu by way of softening the slime preparatory to washing. Tnins. 

 An arroba is 2i>ibs. Spanish. Trans. 



