Page:Popular Science Monthly Volume 44.djvu/413

Rh chemically pure aluminum from the crude bauxites and corundums of which considerable quantities have been discovered in the northern United States. The factory at Neuhausen utilizes a part of the falls of the Rhine at Schaffhausen for the propulsion of powerful turbines which directly work the dynamos whence electricity is obtained for the production of aluminum and its alloys. Important manufacturing centers have also been established in England and Germany, and there-are some in France.

By these new methods, which are still susceptible of improvement, a considerable saving over the old purely chemical processes is gained in the treatment of the minerals. In either case the chief effective agent is heat, and it is utilized far more completely in the electrical furnaces than in the older furnaces, which were subject to many cooling influences. Not more than four hundred grammes of coal burned in the furnace of a steam engine driving a dynamo will produce electrical energy sufficient to isolate in a molten electrolyte one kilogramme of aluminum. More than twenty times as much would have been required in the old chemical process. By virtue of this better utilization of heat, with greater profection in the equipment and management of the shops, the price of aluminum has continued to decline, till it is now very near the point when the metal can be profitably applied to the fabrication of many articles.

The alloys of aluminum now occupy a high position in practical industry. Aluminum bronzes and platings, lighter and more tenacious and more resisting than copper, and conducting heat and electricity better, will take its place. The new shops are also working for the production of cast and malleable iron, and they are in request by smiths for refining cast iron and steel.

The metallurgy of iron is now an exact science as well as an industry. Informed by analysis of the exact composition of the elements that enter into the fusion-bed, and of the character of the products at each moment of the operation, the metallurgist can determine with accuracy what be must eliminate and what add to give his product the quality required for the use to which it is to be put. A few hundredths of alloy will decide what it shall be. A little chromium will render artillery projectiles proof against breaking; nickel increases the resisting power of sheathings. Introduced at the right time into the Bessemer converter or the Martin furnace, a small proportion of the alloy of iron and aluminum communicates to the melted metal a fluidity which facilitates the disengagement of the gases that would otherwise remain imprisoned in the metallic bath, producing blow-holes, and destroying homogeneity and resistance in large pieces.

New uses are constantly found for the pure metal; less employed in jewelry, it is more used in the modest ranks of plated