hlorinated water was then drawn off containing the gold in solution
which was deposited as a brown powder by the addition of sulphate of
iron.
Great improvements on this slow and imperfect method have been made of
late years, among the earlier of which was that of Messrs. Newbery
and Vautin. They placed the pulp with water in a gaslight revolving
cylinder, into which the chlorine was introduced, and atmospheric air to
a pressure of 60 lb. to the square inch was pumped in. The cylinder with
its contents was revolved for two hours, then the charge was withdrawn
and drained nearly dry by suction, the resultant liquid being slowly
filtered through broken charcoal on which the chloride crystals were
deposited, in appearance much like the bromo-chlorides of silver ore
seen on some of the black manganic oxides of the Barrier silver
mines. The charcoal, with its adhering chlorides, was conveyed to the
smelting-house and the gold smelted into bars of extremely pure metal.
Messrs. Newbery and Vautin claimed for their process decreased time for
the operation with increased efficiency.
At Mount Morgan, when I visited that celebrated mine, they were using
what might be termed a composite adaptation process. Their chlorination
works, the largest in the world, were putting through 1500 tons per
week. The ore as it came from the mine was fed automatically into Krom
roller mills, and after being crushed and sifted to regulation gauge was
delivered into trucks and conveyed to the roasting furnaces, and thence
to cooling floors, from which it was conveyed to the chlorinating
shed. Here were long rows of revolving barrels, on the Newbery-Vautin
principle, but with this marked difference, that the pressure in the
barrel was obtained from an excess of the gas itself, generated from a
charge of chloride of lime and sulphuric acid. On leaving the barrels
the pulp ran into settling vats, somewhat on the Plattner plan, and
the clear liquid having been drained off was passed through a charcoal
filter, as adopted by Newbery and Vautin. The manager, Mr. Wesley Hall,
stated that he estimated cost per ton was not more than 30s., and he
expected shortly to reduce that when he began making his own sulphuric
acid. As he was obtaining over 4 oz. to the ton the process was paying
very well, but it will be seen that the price would be prohibitive for
poor ores unless they could be concentrated before calcination.
The Pollok process is a newer, and sta
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