Page:Popular Science Monthly Volume 48.djvu/450

418* laboratory curiosities, because of the want of adequate means of obtaining them.

It is easy, with the aid of the electric furnace, to produce abundant meltings of chromium by reducing the sesquioxide. This melting, refined, yields chromium, an unoxidizable metal very different from the specimens which have been hitherto obtained. It can be filed like iron, and takes a fine polish. Chromium, then, more infusible than carbon, can now be used in preparing alloys without the need of the intervention of ferro-chromium, which has the disadvantage of containing up to ten per cent of carbon.

This preparation opens the way for the effective study of the alloys of chromium. In combination with aluminum or copper, it gives interesting results. Pure copper, alloyed with 0•5 per cent of chromium, assumes a double resistance and suffers less change than copper in contact with moist air.

Molybdenum, previously unfused, can also be obtained in notable quantities. By heating, in a continuous electric furnace, a mixture of oxide of molybdenum and charcoal, a melting of the metal is obtained which flows readily and can be easily molded. It furnishes a definite carburet, very well crystallized. It is refined by a new heating in the electric furnace, with an excess of oxide of molybdenum. The melted metal thus obtained has a fine grain and a brilliant surface. It can be filed, and forged, at a red heat, upon the anvil; and with iron it furnishes a steel that can be tempered. These are all new properties.

Tungsten has been heretofore known to chemists only as a powder. Under the action of the electric arc, the oxide of tungsten is reduced by means of carbon, and gives in a few minutes a well-melted bottom, covered with a fine layer of the blue oxide of tungsten. This metal, which is still more infusible than chromium and molybdenum, can be liquefied with great facility. It does not seem to have a strong affinity for carbon, and is obtained without special precautions as one of the purest metals we have prepared.

The different oxides of uranium can not be reduced by carbon at the ordinary temperatures of our furnaces; but when a mixture of the sesquioxide of uranium and carbon is subjected to the high temperature of the electric furnace, the reduction takes place in a few instants. After cooling, an ingot may be drawn from the crucible possessing a brilliant fracture and great hardness. When this uranium is slightly carbureted, it presents the property of striking fire in contact with flint. The particles thrown off burn with an intensity and an energy far superior to those exhibited by a piece of iron.

All these simple bodies melt at more or less high temperatures.