An alembic is the oldest kind of still used for spirits. In simple terms, it’s a rudimentary Pot still.
It is made up of 3 parts: the pot, the alembic lid and the condensing unit. During distillation, the liquid in the pot is gently heated, the vapours rise (ethanol first as it has a lower boiling point) and pass through the narrow neck at the top of the lid and towards the collection. As the vapour moves further from the heat, it recondenses into liquid but to ensure this happens, the neck is connected to a serpentine coil that is surrounded by cold-water, which helps ensure the vapour is returned into a liquid state before it reaches the spout. Simple distillation, simple tools but very effective.
Alembic stills are operated on a batch distillation basis (as opposed to column stills which can operate on a continuous basis). Due to their bulbous shape, the more complex forms are almost always constructed from copper and beaten by hand into the desired shape. It’s not uncommon to see stainless steel pot stills, and irrespective of the material, they can range in size depending on the quantity and style of spirit desired. Some are no more than 2.5L hobby sized offerings, while the largest pot still ever used was once located in the Old Midleton Distillery, County Cork, Ireland and could distil over 140,000 litres at a time.