[f. Gr. εὔδιο-ς clear (weather) (f. εὐ- EU- + διϝ- stem of Ζεύς, Διός the god of the sky and the atmosphere) + μέτρον measure.]
An instrument for testing the purity of the air, or rather the quantity of oxygen it contains.
Various kinds have been in use, but the commonest is that invented by Dr. Ure, consisting of a tube closed at one end, in which certain quantities of hydrogen and atmospheric air are exploded over water by an electric spark. From the rise of the water in the tube inferences are drawn as to the amount of oxygen that was present. The apparatus is also, and now chiefly, employed in the analysis of gases.
1777. De Magellan (title), Glass apparatus, for making mineral waters … with the description of some New Eudiometers.
1792. A. Young, Trav. France, 153. He has a large course of eudiometrical experiments going on at present, particularly with Fontana’s and Volta’s eudiometers.
1807. Pepys, Eudiometer, in Phil. Trans., XCVII. 249. Known quantities of the air to be tried, and of nitrous gas being mixed, were admitted … into a graduated tube, which he [Priestley] denominated a eudiometer.
1825. Faraday, Exp. Res., xxx. 161. Seven volumes of this mixture were detonated in a eudiometer tube by an electric spark.
1877. W. Thomson, Voy. Challenger, I. i. 28–9. The eudiometer … has the legs of glass united by an india-rubber tube of suitable length.
Hence Eudiometric a., of, pertaining to, or requiring the use of the eudiometer or eudiometry. Eudiometrical a. = prec. Eudiometrically adv., in a eudiometric way; by the use of a eudiometer. Eudiometry, the art or practice of using the eudiometer either for ascertaining the purity of the air, or in the analysis of gases.
1854. Scoffern, in Orr’s Circ. Sc., Chem. 321. The analysis … may be … effected by the *eudiometric method.
1859. Todd, Cycl. Anat., V. 378/1. The eudiometric researches of a number of observers.
1792. [see EUDIOMETER].
1794. G. Adams, Nat. & Exp. Philos., I. xi. 437. Graduated glass tubes for *eudiometrical experiments.
1852. Th. Ross, trans. Humboldt’s Trav., I. v. 173. The absorption of two gases in a eudiometrical tube.
1808. Henry, in Phil. Trans., XCVIII. 290. After trying, *eudiometrically, the quality of an aliquot part of the gas in the receiver.
1881. W. Crookes, in Nature, XXIII. 423. Collecting samples [of gas] and analysing them eudiometrically.
1800. Henry, Epit. Chem. (ed. 5), 159. The application of nitrous gas to the purpose of *eudiometry. Ibid. (1826), Elem. Chem., I. 237. Platinum in this form becomes, therefore, a most useful agent in eudiometry.
1853. W. Gregory, Inorg. Chem. (ed. 3), 82. When it is required to ascertain the exact proportion of oxygen in any specimen of air…. The operation is called eudiometry, and the instruments employed eudiometers.
