Trap is designed to eliminate hold up common to the round style of rotary evaporator traps. Tapered sidewalls permit continuous washing with condensed solvent while preventing vapor cooling points along the path of the condenser. The upper stem has 4 large holes flush with the lower end, allowing solvent vapor to flow freely and making this portion of the trap easy to clean. The increased volume of the trap prevents "bumping" and keeps solvent out of the vapor tube.