Oxford Furnace was a furnace used for smeltingiron located in Oxford Township, in Warren County, New Jersey, United States. Built in 1741, it was the third furnace in colonial New Jersey and the first constructed at a site where iron ore was mined. Other furnaces used ore extracted from bogs in South Jersey, impure deposits called bog iron. Oxford Furnace operated the longest of any of the colonial furnaces, not being "blown out" until 1884. In 1835, it was the site of America's first successful use of the hot blast, in which preheated air was blown into the furnace, cutting production time.