A Vigreux column is a piece of scientific equipment that is used for condensing hot vapors. It consists of a straight glass column with walls that are studded with special indentations. This piece of equipment is normally used in chemistry experiments involving fractional distillations or for separating two parts of a mixture based on their boiling points.
The little indentations on the side of the Vigreux column are called plates and crowns. They point downwards and toward the center of the vessel. They increase the surface area that vapor can come in contact with and cool on. The downward slope of the prongs also means that condensed liquid returns to the middle of the column, which allows a larger amount of contact between the vapor phase and the liquid phase. The Vigreux column cools down vapors by having them transfer much of their heat to the glass walls.
This apparatus was invented by French glassblower and chemist Henri Narcisse Vigreux. Because they are more complex to make than traditional straight condensers, Vigreux columns are more expensive than traditional straight condensers. However, Vigreux himself was able to demonstrate that a Vigreux column was more efficient than a traditional condenser four times its size.