In 1884, an Austrian chemist named Carl Auer von Welsbach invented the thorium gas mantle, sometimes called the Welsbach mantle or Auerlicht. It was actually the first commercial use of thorium, and it became the way to light homes, cabins, and eventually camping lanterns like the one you see me use in this video. The mantles start as a mesh fabric dipped in thorium nitrate. Chemists would tweak the mix; add cerium to boost brightness, or beryllium to add strength. Once dried, they were coated with lacquer and made into either soft bag-like mantles or hard dome-shaped ones. When you burn them for the first time, the lacquer and mesh fabric burns away, and the combustion converts the thorium nitrate into thorium oxide. The once flexible mantle becomes a fragile, glowing shell that shines brilliantly when heated by kerosene or propane, a process known as incandescence. The catch? Thorium salts are radioactive. Burning a mantle releases some of its decay products (primarily radium) int...