Charles Martin Hall

Charles Martin Hall
Charles Martin Hall
Born	December 6, 1863 Thompson, Ohio
Died	December 27, 1914 (Age 51) Daytona, Florida
Nationality	United States
Engineering career
Significant advance	Hall-Héroult process

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

Biography

Early years

Hall was born to Herman Bassett Hall and Sophronia H. Brooks on December 6, 1863 in Thompson, Ohio. His father graduated from Oberlin College in 1847, and studied for three years at the Oberlin Theological Seminary, where he met his future wife. They married in 1849, and the next ten years were spent in missionary work in Jamaica, where their first five children were born. They returned to Ohio in 1860, when the outbreak of the Civil War forced the closing of foreign missions. He had one brother and three sisters, one of whom died in infancy. One of his sisters was chemist Julia Brainerd Hall (1859–1925), who helped him in his research.^[1]

Hall began his education at home, and was taught to read at an early age by his mother. At the age of six, he was using his father's 1840's college chemistry book as a reader.^[2] At age 8, he entered public school, and progressed rapidly.

His family moved to Oberlin, Ohio in 1873. He spent three years at Oberlin High School, and a year at Oberlin Academy in preparation for college. During this time he demonstrated his aptitude for chemistry and invention, carrying out experiments in the kitchen and the woodshed attached to his house. In 1880, at the age of 16, he enrolled at Oberlin College.^[3]

Hall was encouraged in his scientific experiments, with ideas and materials from Professor Frank Fanning Jewett (1844–1926). Jewett received his undergraduate and some graduate training from Yale University. From 1883 - 1885, he studied chemistry at the University of Göttingen in Göttingen, Lower Saxony, Germany. There he met Friedrich Wöhler, and obtained a sample of aluminum metal. Upon return to the United States, he spent a year assisting Wolcott Gibbs at Harvard University, then spent a further four years as Professor of Chemistry at the Imperial University of Tokyo in Japan. In 1890, he became the professor of chemistry and mineralogy at Oberlin College. 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. In his second term, Hall attended, with considerable interest, Professor Jewett's lecture on aluminum; it was here that Jewett displayed the sample of aluminum he had obtained from Wöhler, and remarked, "if anyone should invent a process by which aluminum could be made on a commercial scale, not only would he be a benefactor to the world, but would also be able to lay up for himself a great fortune." ^[3]

Discovery

His initial experiments in finding an aluminum reduction process were in 1881; he attempted, unsuccessfully, to produce aluminum from clay by smelting with carbon in contact with charcoal and potassium chlorate. He next attempted to improve the electrolytic methods previously established by investigating cheaper methods to produce aluminum chloride, again unsuccessfully. In his senior year, he attempted to electrolyse aluminum fluoride in water solution, but was unable to produce aluminum at the cathode.

In 1884, after setting up a homemade coal-fired furnace and bellows in a shed behind the family home, he again tried to find a catalyst that would allow him to reduce aluminum with carbon at high temperatures: "I tried mixtures of alumina and carbon with barium salts, with cryolite, and with carbonate of sodium, hoping to get a double reaction by which the final result would be aluminum. I remember buying some metallic sodium and trying to reduce cryolite, but obtained very poor results. I made some aluminum sulphide but found it very unpromising as a source of aluminum then as it has been ever since.".^[3]

He had to fabricate most of his apparatus and prepare his chemicals, and was assisted by his older sister Julia Brainerd 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. ^[4]

After failing to find financial backing at home, Hall went to Pittsburgh where he made contact with the noted metallurgist 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. In the United Kingdom and other countries using British spelling, only aluminium is used. The spelling in virtually all other languages is analogous to the -ium ending.

Hall continued his research and development for the rest of his life and was granted 22 US patents, most on aluminum production. He served on the Oberlin College Board of Trustees. He was vice-president of the Alcoa until his death in 1914 in Daytona, Florida. He died unmarried and childless and was buried in Westwood Cemetery in Oberlin. Hall left the vast majority of his fortune to charity. His generosity contributed to the establishment of the Harvard-Yenching Institute, a leading foundation dedicated to advancing higher education in Asia in the humanities and social sciences.^[5]

Recognition

Hall eventually became one of Oberlin College's most prominent benefactors. Students are fond of the statue of Hall made of aluminum. Because of its light weight, Hall's statue was once known for its frequent changes of location, often due to student pranks. Today the statue is glued to a large granite block and sits more permanently on the second floor of Oberlin's new science center, where students continue to decorate Hall with appropriate trappings on holidays and other occasions.

Hall won the Perkin Medal, the highest award in American industrial chemistry in 1911. In 1997 the production of aluminum metal by electrochemistry discovered by Hall was designated an ACS National Historical Chemical Landmark.^[6]

Patents

• US Patent 400,664, Process of reducing aluminium from its fluoride salts by electrolysis—C. M. Hall, applied 1886, granted 1889 TIFF Image of page from USPTO.

References