Weekly Trinity journal., 1858-04-10
Gold Assaying.

BY the kindness of Mr.. Greenhood, Assayer, of
weaverville, we have been permitted to see the
process of smelling and refining gold He has
small iron furnace, lined with fire brick, which
produces heat of sufficient intensity to fuse the
metal in from fifteen TO forty minutes, according
TO the state of the atmosphere acting on the
draught He has, in addition, every chemical and
scientific appliance, and practical knowledge of
the business, which enables him to assay and
childs in London and, without further test, enter
into commerce at their stamped value. The
house OF Greenhood & Newbauer is extensive and
well known, and has branch houses in the prin-
cipal cities and towns Of this State. Mr. Green
hood, who resides here, is one Of the firm. AS the
American and European credit of the house de-
pends ON the correctness Of tie assay, we watched
the process with great interest and will describe
it.. as wen ss we can, without practical know
ledge of the business
The first process is smelling. An hundred
ounces, or more, are put in a crucible, or pot
made of earth, tempered to endure extreme heat
The crucible is set in the draught furnace the
gold melts at heat of 20l6 degrees, and is then
poured into an open iron mould, where it coolS
the quickest of all metals-so quick that great
expeditionis is required in pouring it in. The bar
is then washed of impurities, and little piece is
cut from each end for assay, the quality OF the
added extremes forming an average Of the whole
bar These little pieces are, separately, accu-
ratey weighed, and, with silver, platinum, cop
per and lead added, are placed in separate cruel
bles, and submitted to white heat. This is
called cupellaton'- little crucibles are call
ed 'cupels,' and are made of the phosphate of
lime OF the residue Of burnt bones the lead and
copper sink into the cupels, which are taken out,
cooled with distilled water and pounded to
pieces, leaving compound Of gold, silver and
platinum only--the residue of each cupel and
contents destroyed. These little pieces are again
heated, aud afterwards rolled, repeatedly through
iron rollers, each to long thin plate which is
then called an assay Each of these assays is
then rolled up and put in matrass' or glass
flask, egg-shaped, with long, narrow neck, and
partly filed with aqua forts; the matrass is set on
hot sand and made to boil for quarter of an
hour The acid is then poured off and an addi-
tional quantity added and boiled for less time.
This too is poured off, and the assay is washed
by filing the matrass with distilled water, The
matrass is then turned upside down, with the
mouth against the bottom of q crucible made of
fine earth. Then comes the annealing process
after having separated the water which fell into
the crueibes after which the annealed gold is
weighed. For certainty two assays are made,
together with third assay on gold the ineness of
which is slready known. Afterwards calculation
is made of the losses from the original compounds
which we did not see and can't explain here
they are private with the assayer.
The process of obtaining pure gold from com
pound of lead copper, silver, platinum and gold
is the most difficult to understand The copper
and lead are destroyed or burned up in the GU
pels; the residue is then treated with sulphuric
acid, which destroys the silver the residuum
boiled in nitric acid parts with the platinum and
leaves the gold pure.
If we have erred in any particular Of the
foregoing, the error must not be attributed to Mr.
Greenhood, but to the writer, who has not at
hand books necessary for a clearer description.
Mr.. Greenhood is thorough instructed assayer,
having been engaged in the business in Europe
long before the discovery of gold here. The gold
dust purchased by their house is run into bars,
assayed, stamped and thus goes to the great bal
ances of the worlds commerce. The bar we saw
made was worth nearly three thousand dollars {;
10 that shape is will probably be moved about by
the puIsations of commerce for hundreds of years.
This is where some Of the gold goes TOTO the
vaults of the Bank Of England straight as wind
and steam can carry it.