Roentgen (unit) Roentgen (unit) The roentgen or röntgen () (symbol R) is a legacy unit of measurement for the exposure of X-rays and gamma rays. It is defined as the electric charge freed by such radiation in a specified volume of air divided by the mass of that air. In 1928 it was the first international measurement quantity for ionising radiation to be defined for radiation protection, and was an easily replicated method of measuring air ionization directly by using an ion chamber. It is named after the German physicist Wilhelm Röntgen, who discovered X-rays. Although relatively easy to measure, it had
Wilhelm Krause in the field of embryology. Among his better known students at Göttingen was bacteriologist Robert Koch (1843-1910). Krause is credited with the publication of over 100 medical articles. Wilhelm Krause Johann Friedrich Wilhelm Krause (July 12, 1833 – February 4, 1910) was a German anatomist born in Hanover. He was the son of anatomist Karl Friedrich Theodor Krause (1797-1868). In 1854 he earned his medical doctorate, and later (1860) became an associate professor at the University of Göttingen. In 1892 he was appointed head of the Anatomical Institute Laboratory in Berlin. Krause is known for the discovery and description of