Quotation from: General Science

Written by: Bertha M. Clark

Commercially, distillation is a very important process. Turpentine,
for example, is made by distilling the sap of pine trees. Incisions
are cut in the bark of the long-leaf pine trees, and these serve as
channels for the escape of crude resin. This crude liquid is collected
in barrels and taken to a distillery, where it is distilled into
turpentine and rosin. The turpentine is the product which passes off
as vapor, and the rosin is the mass left in the boiler after the
distillation of the turpentine.