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A copper retort Alambique 056.jpg
A copper retort
A glass retort My retort.jpg
A glass retort

In a chemistry laboratory, a retort is a device used for distillation or dry distillation of substances. It consists of a spherical vessel with a long downward-pointing neck. The liquid to be distilled is placed in the vessel and heated. The neck acts as a condenser, allowing the vapors to condense and flow along the neck to a collection vessel placed underneath. [1]


In the chemical industry, a retort is an airtight vessel in which substances are heated for a chemical reaction producing gaseous products to be collected in a collection vessel or for further processing. Such industrial-scale retorts are used in shale oil extraction, the production of charcoal and in the recovery of mercury in gold mining processes and hazardous waste. A process of heating oil shale to produce shale oil, oil shale gas, and spent shale is commonly called retorting. Airtight vessels to apply pressure as well as heat are called autoclaves.

In the food industry, pressure cookers are often referred to as retorts, meaning "canning retorts", for sterilization under high temperature (116–130 °C).

Retort in use Distillation by Retort.png
Retort in use


Retorts were widely used by alchemists, and images of retorts appear in many drawings and sketches of their laboratories. Before the advent of modern condensers, retorts were used by many prominent chemists, such as Antoine Lavoisier and Jöns Berzelius. [2]

An early method for producing phosphorus starts by roasting bones, and uses clay retorts encased in a very hot brick furnace to distill out the highly toxic product. [3]

The term retort comes by way of Middle French, but ultimately from Latin retortus, twisted back, for the shape of the neck.

Role in analytical chemistry

In laboratory use, due to advances in technology, especially the invention of the Liebig condenser, retorts were largely considered to have been rendered obsolete as early as the beginning of the 20th century. [4] However, some laboratory techniques that involve simple distillation and do not require sophisticated apparatus may use a retort as a substitute for more complex distillation equipment.

In biochar-pyrolysis industry

A retort is a reactor that has the ability to pyrolyze pile-wood, or wood logs over 30 centimetres (12 in) long and up to 18 centimetres (7.1 in) in diameter. [5]

See also

Related Research Articles

Distillation Method of separating mixtures

Distillation is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation. Distillation may result in essentially complete separation, or it may be a partial separation that increases the concentration of selected components in the mixture. In either case, the process exploits differences in the relative volatility of the mixture's components. In industrial chemistry, distillation is a unit operation of practically universal importance, but it is a physical separation process, not a chemical reaction.

Fractional distillation is the separation of a mixture into its component parts, or fractions. Chemical compounds are separated by heating them to a temperature at which one or more fractions of the mixture will vaporize. It uses distillation to fractionate. Generally the component parts have boiling points that differ by less than 25 °C (45 °F) from each other under a pressure of one atmosphere. If the difference in boiling points is greater than 25 °C, a simple distillation is typically used.

The Liebig condenser or straight condenser is a piece of laboratory equipment, specifically a condenser consisting of a straight glass tube surrounded by a water jacket.

Alembic Alchemical still

An alembic is an alchemical still consisting of two vessels connected by a tube, used for distilling.

Dry distillation heating of solid materials to produce gaseous products (which may condense into liquids or solids)

Dry distillation is the heating of solid materials to produce gaseous products. The method may involve pyrolysis or thermolysis, or it may not. If there are no chemical changes, just phase changes, it resembles classical distillation, although it will generally need higher temperatures. Dry distillation in which chemical changes occur is a type of destructive distillation or cracking.

Steam distillation Steam distillation is a type of distillation (a separation or extraction process) for natural aromatic compounds from temperature-sensitive plants. It differs from hydrodistillation, where the plant can be immersed in water with or without steam.

Steam distillation is a separation process which consists in distilling water together with other volatile and non-volatile components. The steam from the boiling water carries the vapor of the volatiles to a condenser, where both are cooled and return to the liquid or solid state; while the non-volatile residues remain behind in the boiling container.

Laboratory flask type of laboratory glassware

Laboratory flasks are vessels or containers that fall into the category of laboratory equipment known as glassware. In laboratory and other scientific settings, they are usually referred to simply as flasks. Flasks come in a number of shapes and a wide range of sizes, but a common distinguishing aspect in their shapes is a wider vessel "body" and one narrower tubular sections at the top called necks which have an opening at the top. Laboratory flask sizes are specified by the volume they can hold, typically in metric units such as milliliters or liters. Laboratory flasks have traditionally been made of glass, but can also be made of plastic.

