is cheaper; but in beneficiating they would probably lose as much as they saved on the crushing, if the American system of reduction and amalgamation was fully adopted here.
Mr. Parkman's tortas are an improvement. He has seven of them, each sixty feet in diameter, and holding one hundred and twelve tons of pulp. The mules—only two in number—travel around the outside, and draw a shaft which works on a pinion in the center, on which there is a pair of heavy wagon wheels, which, by an adjustable scale, are made to run in a smaller or larger circle, thus working over all the pulp in time. As the pulp works outward toward the side of the torta, it is shoveled back towards the center, by hand, and is thus well mixed. The time required in beneficiating is twenty-five days in Mr. Parkman's hacienda, and the work is always well done. The ore is not of a very refractory character, being mainly pure black and bronze sulphites, and the patio process appears to save more of the silver than any other. I am told that there are occasionally small deposits of chlorides found here, but that by the patio process none of it is saved.
The great mine of San José de Valenciano, which is said to have produced in its day eight hundred million dollars, was not visited by Mr. Seward, but I had the good fortune to see it.
This mine is situated on the mountain, high above the city on the North-east, and occupies a large and rich portion of the Veta Madre or "Mother Vein," of Guanajuato. It was discovered immediately after the conquest by the Spaniards, and for many years was a wonder of wonders. For forty years in succession it
