Gilpin observer., 1899-05-11

western firms have offered for sale
from time to time portable apparatus
determining gold in minerals, which
were supposed to enable the prospector
to decide whether the ore contpined
any gold or not by the simple opera
tion of dissolvlng the ore in acids and
adding stannous chloride to the solu-
tion obtained. 1t was assumed that
the formation of purple of Cassius
would give in all cases sufficient con-
firmation of the presence of gold.
Those who tried this process have
discovered, however, that the forma-
ton of the purple could not be ascer-
tanned with satisfaction in solutions of
gold ores containing but little of the
precious metal, and have declared the
method to be unsatisfactory in such
cases.
At the present status of gold recov-
cry, when ore containing $3 gold to the
ton is treated with profit, the knowl-
edge of reliable and simple method
for the determination of the presence
of gold is Of vital Importance. The ap-
Ibaratus required, if at all acceptable to
the prospector, should involve but lit
tie expense, occupy but little space and
do away with the application of heat
as produced by spirit lamp, candle or
oil stove. In fact, any cumbersome
apparatus or complicated operation is
out of the question for obvious rea-
sons.
\ The following methods. which allow
of the detection of OOPS OF. of gold to
the ton with certainty, offer all the ad-
vantages pointed out above and leave
nothing to be desired as to practicable
ity or efficiency:
1. About or. of the finely pulverized
ore is placed in bottle, an equal vol
ume of tincture of iodine is added and
the mixture agitated. The contents of
the bottle are kept in contact for an
hour at most. with occasional agita-
ton, and finally allowed to settle. A
strip of Swedish filter paper is then
introduced into the clear solution and
dried. these two operations being re-
peated six times, so rs to saturate the
paper thoroughly. The strip is then
burnt. when the ash, in case gold is
present, will show a purple coloration.
which. on pouring brOmine water over
it. will quickly dlsappear-a sure in
dlcation of the presence of gold. This
operation is best performed on plate.
2. The test for gold described above
may be altered in the following man
ner: About OF. of the finely divided
ore is covered with an equal volume of
Dromine water In the same manner as
above. After standing and agitating
for an hour, the solution is filtered and
tin chloride solution added to the fl
trate to produce the purple of Cassius.
the appearance of which will indicate
the presence of gold.
The methods given are especially
adapted for the separation of gold from
.sulphides. 1t is necessary. however. in
this case to roast the sulphides before
the application of the process; an Op-
Grafton which can be readily accom-
plished in can or pan, over the camp
fire. When roasting pyrites for this
purpose the temperature toward the
end should be raised to full red heat,
so as to induce complete decomposition
and render the product porous and
. readily permeable for the iodine or
bromine solutions. If the ores to be
treated contain an excess of carbonate
of lime. the roasted mineral should be
gently reignited with ammonium car
Donate. so as to prevent the entry of
much lime into the iodine or bromine
preparations.
To execute the tests described above
there would be required few empty
bottles. bottle of iodine tincture, an
other of brOmine water. one containing
a solution of stannOus chloride n cou-
pie of glass tunnels, some filter pa
per and some ammonium carbonate.
surely list that cannot be surpassed
in simplicity. cheapness and adapted
ness.-Dr. ]. Ably, in Engineering and
Mining Journal.