The weekly Butte record., 1861-12-28
How Gold is Coined.


es through which the gold goes in the Mint:
The first room in the regular order of the
business OF the Mint, is the deposit room--
Here the metal is taken and weighed, and a
receipt given. The gold is then taken to the
melting room, where each deposit is melted se-
parately, in black lead crucible, and upon the
melted mass saltpetre and soda are thrown and
stirred round TO oxydize the base metals, and
the gold and more sterling metals, thoroughly
mixed, are cast into bar. After being taken
TO the Weight Room and weighed, it is ready
for the Assay Department. The assayer, with
a chisel, chips off corner from the bar, and
the chip is melted and cast into button, to
give round form, so that it may be easily
rolled out. 1t is rolled into ribbon, and filed
down till it weighed exactly ten grains, weigh
ed by scale which turns at the thousandth
part of a grain. The ribbon is rolled up with
sheet lead, placed in a cup called a cupel, made
of calcined bone ashes, and placed in heat
sufficient to melt the gold, and the base metals,
copper, tin, etc are absorbed by the porous
material Of the cupel, or carried off in oxyda-
tion. The gold is then pure, except an admix-
ture of silver. The button is again rolled out
into a ribbon about as thick as ordinary letter
paper, and boiled in nitric acid, which dis
solves the silver and leaves the gold pure,
which is weighed, and the amount which it
has lost gives an exact measure of the quantity
of impurity in the original bar. Thus, if the
piece assayed weighs nine grains, then nine
tenths of the bar is pure gold and the clerk
in the Deposit Room can Immediately give a
certificate of the amount of coin due the de
positor.
After the bars have been assayed, they are,
as a general rule, thrown in together, inds-
criminatey, as the property Of the Mint. The
first process in the granulating room, is to melt
the gold with twice the weight of silver; and
while melted, it is poured into water mixed
with little nitric acid, and the metal falls to
the bottom in fine grains. The granulated gold
is taken out, and cast into large stone or por-
celain pots, holding about fifteen gallons OF
nitric acid. These pots sit in hot water, heat
ed by steam, and the boiling acid soon leaves
the gold pure from all silver, copper, lead, tin,
zinc or other base metals. 1t is taken out, FL
tered, washed, dried and again taken to the
melting room, where it is melted with nine per
cent. of copper, and one per cent. Of silver, to
make it of the standard alloy of nine hundred
thousandths fine.
The gold thus aIloyed is run into bars foot
long, an inch thick, and of the proper width
for coin, from an inch and half for double
eagles, down to half an inch for dollars The
bars are delivered over to the coner.
The coiner's first process is to put the bars
through the rolling mill, which has two heavy
rollers of cast steel, ten inches long ard eight
inches in diameter, rolling together. The bars
are thus rolled out number of times, until
they are nearly the proper thickness of the
coin The rolling mill is made so that the
bars can be rolled out of any thickness. The
bars, when rolled out several times, become
somewhat brittle, and are then taken to the
Annealing Room. This room contains a large
furnace of brick-work, with long chambers to
tubes and heated to cherry red. The gold
is thus made softer and more ductile, and is
again taken to the rolling mill, rolled sufficient
ly and again annealed previous to being drawn.
The bars cannot be rolled out to an exactly
equal thickness, aud to secure exactness 10 this
respect, the bar is drawn through an ori6ce in
piece of steel, and this orifce being some-
what smaller than the bar as rolled, reduces
the whole to the same exact width aud thick
ness. The bar, not quite as thick as the coin,
is taken thence to the cutting machine, which,
by punch, cuts out from the bar round pieces,
little larger than the coin. These pieces are
called blanks. They are carried to the An
healing Room, again annealed and then washed
with soap and water. They are then taken TO
the Adjusting Room. Here each blank is
weighed separately, and made the exact weight
for the coin. If too heavy, the blank is filed
down if too light, it is thrown into box to
be re-melted The work in this room is done
entirely by women.
The adjusted blanks are run through the
milling machine, which congresses the blank
to the exact diameter of the coin and raises
the edge The purpose of making the edge
thicker is to make the coin pile neatly, to pro-
tect the figures and to improve the general ap-
pearance. About two hundred and fifty blanks
are milled in minute.
The mlled blanks are carried back to the
annealing room, placed in an air-tight cast iron
box and placed in the furnace TO be anealed
so that they may take the impression WE'LL
When they are at cherry red they are takeni
out and poured Immediately into water with
little sulphufic acid. This softens and cleanses
the gold. The blanks are taken out, washed
with cold water, put into hot water again, Ia
ken out, mixed in with saw-dust, which is then
sifted off and the blanks are dried and perfectly
clean.
They are taken to the coming and milling
room, and stamped. The coming machine is
elegant and MASSIVE The blanks are placed
in tube or pipe, and from this the machine