floor below. There are 4 lead-lined filters to each barrel, their sizes being 6 by 8 feet by 18 inches deep in front and 17 inches in back. The bottom is covered with mineraline ' tiles 12 by 12 inches by 1 inch thick, perforated and having -|-inch gutters underneath; on top of these is placed a rack of ltj-inch wooden slats, 4 inches high and 8 inches apart; the first layer above the tiles consists of 4 inches of coarse quartz pebbles (4, to | inch size), and this is covered by from 1 to 2 inches of ordinary clean sand. Before emptying the contents of the barrel, the filter is flooded with water to the level of the top of the filter-bed to act as a cushion. Then the original solution is passed through, striking on a float to prevent breaking the filter-bed. The ore-pulp is washed twice with clean water; the first time enough is added to stand 4 inches above the surface of the pulp, and the second time the tank is entirely filled. This amount is found sufficient to thoroughly remove all traces of chloride of gold from the pulp (tests are made with FeS04). The filtered solutions are stored in two stock-tanks on the second floor, and are drawn off from these into the precipitating-tanks as required. The latter are 8 feet in diameter and 3 feet high, made of wood, the interior coated with asphalt. They are provided with three outlets, the upper one 18 inches from the top, the middle one 1 inch above the bottom and the lowest one in the jamb. The gold is precipitated in the metallic state with an excess of fresh ferrous sulphate, made in a small lead-lined tank. In warmer weather 48 hours suffice for settling, and in colder weather from 3 to 4 days. The supernatant liquor is drawn off through the two upper outlets, opened one after the other (in order to prevent any stirring of the precipitates), and passed through a box filled with sawdust to catch any precipitate. The gold precipitate is drawn from the tanks through the jamb-opening into a small lead-lined settling-tank 2 by 2 by 4 feet. After standing 24 hours the supernatant liquor is siphoned off, and the precipitate filtered on paper. This is dried and mixed with about half its weight of borax and soda in almost equal proportions. Should iron salts be present, a little quartz sand is added. It is melted in graphite crucibles and cast into ingots of about 1*00 fineness. The whole operation is so simple that the most ordinary laborer can acquire the mechanical knowledge in a day. The repairs are practically nil."
LABOR, COSTS, ETC., AT THE HAIT.E MINK.
Some of the figures of costs of labor and working at the Haile mineare given below. For private business reasons it is impossible to give these as fully as we should like to.
1 A melted mixture of sulphur and quartz.
2 The Thies chlorination process has been described in detail by T. K. Rose, in his Metallurgy of Gold. C. Griffin & Co., London, 1894.