The Dean–Stark apparatus, Dean–Stark receiver, distilling trap, or Dean–Stark Head is a piece of laboratory glassware used in synthetic chemistry to collect water from a reactor. It is used in combination with a reflux condenser and a batch reactor for continuous removal of the water that is produced during a chemical reaction performed at reflux temperature. It was invented by the American chemists Ernest Woodward Dean (1888–1959) and David Dewey Stark (1893–1979) in 1920 for determination of the water content in petroleum.

Round-bottom flask Type of flask used in chemical or biochemical laboratories

Round-bottom flasks are types of flasks having spherical bottoms used as laboratory glassware, mostly for chemical or biochemical work. They are typically made of glass for chemical inertness; and in modern days, they are usually made of heat-resistant borosilicate glass. There is at least one tubular section known as the neck with an opening at the tip. Two or three-necked flasks are common as well. Round bottom flasks come in many sizes, from 5 mL to 20 L, with the sizes usually inscribed on the glass. In pilot plants even larger flasks are encountered.

Shale oil extraction Process for extracting oil from oil shale

Shale oil extraction is an industrial process for unconventional oil production. This process converts kerogen in oil shale into shale oil by pyrolysis, hydrogenation, or thermal dissolution. The resultant shale oil is used as fuel oil or upgraded to meet refinery feedstock specifications by adding hydrogen and removing sulfur and nitrogen impurities.

Condenser (laboratory) laboratory apparatus used to condense gases into liquids

In chemistry, a condenser is laboratory apparatus used to condense vapors — that is, turn them into liquids — by cooling them down.

Condenser (heat transfer) System for condensing gas into liquid by cooling

In systems involving heat transfer, a condenser is a device or unit used to condense a gaseous substance into a liquid state through cooling. In so doing, the latent heat is released by the substance and transferred to the surrounding environment. Condensers are used for efficient heat rejection in many industrial systems. Condensers can be made according to numerous designs, and come in many sizes ranging from rather small (hand-held) to very large. For example, a refrigerator uses a condenser to get rid of heat extracted from the interior of the unit to the outside air.

Zinc smelting is the process of converting zinc concentrates into pure zinc. Zinc smelting has historically been more difficult than the smelting of other metals, e.g. iron, because in contrast, zinc has a low boiling point. At temperatures typically used for smelting metals, zinc is a gas that will escape from a furnace with the flue gas and be lost, unless specific measures are taken to prevent it.

The Fischer assay is a standardized laboratory test for determining the oil yield from oil shale to be expected from a conventional shale oil extraction. A 100 gram oil shale sample crushed to <2.38 mm is heated in a small aluminum retort to 500 °C (930 °F) at a rate of 12°C/min (22°F/min), and held at that temperature for 40 minutes. The distilled vapors of oil, gas, and water are passed through a condenser and cooled with ice water into a graduated centrifuge tube. The oil yields achieved by other technologies are often reported as a percentage of the Fischer Assay oil yield.

The Lurgi–Ruhrgas process is an above-ground coal liquefaction and shale oil extraction technology. It is classified as a hot recycled solids technology.

Reflux Condensation of vapors and their return to where they originated

Reflux is a technique involving the condensation of vapors and the return of this condensate to the system from which it originated. It is used in industrial and laboratory distillations. It is also used in chemistry to supply energy to reactions over a long period of time.

The Shell Spher process is an above ground fluidization bed retorting technology for shale oil extraction. It is classified as a hot recycled solids technology.

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Petroleum refining processes are the chemical engineering processes and other facilities used in petroleum refineries to transform crude oil into useful products such as liquefied petroleum gas (LPG), gasoline or petrol, kerosene, jet fuel, diesel oil and fuel oils.

Lute (material) cement

Lute was a substance used to seal and affix apparatus employed in chemistry and alchemy, and to protect component vessels against heat damage by fire; it was also used to line furnaces. Lutation was thus the act of "cementing vessels with lute".

Luther Atwood

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  1. "retort." Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2011. Web. 21 Nov. 2011. <>.
  2. "Retort." - The Chemistry Information Portal from Laboratory to Process. Web. 17 Nov. 2011.
  3. Pg. 416 - Dictionary of chemistry with its applications to mineralogy, physiology and the arts <>
  4. Chisholm, Hugh, ed. (1911). "Distillation"  . Encyclopædia Britannica . 8 (11th ed.). Cambridge University Press. p. 320.
  5. Emrich, W. 'Handbook of Charcoal Making, the Traditional and Industrial Methods'. D. Reidel Pub. Co., Hingham, MA, 1985, p 296