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Violet (color)

Violet is the color of light at the short wavelength end of the visible spectrum. It is one of the seven colors that Isaac Newton labeled when dividing the spectrum of visible light in 1672. Violet light has a wavelength between approximately 380 and 435 nanometers. The color's name is derived from the Viola genus of flowers.

In the RGB color model used in computer and television screens, violet is produced by mixing red and blue light, with more blue than red. In the RYB color model historically used by painters, violet is created with a combination of red and blue pigments and is located between blue and purple on the color wheel. In the CMYK color model used in printing, violet is created with a combination of magenta and cyan pigments, with more magenta than cyan. On the RGB/CMY(K) color wheel, violet is located between blue and magenta.

Violet is closely associated with purple. In optics, violet is a spectral color (referring to the color of different single wavelengths of light), whereas purple is the color of various combinations of red and blue (or violet) light, some of which humans perceive as similar to violet. In common usage, both terms are used to refer to a variety of colors between blue and red in hue.

Violet has a long history of association with royalty, originally because Tyrian purple dye was extremely expensive in antiquity. The emperors of Rome wore purple togas, as did the Byzantine emperors. During the Middle Ages, violet was worn by bishops and university professors and was often used in art as the color of the robes of the Virgin Mary. In Chinese painting, the color violet represents the "unity transcending the duality of Yin and yang" and "the ultimate harmony of the universe". In New Age thinking, purple and/or violet is associated with the crown chakra. One European study suggests that violet is the color people most often associate with extravagance, individualism, vanity and ambiguity.

Etymology and definitions
The word violet as a color name derives from the Middle English and Old French violete, in turn from the Latin viola, the name of the violet flower. The first recorded use as a color name in English was in 1370.

Relationship to purple
Violet is closely associated with purple. In optics, violet is a spectral color: It refers to the color of any different single wavelength of light on the short wavelength end of the visible spectrum (between approximately 380 and 435 nanometers), whereas purple is the color of various combinations of red, blue and violet light, some of which humans perceive as similar to violet. In common usage, both terms are used to refer to a variety of colors between blue and red in hue. Historically, violet has tended to be used for bluer hues and purple for redder hues. In the traditional color wheel used by painters, violet and purple are both placed between red and blue, with violet being closer to blue.

Optics
Violet is at one end of the spectrum of visible light, between blue light, which has a longer wavelength, and ultraviolet light, which has a shorter wavelength and is not visible to humans. Violet wavelengths are between approximately 380 and 435 nanometers. Violet objects often appear dark, because human vision becomes less sensitive at wavelengths this short. The reason why to (typical trichromat) humans violet light appears a bit reddish compared to spectral blue (despite spectral red being at the other end of the visible spectrum) is, according to the opponent process hypothesis of color vision, that the S-cone type (i.e. the one most sensitive to short wavelengths) contributes a bit of red to the red-versus-green opponent channel (which at the longer blue wavelengths gets counteracted by the M-cone type). Computer and television screens, using the RGB color model, cannot produce actual violet light and instead mimic it by combining blue light at high intensity with red light at less intensity.

Violet objects are normally composed-light violet. Objects reflecting spectral violet appear very dark, because human vision is relatively insensitive to those wavelengths. Monochromatic lamps emitting spectral-violet wavelengths can be roughly approximated by the color named electric violet, which is a composed-light violet producing a similar effect to the human eye.

Chemistry – pigments and dyes
The earliest violet pigments used by humans, found in prehistoric cave paintings, were made from the minerals manganese and hematite. Manganese is still used today by the Aranda people, a group of indigenous Australians, as a traditional pigment for coloring the skin during rituals. It is also used by the Hopi Indians of Arizona to color ritual objects.

The most famous violet-purple dye in the ancient world was Tyrian purple, made from a type of sea snail called the murex, found around the Mediterranean.

In western Polynesia, residents of the islands made a violet dye similar to Tyrian purple from the sea urchin. In Central America, the inhabitants made a dye from a different sea snail, the purpura, found on the coasts of Costa Rica and Nicaragua. The Mayans used this color to dye fabric for religious ceremonies, and the Aztecs used it for paintings of ideograms, where it symbolized royalty.

During the Middle Ages, most artists made purple or violet on their paintings by combining red and blue pigments; usually blue azurite or lapis-lazuli with red ochre, cinnabar or minium. They also combined lake colors by mixing dye with powder; woad or indigo dye for blue and cochineal dye for red.

Orcein, or purple moss, was another common violet dye. It was known to the ancient Greeks and Hebrews, was made from a Mediterranean lichen called archil or dyer's moss (Roccella tinctoria), combined with an ammoniac, usually urine. Orcein began to achieve popularity again in the 19th century, when violet and purple became the color of demi-mourning, worn after a widow or widower had worn black for a certain time, before he or she returned to wearing ordinary colors.

In the 18th century, chemists in England, France and Germany began to create the first synthetic dyes. Two synthetic purple dyes were invented at about the same time. Cudbear is a dye extracted from orchil lichens that can be used to dye wool and silk, without the use of mordant. Cudbear was developed by Cuthbert Gordon of Scotland: production began in 1758, The lichen is first boiled in a solution of ammonium carbonate. The mixture is then cooled and ammonia is added and the mixture is kept damp for 3–4 weeks. Then the lichen is dried and ground to powder. The manufacture details were carefully protected, with a ten-foot high wall built around the manufacturing facility, and staff consisting of Highlanders sworn to secrecy.

French purple was developed in France at about the same time. The lichen is extracted by urine or ammonia. Then the extract is acidified, the dissolved dye precipitates and is washed. Then it is dissolved in ammonia again, the solution is heated in air until it becomes purple, then it is precipitated with calcium chloride; the resulting dye was more solid and stable than other purples.

Cobalt violet is a synthetic pigment that was invented in the second half of the 19th century, and is made by a similar process as cobalt blue, cerulean blue and cobalt green. It is the violet pigment most commonly used today by artists, along with manganese violet.

Mauveine, also known as aniline purple and Perkin's mauve, was the first synthetic organic chemical dye, discovered serendipitously in 1856. Its chemical name is 3-amino-2,±9-dimethyl-5-phenyl-7-(p-tolylamino) phenazinium acetate.

In the 1950s, a new family of violet synthetic organic pigments called quinacridones came onto the market. They had originally been discovered in 1896, synthesized in 1936 and manufactured in the 1950s. The colors in the group range from deep red to violet in color, and have the molecular formula C20H12N2O2. They have strong resistance to sunlight and washing, and are used in oil paints, watercolors and acrylics, as well as in automobile coatings and other industrial coatings.

Prehistory and antiquity
Violet is one of the oldest colors used by humans. Traces of very dark violet, made by grinding the mineral manganese, mixed with water or animal fat and then brushed on the cave wall or applied with the fingers, are found in the prehistoric cave art in Pech Merle, in France, dating back about 25,000 years. It has also been found in the cave of Altamira and Lascaux. It was sometimes used as an alternative to black charcoal. Sticks of manganese, used for drawing, have been found at sites occupied by Neanderthals in France and Israel. From the grinding tools at various sites, it appears it may also have been used to color the body and to decorate animal skins.

