eed for soldered seals. In addition, it is easier to paint a decoration or a logo directly on the aluminum, so no more costly paper wrappers are used on steel cans. (Knapp, 23) Aluminum compounds can be used both as a source of carbon dioxide gas and a source of foam. Carbon dioxide gas can, in turn, put out fires. For this reason such combinations were used to make liquid-type fire extinguishers for many years. In the extinguisher the two reagents, the liquids that will react, are kept apart until the extinguisher is to be used. Then a knob on the extinguisher is struck, breaking the seal between the liquids and causing them to react. The reaction produces a gelatinous precipitate of aluminum hydroxide and carbon dioxide gas. The gas cannot easily excape through the sticky liquid, and instead forms bubbles inside it. The result is a foam containing carbon dioxide that immediately squirts from the extinguisher nozzle. (Knapp, 38, 39) This has the effect of blanketing the fire with materials that will not burn, thus preventing oxygen from feeding the flames. The history of aluminum is quite short. The industrial method for separating aluminum from bauxite ore was only discovered in 1854, and the first aluminum was produced in 1859. Now though, it is one of the most important metal industries in the world. The aluminum industry had to wait for the development of electricity before it could exist. In fact the person who first separated aluminum from its ore was Danish professor Hans Christian Oersted, one of the pioneers of electricity. (Bowman, 393) However, only after discoveries in 1886 by Charles Martin Hall of Ohio, Paul L. T. Hroult of France, and in 1888 by Karl Joseph Bayer of Germany, did it become possible to refine large amounts of aluminum. Even then, large-scale processing did not get under way until the early part pf the 20th century. This is because relatively cheap electrical supplies were needed, and it took some time for ...
