An alembic (, , possibly from Semitic) is an alchemical still consisting of two vessels connected by a tube, used for distilling chemicals. Technically, the alembic is the lid with a tube attachment (the still-head), which is placed on top of a flask, the cucurbit, containing the material to be distilled, but the word is often used to refer to the entire distillation apparatus. If the lid and flask are in one piece, it may be called a retort. The liquid in the cucurbit flask is heated or boiled; the vapour rises into the alembic hood, where it cools by contact with the walls and condenses, running down the spout into a receiving flask.