Infobox Laboratory equipment
name = Eudiometer

caption = Closed end of an eudiometer
uses = Gas volume measurement
notable_experiments = Volta pistol
inventor = Joseph Priestley ["Eudiometer". IMSS. 14 Jan 2008.]
related = Barometer Burette

An eudiometer is a laboratory glassware that measures the change in volume of a gas mixture following a chemical reaction ["Eudiometer". McGraw-Hill Dictionary of Scientific and Technical Terms, 6 Ed.] .


Depending on the reaction that is being measured, the device can take on a variety of forms. In general, it is similar to a graduated cylinder, and is most commonly found in two sizes: 50 mL and 100 mL. It is closed at the top end with the bottom end immersed in water or mercury. The liquid traps a sample of gas in the cylinder, and the graduation allows the volume of the gas to be measured. For some reactions, two platinum wires (chosen for their non-reactivity) are placed in the sealed end so an electric spark can be created between them. The electric spark can initiate a reaction in the gas mixture and the graduation on the cylinder can be read to determine the change in volume resulting from the reaction. The use of the device is quite similar to the original barometer, except that the gas inside displaces some of the liquid that is used.

Eudiometers can be purchased at any laboratory supply store and are usually priced from $30 to $50 ["Eudiometers". Science Lab. 14 Jan 2008 ] .


In 1772, Joseph Priestley began experimenting with different “airs” using his own redesigned pneumatic trough in which mercury instead of water would trap gases that were usually soluble in water. From these experiments Priestley is credited with discovering many new gases such as oxygen, hydrogen chloride, and ammonia. He also discovered a way to find the purity or “goodness” of air using “nitrous air test”. This test was conducted by mixing nitrous gas with a test sample of another gas and trapping it in the pneumatic trough, essentially the greater the decrease in volume, the more pure the sample of gas was (key principle in eudiometry).

It is from these experiments that Professor Marsilio Landriani became inspired to create a more useful tool in measuring the “healthiness” of air. In 1775, Landriani invented the first eudiometer and used it to conduct his own experiments. From these experiments Landriani theorized about the temperament of certain gases and the atmosphere and later published a paper called "Ricerche fisiche intorno alla salubrità dell'aria" (Physical researches on the salubrity of air). Though many of his findings were incorrect, his invention was the building block for the modern day eudiometer.

Although the eudiometer was initially invented by Marsilio Landriani ["Eudiometer". IMSS. 14 Jan 2008. ] , it was truly pioneered by Count Alessandro Volta (1745-1827), an Italian physicist who is well-known for his contributions to the electric battery and electricity ["Volta: A pioneer in Electrochemistry". 13 Jan 2008.] . Aside from its laboratory function, the eudiometer is also known for its part in the "Volta pistol". ["Apparatus for Natural Philosophy Volta's Pistol". Thomas B. Greensdale Jr.. 17 Jan 2008.] Volta invented this instrument in 1777 for the purpose of testing the "goodness" of air, analyzing the flammability of gases, or to demonstrate the chemical effects of electricity. Volta's Pistol had a long glass tube that was closed at the top, like an eudiometer. Two electrodes were fed through the tube and produced a spark gap inside the tube. Volta's initial use of this instrument concerned the study of swamp gases in particular. Volta's pistol was filled with oxygen and another gas. The homogeneous mixture was taped shut with a cork. A spark could be introduced into the gas chamber by electrodes, and possibly catalyze a reaction by static electricity. If the gases were flammable, they would explode, and increase the pressure within the gas chamber. This pressure would be too great and eventually cause the cork to become airborne. Volta's pistol was made with either glass or brass, however due to the electricity the glass was vulnerable to exploding. Volta's extensive studies on measuring and creating high levels of electric currents caused the electrical unit, the volt, to be named after him ["Eudiometer". Kenyon College. 13 Jan 2008.] .


Eudiometer comes from the Greek root "eúdio(s)" meaning clear or mild, which is the combination of the prefix "eu-" meaning "good", and "dios" meaning "heavenly" or "of Zeus" (the god of the sky and atmosphere) ["Eudiometer." HighBeam Encyclopedia. 3 Dec. 2007 .] , with the suffix "-meter" meaning "measure". [ "Eudiometer." New World Dictionary. 2nd ed. 1979. ] Because the eudiometer was originally used to measure the amount of oxygen in the air, which was thought to be greater in "nice" weather, [ "Eudiometer." New Oxford American Dictionary. 2nd ed. 2006.] the root "eúdio(s)" appropriately describes the apparatus.


One way a person may use the eudiometer is by analyzing gases and determine the differences in chemical reactions. To use an eudiometer, it is filled with water, flipped over so that the open end is facing the ground (while holding the open end so that no water pours out), and submersed in a basin of water. A chemical reaction is taking place through which gas is created. One reactant is typically at the bottom of the eudiometer (which flows downward when the eudiometer is inverted) and the other reactant is suspended on the rim of the eudiometer, typically by means of a platinum or copper wire (due to their low reactivity). When the gas created by the chemical reaction is released, it should rise into the eudiometer so that the experimenter may accurately read the volume of the gas produced at any given time. Normally a person would read the volume when the reaction is completed. This procedure is followed in many experiments, including an experiment in which one experimentally determines the Ideal gas law constant R.

