ALUMINUM 



218 



ALVA 



Its Uses. The uses of aluminum are con- 

 stantly increasing. It is a good conductor of 

 electricity, and sometimes takes the place of 

 copper wire in the construction of electric 

 lines. The top of the Washington Monument 

 is covered by a thin sheet of aluminum, which 

 is connected with a lightning rod. One of its 

 most important usi-s is in the- manufacture 

 of steel; the addition of an almost impercep- 

 tible amount, say five thousandths of one per 

 cent, eliminates air-holes, and makes the steel 

 solid. It is also used in the manufacture of 

 numerous household utensils, for which it is 

 especially suited, since it is light, durable, does 

 not rust like tinware nor chip like granite, 

 and is not easily acted upon by vegetable 

 acids. Hairpins, thimbles, combs, mirror 

 frames, a substitute for tinfoil and dozens of 

 other articles are also made from it. 



There are numerous alloys of aluminum and 

 other metals, such as aluminum bronze, an 

 alloy with copper, and magnalium, an alloy 

 with magnesium (see ALLOY). Aluminum gold, 

 which is a compound of aluminum and copper, 

 when new closely resembles real gold, and 

 is often used in the manufacture of watch cases 

 and cheap jewelry; it tarnishes quickly, how- 

 ever, and is then worthless as an ornament. 

 Other alloys, some made by secret processes, 

 are used in boats and automobiles and for the 

 framework of aeroplanes and dirigible balloons. 



So varied are the uses of aluminum that it 

 seems as if man must have known of its ex- 

 istence for ages, yet it was unknown before 

 the beginning of the nineteenth century, and 

 it has not, in any part of the world, been found 

 in a pure form. Pure aluminum was not in 

 existence until 1854, when it was produced 

 chemically. The metal was of no practical 

 value until the last decade of the nineteenth 

 century, after a new process was discovered 

 for the reduction of aluminum by electrolysis 

 (which see). 



Its Manufacture. In this method, known 

 in America as the Hall process and in Europe 

 as the Hcroult process, aluminum ore in the 

 form of bauxite is mixed with a readily fusible 

 mineral called cryolite. An electric current is 

 passed through the mixture. The poorly con- 

 ducting mixture soon becomes hot enough 

 to melt the cryolite. The bauxite dissolves 

 in the molten cryolite and is decomposed by 

 the current. Molten aluminum is set free at 

 the negative electrode and runs down to the 

 bottom of the crucible, whence it is drawn off 

 through a tap-hole. At the positive electrode 



oxygen is set free. The operation is carried 

 on in a furnace which is practically a huge 

 crucible made of blocks of carbon. The posi- 

 tive electrode is composed of heavy carbon 

 plates or cylinders. This is attached to a chain 

 and a derrick so it can be lowered into the 

 crucible as fast as the end is burned off by 

 the liberated or nascent oxygen (see HYDRO- 

 GEN PEROXIDE). The carbon-lined crucible is 

 itself the negative electrode. The bauxite is 

 fed into the crucible as fast as it is reduced, 

 and the process continues until the carbon 

 electrode has been entirely consumed. An 

 ordinary furnace will produce about 400 pounds 

 in twenty-four hours. 



Production and Prices. The first smelter 

 using the Hall process was built in Pittsburgh 

 in 1889, and in 1895 the works were moved to 

 Niagara Falls so as to take advantage of the 

 cheap water power there for the production of 

 the electric power. A third large smelter is 

 at Shawinigan Falls, Que. The production of 

 aluminum in the United States increased from 

 1.5 tons in 1886 to 75 tons in 1891, 3,575 tons 

 in 1901 and 23,062 tons in 1911. The average 

 annual production is now 35,000 to 40,000 tons. 

 In Canada, the annual average has increased 

 from less than 1,000 tons to 15,000 tons; all 

 the aluminum produced in Canada is from 

 imported ores. 



At the same time that the production of 

 aluminum has increased, its price has de- 

 creased. In 1855 the chemists sold it at the 

 rate of $90 a pound. By 1890 the price had 

 fallen to $2 a pound, and to-day it fluctuates 

 from eighteen to twenty-five cents, the aver- 

 age being about twenty cents. This enormous 

 decrease in price is the result of perfected 

 processes of manufacture and of the increase 

 in use. One vast and comparatively new de- 

 mand for it is in the manufacture of auto- 

 mobiles, both body and chassis. J.F.S. 



Consult 1911 Bulletin of United States Geologi- 

 cal Survey, Mineral Resources of the United 

 States; Minet's The Production of Aluminum and 

 Its Industrial Use. 



AL'VA, or AL'BA, FERDINAND ALVAREZ DE 

 TOLEDO, Duke of (1508-1582), a Spanish gen- 

 eral and statesman whose name became a 

 synonym for cruelty and tyranny. Under 

 Charles V and Philip II he fought in the 

 armies of Spain, winning some distinction, but 

 his real part in history did not begin until he 

 was sent in 1567 as governor to the Nether- 

 lands. Philip II had given him authority to 

 reduce the country to order, and thorough 



