The evening telegraph. [volume] (Philadelphia [Pa.]) 1864-1918, 1869-02-09
CITY INTELLIGENCE
u. s.. COINS.
Processes Employed in AssayIng Them
Rt the Mint

Rronoreee Employed I'm AssayIng Then
Rt the Mint
We yesterday stated that the annual assay o
The gold and silver.coins of the United state
was begun at the Mint on Chesnut street, II
presence of the Board OF Commissioners ap
pointed by the President. While the assay I
IN progress q brief account OF the testing pro
cssseb used may not prove devoid OF lnIeresS
ASSAY OF GOLD COINS.
According to law, the standard gold aoS oI nart S
United states is constituted that In lVvV pa y
BY weight 900 shall be of pure gold, anu lyT T,h
an alloy composed 1t e9pRsa sat the Copper and
silver be both entirely removed toll SnS sVr &c
and to eec! bs InT rss nW is for the removal tne
Dnsr. and this is done by q method called
eupettds'O's s,m,nai composed of calcined bones:
mace, tn tnapaTstion of the silver from the gold rs
effected by process acd of dissoVing silver,
IYithont acting upon gold bV tIs hs sotn
may not PTo'eUT ,i,st frst be added to make II at
inast two.thlrds of the mass Ihe IeseLyeo soiS3 sS
coins are placed IN 9lsGs assist the Sxing and to
cTeyent oxidation OF the copper hirlOy, fi 10y
are thus melted aoEH y eeoted so that an assay
ntece may be taken from any part Oh Che p"r
Cost 0us' 90 next weighed ont for the quartation
% "a as the assay. piece, If standard, snould CON
tain 900 thousandths Of gold theTe sS of o9
tbrse times this weight or X1O0 tnQusanuousg oi
stiver and this IS, accordingly, the quantlty
nsSd ,ood Bsea for the cupellation is kept pre-
d,d in thin sheets cut into square pieces
pnich should each weigh about ten Times as
much as the goi11 i1e In fopm of a Hollow cone, and
into this are introduced the assay golu an9
the quartaton silver %hHn EMO sae ba ga Tbe fSr
nece having been properly heated, and the
cunels placed In 1t, the leaden Dail, WIN its
oonPPtents ia nut into one of the cupels, ana the
SOareIion allowed TO proceed until all agitation
has &c ased to be observed In tne meIteo netal
and It's surface has become brlgnL. Inls IL an
anu h,s,, iSS so 1ho hot the whole OF the base metals
nave neen converted into oxides and absorbed
by the Cupe The cupeliaoison, ai DeIns s,oIIH GGTs
6niehed the metal is allowed 10 cool SLOWLY.
ami the disc or button which IT forms Is detache9
from the cupel. The button Is then natlened
cSii called a coya,ct 1t is now ready for the
process OF auartation. For this purpose, IL is
introduced into matrass a1 am oPu1 ra A
meter: and in this acid IL is Dolleo LOT Ten
minutes. The acid is then poured on.
and three fourths of ounce OF stronger
acid at 800 is substituted for 1t, In
which the gold is boiled for ten minutes This
second acid is then also poured off, and another
canal charge of acid of the same strength is in
troduced, in which the gold is KEPT LOT Ten
minutes longer. II Is then presumed Gnat me Inc
gold is taken out and washed in pure water.
Lastly, the cornet OF fine gold thus formed is
placed in the assay balance and the number OF
thousandThs which 1t weighs expresses the
oneness Of the gold assayed, in thousandths.,
The silver and copper naay both be entirely
dissolyed in nitric acid; and If to solution
thus made, another of common salt In water De
added the silver w De p a ad he
a
chloride, while the copper Will remain un-
affected. =,
weight of pure salt will convert into chloride
Of silver just 1926 parts OF pure silver. Conse'
puently the quantity of salt necessary to con-
vert into chloride 1000 parts of silver is 5i274,
1926 100 : (: 1000 5d2 IA.
standard solution of salt is accordingly so
prepared rs that given measure (the French
deciltre) shall contain 54274 thousandths of
xranme of salt. The normal weight employed
for silver ASSAYS Is the grarnme leQual to ABOUT
lb4 troy grains) which Is marked lOOO and has
Its subdivisions, in practical weighings, to the
half or quarter thousandth.
The reserved silver coins are melted together
In black lead crucible. After stirring, small
portion OF the fluid metal is poured quickly
Into water, producinga graluidsiOH; from which
the portion for assay is taken.
From this sample the weight OF lll5 thou.
bapdths is taken; which is dissolved in glass
bottle with nitric acid. Into this solution the
large plpette-ful of standard solution OF salt is
introduced, and IL produces Immediately
white precpttate, which.s chloride OF silver
and which con tsins, of the metallic silver, 1000
parts. To make this chloride suhside to the
bottom Of the vessel and leave the liquid clear,
IL is necessary that IL be violently shaken In
the bottle; and this is accordingly done. by a
mechanical arrangement, for the necessary
time. Unless the coins have CHANGED TO be
below the allowable limit OF standard, the liquid
WILL contain silver In solution, and accordingly a
portion Of the decimal solution issintroduced,
from the small pipette, capable OF precipitating
athousandJn OF silver, and white cloud OF
chloride will show itself. More doses are
added, II the Indications require it. The LIQUID
is again shaken, and cleared; and the process
ls thus repeated until the addition OF the salt
water shows only q faint trace OF chloride
below theupper surface ofthe liquid.
FOR the foregoing process to be exact, 1t is
necessary that the saline solution be OF the
True standard strength, or be such that the
quantity OF 1t, measured in the large p pette
shall be just sufficient to prec pitate 1000 parts
OF silver. This cannot be assumed without
proO1, and test assay Is accordingly made as
A rQl Of silver, known to be of absolute
purity, Is kept from year to year in an en-.
Velope under the seal of the chairman OF the
Assay Commissioners. This being opened in
their presence. portion OF the silver is taken.
and lOO4 parts carefully weighed Off and sub,
Matted TO the process of assay described above
~ !, tne SAY wafer used be OF the exact standard
It's evident that as the solution in the laTger
plpelte Will preciptate 1900 parts OF silver f6nr
measures OF the decimal solution will ne re-
an, SfeG 20 Ppecipitate the remaining four parts.
bnt az Inc normal or standard solution is
aneeted, from day to day by changes of tann
perature, or other Influences the fnisSing
,Snn Todal uoses may be more or fewer; and the
o,her assays are TO be corrected by the proof.
piece accordingly.
a Observation-Disclosures John Hurley has
4 nelo george Shaffer for further hearing Lc
answer the charge of obtaining money bv false
ana fraudulent representations. The defen dam
mas Ior the past week, been unlawfully collect
pany. Several parties mad been victimized by
him, and yesterday Shafsr was TAX en- into cus
i t0dy at Second street and Church alleV. Eigh
dollars and hNlf were found in his posse ssi1n
This amount he alleged he had collected n,
Tuesday, but had not been engaged In tn
4 swindle before.
FINE ARTs.-Crystal medallions and Ameri
Gallery, NO 1920 Chestnut street, being tn
entire collection of the American Art Gallery
New York, an institution established by Tn
present proprietor in lS33, for the encourage
ment of artists. The catalogue Is represente
by gems OF the highest order. Each picture
hahdsomely framed In fne gold leaf. ,rI They al