Charles Martin Hall (December 6, 1863–December 27, 1914) was an American inventor and engineer. He is best known for his invention in 1886 of an inexpensive method for producing aluminum, which became the first metal to attain widespread use since the prehistoric discovery of iron.

Biography
Charles Hall was born the son of Rev. Heman Bassett Hall and Sophronia H. Brooks in December 6, 1863 in Thompson, Ohio. He had one brother and three sisters, one of whom died in infancy. His family moved to Oberlin, Ohio in 1873, and he graduated from Oberlin High School. In 1880 he enrolled in Oberlin College, where he received a Bachelor of Arts degree in 1885. Hall was encouraged in his scientific experiments, which took place in a woodshed behind his family home, with ideas and materials from Professor of Chemistry Frank Fanning Jewett (1844-1926). The Jewett home is preserved in Oberlin as the Oberlin Heritage Center. The center features an exhibit called Aluminum: The Oberlin Connection, which includes a re-creation of Hall's 1886 woodshed experiment. The Hall House is also preserved in Oberlin, although the woodshed was demolished long ago.
The invention Hall produced the first samples of metal on February 23, 1886, after several years of intensive work. He had to fabricate most of his apparatus and prepare his chemicals, and was assisted by his older sister Julia Hall (see Craig 1986, CIM Bulletin). The basic invention involves passing an electric current through a bath of alumina dissolved in cryolite, which results in a puddle of aluminum forming in the bottom of the retort. On July 9, 1886, Hall filed for his first patent. This process was also discovered at nearly the same time by the Frenchman Paul Héroult, and it has come to be known as the Hall-Héroult process.(Asimov 1982, p. 933)
After failing to find financial backing at home, Hall went to Pittsburgh where he made contact with the noted metalurgist Alfred E. Hunt. They formed the Reduction Company of Pittsburgh which opened the first large-scale aluminum production plants. The Reduction Company later became the Aluminum Company of America, then Alcoa. Hall was a major stockholder, and became wealthy.
The Hall-Héroult process eventually resulted in reducing the price of aluminum by a factor of 200, making it affordable for many practical uses. By 1900, annual production reached about 8 thousand tons. Today, more aluminum is produced than all other non-ferrous metals combined.
Hall is considered the originator of the American spelling of aluminum. According to Oberlin College, he misspelled it on a handbill publicizing his aluminum refinement process. The process was so revolutionary, and brought the metal to such prominence, that Americans have spelled aluminum with one i since.

Recognition

US Patent - [2]Process of reducing aluminium from its fluoride salts by electrolysis -- C. M. Hall, applied 1886, granted 1889.