purifying effect.

In retorting amalgam, much care and attention is required.

First, never fill the retort too full, give plenty of room for
expansion; for, when the heat is applied, the amalgam will rise like
dough in an oven, and may be forced into the discharge pipe, the
consequence being a loss of amalgam or the possible bursting of the
retort. Next, be careful in applying the heat, which should be done
gradually, commencing at the top. This is essential to prevent waste and
to turn out a good-looking cake of gold, which all battery managers like
to do, even if they purpose smelting into bars.

Sometimes special difficulties crop up in the process of separating the
gold from the amalgam. At the first "cleaning up" on the Frasers Mine at
Southern Cross, West Australia, great consternation was excited by the
appearance of the retorted gold, which, as an old miner graphically
put it, was "as black as the hind leg of a crow," and utterly unfit for
smelting, owing to the presence of base metals. Some time after this I
was largely interested in the Blackborne mine in the same district when
a similar trouble arose. This I succeeded in surmounting, but a still
more serious one was too much for me--i.e., the absence of payable
gold in the stone. I give here an extract from the _Australian Mining
Standard_, of December 9th, 1893, with reference to the mode of cleaning
the amalgam which I adopted.

NEW METHOD OF SEPARATING GOLD FROM IMPURE AMALGAM.

I had submitted to me lately a sample of amalgam from a mine in West
Australia which amalgam had proved a complete puzzle to the manager
and amalgamator. The Mint returns showed a very large proportion
of impurity, even in the smelted gold. When retorted only, the Mint
authorities refused to take it after they had treated two cakes, one of
119 oz., which yielded only 35 oz. 5 dwt. standard gold, and one of 140
oz., which gave 41 oz. 10 dwt. The gold smelted on the mine was nearly
as bad proportionately. Thus, 128 oz. smelted down at the Mint to 87 oz.
8 dwt. and 109 oz. to 55 oz. 10 dwt. The impurity was principally
iron, a most unusual thing in my experience, and was due to two causes
revealed by assay of the ore and analysis of the mine water, viz.,
an excess of arsenate of iron in the stone, and the presence in large
proportions of mineral salts, principally chloride of Calcium CaCl.,
sodium NaCl, and magnesium MgCl2, in the mine water used in the battery.
The exact analys