By Harold McGee
The second way in which distillers can separate the desirable volatiles from the rest is by their position in a column still, an elongated chamber developed by French and British distillers during the Industrial Revolution. In a column still, the starting wine or beer is fed into the column from the top, and the column is heated from the bottom with steam. The bottom of the column is therefore the hottest region, the top the coolest. Methanol and other low-boiling substances remain vaporized throughout all but the very top of the column, while fusel oils and other aromatics with high boiling points will condense on collection plates at hotter positions toward the bottom of the column, and alcohol will condense—and can be collected—at an intermediate point. The advantage of the column still is that it can be operated continuously and without the necessity of close monitoring; the disadvantage is that it offers less opportunity than the pot still for the distiller to control the composition of the distillate. When two or more columns are run together in series, they’re capable of producing a neutral distillate that is 90–95% alcohol.