The Evolution of the Stamp Mill [pp. 522-531]

Thle Evolution of the Stamp Mill.
Cockran of Tuolumne County, who invented
the Hendy Challenge Feeder. In all the
improvements the " lever regulated by a set
screw" gave Stanford a royalty, as this is the
indispensable feature of all self-feeders.
Silver plates as now used constitute a very
valuable feature in the California mill.
Mercurialized copper plates were used quite
early, and soon became popular. They
were displaced in about I862 by silver plating. Thus the California mill, as far as free
gold working is concerned, is very complete.
I have said nothing as to rock breakers, for
the reason that there has been but little
effective improvement over the original
Blake. The Giant or Dodge, as made by
the Parke & Lacy Company, of San Francisco has all the advances to date.
The next important step is the concentrator. Even in the earlier days of milling
we knew there was a value in the sulphurets,
and many were the devices for securing this
value. It was not until about I853 that
any especial attention was given to saving
them, and then the blanket was introduced
into the sluices. These at stated periods
were washed by hand, in tubs specially
made for the purpose. Shaking tables,
Cornish buddles, jiggs, etc., were given a
trial. In Soggs's mill, near Nevada City, a
small copper vibrating table, called the
Bradford separator, was used to a very good
purpose, both for securing fine gold, amal gam, and sulphurets. The drawback to
these machines was the small amount of
work that could be done in twenty-four
hours. At Grass Valley Mr. Fricot, of the
French mill, introduced a rocker that did
good concentration. This was very simple
and practical. It was a two-inch board
about twenty-four inches wide and some
eight feet long, with six-inch sides. The
tailings were thrown in at the head and water
was introduced. Then the rocking motion
spread them as they moved down the board.
The upper or more concentrated portion
were pushed back by a wooden shovel
almost as wide as the bottom of the rocker.
This was repeated until a very complete concentration was made. Several of these machines were attached together, all moved by
power.
Various have been the devices for saving
sulphurets, all of which, save the Frue,
Woodberry, McGlew, Johnson, and Triumph, have been relegated to the past.
The Morris table can be classified as a concentrator, and is often used after the above
for the taking up of the very finest gold.
Perfection of concentration by one machine
is not possible without sizing of the sands.
In our grand effort to handle quantity we
overlook completeness, and the question of
profit and loss is to be studied in connection with the per cent of concentrates.
The reader can now see what changes
forty-six years have brought, but we are not
standing still, what we may call perfection
today, may be buried before the next generation of mining men come to the front.
We are now dealing with two new elements
in the reduction and manipulation of the
precious metals which may produce a great
revolution. One is electricity, and the
other chemical solutions,- the results may
be beyond our present conception.
Mining is a great study and Californians
have studied it well. Not only has California taught the world how to design a battery,
but we have brought forth the most complete self-feeders and concentrators,- and
not only these, but designs for construction
of frame-work, whereby the movement of
ore from the dumping car to the taking up
of gold amalgam all is automatic. And we
have taught the cheap extraction of silver as
well. The iron pan process for silver, as
used now and for years in every mining
country of the world, was invented in California. I claim to be the inventor of this
mode of working, and although I first introduced it on a large scale on the Comstock,
[May,
530