OSTUNI, a picturesque walled city of Apulia, Italy, province of Brindisi, 23 m. N.W. of Brindisi. Pop. (1921) 19,298 (town) ; 24,914 (commune). It has a 15th century cathedral. OSTWALD, WILHELM 2 ), German chemist, was born in Riga Sept. 2, 1853, and educated at the University of Dorpat. In 1882 he became a professor in Riga, and five years later was appointed professor of physical chemistry in the University of Leipzig, where he was later director of the Physicochemical Institute. In 1906 he resigned his university appointments and subsequently lived in retirement in Saxony. Ostwald may be regarded as one of the pioneers of modern physi cal chemistry and with van't Hoff (q.v.) he founded the important Zeitschrift fiir physikalische Cliemie. His own contributions to the science have been mainly in the fields of electrochemistry and solutions. He applied the law of mass action to the equilibrium resulting from electrolytic dissociation and obtained in this way the affinity constants of acids and bases. By means of these con stants, and by the use of other methods which he developed, he was able to compare the strengths of these reagents. Ostwald
made some experiments on the viscosity of solutions and devised the viscometer known by his name. On the technical side he will be chiefly remembered for his discovery in 1900 of a method of oxidizing ammonia to form oxides of nitrogen; a mixture of air and ammonia being passed over a platinum catalyst. By means of this process and by later developments in connection with it, Germany was enabled to continue the manufacture of explosives during the World War after the Allied blockade had been en forced; the method is being used in various countries, under the name of the Ostwald-Brauer process, for the manufacture of nitric acid from ammonia. In 1909 Ostwald was awarded the Nobel Prize for chemistry. His published works include Lehrbuch der allgemeinen Chemie (2nd ed. 1884-87), Grundlinien der anor ganischen Chemie (5th ed. 1922) and Die wissenschaf tlichen Grundlagen der analytischen Chemie (1894) which have been translated into English. Ostwald died in 1932.