Charles Martin Hall

Charles Martin Hall (December 6, 1863 in Thompson, Ohio, † December 27, 1914 in Daytona, Florida ) was an American inventor, engineer and entrepreneur. He was known by the discovery of an inexpensive method for producing aluminum.

  • 2.1 The environment
  • 2.2 The invention
  • 2.3 Economic Success
  • 2.4 The modern fusion electrolysis
  • 2.5 A missing "i"


The Early Years

Charles Hall was born the son of the Reverend Herman Bassett Hall and Sophronia H. Brooks of. He had a brother and three sisters, one of which died in infancy. His family moved in 1873 to Oberlin (Ohio ) and Charles attended first the Oberlin High School and Oberlin College in 1880, where he earned a 1885 Bachelor of Arts. His focus of interest were the natural sciences.

Hall was excited about his scientific experiments with ideas and materials of its chemistry professor Frank Fanning Jewett ( 1844-1926 ). Meanwhile remark, who find an effective process for aluminum production could be rich, the students could be noisy. Whether this process has liked to tell actually happened, however, is not certain.

Hall conducted his experiments in a wooden shed located behind his family's house. Both the Jewett house as the Hall - house there in Oberlin yet, only the woodshed was demolished long ago. However, The Oberlin Connection, a replica of the woodshed experiment of 1886: The Oberlin Heritage Center in Jewett House, the exhibition shows aluminum.

The later years

After his successful aluminum extraction Hall sat his research and developments to death continued. He was given 22 U.S. patents, most for aluminum production to be. He belonged to the Oberlin College Board of Trustees, the Board of Directors of his college. Charles Hall was Vice President of Alcoa until his death in 1914 in Daytona, Florida, overtook him. The inventor died unmarried and childless and was buried in the Woodland Cemetery in Oberlin.

A preference for aluminum

The environment

Aluminum is in the earth's crust as the second most common non-ferrous metal for silicon before, but not in pure ( tasteful ) form. On aluminum, people became aware in 1808 according to research by Sir Humphry Davy. However, he failed in the effort, this substance, which he called alumium to isolate from its compounds. They succeeded to the Danish chemist Hans Christian Ørsted in 1825 from clay. The amount was tiny, the metal unclean. In 1827 he succeeded Friedrich Wöhler, for the first time to produce aluminum in the pure state, but even here only in low yield. The metal at that time was significantly more expensive than gold. This treasure sparked the interest of individual nobleman to possess it prepared items.

In 1846, the Frenchman Henri Etienne Sainte -Claire Deville proceeded to refine the manufacturing process Wöhler, produced from 1854 aluminum and gave his findings in 1859 in book form out. Emperor Napoléon III. ordered his scientists to think about possibilities for a recovery of the substance in larger amounts. The complex chemical process Deville allowed in 1857, only an annual production of about 750 kg, which took place exclusively in France.

The invention

Halls considerations revolving around the melting analysis described by Humphry Davy. He set out to search for a way to the fusible only at high temperatures clay from which the aluminum was to win to get easier to melt. In the year after his graduation he began the first experiments. Most of his equipment he needed to establish himself. He was supported by his older sister Julia.

In his experiments, Charles Hall found that the melting point of about 2050 ° C for pure alumina by the addition of cryolite at about 950 ° C was lower. He developed a method in which a large electric current was passed through a mixture of alumina and alumina - cryolite. Thereby forming on the bottom of the reaction vessel, a pool of aluminum.

Hall produced the first samples of the pure metal with his experimental arrangement on 23 February 1886 after several years of intensive work. After he was able to initially produce only beads made ​​of pure aluminum, he continued his experiments until he succeeded in the production of aluminum ingots. On July 9, 1886 Hall filed his patent " Process of reducing aluminum from its fluoride salts by electrolysis " one at the U.S. Patent Office; the patent was granted on April 2, 1889.

Whatever Hall of Frenchman Paul Heroult had discovered the process and received a patent in France about the same time. Therefore, it was between two first legal disputes, but they finally agreed. The manufacturing process was called in honor of both later as a Hall Heroult process. Heroult in France came to lack of interest in the use of his invention, and therefore teamed up with three industrialists in Switzerland.

Economic Success

After Hall was unable to find financial backers for industrial evaluation of its invention in Ohio, he went to Pittsburgh, where he made ​​contact with the well-known metallurgist Alfred E. Hunt. They formed in 1888 with other industrialists Reduction Company of Pittsburgh, after its success founded more large farms aluminum production only a little work and. 1907 ran the company bauxite mines in Arkansas, a refinery in Illinois and three aluminum smelters in New York and Canada. Hall was one of the main shareholders to the rich man.

From Reduction Company in 1907, the Aluminum Company of America, later shortened to Alcoa. She had long been a monopoly in the industrial aluminum production and is today the world market leader.

The Hall - Heroult process raised the price of aluminum falls by a factor of 200, making it affordable for practical use. By the year 1900, the annual production rose to about eight thousand tons. Today more is produced of aluminum than any other non-ferrous metals together.

The modern fusion electrolysis

The Hall - Heroult process, which the Austrian Carl Josef Bayer further improved by the Bayer process for the purification of bauxite from oxides and silicates, is the basic procedure for today's aluminum production. These igneous electrolysis allowed for the economical production of the material of suitable clay. As the electrolyte to take a mixture of alumina and cryolite. Next carbon anodes and cathodes coal are used. By supplying power ( DC to 200,000 amps) the materials begin to melt in the electrolytic bath at a temperature of about 950 ° C. The heavier molten aluminum collects in the bottom and is removed by suction.

A missing "i"

Because Hall write the Americans the name of the metal aluminum today than aluminum and not as aluminum as the British. In a handout for publication he had fälschlichweise the name, but coincidentally, written with the Oberlin College without the second i: aluminum refinement process. Because his invention was so revolutionary and made very aware of the metal, these names form prevailed in the United States. The different spelling in English texts often leads to the conclusion on their origin.


Hall was awarded in 1911 for his work the Perkin Medal, the highest award in the U.S. chemical industry.

Hall was one of the most well-known benefactor of Oberlin College, where they honored him with a monument, a statue made ​​of aluminum, which is thus comparatively easy. Students therefore often exaggerated their jokes with her and she staggered not rare. Today the statue is securely fastened on a large granite block on the second floor of the Oberlin New Science Center, but is decorated with holidays and similar occasions with all kinds of " jewelry ".