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Improvements in the Recovery of Gold and. Silver prom their Solutions. We, Carl Wilhelm Heinrich Gopner, of Canalstrasse, 46, 48, Uhlenhorst, Hamburg, Germany, chemical manufacturer, and Heinrich Ludwig Diehl, of Xl Grassbrook Vogelreth, 8, Hamburg, Germany, chemist, do hereby declare the nature of our invention for " Improvements in the Recovery of Gold and Silver from their Solutions," and in what manner the same is to be used and performed, to be particularly described and ascertained in and by the following statement : — The leaching of auriferous ores or tailings by solutions of potassium-cyanide gives solutions containing free alkali, the gold in solution as potassium-aurocyanide, or sometimes as potassiumauricyanide, and a large excess of potassium-cyanide. When silver is present in the ores or tailings it is also found in the solution as a cyanide. This invention relates to the treatment of such solutions in such a manner as to effect precipitation of the gold and silver cyanides and regeneration of the leaching material. For this purpose the solution resulting from the leaching has added to it cupreous cyanide, which is acted on by the potassium-cyanide, forming soluble cupreous potassic-cyanide. There is then added an acid, such as sulphuric acid, capable of decomposing potassium-cyanide, whereupon the ingredients of the solution are decomposed, forming hydrocyanic acid and potassium-sulphate, which remain in solution while auro- or auri-cyanide and cupreous cyanide are precipitated, as well as silver cyanide when there is silver in the solution treated. In the practice of the process it is of advantage to add the cupreous cyanide in excess, so as to render the precipitation of the gold as complete as possible, the precipitate consisting then of auro-cupreous cyanide and cupreous cyanide. The solution, decanted or otherwise separated from the precipitate, is slightly supersaturated with caustic potassa, so as to produce fresh potassium-cyanide, which can be used for again leaching. In order to obtain gold in the precipitate in sufficient amount to render it suitable for treatment to recover the gold the precipitate from the first operation is dissolved, wholly or partially, in a fresh quantity of the solution obtained by the leaching, and fresh cupreous cyanide is added, if necessary, and then acid to effect a fresh precipitation, and this may be repeated a number of times until sufficient gold is accumulated. When cupreous cyanide is added in considerable quantities in the first operation a number of successive precipitations may be effected without further additions of cupreous cyanide. The process described is applicable where the solution obtained by leaching already contains copper, but in such case the quantity of cupreous cyanide added may be less than when no copper is present. When silver as well as gold is present in the solution obtained from the leaching the process may be modified as follows : A soluble salt of silver, such as the nitrate or sulphate, is added to the solution, but not in such quantity as to effect precipitation ; or a silver salt insoluble in water, such as the cyanide or the chloride, may be added, but the quantity should be such that very little of it remains undissolved in the solution. Acid is then added, and thus the silver as well as the gold is precipitated as a cyanide. The quality of silver salt added should be such that the silver in it, together with that in the solution treated, should be considerably in excess of the gold. In the leaching and precipitation processes sodium-cyanide may be used instead of potassiumcyanide, this being regenerated by adding soda instead of potassa to the solution separated from the precipitate. Also mixtures of sodium and potassium cyanides may be used for leaching, and may be regenerated from the separated solution. Having now particularly described and ascertained the nature of our said invention, and in what manner the same is to be performed, we declare that what we claim is,— 1. The herein-described process for precipitating gold and silver from their cyanide solutions by adding to these cupreous cyanide and then an acid. 2. The repetition of the process on the precipitate with fresh quantities of solution, so as to accumulate gold in the precipitate. 3. The regeneration of the leaching solution by adding caustic alkali to the solution separated from the precipitate. 4. In applying the process to solutions containing silver as well as gold, the use of a silver salt for effecting the precipitation. Dated this 10th day of September, 1896. C. Gopner. L. Diehl.

An Improved Process for the Extraction of Gold and Silver from their Ores. I, Kate Alberta May, of 42, Blyth Road, London, England, gentlewoman, do hereby declare the nature of my invention for "An Improved Process for the Extraction of Gold and Silver from their Ores," and in what manner the same is to be performed, to be particularly described and ascertained in and by the following statement: — My invention relates to an improved process for the extraction of gold and silver from their ores, and has for its object the removal from the crushed ore by treatment before amalgamation of deleterious compounds, such as sulphides of iron, or arsenical, antimonial, and cupric compounds which occur in some gold- or silver-ores. To carry my process into effect the ore is first crushed in any usual manner, and the crushed ore may be treated by leaching with a solution of mixed alkaline hydrate and carbonate, either cold in the case of weakly pyritic ores, or hot in other cases, but preferably in most cases the ore is boiled for about one hour in a solution containing about 5 per cent, of an alkaline hydrate such as caustic soda, and 5 per cent, of an alkaline carbonate such as carbonate of soda. The boiling solution may be agitated with or percolated through the ore, and after one hour's boiling is allowed to stand for at least twenty-four hours.