Pot and patent still methods of spirit distillation differ in that the former is based on a batch while the latter is a continuous process. A pot still, as the simplest, oldest form of distillation, places a mash of fermented liquid known as a wash into a copper kettle.
The wash is heated to between 172 and 212 degrees Fahrenheit, above the boiling point of alcohol but below that of water. The alcohol turns into vapor and funnels into a long tube that runs into a condensing unit, where the alcohol is cooled into a liquid and collected.
The patent still, also known as the continuous, column or Coffey still, was developed in the 18th century by Aeneas Coffey. It continuously pumps wash through two columns, separating alcohol from all other substances in the wash. It is significantly more efficient than a pot still.