As different spirits have evolved, they’ve taken on different setups. In Ireland, they use three pot stills to make whisky; in Scotland, it’s two. Clear, light, Puerto Rican rum uses a continuous still, but heavier, darker styles of rum generally use two or three pot stills chained together. Of French brandies, Armagnac is distilled only once in a copper pot still, but cognac twice. Eau de vie is double distilled in a copper pot; aquavit comes off a continuous still.
Adam Rogers in Proof