at Bruern and Thame; of Benedictines, at Cogges, Eynsham, Milton; of Mathurins, at Nuffield; of Gilbertines, at Clattercote; of Templars, at Sandford-on-Thames. There was at Gosford one of the only two preceptories of female Templars in England. Of all these, excepting the abbey church at Dorchester, remains are scanty. A few domestic buildings remain at Studley; the boundary walls still stand of Godstow Nunnery on the Thames, the retreat and burial-place of Rosamund Clifford or “Fair Rosamund,” the object of Henry II.’s famous courtship; and there are traces of Rewley Abbey within Oxford.
In ecclesiastical architecture Oxfordshire, apart from Oxford itself, is remarkably rich, but there is no dominant style, nearly all the churches being of mixed dates. In fact, of the most important churches only Iffley, Adderbury and Minster Lovell need be taken as types of a single style. Iffley, picturesquely placed above the Thames 1 m. S. of Oxford, is one of the finest examples of pure Norman in England, with a highly ornate west front. Adderbury, 4 m. S. of Banbury, is a great cruciform Decorated church with a massive central tower and spire. Minster Lovell, also cruciform, is pure Perpendicular; its central tower is supported, with beautiful and unusual effect, on four detached piers. For the rest, one feature common to several is to be noticed. The short ungainly spire of Oxford cathedral was among the earliest, if not the first, constructed in England, and served as a model from which were probably developed the splendid central spires of the great churches at Witney, Bampton, Shipton-under-Wychwood and Bradwell. There are also three fine spires in the north: Bloxham, Adderbury and King’s Sutton (across the border in Northamptonshire), which are locally proverbial as typifying length, strength and beauty. Bloxham church, mainly Decorated, with Norman portions and a remarkable Early English west front, is one of the largest and most beautiful in the county. In the west Burford (Norman and later) is noteworthy, and in the porch of the fine Norman church of Langford is seen the rare feature of a crucifix with the figure cloaked. At South Leigh are remarkable mural paintings of the 15th century. About 5 m. N. of Oxford there are Kidlington (Decorated) with a beautiful needle-like Perpendicular spire, and Islip, which, as the birthplace of Edward the Confessor, retains a connexion with his Abbey of Westminster, the Dean and Chapter of which are lords of the manor and patrons of the living. In the south-east, Dorchester Abbey, with its nave of transitional Norman, has a curious Decorated Jesse window, the tracery representing the genealogical tree of the patriarch. At Cuddesdon there is another large cruciform church, Norman and later. Ewelme church (Perpendicular) is remarkable for the tomb of Alice, Duchess of Suffolk (1475), gorgeous with tracery and gilded canopy, and that of Sir Thomas Chaucer (1434), ornamented with enamelled coats of arms. Here William de la Pole, Duke of Suffolk, founded in 1436 the picturesque hospital and free school still standing.
Authorities.—The Natural History of Oxfordshire (Oxford, 1677, 2nd ed. 1705); Shelton, Engraved Illustrations of the principal Antiquities of Oxfordshire, from drawings by T. Mackenzie (Oxford, 1823); Sir T. Phillips, Oxfordshire Pedigrees (Evesham, 1825); J. M. Davenport, Lords Lieutenant and High Sheriffs of Oxford, 1086 (Oxford, 1868), and Oxfordshire Annals (Oxford, 1869).
OXIDE, in chemistry, a binary compound of oxygen and other elements. In general, oxides are the most important compounds with which the chemist has to deal, a study of their composition and properties permitting a valuable comparative investigation of the elements. It is possible to bring about the direct combination of oxygen with most of the elements (the presence of traces of water vapour is generally necessary according to the researches of H. B. Baker), and when this is not so, indirect methods are available, except with bromine and fluorine (and also with the so-called inert gases—argon, helium, &c.), which
so far have yielded no oxides. Most of the elements combine
with oxygen in several proportions, for example nitrogen has five
oxides: N2O, NO, N2O3, NO2, N2O5; for classificatory purposes,
however, it is advantageous to assign a typical oxide to each
element, which, in general, is the highest having a basic or acid
character. Thus in Group I. of the periodic system, the typical
oxide is M2O, of Group II. MO, of Group III. M2O3, of Group IV.
MO2, of Group V. M2O5, of Group VI. MO3.
