e of the
ore is separately acted upon in a rapid and efficient manner; that the
apparatus is adaptable to existing milling plants; and that there is
an absence of elaborate and expensive plant and of the refinements of
electrical or chemical science. These advantages imply that the work
can be done so economically as to commend the new process to the
favorable consideration of all who are interested in mines or mining
property.--_Iron._

* * * * *

REFINING SILVER BULLION.

A number of years ago the author devised a method for refining silver
bullion by sulphuric acid, in which iron was substituted for copper as
precipitant of silver, the principal feature being the separation of
pure crystals of silver sulphate. A full description of this process
may be found in Percy's Metallurgy, "Silver and Gold," page 479. The
process has been extensively worked in San Francisco and in Germany in
refining bullion to the amount of more than a hundred million dollars'
worth of silver. Its more general application has been hampered,
however, by the circumstance that the patent had been secured by one
firm which limited itself to its utilization in its California works.
The patent having expired, the author lately introduced a modification
of the process by which the apparatus and manipulations are greatly
cheapened and simplified. In the following account is given a short
description of the process in its present shape.

_Preparing the Silver Sulphate._--The bullion, containing,
essentially, silver, copper and gold, is dissolved by boiling with
sulphuric acid in cast iron pots. The difference between the new
process and the usual practice consists in the use of a much larger
quantity of acid. Thus, in refining ordinary silver "dore," four parts
of acid are used to one part of bullion. Of this acid one part is
chemically and mechanically consumed in the dissolving process, and
the remaining three parts are fully recovered and at once ready for
reutilization, as will be described hereafter. In the usual
process--understanding thereby, here and in the following, the process
practiced at the United States mints, for instance--two parts of acid
are employed for one of bullion; all of this is lost, partly through
the dissolving and partly in being afterward mixed with water,
previous to the precipitation of the silver by copper. Economy in acid
being therefore imperative, the silver solution final