Friedrich Kohlrausch (physicist)

Friedrich Wilhelm Georg Kohlrausch (1840 to 1910) was a German experimental physicist who studied the conductive properties of electrolytes. Born in Rinteln and trained at Erlangen and Göttingen, he held professorships at Göttingen, ETH Zurich, Darmstadt, Würzburg, Strasbourg and Berlin, and from 1895 to 1905 he was president of the Physikalisch-Technische Reichsanstalt, succeeding Hermann von Helmholtz. His measurements with alternating current led to the law of the independent migration of ions, which says each ion has its own limiting molar conductivity whatever ions accompany it, and he showed that weak electrolytes conduct better as they are diluted. He also worked on elasticity, thermal conduction and precise electrical and magnetic measurement, designed instruments such as the Kohlrausch bridge, and wrote the laboratory textbook Leitfaden der praktischen Physik, which became the standard German text on physical measurement.