New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1898-11-13
GOLD ASSAYING.
DETAILS OF THE WORK BY WHICH
MINE VALUES ARE DETERMINED.

10 california or India. Situate your mine
where you will; SO long it be a gold mine tuo
nrocedIIre Of assaying Is the same all the Wiuo
world over Select mass OF ore weghihs' Pei
hans fifty pounds, and smash it up. DO not eA-
pect to see any gold in it. because the precious
metal is probably so thiniy ana uhIorl s;,Ie 70
tered through the quartz that it is impossipie 70
spot a grain together Continue grinding inc
ore till it is in the form Of powder rms powoeI
is heaped into a cone. which Is divided INTO TOUT
narts of which the sampler takes two whose
angles are opposite to one another. MIX tneso
two parts thoroughly and again dNlue Iuto
four: take two portions again. ana 50 Vi, III,
sample of convenient bulk is obtained by this
logical method the sample yielded 49, on any
4 ordinary calculation Of probability certain l"
represent accurately the original mass taken.
4 certain quantity Of TINS Sample - Nv"
weighed out two equal amounts being taken as
checks upon each other. The Weighing may -
done in UNCONVENTIONAL m values u 10, is
grammes or assay tons. The assay toh 10 a
most convenient invention, and is very sltnPSy
explained. The ordinary ton contains o-,ooo.Vv
weighing 81 500 grammes. each WI - % a
gramme will equal one ounce per ION; nus us
no calculation is needed at all to estimate 'n'
gold richness Of an ore per ton
say we weigh out. then, two separate Po.
tons of the ore Of one assay ton "a. ~ eacn-
With each mix thoroughly bcarbonate or sooa'
litharge. borax, glass, and our IN na'yr's oaIor
portions when thoroughly uniform IN coio.;
empty the mixtures in freclay cruclples, anu
strew on the top thin layer OF SAT- Iu ~.
the lids Of the two crucibles anu scrrouhu 49,
with living coal coke, or burning Vaporneu oer
zoline in crucible furnace. The crucipies ar
heated till the masses Of ore and nuxes ar IA
a state OF tranquil fuson-that is. not ouDpins
or boiling The whte-hot huid Is theh Poul-N
into iron mOuds and allowed to cool Oh en en-
animation after cooling. the fused masses VIZ
be found to consist Of: a. aver OF VIM. :.
substance whi,h is salt. CD Stag. This ID
usually dark in color. often resembling mana
chite and is formed by the fusion or the potaA
and soda with the worthless or earny D,oduced
from the litharge or lead oxide. originally miAeo
in thu charge This lead button contains all the
silver and gold in the ore. The neat or the lur
mace drives off from the lead oxide ts oxygen
so that pure lead is left; this, in virtue OF us
weight percola:es downward through tne sias
during the heating in the furnace, colectms
all the gold and silver present. ana eVentuany
forms a button weighing. if proper amount Vi
flour has been added originally, ALc Ut sixteen
| to twenty grammes The -four has the effect OK
VARYING the size OF lead button produced ana
is said to possess reducing action.
The next step in the process is to get rid ot
the lead without also losing the gold ana sllger'
This is done by an operation known as cupelia-
ton The cupel is small round bone-ash cup
which is placed in sort OF hreeay tunnel w IVA
one end closed up. known as mutle. Inc
muile is heated from the outside, either py
burying it with Goals OF by playing burning gas
tanned the heat Of the interior Of the muffe, the
lead button is placed in it and the door or the
muflle shut. as to procure the greatest
amount Of heat possible When the lead is seen
to be melted and tuning the muile door IS
opened to admit the iir, which Is sucked IN by
the intense heat
/ The oxygen contained in the air oxydizes the
lead into lead oxide and the bone ash cupel abb
orbs lead oxide like "A sponge, but refuses 70
absorb the gold and silver; 50 that at Length
there is left in the cupel only button OF the
two precious metals. 1t is To be supposed that
two ore samples have been treated similarly
both in the crucibes and cupels. but for the
sake Of convenience il is better to explain the
treatment Of one only. The bead OF gold ana
silver obtained weighs let us say. .O0lG OF a
gramme This is noted down. The bead after
weighing is nattened out in a latting mill. so
as to expose as large a surface as possible to the
nitric acid which is then added To II. on neat
ing the silver is dissolved. but, of course, the
gold is untouched by the action Of any single
acid The remaining pure gold is treated with
stronger acid called parting acid. to drive on
any suspected trace Of silver, and then washed
with water. If the parting Of the gold from
/ the silver has been successful the gold is left
as a thin small sheet. From this all moisture
is driven off by heat. on weighing the gold
may be heavy as .OOOI of gramne. Then.
as il has previously Oeen noted that the total gold
and silver bead had weighed .OOl6 Of gramme.
the weight of silver present must have been
OOt9 Of "A gramme. That is To say. in one assay
ton of 81 66,iI grammes there are .OoOi gramme
of gold and .OOO9 gramme Of silver 1t has
been stated at the commencement Of this article
that in an assay ton each .OOl Of gramme
represents in real Ton one ounce. Therefore
we have seven-tenths Of an ounce OF god-that
is. II pennyweghts GO dwt. - oz)-and nine
tenths of an ounce Of silver-that Is Is penny
weights To the ton. QuOd erat faciendum
Many minor processes, such az roasting. scori-
fication and inquartation, enter into the WorR
done in an assay; but il has been desirable to
make the process clear and free from COM
plication as possible and for this reason SIM
pie ore has been selected. OF course the results
obtained from two assay tons assayed smuI
taneously ought TO be coincident with one an
other and this is why two assay tons have been
nIapppaSon