Encyclopædia Britannica Australia -

Encyclopedias since 1768

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oxalic acid ... Oz Beg

oxalic acid: a colourless, crystalline, toxic organic compound belonging to the family of carboxylic acids. Oxalic acid is widely used as an acid rinse in laundries, where it is effective in removing rust and ink stains because it converts most insoluble iron ...
Oxalis: genus of small herbaceous plants, in the family Oxalidaceae, comprising about 850 species, native primarily to southern Africa and tropical and South America. A few South American species have edible tubers or roots, but most members of the genus are ...
oxbird: any of certain small sandpipers, especially the dunlin (q.v.). In Africa the buffalo weaver (q.v.) and the oxpecker are called oxbirds.
oxbow lake: small lake located in an abandoned meander loop of a river channel. It is generally formed as a river cuts through a meander neck to shorten its course, causes the old channel to be rapidly blocked off, and then migrates ...
Oxenstierna, Axel, Greve: chancellor of Sweden (1612-54), successively under King Gustav II Adolf and Queen Christina. He was noted for his administrative reforms and for his diplomacy and military command during the Thirty Years' War. He was created a count in 1645.
Oxenstierna, Bengt Gabrielsson, Greve: Swedish statesman who, as the principal foreign policy adviser of King Charles XI, established a virtually neutral foreign policy for Sweden, breaking the existing alliance with France and forming ties with the Netherlands, England, and the Holy Roman Empire.
oxeye: in Britain, any of certain small sandpipers (especially the dunlin; q.v.) and the great tit (titmouse). See also tit.
Oxfam International: privately funded, international organization that provides relief and development aid to impoverished or disaster-stricken communities worldwide. The original Oxfam was founded at Oxford, England, in 1942 to raise funds for the feeding of hungry children in war-torn Greece. It is ...
Oxford: city, seat (1837) of Lafayette county, northern Mississippi, U.S. It is situated about 75 miles (120 km) southeast of Memphis, Tennessee. Originating as a trading post, it was incorporated in 1837 and named for the English centre of learning, reflecting ...
Oxford: city (district), administrative and historic county of Oxfordshire, England, best known for the University of Oxford, which is located within it.
Oxford: county, western Maine, U.S. It consists of a mountainous region bordered to the west by New Hampshire and to the north by Quebec, Canada. The Appalachian National Scenic Trail crosses the Maine-New Hampshire border along the Mahoosuc Range and traverses ...
Oxford English Dictionary, The: definitive historical dictionary of the English language, originally consisting of 12 volumes and a 1-volume supplement. The dictionary is a corrected and updated revision of A New English Dictionary on Historical Principles (NED), which was published in 10 volumes from ...
Oxford movement: 19th-century movement centred at the University of Oxford that sought a renewal of "catholic," or Roman Catholic, thought and practice within the Church of England in opposition to the Protestant tendencies of the church. The argument was that the Anglican ...
Oxford, Edward de Vere, 17th Earl of: English lyric poet and patron of an acting company, Oxford's Men, who became, in the 20th century, the strongest candidate proposed (next to William Shakespeare himself) for the authorship of Shakespeare's plays.
Oxford, John de Vere, 13th Earl of: English soldier and royal official, a Lancastrian leader in the Wars of the Roses. He helped to restore the deposed King Henry VI (1470) and later (1485) to secure the English throne for the last surviving male claimant from the ...
Oxford, Provisions of: (1258), in English history, a plan of reform accepted by Henry III, in return for the promise of financial aid from his barons. It can be regarded as England's first written constitution.
Oxford, Robert de Vere, 9th earl of: favourite of King Richard II of England (ruled 1377-99) during that monarch's minority. He led the group of courtiers who unsuccessfully supported Richard's efforts in 1385-87 to wrest control of the government from powerful nobles.
Oxford, Robert Harley, 1st Earl of, Earl Mortimer, Baron Harley Of Wigmore: British statesman who headed the Tory ministry from 1710 to 1714. Although by birth and education he was a Whig and a Dissenter, he gradually over the years changed his politics, becoming the leader of the Tory and Anglican party.
Oxford, University of: English autonomous institution of higher learning at Oxford, Oxfordshire, England, one of the world's great universities. It lies along the Upper River Thames (called by Oxonians the Isis), 50 miles (80 km) north-northwest of London.
Oxfordshire: administrative and historic county of south-central England, bounded on the north by Warwickshire and Northamptonshire, on the west by Gloucestershire, on the south by Berkshire, and on the east by Buckinghamshire. Wiltshire lies to the southwest of the administrative county, ...
oxidation number: the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.
oxidation-reduction reaction: any chemical reaction in which the oxidation number of a participating chemical species changes. The term covers a large and diverse body of processes. Many oxidation-reduction reactions are as common and familiar as fire, the rusting and dissolution of metals, ...
oxide: any of a large and important class of chemical compounds in which oxygen is combined with another element.
oxide mineral: any naturally occurring inorganic compound with a structure based on close-packed oxygen atoms in which smaller, positively charged metal or other ions occur in interstices. Oxides are distinguished from other oxygen-bearing compounds such as ...
oxidoreductase: any member of a class of enzymes, commonly known as dehydrogenases or oxidases, that catalyze the removal of hydrogen atoms and electrons from the compounds on which they act. Substances called coenzymes, associated with the oxidoreductase enzymes and necessary for ...
oxime: any of a class of nitrogen-containing organic compounds usually prepared from hydroxylamine and an aldehyde, a ketone, or a quinone. Oximes have the structure X\Y/C&doublehorzbond; N&singlehorzbond;OH, in which X and Y are hydrogen atoms or organic groups derived by removal ...
