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"The precipitator B is preferably mounted on trunnions and bearings B", so that its contents (when the top is removed) can be readily tipped into the washer S, which has a cover S 3 which is opened for charging. Or I may heat the zinc and gold in a closed vessel until the zinc has passed off in the form of vapour, and so recover the precious metal. "If, instead of using the agents hereinbefore mentioned for chlorinating, the vat should be lined with an acid-resisting material, or, with the exception of the covers, be built of wood, and chloride of lime having been mixed with the ore, and the mixture introduced into the vat, a solution is then prepared of chloride of sodium in water of a density of preferably 1,150 (water being reckoned at 1,000), and sulphuric or hydrochloric acid is added at intervals to decompose the chloride of lime and free chlorine, for the purpose of dissolving the gold, or the acid may be used without the salt. " The solution will then be circulated through the mixture in the vat as hereinbefore described, until the gold is dissolved, when the solution, charged with gold, may be passed through the precipitator, which in this case may contain copper-sulphide, or the gold may be obtained in any usual or suitable way for obtaining it from such solution. " Having now particularly described and ascertained the nature of my said invention, and in what manner the same is to be performed, I declare that what I claim is,— "1. For the purpose described, the employment of a ieaching-solution of, or containing, cyanide fof potassium and carbonate of sodium, or chloride of sodium (or both), substantially as hereinbefore described. " 2. For the purpose described, the employment of a leaching solution of, or containing, cyanide of potassium, acid carbonate, or chloride of sodium (or both), as described, the liquid from the leaching-operation being passed through zinc alloyed with an electro-positive metal, such as sodium or potassium, as hereinbefore described. " 3. The obtainment of gold or silver, or both, from solutions thereof by passing the solution in contact with shavings or particles of an alloy of zinc with an. electro-positive metal such as sodium or potassium. " 4. For the separation of gold or silver, or both, from ores or materials containing them, the mixture with the ore or materials of chloride of lime, and then forcing upwardly through the mixture an acid leaching-solution, whether containing chloride of sodium or not, substantially as hereinbefore described. " 5. In appartus for effecting the leaching by upward filtration of ores, or materials containing gold or silver, or both, a leaching-vat or vessel with a filter at each end, and capable of being reversed so that either filter can be brought uppermost, substantially as hereinbefore described. " 6. A leaching-vat having a filter at each end, and capable of being turned upon trunnions, or in bearings in which are the passage, for the solution, so that the inlets and outlets to and from the vat are reversed at the same time that the vat is reversed, substantially as hereinbefore described. "7. A leaching-vat, constructed and arranged substantially as hereinbefore described, and shown in the accompanying drawing. " 8. For the purpose described, the arrangement and combination of parts as a whole, constituting the apparatus hereinbefore described, and illustrated in the accompanying drawing. "Dated this 15th day of December, 1891. " W. D. Bohm." " I certify this to be a true copy.—-W. D. Bohm."

" Specification.—Chlorination Plant. " Improvements in the Separation of Gold and Silver from Ores or Materials containing them. " I, William Dunsmore Bohm, of 51, The Avenue, Acton, in the County of Middlesex, England, Metallurgical Chemist and Engineer, do hereby declare the nature of my invention for ' Improvements in the separation of gold and silver from ores or materials containing them,' and in what manner the same is to be performed to be particularly described and ascertained in and by the following statement : — " My invention has for its object to provide means whereby gold or silver or both are obtained from ores or materials containing them in a more ready, perfect, and efficient manner than hitherto, and my said invention has reference more particularly to a leaching-process such as that known as the ' Hungarian process.' " According to the said Hungarian process the ground ores or materials after being roasted with chloride of sodium, and with added copper-pyrites or sulphide of copper (if copper be not present in sufficient quantity in the ore or material), are treated with a solution of chloride of sodium and chloride of copper in water, which is caused to percolate through the ore or material, the proportion of chloride of sodium being usually sufficient to make a solution of 1,150 density, reckoning water at 1,000, and the chloride of copper being added as a strong solution usually in about the proportion of not more than 1 per cent, of the chloride of sodium solution. The liquid is conducted into vessels in which the gold and silver are precipitated by means of a solution of oxide of calcium and sulphur with or without chloride of sodium. When precipitation has taken place the supernatant liquor is run off for re-use. " According to my invention, in carrying out the process I add to the aforesaid leaching-solu-tion hydrochloric acid or bromine, or both, as hereinafter described, before the solution is passed through the ore or material, and afterwards. I treat the solution after it comes from the leachingvats with a precipitant. I filter the solution and separate the precipitate and the solution which passes through the filter. I bring up to its normal working strength by the addition of fresh quantities of the aforesaid components of the leaching solution, and again pass it through the leaching-vats, and so on. I preferably heat the solution before it is used in the leaching-vats. I find in most cases one part of bromine (added gradually to the solution as it circulates) to each