Where base metals are present in the lode stuff frequent retortings of the mercury, say not less than once a month, will be found to have a good effect in keeping it pure and active. For this purpose, and in order to prevent stoppage of the machinery, a double quantity is necessary, so that half may be used alternately. Less care is required in retorting the mercury than in treating the amalgam, as the object in the one case is more to cleanse the metal of impurities than to save gold, which will for the most part have been extracted by squeezing through the chamois leather or calico. A good strong heat may therefore at once be applied to the retort and continued, the effect being to oxidise the arsenic, antimony, lead, &c., which, in the form of oxides, will not again amalgamate with the mercury, but will either lie on its surface under the water, into which the nozzle of the retort is inserted, or will float away on the surface of the water. I have also found that covering the top of the mercury with a few inches of broken charcoal when retorting has an excellent 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.