More recently, the earliest dates on cave paintings have been pushed back farther than 35,000 years. Hand paintings on rock walls in Australia may be even older, dating back as far as 50,000 years.

Berries of the genus rubus, such as blackberries, were a common source of dyes in antiquity. The ancient Egyptians made a kind of violet dye by combining the juice of the mulberry with crushed green grapes. The Roman historian Pliny the Elder reported that the Gauls used a violet dye made from bilberry to color the clothing of slaves. These dyes made a satisfactory purple, but it faded quickly in sunlight and when washed.

Middle Ages and Renaissance
Violet and purple retained their status as the color of emperors and princes of the church throughout the long rule of the Byzantine Empire.

While violet was worn less frequently by Medieval and Renaissance kings and princes, it was worn by the professors of many of Europe's new universities. Their robes were modeled after those of the clergy, and they often wore square violet caps and violet robes, or black robes with violet trim.

Violet also played an important part in the religious paintings of the Renaissance. Angels and the Virgin Mary were often portrayed wearing violet robes. The 15th-century Florentine painter Cennino Cennini advised artists: "If you want to make a lovely violet colour, take fine lacca, ultramarine blue (the same amount of the one as of the other)..." For fresco painters, he advised a less-expensive version, made of a mixture of blue indigo and red hematite.

18th and 19th centuries
In the 18th century, purple was a color worn by royalty, aristocrats and other wealthy people. Good-quality purple fabric was too expensive for ordinary people.

The first cobalt violet, the intensely red-violet cobalt arsenate, was highly toxic. Although it persisted in some paint lines into the 20th century, it was displaced by less toxic cobalt compounds such as cobalt phosphate. Cobalt violet appeared in the second half of the 19th century, broadening the palette of artists with its range of purple colors. Cobalt violet was used by Paul Signac (1863–1935), Claude Monet (1840–1926) and Georges Seurat (1859–1891). Today, cobalt ammonium phosphate, cobalt lithium phosphate and cobalt phosphate are available for use by artists. Cobalt ammonium phosphate is the most reddish of the three. Cobalt phosphate is available in two varieties — a deep less saturated blueish type and a lighter and brighter somewhat more reddish type. Cobalt lithium phosphate is a saturated lighter-valued bluish violet. A color similar to cobalt ammonium phosphate, cobalt magnesium borate, was introduced in the later 20th century but was not deemed sufficiently lightfast for artistic use. Cobalt violet is the only truly lightfast purple pigment with relatively strong color saturation. All other light-stable purple pigments are dull by comparison. The high price of the pigment and the toxicity of cobalt have limited its use.

In the 1860s, the popularity of using violet colors suddenly rose among painters and other artists. For example, Vincent van Gogh (1853–1890) was an avid student of color theory. He used violet in many of his paintings of the 1880s, including his paintings of irises and the swirling and mysterious skies of his starry night paintings, and often combined it with its complementary color, yellow. In his painting of his bedroom in Arles (1888), he used several sets of complementary colors; violet and yellow, red and green and orange and blue. In a letter about the painting to his brother Theo, he wrote, "The color here...should be suggestive of sleep and repose in general....The walls are a pale violet. The floor is of red tiles. The wood of the bed and the chairs are fresh butter yellow, the sheet and the pillows light lemon green. The bedspread bright scarlet. The window green. The bed table orange. The bowl blue. The doors lilac....The painting should rest the head or the imagination."

In 1856, a young British chemist named William Henry Perkin was trying to make a synthetic quinine. His experiments produced instead an unexpected residue, which turned out to be the first synthetic aniline dye, a deep purple color called mauveine, or abbreviated simply to mauve (the dye being named after the lighter color of the mallow [mauve] flower). Used to dye clothes, it became extremely fashionable among the nobility and upper classes in Europe, particularly after Queen Victoria wore a silk gown dyed with mauveine to the Royal Exhibition of 1862. Prior to Perkin's discovery, mauve was a color which only the aristocracy and rich could afford to wear. Perkin developed an industrial process, built a factory, and produced the dye by the ton so almost anyone could wear mauve. It was the first of a series of modern industrial dyes which completely transformed both the chemical industry and fashion.

20th and 21st centuries
Violet or purple neckties became popular at the end of the first decade of the 21st century, particularly among political and business leaders.

Popularity
In a European survey, three percent of respondents said violet is their favorite color, ranking it behind blue, green, red, black and yellow (in that order), and tied with orange. Ten percent called it their least favorite color; brown, pink and gray were more unpopular.

Royalty and luxury
Because of its status as the color of Roman emperors, monarchs and princes, purple and violet are often associated with luxury. Certain luxury goods, such as watches and jewelry, are often placed in boxes lined with violet velvet, since violet is the complementary color of yellow and shows gold to best advantage.

Vanity, extravagance and individualism
While violet is the color of humility in the symbolism of the Catholic Church, it has exactly the opposite meaning in general society. A European poll in 2000 showed it was the color most commonly associated with vanity. As a color that rarely exists in nature and so attracts attention, it is seen as a color of individualism and extravagance.

Heian period
In Japan, violet was a popular color introduced into dress during the Heian period (794–1185). The dye was made from the root of the alkanet plant (Anchusa officinalis), known as murasaki in Japanese. At about the same time, Japanese painters began to use a pigment made from the same plant.

New Age
The "New Age Prophetess", Alice Bailey, in her system called the Seven Rays which classifies humans into seven different metaphysical psychological types, the "seventh ray" of "Ceremonial Order" is represented by the color violet. People who have this metaphysical psychological type are said to be "on the Violet Ray".

In the Ascended Master Teachings, the color violet is used to represent the Ascended Master St. Germain.

The Invocation of the Violet Flame is a system of meditation practice used in the "I AM" Activity and by the Church Universal and Triumphant (both Ascended Master Teaching religions).

Religion
In the Roman Catholic church, violet is worn by bishops and archbishops, red by cardinals and white by the Pope. Ordinary priests wear black. As in many other Western churches, violet is the liturgical color of Advent and Lent, which respectively celebrate the expectant waiting and preparation for the celebration of the Crucifixion of Jesus and the time for penance and/or mourning.

A stained glass window installed in the early 1920s in the Cathedral of Our Lady of the Angels in Los Angeles depicts God the Father wearing a violet robe.

After the Vatican II Council, which modified many of the rules of the Catholic church, priests began to wear violet robes when celebrating masses for the dead. Black was no longer used, since it was the color of mourning outside the church and deemed inappropriate in a religious ceremony.

In Hinduism, violet is used to symbolically represent the seventh, crown chakra (Sahasrara).

Politics

In the early 20th century, violet, white and gold were the colors of the women's suffrage movement in the United States, seeking the right to vote for women. The colors were said to represent liberty and dignity. For this reason, the postage stamp issued in 1936 to honor Susan B. Anthony, a prominent leader of the suffrage movement in the United States, was colored the reddish tone of violet sometimes known as red-violet.

