Distillation

Distillation is counted the sixth of the seven operations into which the alchemical Great Work is often divided. In the laboratory it named the raising and re-condensing of the volatile part through repeated boiling.

Operation and its meaning

Read symbolically, as the alchemists read their own work, Distillation stood for the refining and purifying of the quickened matter, the separation of the subtle from the still-gross by many passes. In the scheme of correspondences that links the operations to the seven classical planets, it is attributed to Mercury.

The alchemists worked at once with real chemical processes and with a language of spiritual transformation, so that a single term carried both a bench meaning and an inner one. The operation is described here within that documented tradition of European alchemy, whose sources run from the Hellenistic and Arabic writers through the Latin Middle Ages and the early modern laboratory.

Of all the operations, distillation is the one where alchemy left the most durable mark on the world outside it.

What the word describes

Distillatio means heating a liquid until it vaporises, then cooling the vapour so that it condenses in a separate vessel, leaving behind whatever did not rise. Repeating the operation concentrates the volatile fraction further, which is why the texts insist on doing it again and again.

What it produced

The apparatus for this operation, the still and its cooled head, was developed and refined by alchemical practitioners over centuries, and the equipment and the technique passed directly into pharmacy, perfumery, the production of spirits and eventually into industrial chemistry. Concentrated mineral acids, which made most of early modern chemistry possible, are products of distillation practice.

Whatever is thought of the transmutational programme, this is a case where the laboratory work was straightforwardly productive and its results are still in use.

Where the number seven comes from

The scheme of exactly seven numbered operations matched to the seven planets is modern. The historical sources give varying counts; Ripley's fifteenth-century Compound of Alchymy sets out twelve gates, with sublimation and distillation as distinct items. The atlas records the seven-step scheme as the common modern arrangement and notes that it is one.