Distillation Column Assembly: Flask, "Evaporator" Still-Head, Liebig Condenser and Receivers (Young, 1903)

Use a globular flask, since a flat-bottomed one may crack over a naked flame, no larger than the amount of liquid needs. Fit it with a cork for the still-head. Ours: a round-bottom flask.

Build the still-head of sections joined end to end. Each outer tube is 22 to 24 mm inside and about 10 to 10.5 cm long, constricted at the bottom. In it stands a thin inner tube, 7.5 to 8 mm inside and 60 mm long, open at both ends, with two large holes near its top. Its lower end widens into a funnel resting on the constriction, with three or four tiny glass beads fused to the rim so it does not fit too tightly. Over it stands an intermediate tube about 14 mm inside and 50 mm long, like a small inverted test tube. A small funnel, slightly wider than the dip in the outer tube above, sits on top of it on three glass legs. Small glass projections centre the tubes. Make the head long enough that the thermometer's bulb and stem both sit in the vapour, with a side delivery tube at the top.

Use a Liebig condenser, about 7 or 8 mm inside for the inner tube and 15 mm for the outer, cooled by running water. Pass the delivery tube through a cork into it. Draw out the joint where the wide inlet meets the narrow tube so no pool of liquid lies there. Bend the narrow tube so the condenser can stand upright. Above about 170 °C use a long tube cooled by air instead of water.

Heat with a Bunsen burner, its top about 2 mm below the flask so the small flame touches the glass, shielded from draughts. Add a few pieces of porous porcelain (a broken clay pipe will do) or pumice if the liquid bumps. Set a thermometer in the still-head and a row of small flasks as receivers.

Read the barometer and correct the set temperatures for it. Distil steadily. In each section, condensed liquid seals the narrow passage, so the vapour rises up the inner tube, down between the tubes and up again, while liquid drips from section to section back to the still. Collect the distillate in fractions, changing the receiver each time the temperature reaches one of the values fixed beforehand.