The Council Bluffs nonpareil. [volume] (Council Bluffs [Iowa]) 1857-1867, 1861-11-09
rHE AssAY OF colo.

10 ms very entefta tanning arsscle On sNAk.
ing Money" 10 Harper's Mega-ine for
Novenber, Waldo Abbott sates " se The
New York Assay oaiee, gets % to deposit .
little bullion, shows us how Uncle Sam's
men ron it into bars, and then gives ~
. description Of the way 10 which Dr.. Tor
rsy, the head assayer, 6nds out
HOW MUCH We ARE WORTH,
Two small bits, called .sassay slips,' are
cot from dffsrens parts of the bar Of each
deposit. These are taken TO the laboratory
OF the assayer, where they are hammered
and rolled into slips so thin that they can
easily be..cut BY scissors. These siips mark
ed 50 as to show to what deposit they be-
long, are given to an assayer, who has be.
fore him, enclosed 10 glass ease, pair Of
scales with weights so delicate she half mill.
ionth part of an ounce; the smallest weight
resembling = oit Of horse hair an eighth Of
an inch long. The operator cuts from the
slip piece weighing exactly half gromms
tthe gramms being French weight equiva-
lent 10 about the thirtieth part Of an ounce y
to this be adds gramme Of pure silver and
encioses them in wrapper Of lead foil,
weighing about ten times ~ much ~ both
gold and silver. This is rolled into little
ball and taken TO an adjoining room, where
II undergoes two operations, one Of which
removes the base metals, and tho other sep,
arates the silver from the gold.
The first OF these oper eratious Is called
"cupeliatat Atom and depends upon the prin-
cip!e that base metals, when melted and
raised TO high temperature, combine with
the oxygen OF the mir and become oxydixed,
while gold and silver are not effected. This
operation is performed in .Alufls Furnace,s
which contains an oven large enough to hold
about dozen small crucibles, called Gu
pels. These are mado of cslcincd bone dust,
and are about the size Of large pill
box, with . shallow depression TO hold the
metal. The cupels being heated red hot.
the little ball - dropped into one Of them.
II melts immediately, forming Z bright
globule, which boils and spins around. The
surface rapidly oxydises, and tho oxyd runs
down the sides OF the globule aud sinks into
the pores Of the cupei. Lead forms very
liquid oxyd which washes away, as it we're
the oxydes, Of the other metals; and is added
for this purpose. Ia about ten minutes The
scum disappears and the little globuie sud-
denly brightens up; the copel is removed
from the furnace, and metal, forming little
button about the sire of buck shot, is
taken out. This contains only gold and sil.
yer; all base metals hlving disappeared.
This button is hammered and rolled out
and then formed into q coil about 40
large as pencil, the is called cornet,
and is to be subjected to the second pro-
cess, for separating the silver from the gold.
This is based on the fact that nitric acid will
dissolve silver, while il will not act upon
gold. But the proportion OF silver in or
dlnary bullion lie 30 small that each particle
ls surroun ed and protected by the gold.
The silver was added BY the assayer in or.
der to diffuse the gold, and enable the nitric
acid to come to the silver.
The cornet is put into "mattrass,"
vial with broad base and long neck. Into
this is poured about an ounce Of diluted
nitric acid, which is boiled by placing the
vial in bed Of hot Sand. Bright red dfumes
soon arise, showing that the action Of the
acid upon the silver has begun. lns.bout
ten minutes the acid 10 poured of, ,s&Ad q
quantity OF less dilution is poured 10 to dis
solve on. the last traces Of the silver. The
silver and nitric acid uniting have formed
nitrate OF silver, and the remainder Of the
cornet is pure gold. lite fragile roll look
ing very like the brown tinder left in burn
ing writing paper.
This is taken ont, washed in distilled VA
Ter, and melted in a crucible, when it at once
resumes its metallic appearance. Itis care
fully weighed in the operators delicate
scales, the result showing the ineness Of the
bullion, or how large portion OF il VAS
gold and how large alloy. The value Of an
ounce Of any fneness being already known,
the whole value Of the gold in our deposit
is readily ascertaioed.