Royal Swedish Academy of Sciences
What organization did Friedrich Kohlrausch (physicist) join in 1902?
Friedrich Kohlrausch ( physicist ) Friedrich Wilhelm Georg Kohlrausch ( 14 October 1840 – 17 January 1910 ) was a German physicist who investigated the conductive properties of electrolytes and contributed to knowledge of their behaviour . He also investigated elasticity , thermoelasticity , and thermal conduction as well as magnetic and electrical precision measurements . Nowadays , Friedrich Kohlrausch is classed as one of the most important experimental physicists . His early work helped to extend the absolute system of Carl Friedrich Gauss and Wilhelm Weber to include electrical and magnetic measuring units . Biography . Education . Son of Rudolf Kohlrausch , Friedrich Wilhelm Georg Kohlrausch was born on October 14 , 1840 , in Rinteln , Germany . After studying physics at Erlangen and Göttingen , Friedrich Kohlrausch completed his doctorate in Göttingen . Teaching . After a two-year work as a lecturer in Frankfurt , Kohlrausch was appointed a professor of physics at the University of Göttingen ( 1866–70 ) . During 1870 Kohlrausch became a professor at ETH Zurich in Switzerland . One year later , he moved to the Darmstadt University of Technology in Germany . In 1875 , he responded to an offer from the University of Würzburg in southern Germany , where he subsequently conducted his experiments in quantity determination and the conductivity of electrolytes . From 1888 he researched and taught at Strasbourg University . He refused a professorship at the Humboldt University in Berlin in 1894 , but from 1900 he was also a professor there . He was elected a member of the Royal Swedish Academy of Sciences during 1902 . Research work . Kohlrausch was an important researcher of electrochemistry for many reasons . First , the experiments from which he deduced his law of independent migration of ions became canonical and disseminated from Kohlrauschs laboratories in Göttingen , Zurich , and Darmstadt ; Svante Arrhenius , Wilhelm Ostwald and Jacobus Henricus van t Hoff , the original Ionists , all trained with methods and equipment of Kohlrauschian lineage . Moreover , because Kohlrausch also continued to test and confirm the Ionist theory after it had been first proposed , his work tied measuring physics and its consequent capability of producing plenty of empirical data to the results and methods of the Ionists and their devotees . Electrolyte conductivity in solution . In 1874 he demonstrated that an electrolyte has a definite and constant amount of electrical resistance . By observing the dependence of conductivity upon dilution , he could determine the transfer velocities of the ions ( charged atoms or molecules ) in solution . He used alternating current to prevent the deposition of electrolysis products ; this enabled him to obtain very precise results . From 1875 to 1879 , he examined numerous salt solutions , acids and solutions of other materials . His efforts resulted in the law of the independent migration of ions , that is , each type of migrating ion has a specific limiting molar conductivity no matter what combination of ions are in solution , and therefore that a solutions electrical resistance is due only to the migrating ions of a given substances . Kohlrausch showed for weak ( incompletely dissociated ) electrolytes that the more dilute a solution , the greater its molar conductivity due to increased ionic dissociation . Measuring techniques and instruments . During 1895 he succeeded Hermann von Helmholtz as President of the Physikalisch-Technische Reichsanstalt ( PTR – Imperial Physical Technical Institute ) , an office which he held until 1905 . Here , as in the past , his activities were focused on experimental and instrumental physics : he constructed instruments and devised new measuring techniques to examine electrolytic conduction in solutions . He concluded the setup of the PTR , a task which had not yet been completed on the death of its first president . He introduced fixed regulations , work schedules and working hours for the Institute . Under direction of Kohlrausch , the PTR created numerous standards and calibration standards which were also used internationally outside Germany . Kohlrausch was intent on creating optimum working conditions in the laboratories and to shield the labs from unwanted external influences . For six years , for instance , he fought against a streetcar line which was due to be laid near the PTR . However , before the streetcar was to make its first journey , the institute succeeded in developing an astatic torsion magnetometer which was uninfluenced by disturbing electromagnetic fields . The use of this instrument and the shielded wire galvanometer developed by du Bois and Rubens meant that precision electrical and magnetic work continued to be possible . Over the years , Kohlrausch added experiments which met the needs of physical chemistry and electrical technology in particular . He improved precision measuring instruments and developed numerous measuring methods in almost all of the fields of physics known during his lifetime , including a reflectivity meter , a tangent galvanometer , and various types of magnetometers and dynamometers . The Kohlrausch bridge , which he invented at that time for the purpose of measuring conductivity , is still well known today . Like Helmholtz and Siemens , Kohlrausch also saw the possibilities inherent in applied and basic research in the natural sciences and technology . He lay the foundations for scientific knowledge which promoted and advanced industry and technology . The PTR developed standardized precision instruments for university research institutes and industrial laboratories . It introduced uniform electrical units for Germany and also played a significant role in their international usage . In the period to 1905 , there were many examples of the importance of the PTR for German industry , in particular for the high technologies of the time – the electrical , optical and mechanical industries . Overall , Kohlrausch was involved in the measurement of electrical , magnetic and electrochemical phenomena for almost 50 years . In 1905 Kohlrausch retired from his post as President of the PTR . Friedrich Kohlrausch died in Marburg on 17 January 1910 at the age of 69 . Writings . In the University of Göttingen , Kohlrausch documented his practical experiments resulting in the book Leitfaden der praktischen Physik ( Guidelines to Practical Physics ) , which was published in 1870 as the first book of its type in Germany . It contained not only descriptions of experiments , experimental setups and measuring techniques , but also tables of physical quantities . It was issued in many editions ( the 9th enlarged and revised edition of 1901 being entitled Lehrbuch der praktischen Physik ; a more elementary work based on it being entitled Kleiner Leitfaden der praktischen Physik ) and translated into English . It was considered the standard work on physical laboratory methods and measurements . To this day , the textbook Praktische Physik ( Practical Physics ) , which originated in Kohlrauschs Leitfaden der praktischen Physik , is standard reading for physicists and engineers in Germany . This is attributable , above all , to the detailed descriptions provided of the measuring methods that form the basis of technical and experimental applications in many fields in physics . Kohlrausch was also the author of Ueber den absoluten Leitungswiderstand des Quecksilbers ( On the electrical resistance of mercury , 1888 ) , and of many papers contributed to the Annalen der Physik und Chemie , and other scientific journals .