The Cape Girardeau Democrat. (Cape Girardeau, Mo.) 1876-1909, 1896-01-25
TESTING H ORES.
How Samples from the Diggings Are Pre-
pared for the Assay Office.

pared for the Assay Office.
To the uninitiated but observant
stranger who wanders up and down in
the labyrinth of shafts and tunnels,
diggings and dumps OF Il genuine min
ing camp perhaps there is no subject
more full CT interest than the process
by which a lump of brown ore, which,
to his inexperienced eye, looks not in
the least attractive, is made to yield
its 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 4 ton of that ore will
go S2.33 ounces in silver and Sl1.55 in
gold. Even the eastern mining expert
or graduate from some mining school
will wonder how. in the log cabin or
pine shanty. destituts of all the elab-
crate paraphernalia 10 which he has
been accustomed. these results are so
readily ani accurately obtained.
AS a general rule tn: 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, 20 that, en-
cept for m~etallurgical purposes. it is I'M
necessary to seek to determine with
much accuracy the contents and value
of such ores. In ease 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-
III - tnly- ar,1 1n a nep+nIn1l- the Hulnp
OF the entire lot. The methods by
which this knowledge is obtained are
so simple as to be easily understood
and practiccd By many Il man who does
not know the technical symbols of the
metals he is determining or could not
give Il 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 he SAM
pied for assaying it is first broken by
an ordinary rock crushcr into pieces
the size OF an English walnut. after
which it is shoyelcd back into the car,
but in such Il manner that every fifth
shovelful is thrown aside by itself. tho
remaining four-iifths being finally
taken away. This fifth portion. known
as the sample" is then reduced to n
much greater degree of fin"ness by
means OF Cornish rolls. 1t is then piled
on the foo" in Il one fattenrd ont, ard
divided into four eQral portions. and
tvooppositc quarters are then removed.
The remaining quarters lie again
thoroughly mixed ana again piled in
a core. fattcned and quart"red; this
operation being repeated until the sam
pie is reduced 10 100 pounds. Il is then
waighcd repeatedly for the purpose of
determining the amount Of moisture
contained in the ore, which in some
ores. especially thosn of The concen-
trates. is so considerable as to make
n very appreciate difference in the
weight. Xhe moisture is then expelled
| and the orc is crushed 10 such a degree
of fineneSs that it can he paSs"dthrough
a sieve containing 100 holes to the linear
inch. The sample is next put up in
small bottles, which are scaled with
scaling wax and then stamped for the
purpose of preventing the possibility
of their being opened or tampered 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 a small portion Ct it will be used
for that purpose, and the quantity gen
orally taken is what is known as an
"assay tor" which weighs %. 166 milf
grams, or a little more than $50 grains
troy weight. This definite amount is
taken, partly as Il matter of conVen-
fence. and also because the assayer
wishes 10 ascertain. as quickly as posi-
bic. how many ounces of thu precious
metals to the ton are contained in this
ore. The method used depends upon
the following principle: The a"oirdu-
pois grams ton of 1000 pounds contains
29.1G6 ounces troy weight; hence. when
29.166 ~milligrams of the ~UnasSaycd 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
Columbia School Of Mines in New York
city and is in general use throughout
the world wherever there is arsaying &c
be doue.-Boston Transcript.
THE Care of the Feet.
There is no necessity whatever for