Glass Distillation Columns separate liquid mixtures by boiling point, with vapour rising through the column and condensing back so lighter components concentrate at the top while heavier ones return to the still. Reflux ratio control sets how much condensate returns to the column, trading throughput against purity. Still capacities run from 2 to 100 L, operating from minus 20 to 200 degrees C and down to 1 mbar vacuum for heat-sensitive compounds, with condenser areas of 0.2 to 0.8 m2. Glass construction resists acids and solvents and lets operators watch the column. Typical uses include solvent purification, essential oil steam distillation, solvent recovery and pilot process development.