1834 W. Whewell Let. 5 May in I. Todhunter William Whewell (1876) II. 182 If you take anode and cathode, I would propose for the two elements resulting from electrolysis the terms anion and cation,..and for the two together you might use the term ions.

1834 M. Faraday in Philos. Trans. (Royal Soc.) 124 79 I require a term to express those bodies which can pass to the electrodes... I propose to distinguish these bodies by calling those anions which go to the anode of the decomposing body; and those passing to the cathode, cations; and when I have occasion to speak of these together, I shall call them ions. [Note] Since this paper was read [on 23 Jan., 6 and 13 Feb., 1834], I have changed some of the terms which were first proposed.

1834 E. Turner Elem. Chem. (ed. 5) 161 It has been ascertained that most of the elements are ions..; but there are several important elements, such as nitrogen, carbon, phosphorus,..which have not yet been proved to be ions... A single ion, that is, one ion not in combination with another, has no tendency to pass to either of the electrodes..unless it be itself a compound ion, and therefore electrolyzable.

1856 W. A. Miller Elements Chem. II. xviii. 1110 When a binary compound, such as a fused chloride,..is submitted to electrolysis, the ions or components of the compound are separated at the respective electrodes in equivalent proportions.

1896 E. Rutherford & J. J. Thomson in London, Edinb. & Dublin Philos. Mag. 5th Ser. 42 405 A current of electricity passes through a gas... The absence of polarization implies..that the ions are able to give up their charges to the metal electrodes.

1898 W. Crookes Addr. Brit. Assoc. 22 It becomes more and more clear that cathode rays consist of electrified atoms or ions in rapid progressive motion.

1927 N. V. Sidgwick Electronic Theory of Valency vi. 91 In a crystal like calcium carbonate..this may be taken as evidence that the calcium and the CO₃ are themselves ions, but that the atoms of the CO₃ group are covalently linked to one another.

1942 M. C. Sneed & J. L. Maynard Gen. Inorg. Chem. xviii. 438 Chlorine oxidizes bromide ions and iodide ions to free bromine and iodine respectively.

1967 New Scientist 30 Nov. 531/1 There is a very strong electric field which ionizes the gas atoms, giving ions and electrons.

1991 C. Mansall Discover Astrol. i. 13/2 People are affected differently according to the build-up of positive ions in the atmosphere.

2005 C. Mendelson Laundry i. xii. 171 Hard water contains calcium or magnesium ions that combine with the soap to form insoluble salts, or scum.

2009 B. D. Cullity & C. D. Graham Introd. Magn. Materials (ed. 2) vi. 191 The only magnetic ions in barium ferrite are the Fe³⁺ ions.

1935 Physical Rev. 47 99/1 The large masses of iron and copper which make up the magnet forming part of the ion accelerator are very efficient scatterers.

1958 Times 27 Oct. 7/2 The vehicle would be propelled in space by an ion accelerator and all moving parts would be driven by electrical power from solar batteries.

1989 J. Avison World of Physics (ed. 2) xviii. 398/2 The radiocarbon accelerator laboratory at Oxford uses a 3 MV ion accelerator to separate carbon-14 ions from the carbon-12 and carbon-13 ions in a mass spectrometer.

2006 S. Pfalzner Introd. Inertial Confinement Fusion x. 192 The most expensive part of a heavy-ion fusion power plant would be the ion accelerator itself.

1928 Math. Proc. Cambr. Philos. Soc. 24 457 The secondary emission falls off for high current densities of the primary positive ion beam.]

1930 Jrnl. Franklin Inst. 209 9 The ion beam struck no solid material until well down in the brass channel.

1951 Jrnl. Brit. Interplanetary Soc. 10 253 The acceleration of a space ship by an ion beam seems to offer no particular difficulties.

2007 T. Friend Third Domain vii. 205 The instrument fires ion beams at the crystal with such precision it can ‘blast a small number of atoms off any targeted part of a zircon's surface’.

1942 U.S. Patent 2,296,324 1/2 By increasing the area of the cathode which may be ion bombarded during starting, the rate of loss of emission for any given unit area opposite the grid aperture is probably decreased.

1966 D. G. Brandon Mod. Techniques Metallogr. iii. 124 We shall also consider the possibility of ion-bombarding a specimen to sputter a thin layer from the surface.

