desired, to treat the powder with
hydrochloric acid, and thus remove all the iron, but in a large way this
would be too expensive, and my laboratory treatment, though necessarily
on a small scale, was intended to be on a practical basis.

The amalgam at this mine was in this way afterwards treated with great
success.

For the information of readers who do not understand the chemical
symbols it may be said that

FeCO3 is carbonate of iron;
CaCO3 is carbonate of calcium;
CaSO4 is sulphate of calcium;
CaCl2 is chloride of calcium;
MgCl2 is chloride of magnesium;
NaCl is chloride of sodium, or common salt.

CHAPTER VII

GOLD EXTRACTION--SECONDARY PROCESSES AND LIXIVIATION

Before any plan is adopted for treating the ore in a new mine the
management should very seriously and carefully consider the whole
circumstances of the case, taking into account the quantity and quality
of the lode stuff to be operated on, and ascertain by analysis what are
its component parts, for, as before stated, the treatment which will
yield most satisfactory results with a certain class of gangue on one
mine will sometimes, even when the material is apparently similar, prove
a disastrous failure in another. Some time since I was glad to note that
the manager of a prominent mine strongly discountenanced the purchase of
any extracting plant until he was fully satisfied as to the character
of the bulk of the ore he would have to treat. It would be well for the
pockets of shareholders and the reputation of managers, if more of our
mine superintendents followed this prudent and sensible course.

Having treated on gold extraction with mercury by amalgamated plates
and their accessories, something must be said about secondary modes
of saving in connection with the amalgamation process. The operations
described hitherto have been the disintegration of the gold-bearing
material and the extraction therefrom of the coarser free gold. But it
must be understood that most auriferous lode stuff contains a proportion
of sulphides of various metals, wherein a part of the gold, usually in a
very finely divided state, is enclosed, and on this gold the mercury has
no influence. Also many lodes contain hard heavy ferric ores, such as
titanic iron, tungstate of iron, and hematite, in which gold is held.
In others, again, are found considerable quantities of soft powdery iron
oxide or "gossan," and compounds such as limonit