Aludel
An aludel (Arabic: ﺍﻟﻮﺛﻞ al-ūṯal from Greek αἰθαλίων aithaliōn, 'smoky, sooty, burnt-colored') is a subliming pot used in alchemy. The term refers to a range of earthen tubes, or pots without bottoms, fitted one over another, and diminishing as they advance towards the top.