Gibbs, Josiah Willard, 1839–1903, American mathematical physicist, b. New Haven, Conn., grad. Yale, 1858. He studied abroad and was professor of mathematical physics at Yale from 1871. His great contributions to physical chemistry and thermodynamics have had a profound effect on industry, notably in the production of ammonia. He formulated the concept of chemical potential. In mathematics he wrote on quaternions and was influential in developing vector analysis. His work in statistical mechanics was especially important. Gibbs also contributed to crystallography, the determination of planetary and comet orbits, and electromagnetic theory. James Clerk Maxwell was one of the first European scientists to recognize Gibbs as a theoretical physicist of international stature. Gibbs was also interested in the practical side of science; his doctorate was the first granted by Yale for an engineering thesis, and he received a patent (1866) for an improved type of railroad brake. His *Scientific Papers* appeared in 1906 (repr. 1961) and his *Collected Works* in 1928.

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