SUMMARY / RELATED TOPICS

Rust

Rust is an iron oxide, a red oxide formed by the redox reaction of iron and oxygen in the presence of water or air moisture. Several forms of rust are distinguishable both visually and by spectroscopy, form under different circumstances. Rust consists of hydrated iron oxides Fe2O3·nH2O and iron oxide-hydroxide. Given sufficient time and water, any iron mass will convert to rust and disintegrate. Surface rust is flaky and friable, it provides no protection to the underlying iron, unlike the formation of patina on copper surfaces. Rusting is the common term for corrosion such as steel. Many other metals undergo similar corrosion, but the resulting oxides are not called rust. Other forms of rust exist, like the result of reactions between iron and chloride in an environment deprived of oxygen. Rebar used in underwater concrete pillars, which generates green rust, is an example. Although rusting is a negative aspect of iron, a particular form of rusting, known as "stable rust," causes the object to have a thin coating of rust over the top, if kept in low relative humidity, makes the "stable" layer protective to the iron below, but not to the extent of other oxides, such as aluminum.

Rust is another name for iron oxide, which occurs when iron or an alloy that contains iron, like steel, is exposed to oxygen and moisture for a long period of time. Over time, the oxygen combines with the metal at an atomic level, forming a new compound called an oxide and weakening the bonds of the metal itself. Although some people refer to rust as "oxidation", that term is much more general and describes a vast number of processes involving the loss of electrons or increased oxidation state, as part of a reaction; the best-known of these reactions involve oxygen, hence the name "oxidation". The terms "rust" and "rusting" only mean oxidation of its resulting products. Many other oxidation reactions exist which do not produce rust, but only iron or alloys that contain iron can rust. However, other metals can corrode in similar ways; the main catalyst for the rusting process is water. Iron or steel structures might appear to be solid, but water molecules can penetrate the microscopic pits and cracks in any exposed metal.

The hydrogen atoms present in water molecules can combine with other elements to form acids, which will cause more metal to be exposed. If chloride ions are present, as is the case with saltwater, the corrosion is to occur more quickly. Meanwhile, the oxygen atoms combine with metallic atoms to form the destructive oxide compound; as the atoms combine, they weaken the metal, making the structure crumbly. When impure iron is in contact with water, other strong oxidants, or acids, it rusts. If salt is present, for example in seawater or salt spray, the iron tends to rust more as a result of electrochemical reactions. Iron metal is unaffected by pure water or by dry oxygen; as with other metals, like aluminium, a adhering oxide coating, a passivation layer, protects the bulk iron from further oxidation. The conversion of the passivating ferrous oxide layer to rust results from the combined action of two agents oxygen and water. Other degrading solutions are sulfur dioxide in carbon dioxide in water.

Under these corrosive conditions, iron hydroxide species are formed. Unlike ferrous oxides, the hydroxides do not adhere to the bulk metal; as they form and flake off from the surface, fresh iron is exposed, the corrosion process continues until either all of the iron is consumed or all of the oxygen, carbon dioxide, or sulfur dioxide in the system are removed or consumed. When iron rusts, the oxides take up more volume than the original metal. See economic effect for more details; the rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen. The iron is the reducing agent; the rate of corrosion is affected by water and accelerated by electrolytes, as illustrated by the effects of road salt on the corrosion of automobiles. The key reaction is the reduction of oxygen: O2 + 4 e− + 2 H2O → 4 OH−Because it forms hydroxide ions, this process is affected by the presence of acid. Indeed, the corrosion of most metals by oxygen is accelerated at low pH.

Providing the electrons for the above reaction is the oxidation of iron that may be described as follows: Fe → Fe2+ + 2 e−The following redox reaction occurs in the presence of water and is crucial to the formation of rust: 4 Fe2+ + O2 → 4 Fe3+ + 2 O2−In addition, the following multistep acid–base reactions affect the course of rust formation: Fe2+ + 2 H2O ⇌ Fe2 + 2 H+ Fe3+ + 3 H2O ⇌ Fe3 + 3 H+as do the following dehydration equilibria: Fe2 ⇌ FeO + H2O Fe3 ⇌ FeO + H2O 2 FeO ⇌ Fe2O3 + H2OFrom the above equations, it is seen that the corrosion products are dictated by the availability of water and oxygen. With limited dissolved oxygen, iron-containing materials are favoured, including FeO and black lodestone or magnetite. High oxygen concentrations favour ferric materials with the nominal formulae Fe3−xO​x⁄2; the nature of rust changes with time, reflecting the slow rates of the reactions of solids. Furthermore, these complex processes are affected by the presence of other ions, such as Ca2+, which serve as electrolytes which accelerate rust formation, or combine with the hydroxides and oxides of iron to precipitate a variety of Ca, Fe, O, OH species.

