With some of these ' tailings," large quantities of which have been bought up, we understand, by par ties in Boston for further extraction of the re maining gold, the efficacy ot Berdan's machine ...

EXCLUDING mechanical, smelting, and amalgamation processes, the methods of extracting gold from its ores may conveniently be grouped together under the heading of wet or chemical methods.

He found them to contain from fifty to one hundred cents of gold to the ounoe of sulphate, and succeeded in bringing his machine to such perfection as to enable him to work over a tun of the ...