Soxhlet's extraction tube

Soxhlet's extraction tube

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Description (Brief)
This object is a Soxhlet’s extraction tube made from Pyrex glass. The Soxhlet extraction uses a solvent to extract organic compounds from a solid matrix. The extraction is named for its inventor, Franz Ritter von Soxhlet (1848–1926), a German chemist who worked on issues of milk chemistry. He developed the procedure, first described in 1879, as a way to separate the fats from milk solids. It remains a popular and important method for chemistry, biochemistry, and industry, particularly as they relate to food, plastic, and oil. In the 1980s the procedure was automated through the Soxtec extraction system.
Soxhlet’s original bench extraction requires a specialized piece of glassware known as Soxhlet’s extraction tube. The tube is open at both the top and the bottom and features two side arms. For the extraction, Soxhlet’s extraction tube is assembled into an apparatus with three other pieces of labware: a condenser, a porous thimble (containing the solid), and a boiling flask (placed beneath the extractor).
The solid sample is placed in a porous thimble (essentially a dense tube of filter paper). The thimble rests in the bottom of the body of the extractor tube. The apparatus is then assembled with the condenser on top, extractor in the middle, and boiling flask below. The solvent boils in the boiling flask, and vaporized solvent rises through one side arm of the extractor to the condenser. Once condensed back into a liquid, it drips down through the extraction tube onto the solid within the thimble, passing through it and extracting organic compounds.
The solvent gradually builds up in the bottom of the extraction tube and the siphon side arm. Once the level of the solvent in the side arm reaches the top of the siphon, the siphon drains the main body of the extractor of its solvent. Drained solvent (with its dissolved compounds) returns to the boiling flask, where it revaporizes to continue the extraction.
Pyrex has its origins in the early 1910s, when American glass company Corning Glass Works began looking for new products to feature its borosilicate glass, Nonex. At the suggestion of Bessie Littleton, a Corning scientist’s wife, the company began investigating Nonex for bakeware. After removing lead from Nonex to make the glass safe for cooking, they named the new formula “Pyrex”—“Py” for the pie plate, the first Pyrex product. In 1916 Pyrex found another market in the laboratory. It quickly became a favorite brand in the scientific community for its strength against chemicals, thermal
shock, and mechanical stress.
This object is part of a collection donated by Barbara Keppel, wife of C. Robert Keppel. Robert Keppel taught at the University of Nebraska-Omaha after receiving his B.S. in Chemistry from the University of California, Berkeley, and his Ph.D. in organic chemistry from M.I.T. The glassware in the Keppel collection covers the 19th and early 20th centuries.
Dyer, Davis. The Generations of Corning: The Life and Times of a Global Corporation. Oxford, New York: Oxford University Press, 2001.
Jensen, William B. “The Origin of Pyrex.” Journal of Chemical Education 83, no. 5 (2006): 692. doi:10.1021/ed083p692.
Kraissl, F. “A History of the Chemical Apparatus Industry.” Journal of Chemical Education 10, no. 9 (1933): 519. doi:10.1021/ed010p519.
Mitra, Somenath. Sample Preparation Techniques in Analytical Chemistry. John Wiley & Sons, 2004.
National Museum of American History Accession File #1985.0311
Sella, Andrea. “Classic Kit: Soxhlet Extractor.” Chemistry World, 2007.
Soxhlet Extraction with Dr. Mark Niemczyk, Ph.D. 2015.
“University of Nebraska Omaha.” 2015. Accessed May 4.
Currently not on view
Object Name
extraction tube
date made
Soxhlet, Franz von
Corning Incorporated
Associated Place
United States: New Jersey
Physical Description
pyrex (overall material)
overall: 325 mm x 76 mm; 12 13/16 in x 3 in
overall: 11 7/8 in x 3 in x 2 1/8 in; 30.1625 cm x 7.62 cm x 5.3975 cm
ID Number
catalog number
accession number
Credit Line
Gift of Barbara A. Keppel
Science & Scientific Instruments
See more items in
Medicine and Science: Chemistry
Science & Mathematics
Science Under Glass
Data Source
National Museum of American History
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