The onset of rusting can be detected in the laboratory with the use of ferroxyl indic

Cerball mac DĂșnlainge

Cerball mac Dúnlainge was king of Ossory in south-east Ireland. The kingdom of Ossory occupied the area of modern County Kilkenny and western County Laois and lay between the larger provincial kingdoms of Munster and Leinster. Cerball came to prominence after the death of Fedelmid mac Crimthainn, King of Munster, in 847. Ossory had been subject for a period to the Eóganachta kings of Munster, but Feidlimid was succeeded by a series of weak kings who had to contend with Viking incursions on the coasts of Munster; as a result, Cerball was in a strong position and is said to have been the second most powerful king in Ireland in his years. Upon his death, he was succeeded by his brother Riagan mac Dúnlainge. Kjarvalr Írakonungr, a figure in the Norse sagas who appears as an ancestor of many prominent Icelandic families, is identified with Cerball. A large body of contemporary and near-contemporary material on early medieval Ireland has survived. From the titles of works mentioned in these sources, it is clear that a great deal of additional material has now been lost.

The surviving materials exist in the form of much copies, it is only from comparison of the various texts that the original documents can be reconstructed. The Irish annals which document the ninth century are derived from the now-lost Chronicle of Ireland, being compiled in the midlands of Ireland. All annals include material derived from other sources, or added at a date. None are complete, although the Annals of Ulster and the Annals of Inisfallen cover Cerball's lifetime; the Annals of Clonmacnoise survive only in an eccentric 17th-century English translation, the Annals of Tigernach for this period are lost, although Dubhaltach Mac Fhirbhisigh's abbreviated copy known as the Chronicon Scotorum supplies much of the missing material. The Annals of the Four Masters are late, include some material of doubtful origin. While the annals provide a considerable amount of information, they are terse, most focus their attention on the doings of the Uí Néill, sometimes to the extent of omitting inconvenient events.

A source which concentrates on Cerball's career is the Fragmentary Annals of Ireland, so called because only fragments remain of a longer work, these again copied by Mac Fhirbhisigh in the 17th century from a 15th-century manuscript. The fragment which deals with Cerball's lifetime ends in the early 870s, so that the last fifteen years of his life are missing. Joan Radner and translator of the modern edition of the Fragmentary Annals, argues that these were compiled at the court of Cerball's great-great-grandson Donnchad mac Gilla Pátraic. Although called annals, these are closer to narrative history and are derived from a number of sources; the basic framework is from the Chronicle of Ireland, but to this has been added a variety of material whose source is unknown including early sagas, which concerns Cerball. The Fragmentary Annals were intended to magnify Cerball's achievements, to present his dealings with Vikings and Norse–Gaels in a favourable light. If the various annals are partisan, the remaining sources which concern Cerball are notably unreliable.

Inspired by the Fragmentary Annals, which offer some positive views of Vikings and may have been popular in the Norse-Gael Dublin of the 11th century, many Icelandic genealogies include Cerball—Kjarvalr Írakonungr—as an ancestor. Lastly, The Prophecy of Berchán, an 11th-century verse history of kings in Ireland and Scotland presented as a prophecy, may include Cerball. A large number of genealogies exist, along with geographical and legal texts. Of these last, the Frithfolad Muman, a document purporting to set out the obligations of the Kings of Munster to their allies and subjects is of interest as it sheds light on the position of Osraige within the provincial kingship of Munster. A memory of the kingdom of Osraige survives today in the name and boundaries of the Roman Catholic Diocese of Ossory; the earliest recorded seat of the bishops was at Saighir moved to Aghaboe, this appears to have been the principal church of the kingdom by the eighth century when the life of Saint Cainnech of Aghaboe was composed.

The name Osraige—the Deer people—is among the oldest group of Irish tribal names. Although genealogists in the Early Christian period explained such names by recourse to eponymous ancestors, the names are those of totemic animals or tribal deities. Osraige was only one túath among 150 in Ireland; the average túath was small 500 square kilometres in area with a population of some three to four thousand. Osraige was atypical, much larger than this, covering 2000 square kilometres astride the River Barrow in the modern counties of Kilkenny and Offaly. In principle, each tuath had its own king and court and bishop, but political power rested with the provincial over-kings. At the time of Cerball's birth Osraige lay within the province and kingdom of Munster, ruled by the Eóganachta from the royal centre of Cashel. Osraige lay at the extreme eastern edge of Munster bordering the neighbouring province of Leinster. For a period in the seventh century, most of southern Osraige was ruled by the Corcu Loígde, rulers of Munster before the coming of the Eóganachta.

The Frithfolad Muman text states that the Osraige had once been kings of Munster and makes it clear that they were a privileged and powerful group, but no longer a major force, "the respectable has-beens of Munster politics". The period of Cerball's life covered much of the first Viking Age, he is notably mentioned in Nordic sources; the Icelandic Landnámabók describes Cearbhall as ruler of Dublin a

Drumkee

Drumkee is a townland in the southeast of County Tyrone, Northern Ireland. It is directly south of the area presently known as Coalisland and east, north, of Dungannon, it is situated in the historic barony of Dungannon Middle and the civil parish of Killyman and covers an area of 285 acres. The barony's tax records dated 1666 list two families living in Drumkee; the name derives from the Irish: Druim Ceath. The population of the townland declined during the 19th century: Drumkee presently has a population of around 150, many of its inhabitants are relations. Surnames which appear on the 1666 list include Condson. By the mid-19th century, the name Hunter appears in Drumkee burial records; the surname Mullan appears in a 1910 directory of the area. Drumkee is affiliated with St. Brigids. List of townlands of County Tyrone Map of County Tyrone showing Dungannon, the closest population center to the township of Drumkee. Accessed July 11, 2007