In 1908, Emmeline Pethick-Lawrence, co-editor of the Women's Social and Political Union (WSPU) newspaper, designed the color scheme for the suffragette movement in Britain and Ireland, with violet for loyalty and dignity, white for purity and green for hope.

The pan-European movement Volt Europa and its national subsidiary parties use violet in their uniforms.

A small New Age political party in Germany with about 1,150 members is called The Violet Party. It believes in direct democracy, a guaranteed minimum income and politics based on spirituality. It was founded in Dortmund in 2001.

Lesbianism
Violet flowers and their color became symbolically associated with lesbian love. It was used as a special code by lesbians and bisexual women for self-identification and also to communicate support for the sexual preference. This connection originates from the poet Sappho and fragments of her poems. In one poem, she describes a lost love wearing a garland of "violet tiaras, braided rosebuds, dill and crocus twined around" her neck. In another fragment, she recalls her lover as having "put around yourself [many wreaths] of violets and roses."

The labrys lesbian flag, created in 1999 by graphic designer Sean Campbell, features a labrys superimposed on the inverted black triangle set against a violet background.

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Purple

Purple is a color similar in appearance to violet light. In the RYB color model historically used in the arts, purple is a secondary color created by combining red and blue pigments. In the CMYK color model used in modern printing, purple is made by combining magenta pigment with either cyan pigment, black pigment, or both. In the RGB color model used in computer and television screens, purple is created by mixing red and blue light in order to create colors that appear similar to violet light.

Purple has long been associated with royalty, originally because Tyrian purple dye—made from the secretions of sea snails—was extremely expensive in antiquity. Purple was the color worn by Roman magistrates; it became the imperial color worn by the rulers of the Byzantine Empire and the Holy Roman Empire, and later by Roman Catholic bishops. Similarly in Japan, the color is traditionally associated with the emperor and aristocracy.

According to contemporary surveys in Europe and the United States, purple is the color most often associated with rarity, royalty, luxury, ambition, magic, mystery, piety and spirituality. When combined with pink, it is associated with eroticism, femininity, and seduction.

Etymology and definitions
The modern English word purple comes from the Old English purpul, which derives from Latin purpura, which, in turn, derives from the Greek πορφύρα (porphura), the name of the Tyrian purple dye manufactured in classical antiquity from a mucus secreted by the spiny dye-murex snail. The first recorded use of the word purple dates to the late 900s AD.

In prehistory and the ancient world: Tyrian purple
Purple first appeared in prehistoric art during the Neolithic era. The artists of Pech Merle cave and other Neolithic sites in France used sticks of manganese and hematite powder to draw and paint animals and the outlines of their own hands on the walls of their caves. These works have been dated to between 16,000 and 25,000 BC.

Purple textiles, dating back to the early second millennium BCE, were found in Syria, making them the oldest known purple textiles in the world. These findings include textiles from a burial site in Chagar Bazar, dating back to the 18th-16th centuries BCE, as well as preserved textile samples discovered in gypsum at the Royal Palace of Qatna.

As early as the 15th century BC the citizens of Sidon and Tyre, two cities on the coast of Ancient Phoenicia (present day Lebanon), were producing purple dye from a sea snail called the spiny dye-murex. Clothing colored with the Tyrian dye was mentioned in both the Iliad of Homer and the Aeneid of Virgil. The deep, rich purple dye made from this snail became known as Tyrian purple.

The process of making the dye was long, difficult and expensive. Thousands of the tiny snails had to be found, their shells cracked, the snail removed. Mountains of empty shells have been found at the ancient sites of Sidon and Tyre. The snails were left to soak, then a tiny gland was removed and the juice extracted and put in a basin, which was placed in the sunlight. There, a remarkable transformation took place. In the sunlight the juice turned white, then yellow-green, then green, then violet, then a red which turned darker and darker. The process had to be stopped at exactly the right time to obtain the desired color, which could range from a bright crimson to a dark purple, the color of dried blood. Then either wool, linen or silk would be dyed. The exact hue varied between crimson and violet, but it was always rich, bright and lasting.

Tyrian purple became the color of kings, nobles, priests and magistrates all around the Mediterranean. It was mentioned in the Hebrew Bible (Old Testament); in the Book of Exodus, God instructs Moses to have the Israelites bring him an offering including cloth "of blue, and purple, and scarlet," to be used in the curtains of the Tabernacle and the garments of priests. The term used for purple in the 4th-century Latin Vulgate version of the Bible passage is purpura or Tyrian purple. In the Iliad of Homer, the belt of Ajax is purple, and the tails of the horses of Trojan warriors are dipped in purple. In the Odyssey, the blankets on the wedding bed of Odysseus are purple. In the poems of Sappho (6th century BC) she celebrates the skill of the dyers of the Greek kingdom of Lydia who made purple footwear, and in the play of Aeschylus (525–456 BC), Queen Clytemnestra welcomes back her husband Agamemnon by decorating the palace with purple carpets. In 950 BC, King Solomon was reported to have brought artisans from Tyre to provide purple fabrics to decorate the Temple of Jerusalem.

Alexander the Great (when giving imperial audiences as the basileus of the Macedonian Empire), the basileus of the Seleucid Empire, and the kings of Ptolemaic Egypt all wore Tyrian purple.

The Roman custom of wearing purple togas may have come from the Etruscans; an Etruscan tomb painting from the 4th century BC shows a nobleman wearing a deep purple and embroidered toga.

In Ancient Rome, the Toga praetexta was an ordinary white toga with a broad purple stripe on its border. It was worn by freeborn Roman boys who had not yet come of age, curule magistrates, certain categories of priests, and a few other categories of citizens.

The Toga picta was solid purple, embroidered with gold. During the Roman Republic, it was worn by generals in their triumphs, and by the Praetor Urbanus when he rode in the chariot of the gods into the circus at the Ludi Apollinares. During the Empire, the toga picta was worn by magistrates giving public gladiatorial games, and by the consuls, as well as by the emperor on special occasions.

During the Roman Republic, when a triumph was held, the general being honored wore an entirely purple toga bordered in gold, and Roman Senators wore a toga with a purple stripe. However, during the Roman Empire, purple was more and more associated exclusively with the emperors and their officers. Suetonius claims that the early emperor Caligula had the King of Mauretania murdered for the splendour of his purple cloak, and that Nero forbade the use of certain purple dyes. In the late empire the sale of purple cloth became a state monopoly protected by the death penalty.

According to the New Testament, Jesus Christ, in the hours leading up to his crucifixion, was dressed in purple (πορφύρα: porphura) by the Roman garrison to mock his claim to be 'King of the Jews'.

