Gilding is any decorative technique for applying a thin coating of gold to solid surfaces such as metal, porcelain, or stone. A gilded object is described as "gilt". Where metal is gilded, it was traditionally silver in the West, to make silver-gilt objects, but gilt-bronze is used in China, called ormolu if it is Western. Methods of gilding include hand application and gluing of gold leaf, chemical gilding, electroplating, the last called gold plating. Parcel-gilt objects are only gilded over part of their surfaces; this may mean that all of the inside, none of the outside, of a chalice or similar vessel is gilded, or that patterns or images are made up by using a combination of gilt and ungilted areas. Gilding gives an object a gold appearance at a fraction of the cost of creating a solid gold object. In addition, a solid gold piece would be too soft or too heavy for practical use. A gilt surface does not tarnish as silver does. Herodotus mentions that the Egyptians gilded wood and metals, many such objects have been excavated.
Certain Ancient Greek statues of great prestige were chryselephantine, i.e. made of ivory. Extensive ornamental gilding was used in the ceiling coffers of the Propylaea. Pliny the Elder informs us that the first gilding seen at Rome was after the destruction of Carthage, under the censorship of Lucius Mummius, when the Romans began to gild the ceilings of their temples and palaces, the Capitol being the first place on which this process was used, but he adds that luxury advanced on them so that in little time you might see all private and poor people, gild the walls and other parts of their dwellings. Owing to the comparative thickness of the gold leaf used in ancient gilding, the traces of it that remain are remarkably brilliant and solid. Fire-gilding of metal goes back at least to the 4th century BC, was known to Pliny, Vitruvius and in the Early Mediaeval period to Theophilus. In Europe, silver-gilt has always been more common than gilt-bronze, but in China the opposite has been the case.
The ancient Chinese developed the gilding of porcelain, taken up by the French and other European potters. Modern gilding is applied by various processes. More traditional techniques still form an important part of framemaking and are sometimes still employed in general woodworking, cabinet-work, decorative painting and interior decoration and ornamental leather work, in the decoration of pottery and glass. Mechanical gilding includes all the operations in which gold leaf is prepared, the processes to mechanically attach the gold onto surfaces; the techniques include burnishing, water gilding and oil-gilding used by wood gilders. "Overlaying" or folding or hammering on gold foil or gold leaf is the simplest and most ancient method, is mentioned in Homer's Odyssey and the Old Testament. The Ram in a Thicket of about 2600–2400 BCE from Ur uses this technique on wood, with a thin layer of bitumen underneath to help adhesion; the next advances involved two simple processes. The first involves gold leaf, gold, hammered or cut into thin sheets.
Gold leaf is thinner than standard paper today, when held to the light is semi-transparent. In ancient times it was about ten times thicker than today, half that in the Middle Ages. If gilding on canvas or on wood, the surface was first coated with gesso. "Gesso" is a substance made of chalk mixed with glue. Once the coating of gesso had been applied, allowed to dry, smoothed, it was re-wet with a sizing made of rabbit-skin glue and water or boiled linseed oil mixed with litharge and the gold leaf was layered on using a gilder's tip and left to dry before being burnished with a piece of polished agate; those gilding on canvas and parchment sometimes employed stiffly-beaten egg whites, and/or Armenian bole as sizing, though egg whites and gum both become brittle over time, causing the gold leaf to crack and detach, so honey was sometimes added to make them more flexible. Other gilding processes involved using the gold as pigment in paint: the artist ground the gold into a fine powder and mixed it with a binder such as gum arabic.
