Hall, Charles Martin

(b. Thompson, Ohio, 6 December 1863; d. Daytona, Florida, 27 December 1914)

commercial chemistry.

Charles Martin Hall discovered and developed a commercial process for producing aluminum that brought about its widespread use. Because Paul T. L. Héroult discovered the same process independently and at about the same time in France, the discovery is known as the Hall-Héroult process.

Hall was the son of a Protestant clergyman, Heman Basset Hall, and Sophronia Brooks. Raised in Oberlin, Ohio, from the age of ten, he received his degree from Oberlin College and later became a trustee and benefactor of the school. Hall was determined to become an inventor and was interested in chemistry; he studied the latter subject at Oberlin under Frank F. Jewett, who predicted, in a lecture on aluminum, both financial and social rewards for the inventor of a cheap aluminum production process. Hall, then in his junior year, thereby envisaged how he might fulfill his financial and humanitarian aspirations. He devoted himself to the study of the metal.

At this time, aluminum was being produced expensively on a small scale by the process developed by Henri Sainte-Claire Deville, which used sodium as a chemical reducing agent. Hall read all he could about the element in such sources as were then available to aspiring young scientists and inventors, including the Encyclopaedia Britannica and the Scientific American. He also had access to information from German publications, provided by Jewett. In the family woodshed, he experimented tirelessly, and his life is said to have been divided between work and study—with the emphasis on work.

In 1859 Sainte-Claire Deville had described a means of plating aluminum on copper by electrolysis using fused cryolite (a double fluoride of aluminum and sodium) as an electrolyte. Almost thirty years later, Hall himself experimented with electrolysis using fused cryolite, but as a solvent for alumina, which he hoped to electrolyze. With a crucible of clay Hall’s experiment failed, but after Hall ingeniously lined the clay with carbon, the alumina dissolved like sugar in water and globules of aluminum collected at the cathode.

This first success came on 23 February 1886. Two years later Hall founded a small company to produce aluminum commercially, now the Aluminum Company of America. He patented his production process in 1889. His major patent (No. 400,766, issued 2 April 1889) was challenged unsuccessfully on the grounds that Sainte-Claire Deville had anticipated him.

The not unusual problems of development and finance followed for the single-minded Hall. Among other improvements in his initial process was the abandonment of external heat for the fused cryolite. Largely because of his labors, the price of aluminum went from five dollars per pound in 1886 to seventy cents per pound in 1893. Seeking other major discoveries, Hall continued to experiment in chemistry, but commercial aluminum, for which he received the Perkin Medal in 1911, remains his greatest contribution.

BIBLIOGRAPHY

For works about Hall, see Junius Edwards, The Immortal Woodshed: The Story of the Inventor Who Brought Aluminum to America (New York, 1955), with Hall’s letters; Alfred Cowles, The True Story of Aluminum (Chicago, 1958); Decisions of the Commissioner of Patents... 1894 (Washington, D.C., 1895), pp. 573–594, 637–645, with the decision of Judge William Howard Taft, based on 1500 pages of testimony, in the patent case of “The Pittsburgh Reduction Co. [Hall’s] v. The Cowles Electric Smelting and Aluminum Co.”; Addresses at the Memorial Service, Oberlin, Ohio, Jan. 22, 1915, including contributions by Arthur V. Davis and F. F. Jewett, and Hall’s Perkin address; and Harry N. Holmes, Fifty Years of Industrial Aluminum, Bulletin of Oberlin College, no. 346 (1937), which summarizes Hall’s work authoritatively.

Thomas Parke Hughes