The Ravalli Republican. [volume] (Stevensville, Mont.) 1894-1899, 1896-02-12
TESTING THE ROCK.
How Gold and Silver Orc is Treated Be.
fore Assaying.

oold'lSel WHO Wandcrs up ana dow
in the labyrinth Of shafts and tuu
ncls, diggings and dumps Of Il gen
uine mining camp, perhaps there j:
no subject more full Of interest thar
the process BY which a lump Of browr
ore, which, to his inexperienced eye
looks not the least attractive, i
made to yield it's share CT silver ant
gold, or the means and methods b,
which the mining man at his side s(
confidently assures him that ton @
| that ore will 60 S2.33 ounces in sill
yer and $17.55 in gold. Even tho
eastern mining expert or graduate
from some mining school will wonder
how, il the log cabin or pine shanty
destitute of all the elaborate par
aphernalia to which he has been &C
customcd, these results are so rcadil,
and accurately obtained.
AS general rule the majority OF
the ores, except those containing the
precious metals, for purposes Of pur-
chase and sale are valued according
to the cost Of mining and shipping,
so that except for mctallurgical pur-
poses, it is unnecessary to seek to de-
terminc with much accuracy the con-
tents and value OF such ores. In the
case of ores rich in the precious met
ais. however, it is entirely different,
as in their purchase and sale both
parties. the buyer as well as the
seller, want to ascertain accurately
and to Il certainty the value Of the
entire lot. The methods by which
this knowledge is obtained are 50
simple as to be easy understood and
practiced by many man who does
not know the technical symbols Of
the metals he is determining or
could not give a scientific exposition
of the process, but, nevertheless, in
his line, he is an accurate and sue
ccssful assaycr.
When a quantity Of orc is to be
sampled for assaying it is first broken
by an ordinary rock crushcr into
pieces the size of an English walnut,
after which it is shovclcd back into
the car, but in such a manner that
every fifth shoyelful is thrown aside
by itself, the remaining four -fifths
being finally taken away. Ths'tifth
portion. known as the "samplc," is
then reduced to q much greater de-
r""" ~f ~, ',- ~---.-n.... ~s----.~>-
rolls. 1t is then piled on the floor in
q cone, tlattcncd out and divided
into four equal portions, and two op-
positc quarters arc then removed.
The remaining quarters are again
thoroughly mixed and again piled in
a cone, flattencd and quartered: this
operation being repeated until the
sample is reduced to 100 pounds. 1t
is then weighed repeatedly for the
purpose Of determining the amount
Of moisture contained in the ore,
which in some ores, especially these
OF the concentrates, is SO consider
able as to make a very appreciable
difference in the weight. The
moisture is then expelled and the orc
is crushed to such a degree Of fine
ness that it can be passed through q
sicvt containing 100 holes in the lin
ear inch. The sample is next put up
in small bottles, which are scaled
with sealing wax and then stamped
for the purpose OF preventing the
possibility Of their being opened or
tampcrcd with without detection.
The above is the process Of samp-
ling used among the mines, and the
sample is now ready to be assaycd,
but only a small portion Of it will be
used for that purpose. and the guam
tity generally taken is what is known
as an "assay ton," which weighs 29:-
1866 milliyrams, or a little more than
$50 grains troy weight. The def
mite amount is taken, partly as a
muttcr or convenience: and also be-
cause the assaycr wishes to ascertain,
as quickly as possible, how many
ounces Of The precious metals to the
ton are contained in this ore The
method used depends upon the fol-
lowing principle: The ayoirdupoiS
grams ton Of 1000 pounds contains
20. lGG ounces troy weight; hence,
when 20, lG6 milligrulns Of the ulas.
saved ore is taken, the weight Of the
resulting Hbutton'' OF gold or silver
in the milIigrams represents at once,
without any further calculation, the
number Of troy ounces of gold or sill
yer in the ayoirdupois ton CT ore.
This method WAS invented in the
Columbia School Of Mines III New
York city, and is in general use
throughout the world wherever there
is aSsaying to be donc.--boston Tran
script.
Hucklcn's Arnic: SaIIc.