Bubble caps go into the top of column stills to increase reflux and exposure to copper surfaces. This is a display at the Four Roses distillery of the inside of a bourbon column still. Read more about it here.
Camper English is a cocktails and spirits writer for publications including Saveur (Contributing Drinks Editor), Details.com (Cocktail Columnist), Whisky Advocate, PopSci.com, Drinks International, and many more. Learn about Camper and Alcademics, or read clips of his published work.