The San Francisco call., 1897-02-02
HOW CYANIDE AIDS
THE GOLD MINER
Even So Cent Ore May Be
Proftably Reduced
by II.
Professor Christy's Interesting
Lecture at the Academy
of Sciences.
A Large Audience of Miners and
Students Learn the History and
App ication of the Process.

At the Academy of Sciences last night
an interesting lecture was delivered on
the "Cyanide Process of Gold Extraction" ="
by Samuel B. Chr.sty, professor of mining
and metallurgy at the University of Cali
fornia.
The hall was crowded with q mixed
audience of students and practical miners.
The professors remarks, which were
illustrated throughout by means Of the
stereopticon, tended to prove the many
advantages of the cyanide process in the
treatment, moro particularly of the finer
grades of ore. He stated that in South
Africa, where the process was introduced
several years ago, it has effected an i'm
mense saving in tailings which could not
be proftably worked by any other method
previously adopted. In 1890 the value of
the cyanide product for the Witwatersrand
district was $4,000; in 1891 $50, 600; in 1892,
So, OG0, 900, and in 1894 Sc. 900, and it is
still increasing.
The lecturer after rapidly reviewing the
results achieved by himself and others
notably T. z. EIch baum, G. w Merrill,
Leslie Simpson, II. G. Baldwin, F. Booth
and E. A. Hersam-in the course of inves-
legations pursued in California, proceeded
to describe the actual process as clearly
anu dS dS L46 ucCtSSdIlly
nature of the subject permitted. be
spoke first of the most satisfactory
methods of dissolving the gold in
cyanide solutions and afterward of the
various methods of securing gold precipi-
tation from these solutions. The soiubilitY
of gold in cyanide solutions had been
known, he stated, for nearly a century,
though that knowledge was not actually
applied for purposes OF gold extraction
until ten years ago. In. 1848 the German
chemist Ellsper declared that while zinc
would dissolve in potassium Icyanide
solution the presence OF oxygen was nec-
essary in the case of the nobler metals.
J. S. Macarthur who claims to have in
vented the cyanide process, denied
Ellener's contentious, though as the
result of personally conducted expert
ments, the lecturer had seen fit to con-
firm the Ellsner reaction.
Mr.. Christy discussed the effects of OK
idizing agents, and affirmed that his con-
clusion after three years study was that
with low-grade ores and diluted solutions
the cyanide solution itself will, if properly
aerated, carry oxygen enough 20 dissolve
the gold.
The lecturer, in the course OF his expla-
nation OF the various methods of precipi-
tation from the solution, discussed the
use of electricity. OF metallic zinc and
of copper. The first-named method
in spite OF several disadvantages,
| has been more generally used on
large scale than any other. In this
connection, he pointed out a curious fact,
discovered during the treatment of solu-
tion containing OIL per cent or 1908 pei
ton of gold. Plain strips of polished zinc
failed to induce the slightest precipitation,
whereas when lathe turnings from the
same sheet zinc were used, the gold was
entirely precipitated by filtration OF the
solution through large excess of zinc
shavings.
Several views of the largest plants in
Utah, California and South Africa, where
the process is in operation, were subse-
quently thrown upon the screen and
rapidly described. In closing his address
the speaker advised miners to save tail
fngs even as low as so cents per ton, which
could be profitably treated by the cyanide
process