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Distillation | Definition, Process, & Methods | Britannica Ask the Chatbot Games & Quizzes History & Society Science & Tech Biographies Animals & Nature Geography & Travel Arts & Culture ProCon Money Videos distillation Introduction References & Edit History Quick Facts & Related Topics Images & Videos At a Glance distillation summary Related Questions Is mathematics a physical science? When did science begin? Where was science invented? Contents CITE verified Cite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style MLA APA Chicago Manual of Style Copy Citation Share Share Share to social media Facebook X URL https://www.britannica.com/science/distillation Feedback External Websites Feedback Corrections? Updates? Omissions? Let us know if you have suggestions to improve this article (requires login). Feedback Type Select a type (Required) Factual Correction Spelling/Grammar Correction Link Correction Additional Information Other Your Feedback Submit Feedback Thank you for your feedback Our editors will review what you’ve submitted and determine whether to revise the article. External Websites Chemistry LibreTexts - Distillation Open Library Publishing Platform - BIOTECH 2EC3: Lab Manual - Distillation National Center for Biotechnology Information - PubMed Central - The distillation method: A novel approach for analyzing randomized trials when exposure to the intervention is diluted Iowa State University Digital Press - Distillation University of Babylon - Distillation (PDF) The Essential Chemical Industry - online - Distillation University of Massachusetts Amherst - BMB and Chemistry - Distillation Crude-oil fractional distillation column diagram Schematic diagram of a crude-oil fractional distillation column. (more) distillation chemical process Ask Anything Homework Help Also known as: distillate Written and fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Apr. 10, 2026 • History Britannica AI Ask Anything Table of Contents Table of Contents Ask Anything Top Questions What is distillation in chemistry? What is the main purpose of distillation? How does distillation separate different substances in a mixture? What are the basic steps involved in a simple distillation process? What is the difference between simple and fractional distillation? What are some common uses of distillation in everyday life and industry? Show more Show less distillation , process involving the conversion of a liquid into vapour that is subsequently condensed back to liquid form. It is exemplified at its simplest when steam from a kettle becomes deposited as drops of distilled water on a cold surface . Distillation is used to separate liquids from nonvolatile solids, as in the separation of alcoholic liquors from fermented materials, or in the separation of two or more liquids having different boiling points, as in the separation of gasoline, kerosene, and lubricating oil from crude oil . Other industrial applications include the processing of such chemical products as formaldehyde and phenol and the desalination of seawater. The distillation process appears to have been utilized by the earliest experimentalists. Aristotle (384–322 bce ) mentioned that pure water is made by the evaporation of seawater. Pliny the Elder (23–79 ce ) described a primitive method of condensation in which the oil obtained by heating rosin is collected on wool placed in the upper part of an apparatus known as a still. Most methods of distillation used by industry and in laboratory research are variations of simple distillation. This basic operation requires the use of a still or retort in which a liquid is heated, a condenser to cool the vapour, and a receiver to collect the distillate. In heating a mixture of substances, the most volatile or the lowest boiling distills first, and the others subsequently or not at all. This simple apparatus is entirely satisfactory for the purification of a liquid containing nonvolatile material and is reasonably adequate for separating liquids of widely divergent boiling points. For laboratory use, the apparatus is commonly made of glass and connected with corks, rubber bungs, or ground-glass joints. For industrial applications, larger equipment of metal or ceramic is employed. petroleum refining process diagram Petroleum being refined to produce gasoline and other petroleum products from crude oil. The refining process begins with the fractional distillation of heated crude oil. The crude-oil components (gas, gasoline, naphtha, kerosene, light and heavy gas oils, and residuum) are separated into lighter and heavier hydrocarbons. Light hydrocarbons are drawn off the distilling column at lower temperatures than are heavy hydrocarbons. The components are then treated in many different ways, depending on the desired final products (shown at the bottom). The conversion processes are shown as blue boxes. For simplification, not all of the products of the conversion processes are shown in the diagram. (more) A method called fractional distillation , or differential distillation, has been developed for certain applications, such as petroleum refining , because simple distillation is not efficient for separating liquids whose boiling points lie close to one another. In this operation the vapours from a distillation are repeatedly condensed and revaporized in an insulated vertical column. Especially important in this connection are the still heads, fractionating columns, and condensers that permit the return of some of the condensed vapour toward the still. The objective is to achieve the closest possible contact between rising vapour and descending liquid so as to allow only the most volatile material to proceed in the form of vapour to the receiver while returning the less volatile material as liquid toward the still. The purification of the more volatile component by contact between such countercurrent streams of vapour and liquid is referred to as rectification, or enrichment. More From Britannica chemical analysis: Distillation Multiple-effect distillation , often called multistage-flash evaporation, is another elaboration of simple distillation. This operation, used primarily by large commercial desalting plants, does not require heating to convert a liquid into vapour. The liquid is simply passed from a container under high atmospheric pressure to one under lower pressure. The reduced pressure causes the liquid to vaporize rapidly; the resulting vapour is then condensed into distillate. Key People: Eva Ekeblad (Show more) Related Topics: fractional distillation still multistage flash distillation multiple-effect distillation gas-liquid chromatography (Show more) On the Web: National Center for Biotechnology Information - PubMed Central - The distillation method: A novel approach for analyzing randomized trials when exposure to the intervention is diluted (Apr. 10, 2026) (Show more) See all related content A variation of the reduced-pressure process uses a vacuum pump to produce a very high vacuum. This method, called vacuum distillation , is sometimes employed when dealing with substances that normally boil at inconveniently high temperatures or that decompose when boiling under atmospheric pressure. Steam distillation is an alternative method of achieving distillation at temperatures lower than the normal boiling point . It is applicable when the material to be distilled is immiscible (incapable of mixing) and chemically nonreactive with water. Examples of such materials include fatty acids and soybean oils. The usual procedure is to pass steam into the liquid in the still to supply heat and cause evaporation of the liquid. The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Amy McKenna .