The resulting gold paint, called shell gold, was applied in the same way as with any paint. Sometimes, after either gold-leafing or gold-painting, the artist would heat the piece enough to melt the gold ensuring an coat; these techniques remained the only alternatives for materials like wood, the vellum pages of illuminated manuscripts, gilt-edged stock. Chemical gilding embraces those processes in which the gold is at some stage of chemical combination; these include: In this process the gold is obtained in a state of fine division, applied by mechanical means. Cold gilding on silver is performed by a solution of gold in aqua regia, applied by dipping a linen rag into the solution, burning it, rubbing the black and heavy ashes on the silver with the finger or a piece of leather or cork. Wet gilding is effected by means of a dilute solution of gold chloride in aqua regia with twice its quantity of ether
A penny is a coin or a unit of currency in various countries. Borrowed from the Carolingian denarius, it is the smallest denomination within a currency system. Presently, it is the formal name of the British penny and the informal name of one American cent as well as the informal Irish designation of 1 cent euro coin, it is the informal name of the cent unit of account in Canada, although one cent coins are no longer minted there. The name is used in reference to various historical currencies derived from the Carolingian system, such as the French denier and the German pfennig, it may be informally used to refer to any similar smallest-denomination coin, such as the euro cent or Chinese fen. The Carolingian penny was a.940-fine silver coin weighing 1/240 pound. It was adopted by Offa of Mercia and other English kings and remained the principal currency in Europe over the next few centuries until repeated debasements necessitated the development of more valuable coins; the British penny remained a silver coin until the expense of the Napoleonic Wars prompted the use of base metals in 1797.
Despite the decimalization of currencies in the United States and throughout the British Commonwealth, the name remains in informal use. No penny is formally subdivided, although farthings and half cents have been minted and the mill remains in use as a unit of account in some contexts. Penny is first attested in a 1394 Scots text, a variant of Old English peni, a development of numerous variations including pennig and pending; the etymology of the term "penny" is uncertain, although cognates are common across all Germanic languages and suggest a base *pan-, *pann-, or *pand- with the individualizing suffix -ing. Common suggestions include that it was *panding as a Low Franconian form of Old High German pfant "pawn", it has been proposed that it may represent an early borrowing of Punic pn, as the face of Carthaginian goddess Tanit was represented on nearly all Carthaginian currency. Following decimalization, the British and Irish coins were marked "new penny" until 1982 and 1985, respectively.
The regular plural pennies fell out of use in England from the 16th century, except in reference to coins considered individually. It remains common in Scottish English and is standard for all senses in American English, however, the informal "penny" is only used of the coins in any case, values being expressed in "cents"; the informal name for the American cent seems to have spread from New York State. In British English, prior to decimalization, values from two to eleven pence and of twenty pence are written and spoken as a single word, as twopence or tuppence, threepence or thruppence, &c. Where a single coin represented a number of pence, it was treated as a single noun, as a sixpence or two eightpences. Thus, "a threepence" would be single coin of that value whereas "three pence" would be its value and "three pennies" would be three penny coins. In British English, divisions of a penny were added to such combinations without a conjunction, as sixpence-farthing, such constructions were treated as single nouns.
Adjectival use of such coins used the ending -penny, as sixpenny. The British abbreviation d. derived from the Latin denarius. It followed the amount after a space, it has been replaced since decimalization by p written without a space or period. From this abbreviation, it is common to speak of pennies and values in pence as "p". In North America, it is common to abbreviate cents with the currency symbol ¢. Elsewhere, it is written with a simple c; the medieval silver penny was modeled on similar coins in antiquity, such as the Greek drachma, the Carthaginian shekel, the Roman denarius. Forms of these seem to have reached as far as Sweden; the use of Roman currency in Britain seems to have fallen off after the Roman withdrawal and subsequent Saxon invasions. Charlemagne's father Pepin the Short instituted a major currency reform around AD 755, aiming to reorganise Francia's previous silver standard with a standardized.940-fine denier weighing 1⁄240 pound. Around 790, Charlemagne introduced a new.950 or.960-fine penny with a smaller diameter.
Surviving specimens have an average weight of 1.70 grams, although some estimate the original ideal mass at 1.76 grams. Despite the purity and quality of these pennies, they were rejected by traders throughout the Carolingian period in favor of the gold coins used elsewhere, a situation that led to repeated legislation against such refusal to accept the king's currency; some of the Anglo-Saxons kingdoms copied the solidus, the late Roman gold coin. Around AD 641–670, there seems to have been a movement to use coins with a lower gold content; this decreased their value and may have increased the number that could be minted, but these paler coins do not seem to have solved the problem of the value and scarcity of the currency
Bronze is an alloy consisting of copper with about 12–12.5% tin and with the addition of other metals and sometimes non-metals or metalloids such as arsenic, phosphorus or silicon. These additions produce a range of alloys that may be harder than copper alone, or have other useful properties, such as stiffness, ductility, or machinability; the archeological period in which bronze was the hardest metal in widespread use is known as the Bronze Age. The beginning of the Bronze Age in India and western Eurasia is conventionally dated to the mid-4th millennium BC, to the early 2nd millennium BC in China; the Bronze Age was followed by the Iron Age starting from about 1300 BC and reaching most of Eurasia by about 500 BC, although bronze continued to be much more used than it is in modern times. Because historical pieces were made of brasses and bronzes with different compositions, modern museum and scholarly descriptions of older objects use the more inclusive term "copper alloy" instead. There are two basic theories as to the origin of the word.
