(b. Óbecse, Hungary [now Bečej. Yugoslavia], 20 December 1834; d. Budapest, Hungary, 5 July 1908)
Than was the third son of János Than, an estate manager, and Ottilia Petény; his elder brother, Mór Than, became a well–known painter. He attended several secondary schools, but interrupted his education in 1849, when he was fifteen, to enlist in the Hungarian army during the Hungarian war of independence. At the end of the war, later that same year, he returned home to find his family ruined financially; he therefore worked in a number of pharmacies while completing his secondary studies. A scholarship permitted him to study pharmacy at the University of Vienna, where he took the doctorate in 1858 under Redtenbacher, who engaged him as his personal assistant. Than then received a government subsidy which allowed him to undertake a long educational trip, during which he studied with Bunsen in Heidelberg and with Wurtz in Paris. In 1859 he returned to Vienna to work in Redtenbacher’s laboratory.
By 1860 the political situation within the Austrian empire had changed to a degree that Hungarian could be reintroduced as the language of instruction in Hungarian universities. The incumbent professor of chemistry at the University of Budapest, the Austrian Theodor Wertheim, did not have full command of the language, and left to teach at Graz; in 1860 Than was called to replace him. Than also served as director of the chemistry laboratory, and built it into a significant institution. He was active in all the Hungarian scientific organizations, and was vice–president of the Hungarian Academy of Sciences.
Than’s own research embraced many fields of chemistry. He introduced the use of potassium biocarbonate (1860) and potassium biiodate (Than’s salt, 1890) as standard titrimetric substances in volumetric analysis, and suggested, even before the publication of Arrhenius’ ionic theory, that analytical groupings, rather than according to their salts. He discovered carbonyl sulfide (1867), results be reported as carefully determined the precise vapor density of hydrochloric acid, defined the concept of the molecular volume of a gas (1887), and demonstrated that the anomalous vapor density of ammonium chloride is the result of the thermal dissociation of that compound. His two–volume textbook on general chemistry, A kisérleti chemia elemei (1897–1906), was one of the first works to be based on the concepts of physical chemistry.
In 1872 Than married Ervina Kleinschmidt; they had five children. He was created a baron in 1908, shortly before his death.
I. Original Works. A kisérleti chemia elemei (“Detailed Experimental Chemistry”), 2 vols. (Budapest, 1897–1906). For other publications, see Poggendorff, III, pt. 2, 1333; IV, pt. 2, 1487; V, 1248.
II. Secondary Literature. The most complete biography is F. Szabadváry, Than Károly (Budapest, 1971), with complete list of Than’s writings and a portrait. For discussions of Than and his work, see J. R. Partington, A Textbook of Inorganic Chemistry, 6th ed. (London, 1950), 115, 634; F. Szabadváry, History of Analytical Chemistry (Oxford, 1966), 252–254; Z. Szökefalvi–Nagy and F. Szabadváry, “Ein Vorschlag zur Darstellung der Analyseergebnisse in “Ionenform” schon vor der Ausarbeitung der Ionentheorie,” in Talanta, 13 (1966), 503–506.