Sublimation
Zodiacal correspondence (Pernety, 1758): Libra ♎
Sublimation is the conversion of a solid directly into a vapour by heat, which then resolidifies on a cooler surface, leaving impurities behind. It was valued for purifying volatile solids such as sal ammoniac, sulphur, and mercuric compounds. Pernety assigns the operation to Libra, and Ripley made it his eighth gate. As a means of purification and of raising the 'subtle' part of a substance, sublimation was both an exact laboratory technique and a rich emblem of spiritual elevation.
See also the concept page: Sublimation
Historical Development
Sublimation raises a solid directly into vapour and recondenses it as a purified solid, separating the subtle from the gross. It was a standard purification for substances such as sal ammoniac, sulphur, and mercuric compounds, and it doubled as a favourite emblem of refinement and ascent. Few operations so neatly joined a concrete procedure to a vivid symbolic meaning.
Pernety assigns sublimation to Libra; Ripley made it the eighth of his twelve gates, 'the secret of subtlety.' Here, as with calcination, congelation, solution, separation, fermentation, multiplication and projection, the two schemes agree, marking sublimation as part of the shared operational core that both lists draw upon.
Textual Tradition
The operation is described in detail in the Arabic and Pseudo-Geberian corpus, where the sublimation of salts and 'spirits' is fundamental to preparing reagents. William Newman's edition of the Summa perfectionis shows how precisely sublimation was specified, including the design of the vessels and the regulation of heat.
Modern Scholarship
Newman's broader work on Pseudo-Geber and corpuscular matter theory uses such operations to argue that medieval alchemy rested on exact, repeatable laboratory procedure and a sophisticated theory of matter, countering older views that dismissed it as mere mysticism.