Romance theoryThe Romance theory holds that the word bronze was borrowed from French bronze, itself borrowed from Italian bronzo "bell metal, brass" from either, bróntion, back-formation from Byzantine Greek brontēsíon from Brentḗsion ‘Brindisi’, reputed for its bronze. Proto-Slavic theoryThe Proto-Slavic theory reflects the philological issue that in the most of Slavonic languages word "bronza" corresponds to "war metal" while at the early stages of the Bronze working it was used exclusively for military purposes; the discovery of bronze enabled people to create metal objects which were harder and more durable than possible. Bronze tools, weapons and building materials such as decorative tiles were harder and more durable than their stone and copper predecessors. Bronze was made out of copper and arsenic, forming arsenic bronze, or from or artificially mixed ores of copper and arsenic, with the earliest artifacts so far known coming from the Iranian plateau in the 5th millennium BC, it was only that tin was used, becoming the major non-copper ingredient of bronze in the late 3rd millennium BC.
Tin bronze was superior to arsenic bronze in that the alloying process could be more controlled, the resulting alloy was stronger and easier to cast. Unlike arsenic, metallic tin and fumes from tin refining are not toxic; the earliest tin-alloy bronze dates to 4500 BC in a Vinča culture site in Pločnik. Other early examples date to the late 4th millennium BC in Egypt and some ancient sites in China and Mesopotamia. Ores of copper and the far rarer tin are not found together, so serious bronze work has always involved trade. Tin sources and trade in ancient times had a major influence on the development of cultures. In Europe, a major source of tin was the British deposits of ore in Cornwall, which were traded as far as Phoenicia in the eastern Mediterranean. In many parts of the world, large hoards of bronze artifacts are found, suggesting that bronze represented a store of value and an indicator of social status. In Europe, large hoards of bronze tools socketed axes, are found, which show no signs of wear.
With Chinese ritual bronzes, which are documented in the inscriptions they carry and from other sources, the case is clear. These were made in enormous quantities for elite burials, used by the living for ritual offerings. Though bronze is harder than wrought iron, with Vickers hardness of 60–258 vs. 30–80, the Bronze Age gave way to the Iron Age after a serious disruption of the tin trade: the population migrations of around 1200–1100 BC reduced the shipping of tin around the Mediterranean and from Britain, limiting supplies and raising prices. As the art of working in iron improved, iron improved in quality; as cultures advanced from hand-wrought iron to machine-forged iron, blacksmiths learned how to make steel. Steel holds a sharper edge longer. Bronze was still used during the Iron Age, has continued in use for many purposes to the modern day. There are many different bronze alloys, but modern bronze is 88% copper and 12% tin. Alpha bronze consists of the alpha solid solution of tin in copper.
Alpha bronze alloys of 4–5% tin are used to make coins, springs and blades. Historical "bronzes" are variable in composition, as most metalworkers used whatever scrap was on hand; the proportions of this mixture suggests. The Benin Bronzes are in fact brass, the Romanesque Baptismal font at St Bartholomew's Church, Liège is described as both bronze and brass. In the Bronze Age, two forms of bronze were used: "classic bronze", about 10% tin, was used in
Gold leaf is gold, hammered into thin sheets by goldbeating and is used for gilding. Gold leaf is available in a wide variety of shades; the most used gold is 22-karat yellow gold. Gold leaf is a type of metal leaf, but the term is used when referring to gold leaf; the term metal leaf is used for thin sheets of metal of any color that do not contain any real gold. Pure gold is 24 karats. Real, yellow gold leaf is 91.7% pure gold. Silver-colored white gold is about 50% pure gold. Layering gold leaf over a surface is called gold gilding. Traditional water gilding is the most difficult and regarded form of gold leafing, it has remained unchanged for hundreds of years and is still done by hand. Gold leaf is sometimes used in art without a gilding process. In cultures including the European Bronze Age it was used to wrap objects such as bullae by folding it over, the Classical group of gold lunulae are so thin in the centre, that they might be classed as gold leaf, it has been used in jewellery in various periods as small pieces hanging freely.
