chemical reactions. The eudiometer is filled with water, inverted so that its open end is facing the ground (while holding the open end so that no water escapes), and then 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, a 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. See also Dalton's law Distillation Ideal gas law Laboratory glassware References Further reading Magellan, J. H. De. (2007) 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 Expense: Together With the Description Of Some New Eudiometers, Inman Press. Marcet, William (1888) "A New Form of Eudiometer", Proceedings of the Royal Society of London 44: 383-387. Osman, W. A. (1958) "Alessandro Volta and the inflammable air eudiometer", Annals of Science Vol 14, Number 4: 215-242 (28). Weekes, W. H. (1828) 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 publisher. Laboratory glassware Volumetric instruments Measuring instruments