Ottumwa weekly courier. (Ottumwa, Wapello County, Iowa) 1872-1899, 1878-03-27

rious sort Of machine. The edges Of
the coin are thrown up and grooved
by this process. After another clean
ing with sulphuric acid the coins are
ready for the die. The stamping is
done on screw press, and both sides
of the coin are stamped 1T the same
time. The dies are cylindrical blocks
Of steel upon which are carved the de-
signs to be transferred by pressure to
the coins. Art Of high order as well
as fine mechanism is conspicuous in
this part of the coming process. The
designer, in the case of the new silver
dollar, Mr.. Morgan, first draws his
design on paper, from which is made
. model in wax, of which q plaster
cast is taken, and from this cast An
electrotype is taken, upon which care
full revision is made with the graver.
This electrotype, like the model and
cast which preceded it, is three or four
times larger than the impression
which appears ON the dollar. The de-
sign is transferred to . steel die by
using Hills reducing machine, con-
structcd ON the principle of the pam
tograph. One arm of this instrument,
with blunt point, follows the lines
ON the electrotype, while the other
arm, to which is attached o strong
and rapidly revolving drill, reprodu-
ces the same lines on smaller scale
upon steel block. By means of .
press this impression 10 transferred TO
another block in intaglio, and thence
upon another block, which is the par
ent die. After each transfer the lines
are carefully improved with q graver.
Steel of the same quality a. that Of
which the parent die 10 made 10 used
for the coming dies. They are an
nealed, and trned ON both ends. Two
or three blows in the screw-press,
which is worked with large wheel,
secures . perfect impression, and both
the diverse and reverse Of coin are
struck at once. Machinery places the
planchets between the dyes, and after
ward drops the completed coin In q
box. Two or three pieces Of each
coinage are reserved for the annual
Government assay.
The process Of melting, refining,
and assaying gold and silver are car
ried Oh in the Assay Office, in this
city, on quite 40 large scale % at
the Philadelphia mint. Not only
government work il done here, but
large deposits are made daily of gold
and silver bullion by private individ-
uals. Gold IL always found alloyed
with siver, and it 10 never found
with any other alloy. To separate
the silver from the gold, the bullion
is boiled in sulphuric acid, which re-
moves the alloy the gold is then re-
boiled and reduced to . coarse pow
der resembling clay. Its purity then
10 998 or 999. The silver mixed with
copper is run into vats on . lower
floor, and is purified and granulated,
when it resembles pipe-clay. The
granulated gold and silver are press-
ed into large cheeses in q hydraulic
press. A cheese Of gold II inches in
diameter and three inches thick, is
worth $4,000; silver cheese Of the
same size 10 worth $500. The sulphu-
ric acid, after 1t is used, produces .
sediment Of blue vitriol, which is
much prettier than either the gold or
the silver seen In the Assay Office
The vitriol and the weak acid are
both sold for o. much money as the
original acid costs. The substitution
Of sulphuric for nitric acid, has caus-
ed saving to the New York Assay
Office, alone, Of $l00, 900 . year. De-
positors receive their gold and silver
separately at standard purity, 9O0.-
Pure metal IL also sent TO the Assay
Once from the various refineries to
be alloyed. From United States re-
fineriel silver is generally sent In
large bars or cakes; and Z small
amount Of Mexican metal Is received
lin thin, irregularly shaped piecel