36 



The Patio and Cazo Process. 



a lead or tin amalgam, but this was too viscous, and became easily- 

 red need to powder, so that the loss in silver was increased. 



At the end of a time, more or less long, no mercury is found. 

 The operation is nevertheless continued until the amalgam attains 

 a certain consistence. If, however, the amalgam becomes too 

 thick, a fresh charge of mercury must be made, adding it little 

 by little. Sometimes the assays are made over only a small part 

 of the torta. A little salt will be added in one part and a little 

 magistral in another. Assays are then made to see the effect, in 

 order to show what should be done with the whole pile. 



When the torta is rendlda, it must be washed as soon as possible, 

 If allowed to stand, the sulphur and the sulphate of copper which 

 have not been decomposed commence to act, and cause a con- 

 siderable loss of silver in the state of very finely divided amal- 

 gam, desecho, which will not unite. It is to prevent this as 

 much as possible, that the large excess of mercury is added, but 

 notwithstanding the excess of mercury the pile must be washed 

 at the earliest possible moment. 



c. Separating the Amalgam. — The amalgam, with the excess 

 of mercury, is scattered through a large mass of pulp, from 

 which it must be separated by washing. This should be done once 

 ii* twenty-four hours. 



The washing, lava, is done in a box settler, lavadero, or in a 

 tub, Una; both of these methods being in use in different works. 

 The former is b>y far the most ancient. The tub, which is very much 



like the dolly tub or 

 settler of California, has 

 been in operation for 

 many years, but as it re- 

 quires the use of power, 

 is only adopted in the 

 large haciendas. 



The box, lavadero, 

 Figs. 2, 3, 4, is built of 

 -D- stone on the sides, and 

 lined with cement. It is 

 two meters long, half a 

 meter wide, and one 

 meter deep. It has a 







ft 











Fig. 2 



1 











% 









T/l 



S| 













_ 



SECTION ON CD. 







J- 





III 



r— , 





c-^= 



4 



^r 





— 1 





L 















■ 1- 







PLAN 



B 





LAVADERO (Settle 



r) 



Scale 100 = 1 





Fig. 3. 





