Evening capital. (Annapolis, Md.) 1884-1910, 1906-03-21

~ aN6 AHtf0dAS-Mid DS
Drawn on the Spot
The yield from the gold mines has
increased 60 per cent in less than a
decade. In seeking the reasons for
this truly remarkable development
one Is especially prominent--the great
advance which has Deen made in the
methods followed by the modern gold
seeker. The prospectors, says the Sci
entitic American, have taken advan-
tage OF progress in geology, chemistry
and other sciences and have pro-
yided themselves with mechanical aids
which are far superior to the crude
implements employed by the metal
hunters of the past
In the examination of rock for metal
bearing ore, the arrastra of the Mex
leans and Spaniards has been used
extensively, especially in California
and Oregon This contrivance con.
sists Of vertical shaft or axis, which
supports several wooden bars fastened
at right angles to it, To the ends of
the bars are attached heavy fiat
stones, which, by the movement of the
axis, revolve in a circular pit. stream
Of water is turned upon them and the
arrastra placed in motion by animal
or water power The ore is resolved
into a Shiny sediment By being ground
in the water and passes off through
The sluiceway, which is provided with
rifles for catching the gold
The modern methods for searching
Tor deposits Of precious metal are so
radically different from those describ-
ed that it may be said revolution
has taken place in prospecting in the
United States. In the Rocky Mountain
region the formation has been pierced
as far as 1900 feet in the effort to as
certain the existence of a vein.
Among the mechanical appliances
which have been of great assistance
to the modern prospector is the drill.
With it he can make behring's in
week where, if shaft were sunk,
year would be needed If the forma-
ton is to he examined by shaft,
however, the cost of sinking it is re-
duced to minimum by means of ex-
plosivc cartridges, which are now
manufactured especially for such SER
vice.
Few expeditions of any size are sent
ont without an experienced geologist,
who is usually provided with maps
and other data giving the best infor-
nation available regarding the region
to be explored.
Besides the geologlst, the services
of an expert chemist are also of great
importance and laboratory in min
iature is contained in the packs car
ried by the animals So complete is
this portion of the equipment that a
fairly correct field analysis can be
made of the specimens secured by the
use of the drill or by the other pros
pecting tools If the outcropping of
quartz vein is discovered, enough
is broken off to allow its character
to be studied both from a geological
and a chemical standpoint
After examining ii in connection
with the formation in the vicinity, the
-geologist is often able to indicate
where the surface can be bored with
the possibility of reaching the ore
bearing stratum at once.
The value of the ore from the out.
cropping and that from the interior
can be approximately determined by
tho chemist. To crush the ore is a
slight undertaking, and with the lead
which he has brought along the ma
terial can be readily fused in port
able furnace In fact, he has the es-
sentials for making a dry assay" on
limited scale, for cupels are now
made of such light weight that they
can readily be carried on muleback.
in the outfit of the modern pros
peclor quicksilver has become prac-
tically Indispensable. Its affinity for
gold makes il a most valuable agent.
Where he existence of placer gold
Is imagined the Introduction of mer-
curry INTO tho test washer soon solves
lhe problem and avoids the use of riff
fcs and other crude appliances which
w"Ye formerly dependent upon almost
utrcly. After crushing the speci.
mems Of test ore the quicksilver can
$50 Eo used TO ascertain the quantity
f-fran gold among the particles. AS
be mercury can be eliminated by
eat;ug she composition to sufficient
EE1 temperature, it is now utilized
large quantities by the modern
p~1spactcr
Taking the ingot of lead and of pre-
jous metal he can easily oxidize the
.ad las placing il in his cupel and
@atirg tho latter 20 the required tenn
rr-rrro ~ n'oven constructed Of ma
or,ai Wei - can obtain in the vi
Mtr N-hf n.s nitric acid ne sepa-
sf~ ,he silver which may remain,
avrg tho sod only TO be tested for
value The Proportion Of the gold
o rysp cU7r-i'N Of ore can he de
7r1 IFS -oaicy but by using
IS t~sruSi~ne or block basalt he can
co. f'.- qaalty cf the gold by the
oiav wA 81 ,h5s distance makes
,hen erewn over the surface of the
real