The indicator., 1897-09-18
MINING MATTERS.
FINDING GOLD WITH x-RAYs.
They Also Reveal tn. Presence of Silver
Copper and Lead.

They Also Reveal tho Presence of Silver |
Copper and Lead.
Making assays Of ore supposed Ia
contain precious metals by means of
the ray is the latest phase of the
dcN elopment Of the wonderful device
discovered by Professor Roentgen. Not
only has this been demonstrated to be
possible. but is is also practical,
which Is of a great deal more import
ance. This discovery opens the
way TO rich gold finds in places where
gold would not, under ordinary cir
culnstances be supposed TO exist.
DIR. Il. II. Hennessey of Napa. Califor
mia, who is well known as scientific
investigator is the discoverer of the
unique scheme just referred 10. He has
been at work on it for Il long time,
and all who make scientific research
Cs must. but he is now ready to give
the results of his discoveries to the
world, that all may profit by them,
DIR. Hcnncssey makes no attempt to
keep his methods secret but is willing
that they be utilized where they do
the most good
Gold quartz was the rock with
which he first had any success. In
making his experiments he pivoted in
his results. AT one time he would II"
be- very far of Different exposures
seemed to have very little TO do with
it, for with the same piece of ore ON
the same kind of plates the results
varied to the widest degree The doc
tor then began making records of the
exact condition of his tube during the
different experiments. 1t 50 happened
that he made an exposure when his
tube WAS very ''low' and was surprs-
cI to get a good indication of ore in
n piece of quartz \ little longer "N-
posurc and the result was better And
so it went OIL until the proper time of
exposure was found. He had demon
stratcd that II low tube. or one that
does not produce many N-rays was
the best for the purpose. 1t has Ion"
been known that Il tube Of this kind
always give the strongest contrasts.
but it is undesirable for surgical work
on account of the time required to
make the exposure. In making ASSAYS
this is. of course, a matter of no i'm
p0rtancc.
Why the low tube should produce
better results than the high tube is
easily understood byanybody acquan,-
ed with photography. A dim light in
Il room will make stronger shadows
in photograph than n strong one in
Il given length Of time. In the case
of the N-ray. the high tube creates II
radiance that has tendency to pass
through everything. and so it happens
that by the time certain part of the
plate is exposed enough the other
parts are ovcr-cXposed. and conse-
quently show no contrast. The results
is very much the same as If the plate
had been logged.
After DR.. Hcnnosscy had reached per-
fcction in making N-rly pictures Of
gold ore lie tried different kinds of
other ore, and the results We're most
surprising The difference between
gold and silver is of the widest de
scription, and copper and lead are very
different from either. Gold looks like
frost markings on n window pane
while silver looks like tiny specks
Different ores in the same piece of rock
are all plainly distingnishablc And
not only does the N-ray show that
there is gold in a certain rock, but it
also approNimatcs how much of the
metal there is. DIR. TIennesscy has
tested this. and found that it is quite
reliable. Certainly enough to tell
whether the ore is worth making Il
series of tests Of.
The most surprising discovery made
by DIR. fIennessey. though. is the fact
that the N-ruy will show gold i'll Il rock
that has no outward sign of its exist
cncc. Several pieces found in the Napa
hills. of such character that no miner
would look at them for more than
moment. before throwing them aside
ms worthless. under the N-rav proved
10 contain Il layer of thin gold; small
in quantity. but nevertheless gold. The
accompanying drawings show the out
side views of bits of quartz. Many of
the pieces of quartz examined did not
show any signs of gold on the outside.
even when put under n strong lnlgni-
flying glass.
OF course. the great advantage of the
N-rly in assaying is its chcapnoSs. Ex-
aminutions Of thirty small pieces can
he mada on one plate at Il cas-; of about
81 at the most. The same work done
in the usual manner would cost nt
least $50 II will now he an easy mat
ter for miners to take Il number of
specimens. have them put through the
N-ray process and determine whether
they contain gold or not. Oftentimcs
miners will throw away good spcci-
mems because there are no outward in
dications Of gold. To get these pieces
tested ut 81 apiece is more than most
miners ran AFFORD The time has now
come when the work can most easily
b" done hy N-ray operators for about
10 cents apiece in large lots. This
really means II revolution in prospect
ing. and the ground of the state is
sure TO he more thoroughly worked
than ever before.