Photographic reproduction of an artist's rendering of the Welsbach Gas Light Company site located along the Delaware River in Gloucester City, New Jersey. From 1888 to 1940, the Welsbach Gas Light Company held exclusive manufacturing and sales rights to the Welsbach gas mantle, a device made of fibers impregnated with oxides of thorium and cerium that produced bright white light when heated with a gas flame. Invented in 1880's by Austrian scientist Carl Auer Von Welsbach (1858-1929), these gas mantles were used extensively in street lighting and in gas-powered appliances. The Welsbach gas mantle also was the first industrial product to make use of rare earth elements. At peak production, the Welsbach factory employed 2,000 people, including a large number of women skilled at the sewing and other precision handwork involved in the manufacturing process.