2004 Philos. Trans. (Royal Soc.) A. 362 106 Samples, rotating on a carousel about the central axis..will therefore acquire a negative voltage and be ion bombarded.

1945 V. K. Zworykin et al. Electron Optics & Electron Microscope iv. 127 The ion-bombarded cathode, in modern electron microscopes, has been replaced almost entirely by the second type of source, the thermionic cathode.

2003 Surface Sci. 538 211 (title) The role of an oxygen adsorbate on the secondary emission properties of low energy ion-bombarded magnesium.

1914 Science 6 Mar. 370/2 (title) Secondary electron emissions from a hot cathode caused by positive ion bombardment.]

1931 Proc. Royal Soc. A. 132 634 The thermocouple..was used to maintain the temperature constant by compensating for changes in the heating of the probe by ion bombardment.

1952 Trans. Faraday Soc. 48 747 As a general procedure for cleaning surfaces, the inert gas ion-bombardment has some advantages.

2004 P. Favia in H. Biederman Plasma Polymer Films ii. 38 The ion bombardment increases with the power delivered to the plasmax.

1946 Nature 23 Feb. 228/1 Certain types of cathode-ray tubes in which the luminous spot on the fluorescent screen is moved by magnetic fields are liable to a peculiar defect, known as ‘ion spot’ or ‘ion burn’.

1963 J. R. Davies Understanding Television ii. 62 In some cathode ray tubes, protection against ion burn is achieved by mounting part of the electron gun assembly at an angle, and..applying across the tube neck a fixed magnetic field which causes electrons only to be deflected across the screen.

2009 Internat. Jrnl. Mass Spectrometry 282 29/1 A slight ion burn in a circular shape was apparent (a few cm diameter).

1922 Physical Rev. 20 399 The attempt failed in part because..a portion of the feet [of the current–voltage curves] were apparently due to instrumental irregularities of small magnitude in the ion chamber.

1955 Bull. Atomic Scientists June 213/3 An ion chamber, however, is a device which directly measures the dose to the air volume it encloses.

2003 Plant Physiol. 131 1465/2 Incident intensity was measured using a nitrogen-filled ion chamber.

1964 Ann. Rev. Biochem. 33 86 It has been suggested that the ion channels made available by transducer actions are specific.

1989 B. Alberts et al. Molecular Biol. Cell (ed. 2) xii. 695 The interaction between the receptor and the enzyme or ion channel is mediated by a third protein.

2007 N.Y. Times 23 Jan. (Washington Final ed.) d2/2 The CatSper gene, which makes the proteins that create the ion channel, held the key to..how sperm penetrate eggs.

1966 Jrnl. Lipid Res. 7 717 (title) Separation of lipids by silver ion chromatography.]

1977 J. D. Mulik et al. in W. H. Kirchhoff Methods & Standards Environmental Measurem. xii. 603 H. Small, T. S. Stevens and W. C. Bauman recently reported a new technique called ion chromatography (IC).

1988 Nature 22 Sept. 336/2 Ion chromatography was used for the SO₄²⁻ and Na⁺ determinations.

2009 D. G. Weldon Failure Anal. Paints & Coatings (rev. ed.) viii. 237 The primary application of ion chromatography in failure analysis is the detection of salts.

1947 Astounding Sci. Fiction Mar. 18/1 Lifecraft 18 was a trim steel missile... It had its own ion drive, a regular crew of six, and plenty of additional space for our party.

1960 Aeroplane 98 776/2 Ion-drive cannot be used in propelling space-vehicles from the Earth's surface because of their inherently low thrust.

2009 Sci. Amer. (U.K. ed.) Feb. 52/2 Dozens of ion drives are currently operating on commercial spacecraft—mostly communications satellites.

1945 H. Radd in Jrnl. Amer. Rocket Soc. Dec. 28/2 (heading) The Ion Engine.

1957 West. Aviation May 23/1 Because of its low fuel consumption, an ion-engine could operate for several days or weeks.

1971 Jrnl. Brit. Interplanetary Soc. 24 573 The use of pulsed plasma thrusters rather than ion engines for attitude control has..become a distinct possibility.

