The Patio and Cazo Process. 4!) 



Cost pee Ton of '2.000 lbs. in Working a tojia of 19 Tons. 



Breaking, grinding, and use of tools, - - $6.66 



Amalgamators' wages, ... - l.(;<; 



Scraping arrastra to get out gold amalgam, - - .1.6 



Carrying and washing scrapings, - - .11 



Concentrating tailings of " - - .07 



Carrying slimes from arrastra to patio, - - .42 



Mules and keeping, ----- - 3.72 



Labor, spading and mule-driving, - -1.60 



" washing torta, ----- .56 



Charcoal for retorting silver, - .47 



Concentrating tailings of torta, - 2.00 



Materials, salt, 600 lbs at Sets., - - - 2.53 



sulphate of copper, 125 lbs at 25 cents, - - 1.65 



.87 

 4.37 



precipitated " 



25 " 66 



quicksilver, 



133 " 62i 





Total, - 



S26.91 



There is not only a very great saving in doing the woik by 

 power, but in custom mills, to which these last expenses refer, 

 there is a considerable profit included in the cost, which will not 

 be less than from two to two and a half dollars per ton. It is 

 astonishing how sucb a process has been able to retain its hold 

 nearly three hundred years. In every country where it has been 

 introduced, it, like many another historical process, has yielded 

 before the advance of rapid means of communication, as this 

 undoubtedly will in Mexico. It costs but little to carry it out. and 

 it can be worked on a large scale as well as a small one, the latter 

 having only this disadvantage^ that it increases the loss. The 

 process requires peculiar conditions of climate, which adapt it 

 especially to hot countries. On account of the climatic condi- 

 tions it has been abandoned in the West, where it was formerly 

 used. It always works better on a hot day than on a cold one, 

 in summer than in winter. The cheapness of the plant more than 

 compensates for the time, as money in most of these countries 

 is scarce, while time is of no value. Working the tails by the 

 Von Patera process ha?, in some places, added to the yield in 

 silver and increased the profits. The loss in reagents is easily 

 put up with, as it is the only means by which the precious metals 

 can be obtained. The method is only applicable to such ores 

 as contain the silver native, or as chloride, bromide or iodide, 



