The distillation is made using an alembic, or pot-still....

Of Arabic origin, it is thought that the copper alembic, originally used to produce medicinal essences or perfumes, reached France at the time of the crusades; it has remained the same for the past three centuries. Copper is not only an efficient heat conductor but also plays a purifying role. For its first distillation, the unfiltered wine is brought to boil in the copper pot. Since alcohol evaporates faster than water, alcoholic vapors may be collected in the onion dome shaped cowl and in the swan neck, which slows the rectification process of the flavors, before passing into the long serpentine condenser coil. Vapors condense to the contact of the cooler and turn into a liquid known as 'brouilli'. This brouilli, with an alcoholic content of 27 to 30% vol., is distilled a second time in a process called the 'bonne chauffe'. The distiller's key task is then to choose the moment when to isolate the 'heart' of this second distillation, extracting the 'head' and the 'tail' in the process. This distillation process is a delicate and slow one. It lasts for approximately twenty four hours and requires the constant care of the distiller. It usually begins in November and is conducted day and night for several months. The rule binds it to stop at the latest at the end of March. Distillation is a key factor to confer the Cognac its distinctive character. Its secrets are handed over from generation to generation.