The Patio and Cazo Process. 5,3 



The bottom is made of impure east copper, and is 0.18 m. to 0.20 m. 

 thick, 1.80 m. in diameter, and 0.18 m. deep. On the inside of the 

 rim of the basin a place is cutout to receive the staves, which rest 

 on the bottom of the cut made in the rim of the copper basin. 

 These staves are 0.70 m. long, and are held in position by iron 

 hoops. All the joints between the copper and wood are made 

 tight with clay, and then adobes are built up around the whole 

 to a thickness of 0.45 m. In the centre a raised space is pro- 

 vided for the pivot of the upright arbor which carries two arms, 

 one 0.45 m. from the bottom, of a little less diameter than the 

 interior of t\\e. fondon, and the other at 0.85 m., projecting beyond 

 it for the purpose of hitching a single mule to it. The lower 

 arm carries two pieces of copper, each of which weighs 140 kilos., 

 which are used as mullers. They must be so arranged as to rub 

 over the whole surface of the copper bottom to keep anything 

 from becoming attached to it, as it would otherwise be impos • 

 sible to grind with such soft materials as a copper muller. The 

 whole is placed over a furnace with grate bars, on which the in- 

 ferior fuel of the country is used. Such a fondon will last for 

 ten years. The cost is* 



60 quintals of copper for bottom, at $20, - - $1,200 



Two mullers, ------ 120 



25 staves at 3 reals, ----- 9 



Furnace, ------ 40 



Wood-work for the mules, - - - - 10 



House, ------ 200 



$1,579 



When everything is ready, the fondon is charged with 500 to 

 600 kilos, of rich ore, and 30 to 40 kilos, of the powder of unwashed 

 ore, and sufficient water to form a thin mud. Fire is kiudled on 

 the grate, and the muller set in motion. At the end of two hours 

 the material is boiling; 52 kilos, of salt, or about ten per. cent, 

 of the weight of the ore, are added. This relatively large amount 

 is necessary, as the success of the process depends to a great de- 

 gree upon the quantity of salt used, and the velocity of the 

 mullers. With the richest ores, the quantity of salt does not ex- 



* Ibid., p. 217. 