The actual color of Tyrian purple seems to have varied from a reddish to a bluish purple. According to the Roman writer Vitruvius, (1st century BC), the murex shells coming from northern waters, probably Bolinus brandaris, produced a more bluish color than those of the south, probably Hexaplex trunculus. The most valued shades were said to be those closer to the color of dried blood, as seen in the mosaics of the robes of the Emperor Justinian in Ravenna. The chemical composition of the dye from the murex is close to that of the dye from indigo, and indigo was sometimes used to make a counterfeit Tyrian purple, a crime which was severely punished. What seems to have mattered about Tyrian purple was not its color, but its luster, richness, its resistance to weather and light, and its high price.

In modern times, Tyrian purple has been recreated, at great expense. When the German chemist Paul Friedander tried to recreate Tyrian purple in 2008, he needed twelve thousand mollusks to create 1.4 ounces of dye, enough to color a handkerchief. In the year 2000, a gram of Tyrian purple made from ten thousand mollusks according to the original formula cost two thousand euros.

China
In ancient China, purple was obtained not through the Mediterranean mollusc, but purple gromwell. The dye obtained did not easily adhere to fabrics, making purple fabrics expensive. Purple became a fashionable color in the state of Qi (齊, 1046 BC–221 BC) because its ruler, Duke Huan of Qi, developed a preference for it. As a result, the price of purple fabric was over five times that of plain fabric. His minister, Guan Zhong (管仲), eventually convinced him to relinquish this preference.

China was the first culture to develop a synthetic purple color.

An old hypothesis suggested links between the Chinese purple and blue and Egyptian blue, however, molecular structure analysis and evidence such as the absence of lead in Egyptian blue and the lack of examples of Egyptian blue in China, argued against the hypothesis. The use of quartz, barium, and lead components in ancient Chinese glass and Han purple and Han blue has been used to suggest a connection between glassmaking and the manufacture of pigments, and to prove the independence of the Chinese invention. Taoist alchemists may have developed Han purple from their knowledge of glassmaking.

Lead is used by the pigment maker to lower the melting point of the barium in Han Purple.

Purple was regarded as a secondary color in ancient China. In classical times, secondary colors were not as highly prized as the five primary colors of the Chinese spectrum, and purple was used to allude to impropriety, in contrast to crimson, which was deemed a primary color and symbolized legitimacy. Nevertheless, by the 6th century AD, purple was ranked above crimson. Several changes to the ranks of colors occurred after that time.

Purple in the Byzantine Empire and Carolingian Europe
Through the early Christian era, the rulers of the Byzantine Empire continued the use of purple as the imperial color, for diplomatic gifts, and even for imperial documents and the pages of the Bible. Gospel manuscripts were written in gold lettering on parchment that was colored Tyrian purple. Empresses gave birth in the Purple Chamber, and the emperors born there were known as "born to the purple," to separate them from emperors who won or seized the title through political intrigue or military force. Bishops of the Byzantine church wore white robes with stripes of purple, while government officials wore squares of purple fabric to show their rank.

In western Europe, the Emperor Charlemagne was crowned in 800 wearing a mantle of Tyrian purple, and was buried in 814 in a shroud of the same color, which still exists (see below). However, after the fall of Constantinople to the Ottoman Turks in 1453, the color lost its imperial status. The great dye works of Constantinople were destroyed, and gradually scarlet, made with dye from the cochineal insect, became the royal color in Europe.

The Middle Ages and Renaissance
In 1464, Pope Paul II decreed that cardinals should no longer wear Tyrian purple, and instead wear scarlet, from kermes and alum, since the dye from Byzantium was no longer available. Bishops and archbishops, of a lower status than cardinals, were assigned the color purple, but not the rich Tyrian purple. They wore cloth dyed first with the less expensive indigo blue, then overlaid with red made from kermes dye.

While purple was worn less frequently by Medieval and Renaissance kings and princes, it was worn by the professors of many of Europe's new universities. Their robes were modeled after those of the clergy, and they often wore square/violet or purple/violet caps and robes, or black robes with purple/violet trim. Purple/violet robes were particularly worn by students of divinity.

Purple and violet also played an important part in the religious paintings of the Renaissance. Angels and the Virgin Mary were often portrayed wearing purple or violet robes.

18th and 19th centuries
In the 18th century, purple was still worn on occasion by Catherine the Great and other rulers, by bishops and, in lighter shades, by members of the aristocracy, but rarely by ordinary people, because of its high cost. But in the 19th century, that changed.

In 1856, an eighteen-year-old British chemistry student named William Henry Perkin was trying to make a synthetic quinine. His experiments produced instead the first synthetic aniline dye, a purple shade called mauveine, shortened simply to mauve. It took its name from the mallow flower, which is the same color. The new color quickly became fashionable, particularly after Queen Victoria wore a silk gown dyed with mauveine to the Royal Exhibition of 1862. Prior to Perkin's discovery, mauve was a color which only the aristocracy and rich could afford to wear. Perkin developed an industrial process, built a factory, and produced the dye by the ton, so almost anyone could wear mauve. It was the first of a series of modern industrial dyes which completely transformed both the chemical industry and fashion.

Purple was popular with the pre-Raphaelite painters in Britain, including Arthur Hughes, who loved bright colors and romantic scenes.

20th and 21st centuries
At the turn of the century, purple was a favorite color of the Austrian painter Gustav Klimt, who flooded his pictures with sensual purples and violets.

In the 20th century, purple retained its historic connection with royalty; George VI (1896–1952), wore purple in his official portrait, and it was prominent in every feature of the coronation of Elizabeth II in 1953, from the invitations to the stage design inside Westminster Abbey. But at the same time, it was becoming associated with social change; with the Women's Suffrage movement for the right to vote for women in the early decades of the century, with Feminism in the 1970s, and with the psychedelic drug culture of the 1960s.

In the early 20th century, purple, green, and white were the colors of the Women's Suffrage movement, which fought to win the right to vote for women, finally succeeding with the 19th Amendment to the U.S. Constitution in 1920. Later, in the 1970s, in a tribute to the Suffragettes, it became the color of the women's liberation movement.

In the concentration camps of Nazi Germany, prisoners who were members of non-conformist religious groups, such as the Jehovah's Witnesses, were required to wear a purple triangle.

During the 1960s and early 1970s, it was also associated with counterculture, psychedelics, and musicians like Jimi Hendrix with his 1967 song "Purple Haze", or the English rock band of Deep Purple which formed in 1968. Later, in the 1980s, it was featured in the song and album Purple Rain (1984) by the American musician Prince.

The Purple Rain Protest was a protest against apartheid that took place in Cape Town, South Africa on 2 September 1989, in which a police water cannon with purple dye sprayed thousands of demonstrators. This led to the slogan The Purple Shall Govern.

The violet or purple necktie became very popular at the end of the first decade of the 21st century, particularly among political and business leaders. It combined the assertiveness and confidence of a red necktie with the sense of peace and cooperation of a blue necktie, and it went well with the blue business suit worn by most national and corporate leaders.

Optics
The meanings of the color terms violet and purple varies even among native speakers of English, for example between United Kingdom and United States. Optics research on purple and violet contains contributions of authors from different countries and different native languages, it is likely to be inconsistent in the use and meaning of the two colors.

