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 Kohlrausch's 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. List of works Further reading Biographical sketch and reprint of paper on conductivity External links 1840 births 1910 deaths People from Rinteln 19th-century German physicists Electrochemists Foreign Members of the Royal Society Foreign associates of the National Academy of Sciences Members of the Prussian Academy of Sciences People from the Electorate of Hesse German scientific instrument makers University of Marburg alumni University of Erlangen-Nuremberg alumni University of Göttingen alumni Academic staff of the University of Göttingen Academic staff of ETH Zurich Academic staff of Technische Universität Darmstadt Academic staff