You can see one of these operating on Youtube. Apparently, it uses denatured alcohol.
According to the Wall Lenk website, Patrick Wall was an Irishman who immigrated to Pittsburgh and, in 1864, established the P. Wall Manufacturing Company. The company passed into new ownership in 1921 and continued making oil cans, blow torches, plumber's furnaces, metal gongs used on horse-drawn street cars and in coal mines, and ice cans for producing and transporting ice. The advent of electricity prompted the company to move into electric soldering tools, which continue to be a major product for the Wall Lenk company today, which now operates out of Kinston, North Carolina. Today, the company is a leading supplier of branding, butane, craft, culinary, hobby, soldering, and woodworking tools.