Gold leaf has traditionally been most popular and most common in its use as gilding material for decoration of art or the picture frames that are used to hold or decorate paintings, mixed media, small objects and paper art. Gold glass is gold leaf held between two pieces of glass, was used for decorated Ancient Roman vessels, where some of the gold was scraped off to form an image, as well as tesserae gold mosaics. "Gold-ground" paintings, where the background of the figures was all in gold, was introduced in mosaics in Early Christian art, used in icons and Western panel paintings until the late Middle Ages. Gold leaf is used in Buddhist art to decorate statues and symbols. Gold leafing can be seen on domes in religious and public architecture. "Gold" frames made without leafing are available for a lower price, but traditionally some form of gold or metal leaf was preferred when possible and gold leafed moulding is still available from many of the companies that produce commercially available moulding for use as picture frames.
Gold leaf has long been an integral component of architecture to designate important structures, both for aesthetics and because gold's non-reactive nature provides a protective finish. Gold in architecture became an integral component of Byzantine and Roman churches and basilicas in 400 AD, most notably Basilica di Santa Maria Maggiore in Rome; the church is one of the earliest examples of gold mosaics. The mosaics were made of stone, tile or glass backed on gold leaf walls, giving the church a beautifully intricate backdrop; the Athenian marble columns supporting the nave are older, either come from the first basilica, or from another antique Roman building. The 14th century campanile, or bell tower, is the highest in Rome, at 240 feet; the basilica's 16th-century coffered ceiling, designed by Giuliano da Sangallo, is said to be gilded with gold that Christopher Columbus presented to Ferdinand and Isabella, before being passed on to the Spanish pope, Alexander VI. The apse mosaic, the Coronation of the Virgin, is from 1295, signed by the Franciscan friar, Jacopo Torriti.
In Ottawa, The Centre Block is the main building of the Canadian parliamentary complex on Parliament Hill, containing the House of Commons and Senate chambers, as well as the offices of a number of members of parliament and senior administration for both legislative houses. It is the location of several ceremonial spaces, such as the Hall of Honour, the Memorial Chamber, Confederation Hall. In the east wing of the Centre Block is the Senate chamber, in which are the thrones for the Canadian monarch and her consort, or for the federal viceroy and their consort, from which either the sovereign or the governor general gives the Speech from the Throne and grants Royal Assent to bills passed by parliament; the overall color in the Senate chamber is red, seen in the upholstery and draperies, reflecting the color scheme of the House of Lords in the United Kingdom. Capping the room is a gilt ceiling with deep octagonal coffers, each filled with heraldic symbols, including maple leaves, fleur-de-lis, lions rampant, clàrsach, Welsh Dragons, lions passant.
This plane rests on six pairs and four single pilasters, each of, capped by a caryatid, between which are clerestory windows. Below the windows is a continuous architrave, broken only by baldachins at the base of each of the above pilasters. On the east and west walls of the chamber are eight murals depicting scenes from the First World War. However, the project never eventuated, the works were stored at the National Gallery of Canada until 1921, when the Parliament requested a loan for some of the collection's oil paintings to display in the Centre Block; the murals have remained in the Senate chamber since. In London, the Criterion Restaurant is an opulent building facing Piccadilly Circus in the heart of London, it was built by architect Thomas Verity in Neo-Byzantine style for the partnership Spiers and Pond who opened
Homer is the legendary author of the Iliad and the Odyssey, two epic poems that are the central works of ancient Greek literature. The Iliad is set during the Trojan War, the ten-year siege of the city of Troy by a coalition of Greek kingdoms, it focuses on a quarrel between King Agamemnon and the warrior Achilles lasting a few weeks during the last year of the war. The Odyssey focuses on the ten-year journey home of Odysseus, king of Ithaca, after the fall of Troy. Many accounts of Homer's life circulated in classical antiquity, the most widespread being that he was a blind bard from Ionia, a region of central coastal Anatolia in present-day Turkey. Modern scholars consider these accounts legendary; the Homeric Question – concerning by whom, when and under what circumstances the Iliad and Odyssey were composed – continues to be debated. Broadly speaking, modern scholarly opinion falls into two groups. One holds that most of the Odyssey are the works of a single poet of genius; the other considers the Homeric poems to be the result of a process of working and reworking by many contributors, that "Homer" is best seen as a label for an entire tradition.
