The San Francisco call., 1904-03-15
INSTRUCTIVE JTUDHng
By kNOIEDzfAAfiEI1.IN AND
Ak0MEN


mountain streams.
Through the use of modern machin-
cry Of various sorts it is now possible
veins TO great depths below the earth's
surface. thus putting within the reach
of man supply OF geld that Was here
tofore unthought OF. The celebrated
Comstock vein in Nevada has been
mined for depth Of BOO feet, while
a tunnel 10000 feet long has been dug
To drain the mine. The extreme heat,
developed az such depths presents the
greatest difficulty in working the mine
but It has already yielded more than
$3.50. 600 worth of gold.
The profit to be derived from quartz
mining depends upon a combination of
conditions. a vein Of quartz rich in
gold may be so thin that it viii not
pay to work il at great depths. A
rich vein of greater thickness may be
in such an inaccessible position that
the cost Of working ii would be exces-
sive. One OF the most celebrated eX-
amples of a low grade gold bearing
quartz which has been worked to great
profit because Of its accessibility is the
Douglas mine, near Juneau, in South
eastern Alaska. Here, rising from the
waters edge, is great mass of quartz
with a small amount of gold dissent
mated through it. averaging only about
81 or 50 a ton. But the quantity is al
most unlimited: the stamping mill is
built close by the wharf; the quartz
is mined from the mountainside i'm
mediately in the rear and brought down
TO the uppE story of the mill by grav-
ity. where stamping machines, moved
by water power. are set TO work
upon it.
The final separation Of the gold, espe
cially of that which is in fine particles
distributed through the quartz or grav-
el, has until recently been secured prin-
cipally by the use of mercury, which
has strong affinity for it, and when
mixed with the residuum containing
gold forms an amalgam. which can be
removed and easily subjected 10 sep
arate treatment to again free the gold.
But the most remarkable recent ad-
vancement in the art Of separating gold
has been by the use Of potassium cya-
nide which has the advantage of be-
ing very cheap and Of being able to
be used over and over: while the quartz
for this treatment does not need to be
so finely comminuted as for mercury.
Potassium cyanide dissolves gold, when
the liquid readily yields it up again
on being supplied with certain other
compounds for which il has a greater
affinity. Through the use of this meth
cd, which was discovered only a few
years ago. the production of gold is
likely to be increased almost indefi-
nitely, since ores of much less rich
ness, and indeed immense piles of ref
use discarded by the old process, can
be made to yield a profitable supply Of
gold.
The variations in the supply of the
worlds stock of gold have been re-
markable At the time of Christ it is
estimated that the total amount of
gold and silver in possession of the
world was worth about $4,000. 900. 600.
of which we may suppose that one
half was gold, but this stock gradually
diminished, through abrasion. acci-
dental loss and use in the ornamental
arts. till in the ninth century it was
reduced TO about one-eleventh of that
amount or to about $500. 900, 900
worth. To this amount there was lit
tie increase until after the discovery
Of America, when the mines of Mex
leo, Chile and Peru began to pour in
their supply to the European market.
Between 1893 and 1850 the addition
TO the supply of gold from America
was 3,273,6O0,0 900, while from 1850
to 1879 the addition was 1885,
100000. This great increase in the
supply of gold since 1850 was due
largely to the gold discoveries in Cali
fornia, which were made in 1S4S.
About the same time there were also
remarkable discoveries of gold in Aus
tralia From these two sources alone
there were in twenty years $500
000. 600 worth of gold added to the
stock already in existence; thus nearly
doubling the amount in the posses
sion of the world.
/ Nor has the production of gold in
the United States diminished in
amount but rather increased. The
/ largest production of gold during the
( height of early mining interests in
California amounted to s65. 900 in
I 1853. From this the production gradu-
ally fell to about $4,000, 900 annual
4 ly in 1892. Since that time it has in
I creased until in 1900 the production
of gold in the United Stares, according
to the last report of its Geological Sur
vey (1s01l yas $79,1T1,OOO, and in
1901 s7S.e66, 700.
At present the United States leads
the world IN the production of gold.
/ while Australia continues to produce
about. half the amount furnished by
/ the United States. Another growing
center of gold production with un-
/ known future capacities is Siberia,
where placer mines of immense extent
are found on the flanks of the Altai
| Mountains, in the mountains west of
/ the Yenisei River about Minusinsk,
near the Chinese border, and east of
Yeniseisk. half way down toward the
Arctic regions. Placer mines OF still
greater extent are now worked with
! immense profit in the almost inacces-
! sible headwaters OF the Lena River,
northeast Of Lake Baikal, and in vari-
Gus mountainous districts bordering
the Alnur.
But the most remarkable of all the
recent discoveries of gold are in the
Transvaal, South Africa. Here gold
/ waS discovered In small Quantities in