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speed of rotation all tend to insure intimate fractional contact between the atoms of precious metal and the amalgamated plates, so that even the finest particles of float-gold are retained, and the gentle attrition of this flowing pulp maintains the amalgamated surfaces in a constantly bright and favourable condition. Any amalgam which may become detached is caught in a well at the bottom of the machine, together with such mercury as may have escaped from the dishes, when it is thought desirable to employ it. " To such a high state of perfection is amalgamation carried in this apparatus, that it is capable of extracting nearly all the gold even from pyritic ores without calcination or any other treatment. In making this statement, I expect to incur the condemnation of theorists ; but a study of the table of actual results achieved recorded below will substantiate my opinion ; and a more startling piece of evidence, which may be deducted from this same table of results, is that in all cases the patent process is far cheaper and generally more advantageous than chlorination itself, for whereas chlorination alone costs between £2 and £4 per ton, and seldom less than £3, for a return of 90 to 94 per cent, of the assay-value, the total cost by the patent process is only about ss. to 10s. per ton, and the yield is often equal and sometimes superior to that from chlorination. "The subjoined figures, though quoted on the authority of the inventor of the process, are, in my opinion, reliable. To verify them, I made a trial with ' Edwin Bray' ore, its refractory character affording a crucial test of the process. Three samples before treatment gave an average of loz. 16dwt. 2gr. of gold; and the average gold-contents of three samples of tailings, taken as they left the amalgamator, was, as nearly as possible, 3dwt., or 91-686 per cent, extracted: —

" From the foregoing results of my examination of the patent process, I am of opinion that, notwithstanding the enormous capital represented by existing stamp-batteries, the patent pan possesses so many advantages that it will force its way into use and displace them, whilst for new mills, extensions, and renewals it will be adopted without hesitation. " to the patent amalgamator, there is not a mill in existence where it will not be found advantageous, and where it will not surely supplant the blanket-tables and miscellaneous appliances now in use for saving gold which would otherwise be lost. " Another direction in which it will find highly profitable employment will be in reworking tailings containing much gold that has been passed over by the less efficient processes hitherto employed."— Lock's Ore-dressing Machinery.

Butters's Patent Grinding- and Amalgaiviating-pan. This machine stands on an ordinary wooden bed-plate A, to which are bolted the cast-iron columns B that'support the top framing, one column being required for each grinding-roller employed, the most suitable arrangement being from three to five rollers, according to size of pan. The cast-iron beams C, for carrying roller-spindles D and the vertical driving-shaft E, are bolted to a facing on the columns B, as shown at x. The compressing-springs F, for givinp the required pressure on the grinding-rollers, are held in position by a crosshead and columns, as shown at y, and are so arranged as to be adjustable by means of the hand-wheel and screw G, a jaum-nut being provided to hold the screw in position when the desired pressure has been obtained. On the spindles D the grinding-rollers H are placed, and revolve upon them, the spindles being stationary, held by a feather in the cast-iron beam G. To minimise wear, and to prevent dust getting into the bearing, a specially-designed bush and footstep I are provided. The grinding face of the rollers is fitted with a specially hard facing-piece X, so arranged as to be easily and expeditiously replaced in the event of wear through time. The cast-iron false bottom Lis made specially hard, and is simply laid in position in the recess provided for it in the bottom of the pan on a bed of cement. The space M, between the outside periphery of the false bottom and the side of the pan, acts as a quicksilver-well. The pan Nis keyed on to the vertical driving-shaft, and revolves with it, and thus driving by friction the grinding-rollers at a high speed relative to the difference in the diameters of the pan and rollers. The machine is also fitted with a tailings-pan not shown, so arranged that the reduced materials flow through gratings in the side of the grinding-pan N into it. The special advantages claimed are speed of reduction and amalgamation, a sft. pan with three rollers being capable of reducing half a ton of hard 2in. quartz per hour. No special foundation is required. It is easily driven ; and readily adapts itself to an arrangement of automatic feeding either by elevator or other feeders.— Victorian Mining Beport. 17—C. 3.

No. Description of Ore treated. Gold obtained in Raw Ore before Treatment. Gold contained in Tailings after Treatment. 1 2 3 4 5 6 7 " Welsh" ore, sulphides of iron, copper, lead, &c. Tailings from Transvaal "Indian Consolidated" ore, refractory sulphides ... "Australian Black Jack," arsenical sulphides, very complex Tailings from "Johnson and Matthey " ... " Devala Moyar " ore, complex arsenical pyrites ... " Edwin Bray " ore, pyritic Oz. dwt. gr. 0 1 12 0 2 7 0 1 23 19 9 16 3 0 19 22 2 0 22 Oz. dwt. gc. 0 0 13 0 0 23 0 0 12 0 10 16 0 1 23 0 6 11 0 3 0