It is accepted that the poems were composed at some point around the late eighth or early seventh century BC. The poems are in Homeric Greek known as Epic Greek, a literary language which shows a mixture of features of the Ionic and Aeolic dialects from different centuries. Most researchers believe that the poems were transmitted orally. From antiquity until the present day, the influence of the Homeric epics on Western civilization has been great, inspiring many of its most famous works of literature, music and film; the Homeric epics were the greatest influence on education. Today only the Iliad and Odyssey are associated with the name'Homer'. In antiquity, a large number of other works were sometimes attributed to him, including the Homeric Hymns, the Contest of Homer and Hesiod, the Little Iliad, the Nostoi, the Thebaid, the Cypria, the Epigoni, the comic mini-epic Batrachomyomachia, the Margites, the Capture of Oechalia, the Phocais; these claims are not considered authentic today and were by no means universally accepted in the ancient world.
As with the multitude of legends surrounding Homer's life, they indicate little more than the centrality of Homer to ancient Greek culture. Many traditions circulated in the ancient world concerning Homer. Modern scholarly consensus is; some claims were repeated often. They include that Homer was blind, that he was born in Chios, that he was the son of the river Meles and the nymph Critheïs, that he was a wandering bard, that he composed a varying list of other works, that he died either in Ios or after failing to solve a riddle set by fishermen, various explanations for the name "Homer"; the two best known ancient biographies of Homer are the Life of Homer by the Pseudo-Herodotus and the Contest of Homer and Hesiod. The study of Homer is one of the oldest topics in scholarship, dating back to antiquity. Nonetheless, the aims of Homeric studies have changed over the course of the millennia; the earliest preserved comments on Homer concern his treatment of the gods, which hostile critics such as the poet Xenophanes of Colophon denounced as immoral.
The allegorist Theagenes of Rhegium is said to have defended Homer by arguing that the Homeric poems are allegories. The Iliad and the Odyssey were used as school texts in ancient Greek and Hellenistic cultures, they were the first literary works taught to all students. The Iliad its first few books, was far more intently studied than the Odyssey during the Hellenistic and Roman periods; as a result of the poems' prominence in classical Greek education, extensive commentaries on them developed to explain parts of the poems that were culturally or linguistically difficult. During the Hellenistic and Roman Periods, many interpreters the Stoics, who believed that Homeric poems conveyed Stoic doctrines, regarded them as allegories, containing hidden wisdom; because of the Homeric poems' extensive use in education, many authors believed that Homer's original purpose had been to educate. Homer's wisdom became so praised that he began to acquire the image of a prototypical philosopher. Byzantine scholars such as Eustathius of Thessalonica and John Tzetzes produced commentaries and scholia to Homer in the twelfth century.
Eustathius's commentary on the Iliad alone is massive, sprawling nearly 4,000 oversized pages in a twenty-first century printed version and his commentary on the Odyssey an additional nearly 2,000. In 1488, the Greek scholar Demetrios Chalkokondyles published the editio princeps of the Homeric poems; the earliest modern Homeric scholars started with the same basic approaches towards the Homeric poems as scholars in antiquity. The allegorical interpretation of the Homeric poems, so prevalent in antiquity returned to become the prevailing view of the Renaissance. Renaissance humanists praised Homer as the archetypically wise poet, whose writings contain hidden wisdom, disguised through allegory. In western Europe during the Renaissance, Virgil was more read than Homer and Homer was seen through a Virgilian lens. In 1664, contradicting the widespread praise of Homer as the epitome of wisdom, François Hédelin, abbé d'Aubignac wrote a s
Paul Storr was an English goldsmith and silversmith working in the Neoclassical style during the late eighteenth and early nineteenth centuries. His works range from simple tableware to magnificent sculptural pieces made for royalty. Paul Storr was England's most celebrated silversmith during the first half of the nineteenth century and his legacy lives on today, his pieces and adorn royal palaces and the finest stately homes throughout Europe and the world. Storr's reputation rests on his mastery of the grandiose neo-Classical style developed in the Regency period, he became the most prominent silversmith of the nineteenth century, producing much of the silver purchased by King George III and King George IV. Storr entered his first mark in the first part of 1792, which reflects his short-lived partnership with William Frisbee. Soon after, he began to use his PS mark, which he maintained throughout his career with only minor changes, his first major work was a gold font commissioned by the Duke of Portland in 1797 and in 1799 he created the "Battle of the Nile Cup" for presentation to Lord Nelson.
