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used for concentration the shoes are lifted up to a certain height above the bottom. When there is about 6in. of 3oncentrates in the bottom of the pan it is stopped and cleaned out, and the concentrates are then dried and roasted in a reverberatory furnace, after which the roasted material is ground up-to a fine pulp in one of these pans, and the gold saved by amalgamation. The manager of the New Alma Company spoke highly of these pans as grinding and amalgamating machines ; but they have not yet been sufficiently tested under different conditions to make an accurate comparison with other and older machines now, in use. The price of this pan is £175, and the speed that it has to be driven at is about fifty-live revolutions per minute. The patentees, however, claim for it the following advantages : That it is able to pulverise irhe ore into a fine pulp and amalgamate the precious metals at a very low cost, and also capable of treating large quantities. They estimate the cost of working, including wear and tear and all expenses in connection with working, to be about 3s. per ton, and that one pan is sufficient for every five heads of stamps. They also draw attention to the fact that the ore does not require to be" so carefully crushed to a fine state by the stamping-battery when it goes through one of these grindingpans, and that coarser gratings can be with economy used ; but the same argument applies to any similar grinding-machine. Prom, my own observations on seeing this pan working, it is an inferior grinding-machine to the Mackay pan, but a better amalgamator. A classifier is fixed on the outside of the machine, its three sides tapering towards the bottom, where it communicates with the interior of the machine by a hole. In the classifier a deflectingplate is so arranged that the size of the grains of tailings can be regulated to suit different circumstances. All grains over a certain size are automatically separated and collected in the classifier by this means, and settled by gravitation in comparatively still water, and are sucked through a hole at the bottom into the machine and reground, the waste passing away with the overflow. The total weight of the pan is about three tons. Annexed are sketches of pan in position (see Figs. 22 and 23). Fixing the, Classifier. —This separator is 3ft. 6in. long by 18in. wide. A V table must be fitted to the full width of end of copper table, tapering so as its other end will fit the classifier, making a tight joint. The use of this is to make two classes of stuff; the one class being the worthless soluble mullock, which will flow with the surplus water over the end of the classifier; the other, the valuable material, such as gold, mundie, and .heavy sand, being too heavy to be carried away with the water over a surface 3ft. Bin. in length, sinks, and by the shape of the classifier, assisted by the downward current, is carried into the discharge-pipe, which conducts it into the pans. The pipe is supplied with four cast-iron nozzles, having discharges Jin., fin., fin., -gin. The operator must determine which to use by the material under treatment. If very mulloeky the Jin. would do, the object being to get rid of all the useless mullock, which, if allowed to go into the pan, considerably interferes with amalgamation. The small nozzle is the best to employ so long as the waste flowing over the classifier is found to be of no value. The pan should be fixed so that the top of it is about level with the discharge-pipe of the classifier, thus insuring an easy flow into the pan. The speed of the grinding-muller is fifty-five revolutions per minute, and that of the horizontal spindle on which the pulleys are fitted 110. The speed of cam-shaft being under forty revolutions per minute makes it impossible that the pan can be driven direct off it. The best plan is to drive off an intermediate shaft, which should take motion from the engine-shaft when possible. It is better to get up the speed at once on the intexmediate shaft to 110 revolutions; then a 3ft. pulley, 12in. wide, having a 6in. belt, will give correct speed to pan. The following are tiie inventor's remarks and description of this grinding and amalgamating pan : — " This machine is the invention of Mr. Thomas William Watson, of St. Arnaud, and Mr. Thomas Denny, of South Tarra, Victoria, who have had many years' experience in connection with the extraction of gold, silver, and other metals from their ores, and is now the property of the Watson and Denny Gold and Silver Extracting Company (Limited). "The great advantage of this invention is the extremely low cost of treating large quantities of all classes of auriferous-argentiferous ores. It is a well-known fact that all batteries lose a considerable percentage of gold and silver in the tailings and pyrites, which can nearly all be extracted by this process at a cost of less than 3s. par ton of the ore or quartz crushed. This covers all charges for wear-and-tear and working-expenses, one machine treating and reducing to slime all the material produced by a five-head battery. These machines treat the ores in a raw state, without roasting or other manipulation, no matter what proportion of mundie, pyrites, or other base metals the ores contain. '•' The process is more especially intended to extract the gold and silver now being lost in the tailings and pyrites from the various quartz-batteries and other reduction-works. It has been practically proved on a large scale by this process that from 70 to 95 per cent, can be saved of all the gold and silver known by fire-a.ssay to have been lost in tailings and pyrites. These machines, being continuous and automatic, receive all the sand and pyrites either as they flow direct from the battery-boxes or at the end of the copper and blanket tables, and need very little attention, no additional men being required. It not being necessary to crush the ores so fine as is now the custom, much coarser gratings may be used, consequently a larger quantity can be operated on by the battery in a given time. " In this process, treating free-milling ores, the action of gravity is not depended on to sink the particles of gold and silver to the bottom to be amalgamated, the ore with its metals (no matter how fine and light) being forcedly the motion of the produced currents into the quicksilver, which lies underneath, but not in contact with, the grinding-surfaces ; therefore the quicksilver cannot become floured or sickened. The particles of gold and silver, being caught in this way, are not further roground. The amalgam is coarse, and yields from 30 to 50 per cent, when retorted, as