The eudiometer is similar in structure to the meteorological barometer. Similarly, an eudiometer uses water to release gas into the eudiometer tube, converting the gas into a visible, measurable amount. A correct measurement of the pressure when performing these experiments is crucial for the calculations involved in the "PV"="nRT" equation, because the pressure could change the density of the gas ["Measuring the Molar Mass of an 'unknown' Gas". David Dice. 13 Jan 2008.] .

See also

* Joseph Priestley
* Alessandro Volta
* Ideal Gas Law
* Barometer
* Distillation
* Dalton's law
* Laboratory glassware


Further reading

* Magellan, J. H. De. Description of a Glass Apparatus for Making Mineral Waters- Like those of Pyrmot, Spa, Seltzer, Etc., In a Few Minutes, and With a Very Little Expence: Together With the Description Of Some New Eudiometers. Inman Press, 2007.
* Marcet, William. "A New Form of Eudiometer." Proceedings of the Royal Society of London 44(1888): 383-387.
* Osman, W. A. "Alessandro Volta and the inflammable air eudiometer." Annals of Science Vol 14, Number 4(1958): 215-242 (28).
* Weekes, W. H. A Memoir On the Universal Portable Eudiometer: An Apparatus Designed With a View To Operative Convenience and Accuracy Of Result In the Researches Of Philosophical Chemistry. T. E. Stow, 1828.

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Look at other dictionaries:

  • Eudiometer — Eu di*om e*ter, n. [Gr. ? fair, clear weather, fr. ? fine, clear ( said of the air or weather) + meter: cf. F. ediom[ e]tre.] (Chem.) An instrument for the volumetric measurement of gases; so named because frequently used to determine the purity… …   The Collaborative International Dictionary of English

  • Eudiometer — (v. gr., Luftgütemesser), Vorrichtung, um den Sauerstoffgehalt einer gegebenen Luftmenge zu prüfen. Das frühste war das Priestleysche E., wo Stickoxydgas mit der zu prüfenden Luft vermischt wird, deren Sauerstoff sich mit jenem zu salpetriger… …   Pierer's Universal-Lexikon

  • Eudiomēter — (griech., Luftgütemesser), Instrument zur Bestimmung des in der Luft enthaltenen Sauerstoffes. Die einfachste Form besteht aus einem weiten, mit Skala versehenen Glasrohr, an dessen zugeschmolzenem Ende zwei Platindrähte eingelassen sind, die im… …   Meyers Großes Konversations-Lexikon

  • Eudiometer — Eudiometer, Instrument zur Ermittlung des Sauerstoffgehaltes einer gegebenen Luftmenge, besteht aus einem starkwandigen graduierten Glasrohr von ca. 50 bis 60 cm Länge und ca. 2 cm lichter Weite, an dessen zugeschmolzenem Ende zwei Platin drahte… …   Lexikon der gesamten Technik

  • Eudiometer — (grch.), Luftgütemesser, Instrument zur Bestimmung des Gehalts der Luft an Sauerstoff; Eudiometrīe, Luftgütemessung; Analyse der Luft …   Kleines Konversations-Lexikon

  • Eudiometer — Eudiometer, Oxymeter, ist ein Apparat, mittelst dessen man das Sauerstoffgas, aus seiner Vermischung mit dem Stickstoffgas, in flüssiger od. fester Form überführen und so von letzterm ausscheiden kann. Unter den verschiedenen E. (von Bertholet,… …   Herders Conversations-Lexikon

  • eudiometer — [yo͞o΄dē äm′ət ər] n. [< Gr eudios, clear, fair (< eudia, fair weather < eu (see EU ) + dia, day < IE * diw , glowing day < base dei , to shine > DEITY) + METER] an instrument for measuring and analyzing gases volumetrically,… …   English World dictionary

  • Eudiometer — Das Eudiometer (gr.: Luftgütemesser) ist eine einseitig verschlossene und mit einer Skala versehene Glasröhre.[1] Sie dient der Quantifizierung von Gasvolumina, die während einer chemischen Reaktion entstehen. Funktionsprinzip Das Eudiometer wird …   Deutsch Wikipedia

  • Eudiometer — eudiometras statusas T sritis Standartizacija ir metrologija apibrėžtis Aparatas dujų mišinių sudėčiai analizuoti. atitikmenys: angl. eudiometer vok. Eudiometer, n; Gasmessröhre, f rus. эвдиометр, m pranc. eudiomètre, m …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

  • eudiometer — eudiometras statusas T sritis Standartizacija ir metrologija apibrėžtis Aparatas dujų mišinių sudėčiai analizuoti. atitikmenys: angl. eudiometer vok. Eudiometer, n; Gasmessröhre, f rus. эвдиометр, m pranc. eudiomètre, m …   Penkiakalbis aiškinamasis metrologijos terminų žodynas

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