Much of Storr's success was due to the influence of Philip Rundell, of the popular silver retailing firm, Rundell and Rundell. Rundell's firm nearly monopolised the early nineteenth-century market for superior silver and obtained the Royal Warrant in 1806; this shrewd businessman realised the talent of Paul Storr and began pursuing him in 1803, however it was not until 1807 that Storr joined the firm. After many years of working for Rundell, Storr realised he had lost much of his artistic freedom and by 1819 he left the firm to open his own shop, turning his attentions towards more naturalistic designs and soon began enjoying the patronage he desired. After only a few years of independence, Storr realised he needed a centralised retail location and partnered with John Mortimer, founding Storr and Mortimer in 1822 on New Bond Street. Son of Thomas Storr of Westminster, first silver-chaser innkeeper. Apprenticed c. 1785. Before his first partnership with William Frisbee in 1792 he worked in Church Street, the address of Andrew Fogelberg at which Storr's first separate mark is entered.
First mark entered as plateworker, in partnership with William Frisbee, 2 May 1792. Address: 5 Cock Lane, Snow Hill. Second mark alone, 12 January 1793. Address: 30 Church Street, Soho. Third mark, 27 April 1793. Fourth 8 August 1794. Moved to 20 Air Street, 8 October 1796. Fifth mark, 29 November 1799. Sixth, 21 August 1807. Address 53 Dean Street, Soho. Seventh, 10 February 1808. Eighth? Ninth, 21 October 1813. Tenth, 12 September 1817. Moved to Harrison Street, Gray's Inn Road, 4 March 1819, after severing his connection with Rundell and Rundell. Eleventh mark, 2 September 1883. Address: 17 Harrison Street. Twelfth and last mark, 2 September 1833. Heal records him in partnership with Frisbee and alone at Cock Lane in 1792, at the other addresses and dates above, except Harrison Street. Storr married in 1801, Elizabeth Susanna Beyer of the Saxon family of piano and organ builders of Compton Street, by whom he had ten children, he retired in 1838. He is buried in the churchyard of St Nicholas, Tooting, his will, proved 3 April 1844, shows an estate of £3,000.
There is a memorial to him at the church of St Mary, Suffolk put up in 1845 by his son the Rev. Francis Storr, the incumbent. An example of his work is the cup made for presentation to the British admiral Lord Nelson to mark his victory at the Battle of the Nile. Items from Storr's workshops may be seen at Windsor Castle and during the summer opening season at Buckingham Palace. There are significant holdings of items in the National Silver Collection at the Victoria and Albert Museum as well as in the Wellington Collection at Apsley House. Outside London there are important works at Brighton Pavilion, at the Bowes Museum, Barnard Castle and at Woburn Abbey. In the United States there are holdings of Paul Storr at the Huntington Museum of Art, the Museum of Fine Arts, the Los Angeles County Museum of Art, the Metropolitan Museum of Art, New York, among others; the Birmingham Museum of Art in Alabama has two significant pieces, one of, illustrated here. In Canada, there are significant pieces in the Museum of Fine Arts and the Winnipeg Art Gallery, Manitoba.
