ÎLE-DE-FRANCE, an old district of France, forming a kind of island, bounded by the Seine, the Marne, the Beuvronne, the Thève and the Oise. In this sense the name is not found in written documents before 1429; but in the second half of the 15th century it designated a wide military province of government, bounded N. by Picardy, W. by Normandy, S. by Orléanais and Nivernais, and E. by Champagne. Its capital was Paris. From the territory of Île-de-France were formed under the Revolution the department of the Seine, together with the greater part of Seine-et-Oise, Seine-et-Marne, Oise and Aisne, and a small part of Loiret and Nièvre. (The term Île-de-France is also used for Mauritius, q.v.). See A. Longnon, "L'Île-de-France, son origine, ses limites, ses gouverneurs," in the _Mémoires de la Société de l'histoire de Paris et de l'Île-de-France_, vol. i. (1875). ILETSK, formerly _Fort Iletskaya Zashchita_, a town of Russia, in the government of Orenburg, 48 m. S. of the town of Orenburg by the railway to Tashkent, near the Ilek river, a tributary of the Ural. Pop. 11,802 in 1897. A thick bed of excellent rock-salt is worked here to the extent of about 100,000 tons annually. The place is resorted to for its salt, mud and brine baths, and its koumiss cures. ILFELD, a town in Germany, in the Prussian province of Hanover, situated at the south foot of the Harz, at the entrance to the Bährethal, 8 m. N. from Nordhausen by the railway to Wernigerode. Pop. 1600. It contains an Evangelical church, a celebrated gymnasium, once a monasterial school, with a fine library, and manufactures of parquet-flooring, paper and plaster of Paris, while another industry in the town is brewing. It is also of some repute as a health resort. Ilfeld, as a town, dates from the 14th century, when it sprang up round a Benedictine monastery. Founded about 1190 this latter was reformed in 1545, and a year later converted into the school mentioned above, which under the rectorship of Michael Neander (1525-1595) enjoyed a reputation for scholarship which it has maintained until to-day. See Förstemann, _Monumenta rerum Ilfeldensium_ (Nordhausen, 1843); M. Neander, _Bericht vom Kloster Ilfeld_, edited by Bouterwek (Göttingen, 1873); and K. Meyer, _Geschichte des Klosters Ilfeld_ (Leipzig, 1897).