Gaseous Glowstone is an Item from Thaumic Tinkerer, which is a plugin mod for Thaumcraft 3 . Gaseous Glowstone can be made like every other thaumcraft items. However, you have to research it first.
Gaseous Glowstone, when used, will light up an area and have some cool particle effects. To remove the gaseous glowstone, Shift-Right click while you have the Fume Dissipator in your hand.