Australia has holdings at the National Gallery of Victoria in Melbourne. In Portugal there is a fascinating group of silver made by Storr at the Casa Museu Medeiros e Almeida, whereas in Russia, at the State Hermitage Museum, there is silver supplied to Tsar Nicholas I and members of the aristocracy by Hunt & Roskell, successors to Storr & Mortimer. Mr. and Mrs. Morrie A. Moss collection of Paul Storr silver, 1771–1843, Brooks Memorial Art Gallery, Memphis, 6–27 March 1966 Paul Storr in America, Indianapolis Museum of Art, 8 February – 12 March 1972. Indianapolis, IN: Indianapolis Museum of Art, 1972 OCLC 695930 Hartop, with a foreword by Kathryn Jones, Art in Industry: The Silver of Paul Storr, John Adamson, October 2015 ISBN 978-1-898565-14-7 OCLC 927983072.
Silver is a chemical element with symbol Ag and atomic number 47. A soft, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, reflectivity of any metal; the metal is found in the Earth's crust in the pure, free elemental form, as an alloy with gold and other metals, in minerals such as argentite and chlorargyrite. Most silver is produced as a byproduct of copper, gold and zinc refining. Silver has long been valued as a precious metal. Silver metal is used in many bullion coins, sometimes alongside gold: while it is more abundant than gold, it is much less abundant as a native metal, its purity is measured on a per-mille basis. As one of the seven metals of antiquity, silver has had an enduring role in most human cultures. Other than in currency and as an investment medium, silver is used in solar panels, water filtration, ornaments, high-value tableware and utensils, in electrical contacts and conductors, in specialized mirrors, window coatings, in catalysis of chemical reactions, as a colorant in stained glass and in specialised confectionery.
Its compounds are used in X-ray film. Dilute solutions of silver nitrate and other silver compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings and other medical instruments. Silver is similar in its physical and chemical properties to its two vertical neighbours in group 11 of the periodic table and gold, its 47 electrons are arranged in the configuration 4d105s1 to copper and gold. This distinctive electron configuration, with a single electron in the highest occupied s subshell over a filled d subshell, accounts for many of the singular properties of metallic silver. Silver is an soft and malleable transition metal, though it is less malleable than gold. Silver crystallizes in a face-centered cubic lattice with bulk coordination number 12, where only the single 5s electron is delocalized to copper and gold. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are weak; this observation explains the low high ductility of single crystals of silver.
Silver has a brilliant white metallic luster that can take a high polish, and, so characteristic that the name of the metal itself has become a colour name. Unlike copper and gold, the energy required to excite an electron from the filled d band to the s-p conduction band in silver is large enough that it no longer corresponds to absorption in the visible region of the spectrum, but rather in the ultraviolet. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm. At wavelengths shorter than 450 nm, silver's reflectivity is inferior to that of aluminium and drops to zero near 310 nm. High electrical and thermal conductivity is common to the elements in group 11, because their single s electron is free and does not interact with the filled d subshell, as such interactions lower electron mobility; the electrical conductivity of silver is the greatest of all metals, greater than copper, but it is not used for this property because of the higher cost.
An exception is in radio-frequency engineering at VHF and higher frequencies where silver plating improves electrical conductivity because those currents tend to flow on the surface of conductors rather than through the interior. During World War II in the US, 13540 tons of silver were used in electromagnets for enriching uranium because of the wartime shortage of copper. Pure silver has the highest thermal conductivity of any metal, although the conductivity of carbon and superfluid helium-4 are higher. Silver has the lowest contact resistance of any metal. Silver forms alloys with copper and gold, as well as zinc. Zinc-silver alloys with low zinc concentration may be considered as face-centred cubic solid solutions of zinc in silver, as the structure of the silver is unchanged while the electron concentration rises as more zinc is added. Increasing the electron concentration further leads to body-centred cubic, complex cubic, hexagonal close-packed phases. Occurring silver is composed of two stable isotopes, 107Ag and 109Ag, with 107Ag being more abundant.
This equal abundance is rare in the periodic table. The atomic weight is 107.8682 u. Both isotopes of silver are produced in stars via the s-process, as well as in supernovas via the r-process. Twenty-eight radioisotopes have been characterized, the most stable being 105Ag with a half-life of 41.29 days, 111Ag with a half-life of 7.45 days, 112Ag with a half-life of 3.13 hours. Silver has numerous nuclear isomers, the most stable being 108mAg, 110mAg and 106mAg. All of the remaining radioactive isotopes have half-lives of less than an hour, the majority of these have half-lives of less than three minutes. Isotopes of silver range in relative atomic mass from 92.950 u