ALUMINUM. 723 



thePittsoiirgli Reduction Company, who are now selling pure aluminum 

 at a rate cheaper than nickel 5 and tons of metal are rolled by the Sco- 

 ville Manufacturing Company, of Waterbury, into sheets, bars, rods, and 

 tubing at a price less than German silver. Briefly, the Hall process is 

 this : A flux being discovered that at a moderate temperature takes the 

 aluminum ore into solution, and that is of lighter specific gravity, and 

 that also is unaffected by the passage of an electric current, he fills a 

 series of carbon-lined steel pots with the flux, which is kept in a melted 

 condition. Carbon electrodes are plunged into these baths, through 

 which passes the electric current, which acts to send the aluminum to 

 the sides aiul bottom of each pot. The baths are constantly replenished 

 with ore, and the i^rocess thus goes on for an indefinite period, night 

 and day, at small cost, and demanding but little attention. 



Aluminum, whether pure or in combination, deserves to rank with 

 the noble metals; — although in certain forms it makes the basis of our 

 common clay, every cubic yard of which is said to contain 800 pounds 

 of the metal ; in other forms it is massed in mountains ; and in others 

 still, it shines among the most precious stones, entering into the compo- 

 sition of the ruby, sapphire, topaz, giirnet, lapis-lazuli, and tourmaline. 



Cryolite, found in Greenland, and beauxite, first found at Beaux, in 

 France, but since in Austria, Ireland, and elsewhere, are the ores relied 

 on for the manufacture of aluminum. Cryolite is a snow-white mineral, 

 though often tinged red or yellow by impurities. Beauxite is a hard 

 white clay, occurring in beds many feet thick. Corundum, found in 

 Georgia, is the material relied on in America especially for making the 

 alloys. It varies from dull blue to black, and exists in massive form, as 

 well as in crj'stals. The cost at the factory of these difierent minerals 

 varies from $00 to $1 40 a ton. 



The properties of aluminum are now generally known. Its color is 

 white delicately tinged with blue, and it resembles silver more than any 

 other metal. It takes a brilliant i)olish, and may be rolled or forged as 

 easily as gold or silver, and may be beaten into very thin leaves. It can 

 be pressed or stamped into all sorts of shapes, or drawn into very flue 

 wire. Its elasticity and tenacity are about the same as virgin silver, but 

 change greatly under the hammer. It' is said to resist the graving-tool 

 till properly varnished, nvhen it may be cut like coi)per. Its sonorous- 

 ness is very curious. Cast in bell form its sound is sharp, and not pro- 

 longed ; but struck as a bar, it is remarkabl}^ sweet, pure, and resonant. 

 Its sound is resolved into two tones, related to each other as are D and 

 A. For a musical instrument, fine effects might be had from a series 

 of chromatic bars. 



In estimating the relative cost of aluminum as compared with other 

 metals, we must take its specific gravity into the account. A bar of 

 ahimiuum weighing 1 pound would be about four times as large as a simi- 

 lar bar of silver, brass, bronze, tin, or iron. Hence, at an equal price, 

 aluminum would be four times as cheap as silver, but as it now costs by 



