The Vancouver independent. (Vancouver, W.T. [Wash.]) 1875-1910, 1883-09-06
Refining Metals.

AS the perfect performance of this
work is very difficult, requiring thor
ough knowledge of chemistry and metal
lurgy, and the utmost carefulness of
operation and calculation, so on the re-
liability of its results depends the sue
cessful operation of q reduction estab-
lishment.
The first process of the operation is
what is called "sampling" the various
grades and kinds of ores, in order to de-
termine not only their value, but the
proportion of fuxes necessary to secure
the extraction of the finer from the baser
n etals and rock mixed with them in the
ore. The Auxes principally used
are limestone, lead ore and iron
ore, the iron ore being more especially
to take up the sulphur in the other ores,
and all are used in quantities according
to kinds and proportions of metal 10 the
ores to be reduced, the object of the
Auxing being to fuse the undesirable
portions of the ore, so as to enable the
separation of the metal from them. In
order to insure the application oil proper
character and proportion Of the fuxing
material and make the operation COM
plete, the ores must be analysed, so a. to
determine the kind and amount of oil the
materials composing them, and thus the
character and proportion of the fuxes
required.
In sampling ores for this purpose, the
ore, az it comes from the mine, is passed
through what is called o "crusher" and
broken into pieces Of the average size of
q hickory rut. For the purpose Of
sampling, small portion is taken from
the mass in such way as to best secure
as nearly as possible q fair average Of
the whole. This. in turn, is ground in
q sampling mill to fine dust or pulp.
A portion Of this pulp is weighed, about
one-tenth of an ounce being usually
taken for an assay. mixed with grsnu-
lated lead in fire-clay cup, and then
placed in what is called q ''muffie," O
fire. This melts the lead, which collects
all the silver in the ore. and forms what
is called q lead "button," usually Of
about half an ounce weight.
This lead button is then placed in q
cupel, or little cup made Of ground bone
ash moistened and compressed into o
mould, and then replaced in . muffle
and submitted TO nearly white heat.
Great care has to be taken " properly
regulate the heat. lest the metal itself
be destroyed with the lead. The air is
admitted, which burns or oxidixes the
lead, the oxide is absorbed by the bone
ash Of the cup, leaving the silver. Az
this process goes ON the publication sp.
proaches completion, the silver rounds
up into little globule. emitting . vel.
lowish white light, and - the last traces
Of the lead diappear. the pure silver rap
radly brightens and shines out like q
mirror. II is then pure-1000 Ane.
When gold 10 found with silver in the
ore it still remains in the bullion but
ton. This is separted from the silver by
process called parting. To ascetain the
relative proportion Of gold aud silver
in the button, in assaying, the button is
subjected to the action OF nitric acid,
which dissolves the silver, leaving the
gold in the shape Of fine black powder,
which is carefully washed, dried and
weighed. The weight Of the bullion
button being known, . subtraction Of the
weight of the silver il contained, and Q
comparison Of the weight OF the two
metals thus produced with the weight OF
the assayed gives the proportional
amount OF each TO the orc thus sampled
and assayed.