Five species of oxides may be distinguished: (1) basic oxides, (2) acidic oxides, (3) neutral oxides, (4) peroxides, (5) mixed anhydrides and salts. Basic oxides combine with acids or acidic oxides to form salts; similarly acidic oxides combine with basic oxides to form salts also. The former are more usually yielded by the metals (some metals, however, form oxides belonging to the other groups), whilst the latter are usually associated with the non-metals. An oxide may be both acidic and basic, i.e. combine with bases as well as acids; this is the case with elements occurring at the transition between basigenic and oxygenic elements in the periodic classification, e.g. aluminium and zinc. Neutral oxides combine neither with acids nor bases to give salts nor with water to give a base or acid. A typical member is nitric oxide; carbon monoxide and nitrous oxide may also be put in this class, but it must be remembered that these oxides may be regarded, in some measure at least, as the anhydrides of formic and hyponitrous acid, although, at the same time, it is impossible to obtain these acids by simple hydration of these oxides. Peroxides may in most cases be defined as oxides containing more oxygen than the typical oxide. The failure of this definition is seen in the case of lead dioxide, which is certainly a peroxide in properties, but it is also the typical oxide of Group IV. to which lead belongs. All peroxides have oxidizing properties. Peroxides may be basic or acidic. Some basic oxides yield hydrogen peroxide with acids, others yield oxygen (these also liberate chlorine from hydrochloric acid), and may combine with lower acidic oxides to form salts of the normal basic oxide with the higher acidic oxide. Examples are BaO2+H2SO4＝BaSO4+H2O2.; 2MnO2+2H2SO4＝2MnSO4-2H2O+O2; MnO2+4HCl＝MnCl, +2H2O + Cl2; PbO2+SO2＝PbSO4 (i.e. PbO+SO3). Two species of basic peroxides may be distinguished: (1) the superoxides or peroxidates, containing the oxygen atoms in a chain, e.g. Na·O·O·Na, O·Ba·O┌─────┐ , which yield hydrogen peroxide with acids; and (2) the poly oxides, having the oxygen atoms doubly linked to the metallic atom, e.g. O:Mn: O,O:Pb:O, and giving oxygen with sulphuric acid, and chlorine with hydrochloric. L. Marino (Zeit. anorg. Chem., 1907, 56, p. 233) pointed out that manganese and lead dioxide behaved differently with sulphur dioxide, the former giving dithionate and the latter sulphate, and suggested the following formulae: O:Mn:O, O·Pb⫶O┌─────┐ , as explaining this difference. A simpler explanation is that the manganese dioxide first gives a normal sulphite which rearranges to dithionate, thus: MnO2+2SO2＝Mn(SO3)2→MnS2O6, whilst the lead dioxide gives a basic sulphite which rearranges to sulphate, thus: PbO+SO2＝PbOSO3→PbSO4. Acidic peroxides combine with basic oxides to form “per” salts, and by loss of oxygen yield the acidic oxide typical of the element. Mixed anhydrides are oxides, which yield with water two acids, or are salts composed of a basic and acidic oxide of the same metal. Examples of mixed anhydrides are ClO2 and NO2, which give chlorous and chloric acid, and nitrous and nitric acid: 2ClO2+H2O＝HClO2 + HClO3, 2NO2+H2O＝HNO2+HNO3; and of mixed salts Pb2O3 and Pb3O4, which may be regarded as lead meta- and
ortho-plumbate: PbO·PbO2, 2PbO·PbO2.Oxidation and Reduction.—In the narrow sense “oxidation” may be regarded as the combination of a substance with oxygen, and conversely, “reduction” as the abstraction of oxygen; in the wider sense oxidation includes not merely the addition of oxygen, but also of other electro-negative elements or groups, or the removal of hydrogen or an electro-positive element or group. In inorganic chemistry oxidation is associated in many cases with an increase in the active valency. Ignoring processes of oxidation or reduction simply brought about by heat or some other form of energy, we may regard an oxidizing agent as a substance having a strong affinity for electro-positive atoms or groups, and a reducing agent as having a strong affinity for electro-negative atoms or groups; in the actual processes the oxidizing agent suffers reduction and the reducing agent oxidation.
Many substances undergo simultaneous oxidation and reduction when treated in a particular manner; this is known as self- or auto-oxidation. For example, on boiling an aqueous solution of a hypochlorite, a chlorate and a chloride results, part of the original salt being oxidized and part reduced: 3NaOCl＝NaClO3+2NaCl. Similarly phosphorous and hypophosphorous acids give phosphoric acid and phosphine, whilst nitrous acid gives nitric acid and nitric oxide: 4H3PO3＝3H3PO4+PH3; 2H3PO2＝H3PO4+PH3; 3HNO2＝HNO3+2NO+H2O. In organic chemistry, a celebrated example is Cannizzaro’s reaction wherein an aromatic aldehyde gives an acid and an alcohol: 2C6H5CHO+H2O＝C6H5CO2H+C6H5CH2OH.
The important oxidizing agents include: oxygen, ozone, peroxides, the halogens chlorine and bromine, oxyacids such as nitric and those of chlorine, bromine and iodine, and also chromic and permanganic acid. The important reducing agents include hydrogen, hydrides such as those of iodine, sulphur, phosphorus, &c., carbon, many metals, potassium, sodium, aluminium, magnesium, &c., salts of lower oxyacids, lower salts of metals and lower oxides.
OXIMES, in organic chemistry, compounds containing the grouping >C:N·OH, derived from aldehydes and ketones by condensing them with hydroxylamine. Those derived from aldehydes are known as aldoximes, those from ketones as ketoximes. They were first prepared by V. Meyer in 1882 (Ber., 1882, 15, pp. 1324, 1525, 2778). They are either colourless liquids, which boil without decomposition, or crystalline solids; and are both basic and acidic in character. On reduction by sodium amalgam in glacial acetic acid solution they yield primary amines. They are hydrolysed by dilute mineral acids
