The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1901-11-10
HOW BULLION is COINED
PROCESS OF CONVERTING O IL M
SILVER INTO LAWFUL MONEY.
Very Delicate Machinery Required to
stamp, Weigh and Mill the
Precious Metals.
Scientific American.

Scientific American.
The process by which the ore from the
mine is changed into new and glitterlng
coin is long and tedious. The ore as 1t
comes from the ground must first pass
through the smelling process, by means of
which the metal is extracted and converted
into bars Of gold or silver, the methods
naturally varying, according TO the charao-
ter of the ore and the locality.
Some idea Of the enormous amounts that
have been handled by the various minis
and assay offices is shown by the statement
that 1895, 1872, 252.27 represents the total
amount of coinage OF the various minis Of
the United States from the establishment
Of the Philadelphia mint to the end Of June,
1900. OF this great amount the total silver,
1896, III, 1885, and the total minor coinage
amounted to $33, sos, 969. 70. The bars OF gold
or silver, known as bullion" are carefully
assayed, either at the mint or at one or the
assay offices IA New York city, Helena,
Mont, or Denver, Col, and from these the
coins are made. The first step consists In
preparing an alloy for coinage OF the re-
fined gold or silver, which is nearly pure,
with copper, and this is accomplished by
Weighing out quantities OF gold ana copper;
" 4 C1lAGA anu SORP&A ny 49,
together in a large lead-black cruclble; ana
after the molten metals are thorougniy
mixed they are poured into castr0n moius
to produce rectangular bars calico III
gots,'' which vary in size, according TO the
denomination of the coin for which they
are intended; 8, Thus 15Es the in got I 81 in 1ne
thick and ~ inches wide, and weighs on
ounces, while the ingot for the silver dollar
is 1211 inches long u inch thick and lHs
inches wide.
ROLLED INTO STRIPS.
The ingot is then passed between heavy
rolls. from which it issues in long narrow
strips. This operation is called breaking
down." and makes the metal hard and
springy, and If continued would cause 1t
TO crack and split. In order to prevent
this the strips are annealed by being heat
ed in a furnace TO about 1,5OO degrees Fair
enheit. where they remain for about an
hour and a half, according to the heat OF
the furnace and the size OF the strips. 1hey
are then cooled in water and each strip
wiped dry, after which they are Hnally
passed through the rolls. double eagles
and eagles pass through the hnlshlng
rolls three times, while hair ana quar-
ter eagles must so through at least four
times. The strips are again annedleu' CUT
in two for convenience in handling, taken
TO the pointing rolls, so that an men ana
a half of the end may be pointed or Nat
tened, and creased with tallow to permit
their easy passage through the dies OF the
QrdWDenCn. Inc uIdNbSASh OASASN ~
two independent sections, each of wnich
has two dies regulated by set screws, ana
between these dies the pointed end OF the
strip is passed, being seized Dy the Jaws
of the carriage, drawn by means of an end
less chain, which reduces the strip as near
IN as possible TO standard weight. This Is
ascertained by weighing sample blanks or
planchets that are cut from either END.
When the strips are deemed OF proper
weight they are taken 10 the cutting
shears and the pointed ends cut of, after
v-hfcb tbpV mass TO the cutting press,
where, by means of a steel punch working
into a matrix, the planchets are cut there
from. These blanks are then taken 10 the
washing room. where they are cleansed
from grease by washing in a I've composed
of soap, bOraX and water. AFTER rlnslhS
in clear water they are dried IN a large
copper pan heated by steam. They are
then carefully examined on the selecting
table. and all perfect blanks separated
from the imperfect ones, and, In the case
of gold coins. must have the following
weights: Double eagle" 56 grains; ga
gle" 25S grains; half eagle l9 grains,
and quarter eagle 64.5 grains, although
an allowance of half a grain is permitted
in the case of the double eagle ana
eagle" and a quarter grain in the malt
mined in the adjusting room, where each
piece is placed upon the balance. and IL
heavier than the limit is reduced by hing
it's edge; whereas, If lighter ii is condemned
and returned to the smelter. The accepted
pIanchets are then taken to the milling
machine, where the raised edge, technical
| ~ Cdllcu mlAtlh6S 10 BUb OA
USE OF MILLING MACHINE.
The machines known as milling machines
are simply upsetting devices. and the for
mer designation often misleads one not
familiar with minting processes. We illus
trate the latest type. which has just been
installed. It's duty is to upset the blank
after it leaves the cutting press by passing
the piece between a segment and a revolv-
- a;el- CroOvaS ont IN the disk and
segment by a sharp tool, and the shape of
the grooves has been the subject or consld-
cradle experiment in order TO give as square
an edge as possible tosthe finished com
without producing a fin. 1t Is driven by a
three-horse power wound motor
running at 375 revolutions per minute, and
transmits a rotary movement TO the DISK
through back gears. The disk runs at sixty
revolutions per minute. TIL blanks are fed
by the operator into the tube and are
pushed against the disk by a small feeder,
and the friction on the disk carries the
blank around the inside OF the segment,
and then 1t drops it into a box. Thls up
setting machine will upset SO half dollars
per minute, and the machines Tor other de-
nominations will turn out a proportional
amount. Nine of these machines, excepting
the motor. were designed and built at the
United States mint, and il is the intention
of the authorities TO gradually work into
the designing and building of several spe-
cial machines for coming operations.
The advantage of the milling process is
that il protects the surface of the coin
from abrasion. The milled pieces must be
again cleaned and sOftened, which is &C
complished by annealing them at a cherry
red heat, after which they are dipped into
a solution of sulphuric acid and water suf-
fciently strong TO clean and brighten them.
They are then rinsed in boiling water and
shaken i'm SawduSt TO dry them, after which
they are ready for the stamping press. Be
fore stamping a brief description of the die
is necessary. The design being selected, a
drawing is made the exact size of the coin
required, and from this drawing a tracing
is taken for the purpose of transferring the
design TO the die. This is accomplished by
covering the surface of the die, which has
previously been smoth. with a thin coating
of transfer wax; on this wax the tracing is
reproduced by rubbing, leaving the design
on the steel. and as this is easily oblit-
Grated IL is best to go over the lines with a
sharp-pOinted instrument. The next step
is TO remove the steel in the die by means
OF chisels and gravers, so that a relief may
be had on the coin.
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