Flask, Retort (Stoppered)

Quick Answer: A stoppered retort is a round glass vessel with a long neck bent downwards, plus a stoppered opening, called a tubulure, on top of the bulb. The retort flask is used for simple distillation and for heating solids so that the vapour runs down the neck into a receiver.

An Old Design That Still Teaches Distillation

The retort is one of the oldest pieces of chemical glassware, used by alchemists and early chemists long before the water-cooled condenser. The bulb and its downward-sloping neck do the work of a flask, still head and air condenser in one piece: vapour rises from the heated bulb, turns into the neck, cools as it travels, and drips from the tip into a receiver, which can be stood in cold water.

In the stoppered version a second opening on top of the bulb is closed with a ground stopper. It lets reagents be added or a thermometer be inserted without dismantling the set-up, and it makes the retort easier to fill and clean than the plain type, which can only be charged through its long neck.

Retorts are now used mainly for demonstrations and history-of-science lessons, since a distillation flask with a water condenser gives cleaner separation and better temperature control. They remain useful for showing the dry distillation of wood, which gives off flammable gas, tarry liquid and water and leaves charcoal behind. The listing does not state capacity or glass type, and the stopper design should be checked when ordering.

Care & Handling

• Clamp the retort by the neck close to the bulb and support the bulb on a gauze; the long neck makes it front-heavy.
• Heat gently and move the flame around the bulb, because a concentrated hot spot can crack the glass.
• Make sure the neck tip opens freely into the receiver; heating a retort with a blocked or sealed outlet would build dangerous pressure.
• Store with a slip of paper between the stopper and its socket so the ground surfaces do not seize.

Applications

• Demonstrating simple distillation of water from a coloured solution in lessons on separating mixtures
• Dry (destructive) distillation of wood chips in a fume cupboard, showing charcoal, tar and flammable gas as products
• History of chemistry lessons showing how early chemists separated liquids
• Distilling small volumes where a full condenser set-up is not available

Specifications

Why Choose LabEquip

Schools use retorts to connect modern distillation with its history, and teachers value the stoppered version for easier filling and cleaning. The retort appears among LabEquip’s chemistry lab equipment; send the size wanted through the contact page.

Frequently Asked Questions

What does the stopper on a retort do?

It closes a second opening on top of the bulb, called a tubulure. Removing it lets you pour in liquid or solid, insert a thermometer, or clean the bulb without feeding everything through the long neck.

How does a retort condense vapour without a water condenser?

The long neck loses heat to the surrounding air, so much of the vapour condenses on its inner wall and runs down to the tip. Standing the receiver in a basin of cold water or ice condenses what is left.

Is a retort still used in modern laboratories?

Rarely for routine work. A distillation flask or round bottom flask with a water-cooled condenser separates liquids more cleanly and allows the vapour temperature to be read. Retorts remain popular for demonstrations and for teaching the history of chemistry.

Can I dry-distil wood in a glass retort?

Yes, it is a traditional demonstration. Use small, dry wood chips, heat strongly and evenly in a fume cupboard, and collect the liquid in a cooled receiver. The gas given off is flammable, so it must be vented safely or burnt at a jet under supervision.

How should the retort be supported?

Rest the bulb on a wire gauze over a tripod or ring, and clamp the neck lightly near the bulb. Lead the neck tip into a receiver placed lower than the bulb so the distillate runs downhill.

Why has my retort stopper stuck?

Ground stoppers seize when solution dries in the joint or when the retort is heated with the stopper in place. Soak the joint in warm water, tap gently around the socket with a wooden handle, and in future store it with paper between stopper and socket.

Last Updated: September 2026