from
The Collaborative International Dictionary of English v.0.48
Welsbach \Wels"bach\, a.
Of or pertaining to Auer von Welsbach or the incandescent gas
burner invented by him.
{Welsbach burner}, a burner in which the combustion of a
mixture of air and gas or vapor is employed 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 (approx. 99:1), drying,
and, for use, igniting to burn the thread and convert the
nitrates into oxides, which remain as a fragile ash. The
light far exceeds that obtained from the same amount of
gas with the ordinary fishtail burner, but has a slight
greenish hue.
[Webster 1913 Suppl.]