One of the pear-shaped pots open at both ends, and so formed as to be fitted together, the neck of one into the bottom of another in succession; -- used in the process of sublimation.

A pear-shaped pot generally made of earthenware or glass, open at both ends. Each aludel has a short neck at top and bottom, so that a series of them may be conjoined in succession by means of the neck. Also: in alchemy and early chemistry, aludel can refer to a glass vessel used primarily for sublimation*.

Aludels, in ancient chemistry, are subliming pots. 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. The lowest is adapted to a pot, placed in a furnace, wherein the matter to be sublimed is lodged.