American citizen. [volume] (Canton, Miss.) 1864-1890, 1874-09-26
How Gold Is Assayed.

The New York assay office is situated
in Wall street. 1t was established in
1854, and has had since then con-
stantly increasing business. At present
the deposits are made through the banks.
The bullion is received in all forms, gold
dust bars, jewelry, amalgams, and so
forth. The deposits are all made in the
weigh-room, where they are duly weighed.
Payments are, of course, not made to
the depositors until the assayer has made
his report to the quantity of pure gold
in their deposits. For deposits of gold
payments are made either in gold bars
or in coin, according to the option of the
depositOr. The first thing is to attach
number to each deposit, and this number
follows it through all the stages and proc
esses through which it may pass. The
process of melting is very simple, the
bullion being simply placed in crucibles,
which are placed in furnace at some
thing like a white heat. The liquid gold
Is then poured into shapes, and the num-
Der with which it starts is subsequently,
stamped upon it. At this stage the gold
contains, of course, a huge quantity of
base matter. Jewelry, for instance,
which is deposited for melting and re-
timing seldom contains 30 per cent. of
pure gold, this being esteemed in
such case a rather high average The
gold OF jewelry is, however, the
least valuable kind deposited The first
thing to be done in the matter of refining
gold is to put it through process known
as FORMULATION. This is effected by mix
ing two-thirds of silver with one of gold
The result of this process is that the
mixed gold and silver takes the shape of
comparatively small grains or particles; ;
and the object of so dividing it is that
when, for the purpose of publication
the gold is brought into contact with sui
phuric acid, Il larger surface of the metal
shall be exposed to its action. The sep
aration of the silver from the gold is eff
fected in this way: The granulated metal
is put into large iron kettles and boiled
in sulphuric acid. The result is that the
silver becomes united with the acid,
forming sulphate of silver. 1t is held in
solution, and in this form is carried off
though syphOn to tanks in room
downstairs, where the silver is after
ward precipitated. The gold is subse-
quently subjected to several other baths
of sulphuric acid until it is thoroughly
separated from the silver. 1t is then
placed in filter and subjected to the ac-
ton of warm water. At this stage it
simply resembles muddy deposit,
and has not the slightest metallic
luster. 1t is subsequently dried,
and hydraulic pressure is brought
out of it thoroughly. 1t is afterward
cast into bars, and is thoroughly mixed
in the process. When in liquid state,
bone-dust is thrown on the surface and
this takes up its impurities, which are
afterward skinned off. When the bars
are cast, slice is cut off each end and
these are submitted to two assayers, who
are not in communication and who report
separately. Their reports, besides deter
mining the value of the gold, check each
other. The gold is now in a condition to
put upon the market. Meanwhile the
silver which is held in solution in the
sulphuric acid is carried into tanks in
which are copper blocks. Their contact
with the sulphuric acid produces sulphate
of copper, and the silver is precipitated.
In all the processes carried on in the
assay Office there is nothing wasted
Even the sulphurous fumes are carried
into condensers, and are turned into sui
phuric acid, to be again used for refining
The weighing at the assay office is done
with the most fractional minuteness, and
the calculations of the office, which are
of the most intricate and delicate kind,
are performed in distinct department
-Ne,o York Observer.