Year: 1859

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 No 3--AMALGAMAT1oN ODE cAzE,) IN KETTLES

 This mode of amalgamating silver ores was discovered in the seventeenth century by Alonzo Barba Tn South America. It is as follows :- After the ore is finely ground in the arrastra, about l50 pounds of it is placed in a copper kettle, and the sides heightened by wooden slaves Salt is added, and the whole mixed with wooden shovel, with sufficiency of wa ter to give it pasty consistence To this is then added from six to eight times the quantity of quicksilver as silver is supposed to be in the ore, as proved by assay. A slow fire is then lighted, and the mass stirred with the wooden shovel From time to time trial assays are made in the horn spoon to see whether more quicksilver is required. This manipulation lasts from two to four hours, when the mass is emptied into the washing apparatus, where the earthy matter is washed off, The kettle is at once filled with new material. By this process less quicksilver is lost than by that of the patio 5bat the residue of the earthly matter contains much more silver For this reason it is only used for very rich ores, and the residue is re- sworked in the patio. Mazistral is used at times, but with little profit, owing to its injurious eff fleets on the copper kettle.

 NO. 1.-THE FREYBUkG OR BARREL AMALGAMAToR. < This differs principally from the patio by the rapid reduction of the silver from its ores, and from its small loss of quicksilver. have only room to give the general routine of this process; more would be out of place, and useless. The ore, as in the patio is first sorted, crushed, sground fine, and sifted Then the ore is mixed with from five to ten per cent. of salt, and for four to five hours roasted in large reverbera- ting furnace; additions of other substances are needed at times. The object of roasting is to expel most of the volatve metals, as sul phur arsenic, antimony, &c., to convert others into oxides, and the silver into chloride, which takes ] 'lace when the salt decomposes. This requires I | careful watch. The ore requires continual stirring up to expose constantly new surfaces to the action of the heat. Roasting may be def. cient, or it may have been carried on to excess, in which case it is termed to be dead. Either state will cause the loss of silver and uuicksl- yer, and moreover produces very impure sill yer, other metals having gone in the amalgam of the operation next to be described. If this is the case, another operation of separating and refining is needed. After roasting, the ores are ready for the barrels, which are generally of a size to hold half ton of ore, and nearly as much more of other matter To this half d ton of ore, water is added, sufficient to produce a kind of paste After some time some fifty lbs. of mercury are added, regulated by the richness of the ores; also small quantity of iron or copper. Whether copper or iron is to be used, can only be ascertained by practical chemist, as it depends entirely on the composition of the ores. After this the barrels are slowly reyoved around. on iron axles for a space of eighteen or twenty hours, in which time all the silver is anal gamated with the mercury. This is now settled by slower motion, then tapped, filtered and retorted as in the usual mode by the patio process The earthly mass is then run into the vat, where, by the aid of continued agitation and water, it is worked off, leaving any stray parti- cles of silver amalgam and mercury behind The whole operation, after the ore is roasted occupies from twenty-two to twenty-four hours. The silver is more pure as that from the patio and the loss of mercury is far less, being but B ounces to ounces of silver produced

 The barrel process, to be successful, requires however, in the very start, the outlay of large capital and powerful machinery when these are wanting, and other things are favorable, the patio is to be preferred. In these different me thods of silver extraction, some silver is always lost This loss is not permanent in the same mine, nor alike in different localities. No rule for estimating it can be given. But experience has proven it to be greatest in kettle amalga- nation, next in the furnace, next in the patio and last in the barrels.

 NO. 5-DIssoLvING OF ORES WITHOUT MERCURY.

 This process of extracting silver from furnace products and from silver ores is comparatively new, having only come in use within the last fifteen years but for certain classes of ores, il promises to supercede all the other methods hereafter A great many of the Arizona ores ~ko1f k,