Page:Popular Science Monthly Volume 73.djvu/315

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The uses to which electrical power is put in the city of Niagara Falls are most interesting. In 1886 Charles M. Hall, at the age of twenty-two and fresh from Oberlin College, devised a process for the inexpensive production of aluminum. Prior to Mr. Hall's discovery aluminum though the most abundant of all metals was united to other elements in such a way that a separation of the metal from its compounds was very difficult and correspondingly expensive.

Mr. Hall's process for obtaining aluminum from its ore is a reduction or deoxidation process by electrolysis. Into a carbon lined vat or "reducing pot" extend carbon cylinders. The vat is partly filled with powdered cryolite, a beautiful white mineral mined in southern Greenland. When the electric current passes, the resistance