Distilling Well: One Plate, Ten Plates, and the Wall You Cannot Pass

Distillation separates liquids by boiling point, and the catalogue is full of it — alembics, coal tar fractions, essential oils, turpentine, spirits. What none of those blueprints says is how good a separation to expect, or when the apparatus has to change. The answer is in one idea: a **theoretical plate**, one cycle of evaporation and condensation. A simple still is one plate. A column is several, and the number needed follows from how far apart the boiling points are. It is hazard-gated because distillation combines heat, flammable vapour and sealed glassware — the three ingredients of the commonest serious laboratory accident.