According to some speakers/authors of English, purple, unlike violet, is not one of the colors of the visible spectrum. It was not one of the colors of the rainbow identified by Isaac Newton. According to some authors, purple does not have its own wavelength of light. For this reason, it is sometimes called a non-spectral color. It exists in culture and art, but not, in the same way that violet does, in optics. According to some speakers of English, purple is simply a combination, in various proportions, of two primary colors, red and blue. According to other speakers of English, the same range of colors is called violet.

In some textbooks of color theory, and depending on the geographical-cultural origin of the author, a "purple" is defined as any non-spectral color between violet and red (excluding violet and red themselves). In that case, the spectral colors violet and indigo would not be shades of purple. For other speakers of English, these colors are shades of purple.

In the traditional color wheel long used by painters, purple is placed between crimson and violet. However, also here there is much variation in color terminology depending on cultural background of the painters and authors, and sometimes the term violet is used and placed in between red and blue on the traditional color wheel. In a slightly different variation, on the color wheel, purple is placed between magenta and violet. This shade is sometimes called electric purple (See shades of purple).

In the RGB color model, named for the colors red, green, and blue, used to create all the colors on a computer screen or television, the range of purples is created by mixing red and blue light of different intensities on a black screen. The standard HTML color purple is created by red and blue light of equal intensity, at a brightness that is halfway between full power and darkness.

In color printing, purple is sometimes represented by the color magenta, or sometimes by mixing magenta with red or blue. It can also be created by mixing just red and blue alone, but in that case the purple is less bright, with lower saturation or intensity. A less bright purple can also be created with light or paint by adding a certain quantity of the third primary color (green for light or yellow for pigment).

Relationship with violet
Purple is closely associated with violet. In common usage, both refer to a variety of colors between blue and red in hue. Historically, purple has tended to be used for redder hues and violet for bluer hues. In optics, violet is a spectral color; it refers to the color of any different single wavelength of light on the short wavelength end of the visible spectrum, between approximately 380 and 450 nanometers, whereas purple is the color of various combinations of red, blue, and violet light, some of which humans perceive as similar to violet.

On a chromaticity diagram, the straight line connecting the extreme spectral colors (red and violet) is known as the line of purples (or 'purple boundary'); it represents one limit of human color perception. The color magenta used in the CMYK printing process is near the center of the line of purples, but most people associate the term "purple" with a somewhat bluer tone, such as is displayed by the color "electric purple" (a color also directly on the line of purples), shown below.

On the CIE xy chromaticity diagram, violet is on the curved edge in the lower left, while purples are on the straight line connecting the extreme colors red and violet; this line is known as the line of purples, or the purple line.

Pigments

 * Hematite and manganese are the oldest pigments used for the color purple. They were used by Neolithic artists in the form of sticks, like charcoal, or ground and powdered and mixed with fat, and used as a paint. Hematite is a reddish iron oxide which, when ground coarsely, makes a purple pigment. One such pigment is caput mortuum, whose name is also used in reference to mummy brown. The latter is another pigment containing hematite and historically produced with the use of mummified corpses. Some of its compositions produce a purple color and may be called "mummy violet". Manganese was also used in Roman times to color glass purple.
 * Han purple was the first synthetic purple pigment, invented in China in about 700 BC. It was used in wall paintings and pottery and other applications. In color, it was very close to indigo, which had a similar chemical structure.  Han purple was very unstable, and sometimes was the result of the chemical breakdown of Han blue.

During the Middle Ages, artists usually made purple by combining red and blue pigments; most often blue azurite or lapis-lazuli with red ochre, cinnabar, or minium. They also combined lake colors made by mixing dye with powder; using woad or indigo dye for the blue, and dye made from cochineal for the red.

 * Cobalt violet was the first modern synthetic color in the purple family, manufactured in 1859. It was found, along with cobalt blue, in the palette of Claude Monet, Paul Signac, and Georges Seurat. It was stable, but had low tinting power and was expensive, so quickly went out of use.
 * Manganese violet was a stronger color than cobalt violet, and replaced it on the market.
 * Quinacridone violet, one of a modern synthetic organic family of colors, was discovered in 1896 but not marketed until 1955. It is sold today under a number of brand names.

Dyes
The most famous purple dye in the ancient world was Tyrian purple, made from a type of sea snail called the murex, found around the Mediterranean. (See history section above).

In western Polynesia, residents of the islands made a purple dye similar to Tyrian purple from the sea urchin. In Central America, the inhabitants made a dye from a different sea snail, the purpura, found on the coasts of Costa Rica and Nicaragua. The Mayans used this color to dye fabric for religious ceremonies, while the Aztecs used it for paintings of ideograms, where it symbolized royalty.

In the Middle Ages, those who worked with blue and black dyes belonged to separate guilds from those who worked with red and yellow dyes, and were often forbidden to dye any other colors than those of their own guild. Most purple fabric was made by the dyers who worked with red, and who used dye from madder or cochineal, so Medieval violet colors were inclined toward red.

Orcein, or purple moss, was another common purple dye. It was known to the ancient Greeks and Hebrews, and was made from a Mediterranean lichen called archil or dyer's moss (Roccella tinctoria), combined with an ammoniac, usually urine. Orcein began to achieve popularity again in the 19th century, when violet and purple became the color of demi-mourning, worn after a widow or widower had worn black for a certain time, before he or she returned to wearing ordinary colors.

From the Middle Ages onward, purple dyes for the clothing of common people were often made from the blackberry or other red fruit of the genus rubus, or from the mulberry. All of these dyes were more reddish than bluish, and faded easily with washing and exposure to sunlight.

A popular new dye which arrived in Europe from the New World during the Renaissance was made from the wood of the logwood tree (Haematoxylum campechianum), which grew in Spanish Mexico. Depending on the different minerals added to the dye, it produced a blue, red, black or, with the addition of alum, a purple color, it made a good color, but, like earlier dyes, it did not resist sunlight or washing.

In the 18th century, chemists in England, France and Germany began to create the first synthetic dyes. Two synthetic purple dyes were invented at about the same time. Cudbear is a dye extracted from orchil lichens that can be used to dye wool and silk, without the use of mordant. Cudbear was developed by Dr Cuthbert Gordon of Scotland: production began in 1758, The lichen is first boiled in a solution of ammonium carbonate. The mixture is then cooled and ammonia is added and the mixture is kept damp for 3–4 weeks. Then the lichen is dried and ground to powder. The manufacture details were carefully protected, with a ten-feet high wall being built around the manufacturing facility, and staff consisting of Highlanders sworn to secrecy.

French purple was developed in France at about the same time. The lichen is extracted by urine or ammonia. Then the extract is acidified, the dissolved dye precipitates and is washed. Then it is dissolved in ammonia again, the solution is heated in air until it becomes purple, then it is precipitated with calcium chloride; the resulting dye was more solid and stable than other purples.