Oxisol: one of the 12 soil orders in the U.S. Soil Taxonomy. Oxisols form principally in humid tropical zones under rainforest, scrub and thorn forest, or savanna vegetation on flat to gently sloping uplands. They are typically found on old landscapes ...
Oxley, John: surveyor-general and explorer who played an important part in the exploration of eastern Australia and also helped open up Van Diemen's Land (later Tasmania).
Oxnard: city, Ventura county, southwestern California, U.S. It lies near the Pacific coast, between Los Angeles and Santa Barbara. Originally inhabited by Chumash Indians, the city was founded in 1898 near the site of the Spanish colonial Mission San Buenaventura (1782). ...
oxpecker: either of the two species of the African genus Buphagus, of the family Sturnidae (order Passeriformes). Both species-the yellow-billed (B. africanus) and the red-billed (B. erythrorhynchus)-are brown birds 20 cm (8 inches) long, with wide bills, stiff tails, and sharp ...
oxygen: nonmetallic chemical element of Group VIa of the periodic table. Oxygen is a colourless, odourless, tasteless gas, the most plentiful element in the Earth's crust; its most important compound is water.
oxygen cycle: circulation of oxygen in various forms through nature. Free in the air and dissolved in water, oxygen is second only to nitrogen in abundance among uncombined elements in the atmosphere. Plants and animals use oxygen to respire and return it ...
oxygen group element: any of the five chemical elements comprising Group VIa of the periodic classification-namely, oxygen, sulfur, selenium, tellurium, and polonium. (See .) A relationship among the first three members of the group was recognized as early as 1829; tellurium was assigned ...
Oxyrhynchus: ancient capital of the 19th Upper Egyptian nome (province), on the western edge of the Nile Valley, in al-Minya muhafazah (governorate). It is best known for the numerous papyri uncovered there, first by B.P. Grenfell and A.S. Hunt (1897-1907), and ...
oxytocin: hormone used clinically to help begin or to continue labour, to control bleeding following delivery, and to stimulate the secretion of breast milk. Oxytocin was first synthesized (along with the related antidiuretic hormone [ADH]) by Vincent du Vigneaud in 1953, ...
Oya Current: surface oceanic current flowing southwest along the Kamchatka Peninsula and the Kuril Islands. Meeting the Kuro Current Extension east of Japan, part of the cold, less saline water of the Oya Current sinks below the Kuro Current and continues southward; ...
Oyama: city, Tochigi ken (prefecture), Honshu, Japan, on the Omoi River. A castle town in early times, it became a post station and river port during the Tokugawa period (1603-1867). The transport centre of southern Tochigi prefecture, Oyama is the hub ...
Oyapock River: river that forms the border between French Guiana and the Brazilian state of Amapa. It rises in the Tumuc-Humac Mountains and flows northeast for 311 miles (500 km) to empty into the Atlantic near Cape Orange. The country through which ...
Oyem: town, northern Gabon. It lies on a plateau at an elevation of about 3,000 feet (900 m). Oyem is an administrative and transport centre for an agricultural area. Cocoa and coffee, grown on mixed plantations, are the most important cash ...
Oyo: state, western Nigeria. Oyo was reduced in size when Osun state was created out of its eastern portion in 1991. Oyo is bounded by the states of Kwara on the north, Osun on the east, and Ogun on the south ...
Oyo: town, Oyo state, southwestern Nigeria. Oyo lies 32 miles (51 km) north of Ibadan. In the 1830s it was declared the new seat of the alafin of Oyo (the political leader of the Yoruba people) by Alafin Atiba, after Old ...
Oyo empire: Yoruba state north of Lagos, in present-day southwestern Nigeria, that dominated, during its apogee (1650-1750), most of the states between the Volta River in the west and the Niger River in the east. It was the most important and authoritative ...
Oyomeigaku: one of the three major schools of Neo-Confucianism that developed in Japan during the Tokugawa period (1603-1867). See Neo-Confucianism.
Oyono, Ferdinand Leopold: African statesman, actor, and comic writer whose two best-known works-Une Vie de boy (1956; Houseboy) and Le Vieux Negre et la medaille (1956; The Old Man and the Medal), written while he was studying law and administration in Paris-reflect the ...
Oyono-Mbia, Guillaume: African dramatist and short-story writer, one of bilingual Cameroon's few writers to achieve success both in French and in English. Oyono-Mbia attended the College Evangelique at Limbamba and then went to England, graduating from the University of Keele in 1968. ...
Oyrat: any of the peoples speaking western dialects of the Mongol language group.
oyster: any member of the families Ostreidae (true oysters) or Aviculidae (pearl oysters), bivalve mollusks found in temperate and warm coastal waters of all oceans. Bivalves known as thorny oysters (Spondylus) and saddle oysters (Anomia) are sometimes included in the group.
Oyster Bay: town (urbanized township), Nassau county, southeastern New York, U.S. It extends from the north to south shores on central Long Island, and comprises more than 30 incorporated villages and unincorporated communities. Villages include Massapequa Park and Oyster Bay Cove (both ...
oystercatcher: any of several shorebirds, notable for their long, flattened, orange-red bills, constituting the genus Haematopus, family Haematopodidae. Found in temperate to tropical parts of the world, oystercatchers are stout-bodied birds measuring 40 to 50 cm (16 to 20 inches) long, ...
oystershell scale: (Lepidosaphes ulmi), an insect (order Homoptera) whose protective covering resembles a miniature oystershell. The oystershell scale inflicts great damage on the trees and shrubs on which it lives. Control is by dormant spray and natural enemies-i.e., birds, mites, and parasitic ...
Oz Beg: Mongol leader and khan of the Golden Horde, or Kipchak empire, of southern Russia, under whom it attained its greatest power; he reigned from 1312 to 1341. Oz Beg was a convert to Islam, but he also welcomed Christian missionaries ...