2006 N. Asher Polity Agent viii. 193 The ion engines ignited on the outer shell, speeding the ship out of sight.

1956 Bull. Acad. Sci. U.S.S.R.: Eng. Transl. (Columbia Techn. Translations) 20 1051 The current during the glow discharge stage does relatively little harm to the cathode surface; its effect is similar to ion etching.

1970 New Scientist 5 Feb. 256/2 It has been possible to use ion etching to penetrate the cuticular layers of insects.

2008 Appl. Optics 47 5253 The effect of ion etching on the reflectance of Al coatings in the far ultraviolet is investigated.

1938 Physical Rev. 53 937/1 Very minute traces of gas (pressure less than 10⁻⁸ mm of Hg as measured with ion gauge in sealed-off tube).

1989 P. Horowitz & W. Hill Art of Electronics (ed. 2) xv. 1008/1 Ion gauges are usable at pressures..from about 10⁻³ to 10⁻¹¹mm Hg.

2003 R & D (Nexis) 1 June 31 Pressure measurement in high vacuum can be important, but is an ion gauge good enough, or do you need a residual gas analyzer?

1939 U.S. Patent 2,163,740 1 (title) Phase wave ion gun.

1952 Jrnl. Brit. Interplanetary Soc. 11 179 Any rocket system requiring the conversion of electric to kinetic energy will require one or more ion guns.

1987 Science 12 June 1428/1 The spacecraft will operate a separate ion gun.., blasting loose the first few atomic layers in a search for elements implanted over the eons by the solar wind.

2010 C. Binns Introd. Nanosci. & Nanotechnol. iii. 64 If ions from an ion gun are fired at the same substrate..the ones that impact fullerene will be implanted into the cage.

1963 Industr. & Engin. Chem. (Internat. ed.) 55 9 The technique of ion implantation, under development by Ion Physics Corp., almost enables the researcher to pick up an atom and put it where he wants it.

1970 New Scientist 15 Oct. (Suppl.) 16/1 In ion implantation, the necessary impurities are accelerated by an electric field to an energy sufficient to embed them into the silicon to the depth required.

2008 A. Fridman Plasma Chem. xiii. 551 Ion implantation is an important process for semi-conductor doping but also has other practical applications, especially in surface hardening of materials.

1924 Jrnl. Physical Chem. 28 1000 Such ion pairs are never widely separated but each aids in forming the effective surfaces of the electrical double layer.

1933 Jrnl. Amer. Chem. Soc. 55 477 The changes in the properties of the solvent..caused by the presence of undissociated (non-conducting) ion pairs will be neglected.

1988 H. A. Klein Sci. Measurem. l. 663 The alpha rays emitted in the nuclear disintegration of the bismuth isotope Bi-214, also called ‘Radium C’, produce about 25,000 ion pairs per centimeter of travel.

2005 Bios 76 24/2 The thermal stability as a function of the numbers of ion pairs and hydrogen bonds has been analysed for 16 families of proteins.

1921 Electr. World 17 Sept. 562/2 The direction of the ion propulsion at the streamer head is coincident with the direction of the combined fields.

1961 Sci. News Let. 7 Oct. 235/1 The ion propulsion system was described as the possible key to very long-range travel in deep space.

2006 Analog June 41/1 Satellites presently in orbit around Earth use ion propulsion to keep themselves in position and prevent their orbits from decaying over time.

1951 Vacuum 1 263/1 The pumping speed of such an ion pump can easily be estimated.

1955 Q. Rev. Biol. 30 80/1 The nature of ion pumps is examined from a physico-chemical viewpoint.

1984 Internat. Jrnl. Mass Spectrometry 60 283 The vacuum system incorporates a rotary pump..and isolation valve which are used to rough down the ion pump if vacuum is lost.

2000 J. Mann Murder, Magic, & Med. (rev. ed.) ii. 19 They [sc. cardiac glycolsides] all inhibit the functioning of a sodium/potassium ion pump that is needed for maintenance of the normal ion balance in heart muscle cells.

1936 Amazing Stories Oct. 17/1 The hundred foot ship shot suddenly forward under the thrust of her tail ion-rockets.

1953 Ann. Reg. 1952 406 The ‘most feasible project’ was described as consisting of space stations circling the most important planets with ion rockets plying between them.

2007 L. B. Crowell Can Star Syst. be Explored? iii. 26 The density of the plasma beam can be much larger. This will permit higher thrusts than the ion rocket.