Cobalt violet is a synthetic pigment that was invented in the second half of the 19th century, and is made by a similar process as cobalt blue, cerulean blue and cobalt green. It is the violet pigment most commonly used today by artists. In spite of its name, this pigment produces a purple rather than violet color

Mauveine, also known as aniline purple and Perkin's mauve, was the first synthetic organic chemical dye, discovered serendipitously in 1856.

Its chemical name is 3-amino-2,±9-dimethyl-5-phenyl-7-(p-tolylamino)phenazinium acetate.

Fuchsine was another synthetic dye made shortly after mauveine. It produced a brilliant fuchsia color.

In the 1950s, a new family of purple and violet synthetic organic pigments called quinacridone came onto the market. It had originally been discovered in 1896, but were not synthesized until 1936, and not manufactured until the 1950s. The colors in the group range from deep red to bluish purple in color, and have the molecular formula C20H12N2O2. They have strong resistance to sunlight and washing, and are widely used today in oil paints, water colors, and acrylics, as well as in automobile coatings and other industrial coatings.

Anthocyanins
Certain grapes, eggplants, pansies and other fruits, vegetables and flowers may appear purple due to the presence of natural pigments called anthocyanins. These pigments are found in the leaves, roots, stems, vegetables, fruits and flowers of all plants. They aid photosynthesis by blocking harmful wavelengths of light that would damage the leaves. In flowers, the purple anthocyanins help attract insects who pollinate the flowers. Not all anthocyanins are purple; they vary in color from red to purple to blue, green, or yellow, depending upon the level of their pH.

Plants and flowers

 * Purple needlegrass is the state grass of California.

Microbiology

 * Purple bacteria are bacteria that are phototrophic, that is, capable of producing energy through photosynthesis.

 * In April 2007 it was suggested that early archaea may have used retinal, a purple pigment, instead of chlorophyll, to extract energy from the sun. If so, large areas of the ocean and shoreline would have been colored purple; this is called the Purple Earth hypothesis.

Astronomy

 * One of the stars in the Pleiades, called Pleione, is sometimes called Purple Pleione because, being a fast spinning star, it has a purple hue caused by its blue-white color being obscured by a spinning ring of electrically excited red hydrogen gas.
 * The Purple Forbidden enclosure is a name used in traditional Chinese astronomy for those Chinese constellations that surround the north celestial pole.

Geography

 * Purple Mountain is located on the eastern side of Nanjing. Its peaks are often found enveloped in purple clouds at dawn and dusk, hence comes its name "Purple Mountain". The Purple Mountain Observatory is located there.
 * Purple Mountain in County Kerry, Ireland, takes its name from the color of the shivered slate on its summit.
 * Purple Mountain in Wyoming (el. 8392 ft) is a mountain peak in the southern section of the Gallatin Range in Yellowstone National Park.
 * Purple Mountain, Alaska
 * Purple Mountain, Oregon
 * Purple Mountain, Washington
 * Purple Peak, Colorado

Purple mountains phenomenon
It has been observed that the greater the distance between a viewers eyes and mountains, the lighter and more blue or purple they will appear. This phenomenon, long recognized by Leonardo da Vinci and other painters, is called aerial perspective or atmospheric perspective. The more distant the mountains are, the less contrast the eye sees between the mountains and the sky.

The bluish color is caused by an optical effect called Rayleigh scattering. The sunlit sky is blue because air scatters short-wavelength light more than longer wavelengths. Since blue light is at the short wavelength end of the visible spectrum, it is more strongly scattered in the atmosphere than long wavelength red light. The result is that the human eye perceives blue when looking toward parts of the sky other than the sun.

At sunrise and sunset, the light is passing through the atmosphere at a lower angle, and traveling a greater distance through a larger volume of air. Much of the green and blue is scattered away, and more red light comes to the eye, creating the colors of the sunrise and sunset and making the mountains look purple.

The phenomenon is referenced in the song "America the Beautiful", where the lyrics refer to "purple mountains' majesty" among other features of the United States landscape. A Crayola crayon called Purple Mountain Majesty in reference to the lyric was first formulated in 1993.

Mythology
Julius Pollux, a Greek grammarian who lived in the second century AD, attributed the discovery of purple to the Phoenician god and guardian of the city of Tyre, Heracles. According to his account, while walking along the shore with the nymph Tyrus, the god's dog bit into a murex shell, causing his mouth to turn purple. The nymph subsequently requested that Heracles create a garment for her of that same color, with Heracles obliging her demands giving birth to Tyrian purple.

Royalty
In Europe, since some Roman emperors wore a Tyrian purple (purpura) toga praetexta, purple has been the color most associated with power and royalty. The British Royal Family and other European royalty still use it as a ceremonial color on special occasions. In Japan, purple is associated with the emperor and Japanese aristocracy.

Piety, faith, penitence, and theology
In the West, purple or violet is a color often associated with piety and religious faith. In AD 1464, shortly after the Muslim conquest of Constantinople, which terminated the supply of Tyrian purple to Roman Catholic Europe, Pope Paul II decreed that cardinals should henceforth wear scarlet instead of purple, the scarlet being dyed with expensive cochineal. Bishops were assigned the color amaranth, being a pale and pinkish purple made then from a less-expensive mixture of indigo and cochineal.

In the Latin liturgical rites of the Catholic liturgy, purple represents penitence; Anglican and Catholic priests wear a purple stole when they hear confession and a purple stole and chasuble during Advent and Lent. Since the Second Vatican Council of 1962–5, priests may wear purple vestments, but may still wear black ones, when officiating at funerals. The Roman Missal permits black, purple (violet), or white vestments for the funeral Mass. White is worn when a child dies before the age of reason. Students and faculty of theology also wear purple academic dress for graduations and other university ceremonies.

Purple is also often worn by senior pastors of Protestant churches and bishops of the Anglican Communion.

The color purple is also associated with royalty in Christianity, being one of the three traditional offices of Jesus Christ, i. e. king, although such a symbolism was assumed from the earlier Roman association or at least also employed by the ancient Romans.

Vanity, extravagance, individualism
In Europe and America, purple is the color most associated with vanity, extravagance, and individualism. Among the seven deadly sins, it represents pride. It is a color which is used to attract attention.

The artificial, materialism and beauty
Purple is the color most often associated with the artificial and the unconventional. It is the major color that occurs the least frequently in nature, and was the first color to be synthesized.

Ambiguity and ambivalence
Purple is the color most associated with ambiguity. Like other colors made by combining two primary colors, it is seen as uncertain and equivocal.

Mourning
In Britain, purple is sometimes associated with mourning. In Victorian times, close relatives wore black for the first year following a death ("deep mourning"), and then replaced it with purple or dark green trimmed with black. This is rarely practised today.

