a watering place in Hesse-Nassau, on the Lahn River, about 10 mi. e. s. e. of Coblenz. It is noted for its many warm mineral springs, which are famous for their curative powers, especially in lung diseases. The place is visited by over 10,000 patients and many tourists every year. In the neighborhood are very important silver and lead mines. Ems was known to the Romans. In 1172 the counts of Nassau gained possession of it, and in 1866 it was united with Prussia. At this place, in 1870, the famous interview between King William of Prussia and the French ambassador, Benedetti, took place, which brought on the Franco-Prussian War.