Idaho semi-weekly world. [volume] (Idaho City, Idaho Territory) 1875-1908, 1892-01-29
OF INTEREST TO PROsPECTORa
AND MINERS.

the fire assay OF gold bearing rock is |
by no means a satisfactory test as to
the product in gold from such rock,
when treated or run through the
amalgamating mill. The Ere assay
bears about the same relation to al
mill run Of the gold bearing rock that
the humid copper assay does to ere
assay.
In certain sense the investor does
not care to know the ultimate amount
OF metal that an ore contains. What
he desires il the amount of money in
practice tho ore will yield under
skillful treatment. This information
is approximately obtained by FIRE for
copper, and the amalgamation pro-
cess for gold. We know it is true that
there are adopts who can very close
ly guess by panning csrtain quanti-
ty of pulp, or sand, the amount Of
gold to the ton OF rock mill can, or
ought to save, if properly run, by the
number Of "colors," and their size,
the sample shows to the unaided eye.
Of course this method is not very
popular, nor can it ever be, as mat
ter Of weighing and matter Of judg-
ment and practice is required.
! The best method would be to take
say fifteen or twerty pounds of the
rock, crush it all so that it will pass
through 20-mesh screen, then intro
duce it by FIVE or six pound charges
into small amalgamating grinding
pan, with sufficient water to make a
tolerably stiff pulp, then Introduce
from three to four ounces of quick
silver, and grind each charge about
two hours, or if power can be had
one hour will suffice. When COM
pleted pan 1t carefully to regain the
mercury, which will contain all the
free gold that was in the charge. In
troduce another charge into the par
and proceed in the same manner a.
before. Continue the operation by
charges, until all the ore is treated
using the same mercury at every
b charge.
! After all the ore has been worked
- through the amalgamating pan, par
the whole mass carefully by hand t.
:, regain any amalgam or mercury tina
may remain in the tailings, and ais
!. to concentrate the sulphdes or oxide
:, of iron. Take a small iron rotor,
- first carefully coating the same o.
= the inside with moist chalk, or culu
,f aud evaporate all the mercury use
N lido not pass it through buckskin, c
rs anything else), carefully remove a
y the gold adhering to the retort, the
q introduce it into capsule of Leaf
h and cupel the same. Next dry tt
concentrates and take an averaq
sample of them for an assay. TIL
latter ASSAY and the amount obtains
he by amalgamation will show the pr
OF duct that the ore will yield in pra
ng tice.
Tx In the final panning, or cleanup
n it would be we'll to use 3 dilute sol
Ia ton of potassium cyanide when t
ca operation is nearing completion, al
OF scour the mass with the hand VIII
ter in the pan in order to aggregate
the fine particles of mercury, OF ami
ne gam that may remain in the sulphid
OF The cyanide solution will remove
to oxide from the mercury and quick
1ty the result.
'ws Messrs. James Baxter & Son,
on sayers of Boise City, have recen
en- introduced into their laboratory
md complete apparatus for making pr
ard teal tests of both gold and sill
on ores; also a chlorination plant for
ing tracing all the gold from aurifer'
less concentrations.
n a The prospector frequently enco
lon ters class of rock heavily empr
'em mated with iron sulphides (pyrite),
owing to their superior specific gr
OF ity cannot be separated from the
one gold particles sufficiently to ena
om- the miner to estimate anything n
who what the rock is worth, particul;
the as the pyrite is of bright, bra
ia color, is very misleading. The
IS OF lowing method we have often tr
gest and always obtained hattering
be- suits: First, crush sample of
pub rock, pan off the quartz and eal
tiles substances and have the pyrite
etfi- nearly clean as possible. Dry
sample, then mix with it about
mis- and one-half per cent of salt, ado
,gest sufficient water to enable the mas
Boise adhere together. Mould it into
lext, with the hands to about the size {
re- small hens egg. Place the balls