Cultures of Asian countries

 * The Chinese word for purple, zi, is connected with the North Star, Polaris, or zi Wei in Chinese. In Chinese astrology, the North Star was the home of the Celestial Emperor, the ruler of the heavens. The area around the North Star is called the Purple Forbidden Enclosure in Chinese astronomy. For that reason the Forbidden City in Beijing was also known as the Purple Forbidden City (zi Jin cheng). Purple often represents "the highest," holiest, and "most sacred values" in China.
 * In Taoism, purple is a transitional color and metaphysically between yin and yang.
 * Purple was a popular color introduced into Japanese dress during the Heian period (794–1185). The dye was made from the root of the alkanet plant (Anchusa officinalis), also known as murasaki in Japanese. At about the same time, Japanese painters began to use a pigment made from the same plant.

 * In Thailand, widows in mourning wear the color purple. Purple is also associated with Saturday on the Thai solar calendar.

Ancient Rome
Purple represented the height of Roman virtue and cultural values.

Medieval Europe

 * In medieval Europe, purple represented leadership and the king.
 * In European alchemy during this time, "the 'precious purple tincture'" was a term for various substances alchemists hoped to create. The term and goal of the alchemists evoked kingliness, since the divine right of kings was also thought to aid the alchemists' future.

Engineering
The color purple plays a significant role in the traditions of engineering schools across Canada. Purple is also the color of the Engineering Corp in the British Military.

Idioms and expressions

 * Purple prose refers to pretentious or overly embellished writing. For example, a paragraph containing an excessive number of long and unusual words is called a purple passage.
 * Born to the purple means someone who is born into a life of wealth and privilege. It originally was used to describe the rulers of the Byzantine Empire.
 * A purple patch is a period of exceptional success or good luck. The origins are obscure, but it may refer to the symbol of success of the Byzantine Court. Bishops in Byzantium wore a purple patch on their costume as a symbol of rank.
 * Purple haze refers to a state of mind induced by psychedelic drugs, particularly LSD.
 * Wearing purple is a military slang expression in the U.S., Canada and the U.K. for an officer who is serving in a joint assignment with another service, such as an Army officer on assignment to the Navy. The officer is symbolically putting aside his or her traditional uniform color and exclusive loyalty to their service during the joint assignment, though in fact they continue to wear their own service's uniform.
 * Purple squirrel is a term used by employment recruiters to describe a job candidate with precisely the right education, experience, and qualifications that perfectly fits a job's multifaceted requirements. The assumption is that the perfect candidate is as rare as a real-life purple squirrel.

Military

 * The Purple Heart is a United States military decoration awarded in the name of the President to those who have been wounded or killed during their service.

Politics

 * In United States politics, a purple state (typically a swing state) is a state roughly balanced between Republicans (generally symbolized by red in the 21st century) and Democrats (symbolized by blue).
 * In the politics of the Netherlands, Purple (paars) means a coalition government consisting of liberals and social democrats (symbolized by the colors blue and red, respectively), as opposed to the more common coalitions of the Christian Democrats with one of the other two. Between 1994 and 2002 there were two Purple cabinets, both led by Prime Minister Wim Kok.
 * In the politics of Belgium, as with the Netherlands, a purple government includes liberal and social-democratic parties in coalition. Belgium was governed by Purple governments from 1999 to 2007 under the leadership of Prime Minister Guy Verhofstadt.
 * Purple is the primary color used by many European and American political parties, including Volt Europa, the UK Independence Party, the Social Democrats in the Republic of Ireland, the Liberal People's Party in Norway, and the United States Pirate Party. The Left party in Germany, whose primary color is red, is traditionally portrayed in purple on election maps to distinguish it from the Social Democratic Party of Germany.
 * In the United Kingdom, the color scheme for the suffragette movement in Britain and Ireland was designed with purple for loyalty and dignity, white for purity, and green for hope.

Rhyme

 * In the English language, the word "purple" has only one perfect rhyme, curple. Others are obscure perfect rhymes, such as hirple.
 * Robert Burns rhymes purple with curple in his Epistle to Mrs. Scott.
 * Examples of imperfect rhymes or non-word rhymes with purple:
 * In the song Grace Kelly by Mika the word purple is rhymed with "hurtful".
 * In his hit song "Dang Me", Roger Miller sings these lines:

Sexuality
Purple is sometimes associated with the lesbian, gay, bisexual, and transgender (LGBT) community. It is the symbolic color worn on Spirit Day, a commemoration that began in 2010 to show support for young people who are bullied because of their sexual orientation. Purple is closely associated with bisexuality, largely in part to the bisexual pride flag which combines pink – representing homosexuality – and blue – representing heterosexuality – to create the bisexual purple. The purple hand is another symbol sometimes used by the LGBT community during parades and demonstrations.

Sports and games

 * In Motorsport, purple is used to indicate the fastest times of the race.
 * The National Basketball Association's Los Angeles Lakers, Phoenix Suns and Sacramento Kings use purple as their primary color.
 * In the Indian Premier League, purple is the primary color of the Kolkata Knight Riders.
 * In Major League Baseball, purple is one of the primary colors for the Colorado Rockies.
 * In the National Football League, the Minnesota Vikings and Baltimore Ravens use purple as main colors.
 * The Australian Football League's Fremantle Football Club use purple as one of their primary colors.
 * In association football (soccer), Italian Serie A club ACF Fiorentina, Belgian Pro League club and former Europa League winner R.S.C. Anderlecht, French Ligue 1 club Toulouse FC and Ligue 2 club FC Istres, Spanish La Liga club Real Valladolid, Austrian Football Bundesliga club FK Austria Wien, Hungarian Nemzeti Bajnokság I club Újpest FC, Slovenian PrvaLiga club NK Maribor, former Romanian Liga I clubs FC Politehnica Timișoara and FC Argeș Pitești, Andorran Primera Divisió club CE Principat, German club Tennis Borussia Berlin, Italian club A.S.D. Legnano Calcio 1913, Swedish club Fässbergs IF, Japanese club Kyoto Sanga, Australian A-League Club Perth Glory and American Major League Soccer club Orlando City use purple as one of their primary colors.
 * The Melbourne Storm from Australia's National Rugby League use purple as one of their primary colors.
 * Costa Rica's Primera División soccer team Deportivo Saprissa's main color is purple (actually a burgundy like shade), and their nickname is the "Monstruo Morado", or "Purple Monster".
 * In tennis, the official colors of the Wimbledon championships are deep green and purple (traditionally called mauve).
 * In American college athletics, Louisiana State University, Kansas State University, Texas Christian University, the University of Central Arkansas, Northwestern University, the University of Washington, and East Carolina University all have purple as one of their main team colors.
 * The University of Western Ontario in London, Canada, and Bishop's University in Sherbrooke, Canada, have purple as one of its main team colors.
 * Purple is the color of the ball in Snooker Plus with a 10-point value.
 * In the game of pool, purple is the color of the 4-solid and the 12-striped balls.

Business
The British chocolate company Cadbury chose purple as it was Queen Victoria's favourite color. The company trademarked the color purple for chocolates with registrations in 1995 and 2004. However, the validity of these trademarks is the matter of an ongoing legal dispute following objections by Nestlé.

