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In manufacturing operations it is frequently necessary to use apparatus that is not affected by acids. In cases in which glass, porcelain, and similar materials are inadmissible the best material is platinum but the cost of this metal is often prohibitory. M. Jouve recently exhibited to the French Society of Civil Engineers a series of alloys to which he has given the name metillures. They are silicides of iron and manganese, which contain a very large proportion of silicon and resist the action of strong acids, hot or cold, much better than the most resistant specimens of cast iron. For example, apparatus made of these alloys can be employed in distilling nitric acid, or in concentrating sulphuric acid to 66 deg. Baume. The Prussian forests, covering nearly 7,000,000 acres, are made up much as if we should combine the pineries of the Southern States with the forests of some of our Middle Atlantic and Central States. When forestry was begun a great part of them had been injured by mismanagement, much as our forests have, been, and the Prussian foresters had to solve the problem of improving the run-down forests out of the returns from those which were still in good condition. They solved it with striking success. Immense improvement has already taken place and is steadily going on. The method of management adopted calls for a sustained yield--that is, no more wood is cut than the forest produces. Under this management the growth of the forest, and consequently the amount cut, has risen sharply. In 1830 the yield was 20 cubic feet per acre; in 1865, 24 cubic feet; in 1890, 52 cubic feet, and 1904, 65 cubic feet. In other words, Prussian forest management has multiplied the rate of production threefold in seventy-five years. And the quality of the product has improved with the quantity. Between 1830 and 1904 the percentage of saw timber rose from 19 per cent to 54 per cent.
