The Jersey City news. (Jersey City [N.J.]) 1889-1906, 1897-08-16
GOLD In JOHANNESBURG.
How X II sscurtd ny The Chemical

How ~ ~ ny she Ohemica5
.
1t is commonly said that johannesburg
is built on gold; it might be as truly
said that it Is built on science, or, in the
concrete. IN cyanide Of potassium. I
reckon that one-third Of the workable
mines, possibly one-half, are now shut
down or unopened; but had it not been
for the MacArthnr-Forest cyanide pro-
cess~-discovered Just ten years ago--tifty
per cent. OF the workings still open would
be closed. From first to last the ex-
traction of gold Is a matter of chemistry.
has seen specimens of ore with glittering
fakes or crystal grains of the precious
metal.
A well known Canadian geologist was
once taken to a mine and on the strength
of the sheen of splendid ore ON the side
walls Of the mine passages he gave a
certificate Of the richness of the work
ings. The sparkling nuggets had been
placed there, and the Penown of the pro-
fessor suffered somewhat. You may
traverse the underground ways of Jo-
hannesburg for miles without seeing a
CLEAN Of what the miners eaH visible"
It lold i t and a wi9S {aamnea99 m aellS Us m ane I i
he can say exactly how much; but, so
far, 1t passes the wit Of man 70 get IT
Az t put, s, When 4 y lump mp 1f ,n ore lis Is brought go,d 1t
all it is rarely more than one grain in
Coco, oftener one in $4,000. The first
thing to determine is whether there is
any likelihood Of any of the metal. For
this purpose there has lately come into
pretty general use the sorting process.
What IS wanted is the e-onglomerate, the
rock, known as reef. with quartz pebbles
and finty cement. The rest is waste.
l was pleased at the Geldenhuis Deep
to see that the Kafiirs were intelligent
chaff. The rough stone passed before
them on a revolving table, and they
could at once distinguish by, inspection
the Jumps of quartz or sandstone that
were no good, though, as / have said,
there is not from one weeks end to an
other a scintillation of gold to guide
crushed in steel mortars by metal
stamps or pestles weighing over LOCO
pounds each. They pound the stone 50
exceedingly small that it flow out in
a thin stream OF muddy water through
a screen with meshes numbering 100 to
800 per square inch. Night and day these
=p minnteness STAMPS onnrsz. are pebb gIFandi pyrit &c i hala
and fiinty cement that have for untold
ages been buried like misers, embracing
their treasure deep in the rocks. All
The soapy looking water flows over
copper plates faced with quicksilver. Man
himself Is not more eager tina this els
before the liquid has flowed a foot the
mercury has laid hold of all the free
gold. The two form an amalgam, and
the mercury, being easily retorted off by
heat, can be used again and again. But
the mercury has taken out only about
.one-half the gold. The other half is
locked in the embrace of pyritic iron and
other base materials, and from these it
is set free by the use of chlorine gas.
which has an affinity for gold, and the
cyanide of potassium. which causes the
grains of metal floating in the solution
to precipitate and attach themselves to
zinc shavings. Roughly speaking, the
mercury captures fifty per cent. of the
gold, chlorine twelve, and the cyanide
twenty-eighI per cent. There is still left
in the shines ten per cent, more or less,
unrecoyered.
In the course of the year there must
be at least three-quarterS of a million
sterling worth of bullion thrown away
on the Witwatersrand. Treatment of the
shines now in progress is saying a frac-
ton of this Mount The Crown Reef
got 1892 ounces out of the refuse last
month, but someof it will always be lost.
This waste of man is nothing to the
waste b. nature. The reefs that remain
are a mere patch, probably, TO those that
once existed. They are what is left after
ages of d~enudation. But nough remains
Mr.. Rudd recently stated that before the
century was out the Rand might be pro-
ducing bullion for 20. 600, 900 sovereigns per
annum. Near as we are to 1900. the es-
innate is not extravaganza. the
rich deep levels get all to work the erect
will be enormous.-London Telegraph.