apparatus
agitates the water and pyrites to a very considerable degree, in fact
the metalliferous and sandy contents are prevented from settling. While
these arms revolve, a contrivance, consisting of two thorns at the
driving wheel of the bevel gear, working the whole apparatus off a
belt, communicates a rapid striking motion to a compound lever, fixed
at the outside of the tub, at the end of which lever a five-pound
hammer is fixed, which strikes the outside of the tub in the manner
described. These blows tend to settle gradually all the heavier ores
first, followed by the sands after, and thus a very complete separation
of these products is obtained. On completion of a certain quantity, the
spindle is hoisted out of the tub, and below a few inches of sand the
pyrites will be found, worth, in the case of the Idaho Company, after
paying for working expenses, from 50 to 60 dollars per ton, if
manipulated by the chlorination process. There now remain the sands
covering the pyrites in the tossing tub, and those flowing over the top
of the door in the automatic sluices, which constitute the " tailings "
in California.
Inasmuch as these tailings "on assay" show some gold, they are submitted to further and final treatment by means of the McBougal's "float-gold ripples" (Plate
VII.). These are simply sets of tables coupled together, each 18 feet
long, 2 feet 6 inches wide, with a pitch of from 6 to 12 inches for
every length of each table. They are lined with electro-copper plates,-
except where they contract in width, and are covered with a kind of
shoe of peculiar form (Plate VIIa.-). These shoes are set in rows at B, close together, and, as they are hollow, their cast-iron pedicles, a, b, c, d, four
in number, are filled with wooden blocks. The tailings running over
them enter the cross-like aperture on top, shown in the diagram, and
thus a kind of eddy is formed at the base of their four pedicles,
practically resulting in the deposit of someming more than two per
cent, of the finest float, foam, or leaf gold obtainable by these
simple means, and after all these variously elaborate processes of gold extraction described above.
To recapitulate the treatment followed, in short, it would stand thus:—
Empire Company's Process:
From stonebreaker to battery by means of self feeders without mercury;
Brass gauge screens (gratings) with 1,400 holes to the square inch;
Electro-copper-plate ripples. Pan-system:
Grinding, concentrating pans, with concurrent amalgamation.
Note.—Distance covered by various apparatus enumerated above, about 180 feet from boxes without final treatment of tailings or slimes.
