Welsbach burner

A burner in which the combustion of a mixture of air and gas or vapour is used to heat to incandescence a mantle composed of thoria and ceria. The mantle is made by soaking a "stocking" in a solution of nitrates of thorium and cerium, drying, and, for use, igniting to burn the thread and convert the nitrates into oxides, which remain as a fragile ash.