Coagulation

Coagulation is counted the seventh of the seven operations into which the alchemical Great Work is often divided. In the laboratory it named the fixing of the purified essence into a stable, permanent form.

Operation and its meaning

Read symbolically, as the alchemists read their own work, Coagulation stood for the completion of the work, in which the refined matter is made solid and enduring; the goal toward which the earlier stages tend. In the scheme of correspondences that links the operations to the seven classical planets, it is attributed to the Sun.

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.

Coagulation closes the modern seven-step scheme, and it is the operation that gives the whole sequence its shape by returning what was dissolved to a solid.

What the word describes

Coagulatio means fixing a liquid or a vapour into a stable solid: crystallising out of solution, setting, congealing. The related term congelatio appears in the older lists for much the same operation. It is the counterpart of dissolution, and the two are named together in the most quoted phrase in the literature, solve et coagula, dissolve and coagulate.

That phrase describes a repeated alternation rather than two positions in a line. Reading it as steps two and seven of a fixed sequence loses the sense the sources give it, which is that the operator does this many times.

Where the number seven comes from

The numbered run of seven operations mapped onto the seven planets is a modern arrangement, not a medieval or early modern one. The historical treatises do not agree on a count: Ripley's fifteenth-century Compound of Alchymy sets out twelve gates, congelation among them, and other authors give other lists.

The atlas records the seven-step scheme because it is the version a reader will encounter today, and records here that a primary source will not present the material this way.