2008 R. Miller Rockets vii. 95 There have been many different plans for ion rockets since the 1920s, but all work more or less on the same principle.

1938 Amer. Naturalist 72 137 We may suppose that ion-selective points lie scattered [in the plasma membrane] at distances of from 3 or 4 up to 40 × 10⁻⁸ cm apart.

1968 Jrnl. Water Pollution Control Federation 40 1844/1 A variety of membrane-type ion-selective electrodes..show great promise as fast and efficient tools for in situ monitoring and laboratory analysis of municipal and environmental waters and waste streams.

1998 Limnol. & Oceanogr. 43 1728/2 Ion-selective ligands for a variety of ions..are commercially available.

2001 Ann. Bot. 88 976/2 Latterly, studies using ion-selective electrodes have provided direct evidence for the presence of an electrogenic Cl⁻/2H⁺ symporter in the plasma membrane of root-hair cells.

1926 Proc. National Acad. Sci. U.S.A. 12 662 While these experiments were concerned largely with a determination of ϕ+..other experiments with positive ions may be simplified by the use of this ion source.

1950 D. Halliday Introd. Nucl. Physics ix. 342 Protons are injected into the cavity at 4-mev energy, from a pressure-type electrostatic generator which serves as an ion source.

1966 McGraw-Hill Encycl. Sci. & Technol. (rev. ed.) VII. 245/1 The ionizer or ion source converts the propellant from its original stored form to a system of charged corpuscles.

2002 Radiation Res. 158 369/1 Standard ion sources that rely on a reservoir of gas-phase atoms for ion production are limited to gaseous elemental species.

1936 Physical Rev. 49 35/2 Variation of the voltage on the electrode F permitted nice adjustment of the size of the ion spot striking the target.

1940 D. G. Fink Princ. Television Engin. viii. 341 If magneto-static focusing is used, the ion spot is spread over a much larger area (often the full area of the screen) and is much less troublesome, whether electric or magnetic deflection is used.

1953 H. A. Chinn Television Broadcasting ii. 69 Occasionally, a white spot..may be observed in the center of the picture. Such a spot, especially if it is visible on the monitor with the camera lens capped, is probably an ion spot.

2008 Appl. Surface Sci. 254 7401/2 Unfortunately, the stabilization of one of these parameters by a change of the other ones leads to an increase of the ion spot diameter.

1957 L. Biermann in Observatory 77 109 The acceleration of the ion tails of comets (type I of Bredichin) has been recognized as being due to the interaction between the corpuscular radiation of the Sun and the tail plasma.

1984 Sci. News 8 Dec. 362/2 In addition, however, there is the much subtler ‘ion tail’ (sometimes completely invisible to the naked eye).

2007 B. W. Jones Discovering Solar Syst. (ed. 2) iii. 102 All the ions that have been identified in the ion tail could have been produced by the ionisation of atoms and molecular fragments in the coma.

2010 Amer. Geophysical Union Fall Meeting No. P53A 1508 Mercury's ion tail is composed of ions including sodium, potassium, and calcium.

1935 Plant Physiol. 10 222 Root growth is dependent upon ion transport and upon the absorption of water and solutes.

1972 McGraw-Hill Yearbk. Sci. & Technol. 1971 145/2 The toxin's major action is on mucosal ion transport, causing the small bowel to ‘hypersecrete’ its usual product.

2006 Focus Nov. 28/2 The discovery of these genetic defects suggests that migraine is an ionopathy, a disease caused by an ion transport problem.

1905 W. H. Bragg & R. D. Kleeman in London, Edinb. & Dublin Philos. Mag. 6th Ser. 10 321 An arrangement which we find to be of great importance is the ion-trap which is placed under the gauze of the ionization chamber.

1940 D. G. Fink Princ. Television Engin. viii. 342 The ion spot may..be eliminated by an ingenious construction in the electron gun known as an ‘ion trap’.

1989 Independent (Nexis) 13 Nov. (Science section) 17 Put simply, an ion trap confines the motions of charged atomic particles (usually atoms with one electron removed) in a small region of space.

2008 Sci. Amer. (U.K. ed.) Aug. 49/2 Groups at Alcatel–Lucent and Sandia National Laboratories have fabricated even fancier ion traps on silicon chips.