Aludel

## Aludel Aludel

**The aludel** is a pear-shaped vessel, open at both ends, used in sublimation processes. Multiple aludels could be stacked vertically to create a sublimation tower, with the material to be sublimed placed in a vessel at the bottom and the aludels forming a chimney above. When heated, volatile substances would vaporize, rise through the stack of aludels, and condense on the cooler upper surfaces, while non-volatile residues remained at the bottom. The aludel system was particularly important for subliming substances like sulfur, mercury, arsenic compounds, and sal ammoniac, producing purified sublimed materials.

The aludel's name derives from Arabic *al-ʾuthal*, and the apparatus was transmitted to medieval Europe through translations of Arabic alchemical texts. The ability to stack multiple aludels allowed for efficient collection of sublimed materials and for repeated sublimation to achieve greater purity. The joints between aludels were sealed with lute (a paste made from clay, egg white, or other materials) to prevent vapors from escaping. Alchemists used aludels for preparing purified mercury, subliming sulfur, and working with various mineral substances. The apparatus appears frequently in illustrations of alchemical laboratories, often shown as a tower of vessels rising from a furnace.

The aludel represents the principle of sublimation—the transformation of solid directly to vapor and back to solid—which had both practical and symbolic significance in alchemy. Sublimation was seen as a purifying operation that separated the subtle from the gross, the spiritual from the material. The upward movement of vapors through the aludel tower symbolized the ascent of spirit, while the condensation represented the descent of purified matter. The aludel thus represents both a practical apparatus for sublimation and a symbol of the alchemical principle of purification through volatilization and condensation.

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