The citizen. (Frederick City, Md.) 1895-1923, 1896-01-17
TESTING The ORES.
How Samples from the DigginSs Are Pre-
pared for the Assay Ofice.

pared for the Assay Ofice.
To the uninitiated but 0bservant
stranger who wanders up and down III
the labvrinth Of shafts and tunnels,
diggings and dumps of Il genuine MIN
ing camp perhaps there is 10 supiecl
more full Of interest than the process
by which a lump of brown ore, which
to his inexperienced eye, looks not IN
the least attrc ctive, is made to Xicld
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 u ton of that ore VIII
90 $3.50 ounces in silver and $l7.55 in
gold. Even the eastern mining expert
or graduate from qono mining school
will wonder how, in the log cabin or
pine shanty, destitute of all the eIao-
crate paraphernalia tr 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-
cous metals, for purposes OF purchase
and sale are valued according to the
cost of mining and shipping. 50 that. cX-
cept for metallurg;c zeal purFosc s, it IS I'M
necessary to seek to determine with
much accuracy the contents and value
of such ores In case of ores rich in
the precious metals, however, it is en-
tirely different, as in their purchase
and sale both parties, the buyer as well
as the seller, want to ascertain ac-
curately and to 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 a scientific exposition Of the proc
ess, but, nevertheless, in his line, he
is 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 hack into the car,
but in such a 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 a cone, flattened out, and
divided into four equal portions, and
two opposite quarters are then removed.
The remaining quarters lire again
thoroughly mixed and again piled in
a cone, fattened and quartered; this
operation being re peated until the sam
pie 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 those of the concen-
trates, is so considerable as to make
a very appreciate difference in the
weight. The moisture is then expelled
and the ore is crushed to such degree
of fineness that it can be passed through
sieve containing 100 holes to tne 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 tho possibility
of their being opened or tempered with
without detection.
The above is the process of sampling
used among the mines, and the sam
only a small portion of it will be used
for that purpose, and the quantity gen
orally taken is what is known as an
"assay ton" which weighs 9,166 MILL
grams, or little more than $50 grains
troy weight. This definite amount is
taken, partly as a matter of conven-
fence, and also because the assayer
wishes to ascertain, as quickly as posi-
BILE, how many ounces of the precious
metals to the ton are contained in this
ore. The method used depends upon
the following principle: The avoirdu-
pois grams ton of 1000 pounds contains
29,166 ounces troy weight; hence, when
29,166 milligrams of the unassayed ore
are taken, the weight of the resulting
'button'' of gold or silver in the MILL
grams represents at once, without any
further calculation, the number of troy
ounces of gold or silver in the avoirdu-
pois ton of the ore.
This method was invented in the
city and is in general use throughout
the world wherever there is assaying to
be done.-Boston Transcript.
The Care of the Feet.
"There is no necessity whatever for
so much complaint of the feet if people
could only be induced towear the prop
err kind of shoes, said a surgeon who
has made the foot the subject of special
study. THE great mistake that is
made is in selecting shoes that are too
short. No matter how loose they are,
the ShOrtneSS is the cauSe of the from bile