fractional distillation [¦frak·shǝn·ǝl dis·tǝ`lā·shǝn] CHEMISTRY A method to separate a mixture of several volatile components of different boiling points; the mixture is distilled at the lowest boiling point, and the distillate is collected as one fraction until the temperature of the vapor rises, showing that the next higher boiling component of the mixture is beginning to distill; this component is then collected as a separate fraction. |