San Antonio daily light. [volume] (San Antonio, Tex.) 1886-1907, 1896-02-12
TESTING THE ORES.
How Samples from the Diggings Are Pre-
pared for the Assay once.

To the uninitiated but observant
stranger who wanders up and down in
the labyrinth of shafts and tunnels,
diggings and dumps of a genuine min
ing camp perhaps there is no subject
more full of interest than the process
by which lump of brown ore, which,
to his inexperienced eye, looks not in
the least attractive, is made to yield
it's share of silver and gold, or the
means and methods by which the min
ing man at his side so confidently as
sures him that ton of that ore will
go 1898 ounces in silver and S17.55 in
gold. Even the eastern mining expert
or graduate from some mining school
will wonder how, in the log cabin or
pine shanty, destitute of all the elab-
crate paraphernalia TO which he has
been accustomed, these results are so
readily and accurately obtained.
AS a general rule the majority of the
ores, except those containing the pre-
cious metals, for purposes of purchase
and sale are valued according to the
cost of mining and shipping, so that, ex-
cept for metallurgical purposes, it is un-'
necessary to seek to determine with
much accuracy the contents and value
of such ores. In case of ores rich in
bhe precious metals, however, il is en-
Airely different, as in their purchase
and sale both parties, the buyer as we'll
as the seller, want to ascertain ac-
surately and to a certainty the value
of the entire lot. The methods by
which this knowledge is obtained are
so simple as to be easily understood
and practiced by many man who does
not know the technical symbols of the
metals he is determining or could not
give scientific exposition of the proc
ess, but, nevertheless, in his line, he
in an accurate and successful assayer.
When a quantity of ore is to be sam
pied for assaying it is first broken by
an ordinary rock crusher into pieces
the size of an English walnut, after
which it is shoveled back into the car.
but in such manner that every fifth
shovelful is thrown aside by itself, the
remaining four-ffths being finally
taken away. This fifth portion, known
as the Sample" is then reduced to a
much greater degree of fineness by
means of Cornish rolls. 1t is then piled
on the floor in cone, flattened out, and
divided into four equal portions, and
two opposite quarters are then removed.
The remaining quarters are again
thoroughly mixed and again piled in
a cone, fattened and quartered; this
operation being repeated until the sam
pie is reduced to 200 pounds. 1t is then
weighed repeatedly for the purpose of
determining the amount of moisture
contained in the ore, which in some
ores, especially those of the concen-
trates, is so considerable as to make
O very appreciate difference in the
weight. The moisture is then expelled
and the ore is crushed to such a degree
of fineness that it can be passed through
a sieve containing 100 holes to the linear
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 tempered with
| without detection.
The above is the process of sampling
| used among the mines, and the sam
| pie is now ready to be assayed, but
only small portion CT it will be used
for that purpose, and the quantity gen,
| orally taken is what is known as an
"assay ton," which weighs %, 166 MILL
| grams, or a little more than 450 grains
troy weight. This definite amount is
taken, partly as matter of conven'
fence, and also because the assayel
wishes to ascertain, as quickly as posi-
BILE, how many ounces of the precious
metals to the ton are contained in t.i:
ore. The method used depends upor
the following principle: The avoirdu
pois grams ton of 1000 pounds contains
20, 166 ounces troy weight; hence, wher
9,166 milligrams of the unassayed orr
are taken, the weight of the resulting
BUTTON of gold or silver in the mill
grams represents at once, without an,
further calculation, the number of tro.
ounces of gold or silver in the avoirdu
pois ton of the ore.
This method was invented in tn
Columbia School of Mines in New Yorl
city and is in general use Throughout
the world wherever there is assaying t
be done.-Boston Transcript.
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Tne Sense of Hearing.
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