224 feature's 



Electricity is the chief agent in the produc- 

 tion of metallic aluminum. The reduction 

 company buys this alumina, which has been 

 separated from the clay or ores where it is 

 mined. In a large room there are located a 

 great number of iron vats or crucibles, lined 

 with carbon, about two or two and one-half 

 feet deep, five or six feet long and four feet 

 wide. 



Immediately over each vat is constructed a 

 metal framework, through which are inserted 

 a large number of carbon rods about eighteen 

 or twenty inches long and from two to two 

 and one-half inches in diameter. This frame- 

 work is electrically insulated from the iron 

 crucibles. The framework and the carbons 

 are connected with the positive conductor of 

 the electric current, and the vat or crucible 

 with the negative. These conductors are very 

 large, something like a foot in width and an 

 inch in thickness, and made of some good con- 

 ductor of electricity. They have to be very 

 large because they carry a current equal to 

 3050 horse-power. The current is one of great 

 volume, but very low voltage; the electromo- 

 tive force at each vat or crucible being only 

 about seven volts. As the process is elec- 

 trolytic, and not simply a heating process, the 

 direct current must be used, and therefore the 

 current coming from the power-house must 

 be transformed twice; first to bring it to a 