In flags

 * Purple or violet appear in the flags of only two modern sovereign nations, and are merely ancillary colors in both cases. The Flag of Dominica features a sisserou parrot, a national symbol, while the Flag of Nicaragua displays a rainbow in the center, as part of the coat of arms of Nicaragua.
 * The lower band of the flag of the second Spanish republic (1931–39) was colored a tone of purple, to represent the common people as opposed to the red of the Spanish monarchy, unlike other nations of Europe where purple represented royalty and red represented the common people.
 * In Japan, the prefecture of Tokyo's flag is purple, as is the flag of Ichikawa and other Japanese municipalities.
 * Porpora, or purpure, a shade of purple, was added late to the list of colors of European heraldry. A purple lion was the symbol of the old Spanish Kingdom of León (910–1230), and it later appeared on the flag of Spain, when the Kingdom of Castile and Kingdom of León merged.

Further references

 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.
 * "The perception of color", from Schiffman, H.R. (1990). Sensation and perception: An integrated approach (3rd edition). New York: John Wiley & Sons.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Purple


text:
Talk:Tobacco

The Market between Buyers and Sellers of Tobacco Crops
I think it warrants a section that details how the buying and selling of tobacco crops has changed over the years. Previously tobacco was bought and sold in an open air  auction/market between farmers and big companies. That has shifted to where big companies contract out tobacco production with farmers directly and this has caused the open market auction of tobacco to collapse. 15:02, 13 August 2010 Albyva (talk | contribs)

Spanish Monopoly prior to Rolfe
If tobacco was used all over the pre-columbian Americas why would Spain have a monopoly. Neither this page nor the History of tobacco page speak to this.

Child labor and failed verification
The article makes statements about child labor and cites source as "ILO. International Hazard Datasheets on Occupations: Field Crop Worker" with no online source. If one googles this datasheet one finds there's no mention about child labour, tobacco or nicote in it at all. The same claims with same citation are in article Cultivation of tobacco.--Custoo (talk) 16:00, 27 July 2017 (UTC)
 * It seems that some of the statements might be from a Human Rights Watch report cited in the Cultivation of tobacco article.--Custoo (talk) 16:25, 27 July 2017 (UTC)
 * Just a reminder: sources don't have to be online. WP:RS:
 * The term "published" is most commonly associated with text materials, either in traditional printed format or online. However, audio, video, and multimedia materials that have been recorded then broadcast, distributed, or archived by a reputable party may also meet the necessary criteria to be considered reliable sources. Like text sources, media sources must be produced by a reliable third party and be properly cited. Additionally, an archived copy of the media must exist. It is convenient, but by no means necessary, for the archived copy to be accessible via the Internet.
 * --Thnidu (talk) 22:37, 27 July 2017 (UTC)
 * what is the relevance of your reminder? The source can be found online and it doesn't containg any of the things that it is cited for in this article? --Custoo (talk) 14:17, 28 July 2017 (UTC)
 * You wrote
 * The article makes statements about child labor and cites source as "ILO. International Hazard Datasheets on Occupations: Field Crop Worker" with no online source.
 * I see that I reacted too quickly; I could have read your comment more carefully. I apologize. --Thnidu (talk) 16:45, 28 July 2017 (UTC)

Billion Usage
I question the edit of even date by "2601:2c4:c700:4f37:3d68:bbee:7c4:5084" to replace "thousand million" with "billion". It is not a typo; it is explicit usage. "Billion" unfortunately is consistent with usage throughout the article, but it is ambiguous: In North America 1 billion is one thousand million, but in most of the rest of the English-speaking world it is not: 1 billion = one million million. "One thousand million" is unambiguous. I am not going to revert the edit, as "billion" is used passim in this article (presumably in the American sense) and I am certainly not about to change the whole article, especially as I suspect this ambiguity is very widespread in WP; but I wanted to make the point that not all WP users are North American and will interpret "billion" differently. en.wikipedia allows both American and Received English spelling and other usages; I would recommend the Received English usage wherever possible ("one thousand million") because it is unambiguous and can be understood by all. It may also help avoid errors in translation, e.g. French milliard vs. billion. D Anthony Patriarche (talk) 21:18, 9 November 2017 (UTC)

health effects in humans section?
I came here to learn about the health effects of tobacco consumption. Why isn't there a section on that? nhinchey (talk) 03:08, 26 June 2021 (UTC)

Mythology section is bizarre
I’m not even sure how to describe it… it’s like they just copied and pasted excerpts from a religious text, with zero citations or attributions, and no context. It’s a narrative about demons and enlightenment written in nonstandard English, with what appear to be prayers included? It does not seem like something that belongs in an informational article. 2600:1700:6D80:1B4F:7D0A:573F:B389:A954 (talk) 20:51, 8 November 2023 (UTC)

title: Talk:Tobacco


text:
Unexpected hanging paradox

The unexpected hanging paradox or surprise test paradox is a paradox about a person's expectations about the timing of a future event which they are told will occur at an unexpected time. The paradox is variously applied to a prisoner's hanging or a surprise school test. It was first introduced to the public in Martin Gardner's March 1963 Mathematical Games column in Scientific American magazine.

There is no consensus on its precise nature and consequently a canonical resolution has not been agreed on. Logical analyses focus on "truth values", for example by identifying it as paradox of self-reference. Epistemological studies of the paradox instead focus on issues relating to knowledge; for example, one interpretation reduces it to Moore's paradox. Some regard it as a "significant problem" for philosophy.

Description
The paradox has been described as follows:

"A judge tells a condemned prisoner that he will be hanged at noon on one weekday in the following week but that the execution will be a surprise to the prisoner. He will not know the day of the hanging until the executioner knocks on his cell door at noon that day.

Having reflected on his sentence, the prisoner draws the conclusion that he will escape from the hanging. His reasoning is in several parts. He begins by concluding that the 'surprise hanging' can't be on Friday, as if he hasn't been hanged by Thursday, there is only one day left – and so it won't be a surprise if he's hanged on Friday. Since the judge's sentence stipulated that the hanging would be a surprise to him, he concludes it cannot occur on Friday.

He then reasons that the surprise hanging cannot be on Thursday either, because Friday has already been eliminated and if he hasn't been hanged by Wednesday noon, the hanging must occur on Thursday, making a Thursday hanging not a surprise either. By similar reasoning, he concludes that the hanging can also not occur on Wednesday, Tuesday or Monday. Joyfully he retires to his cell confident that the hanging will not occur at all.

The next week, the executioner knocks on the prisoner's door at noon on Wednesday – which, despite all the above, was an utter surprise to him. Everything the judge said came true."

Other versions of the paradox replace the death sentence with a surprise fire drill, examination, pop quiz, A/B test launch, a lion behind a door, or a marriage proposal.

Logical school
Formulation of the judge's announcement into formal logic is made difficult by the vague meaning of the word "surprise". An attempt at formulation might be:

 * The prisoner will be hanged next week and the date (of the hanging) will not be deducible the night before from the assumption that the hanging will occur during the week (A).

Given this announcement the prisoner can deduce that the hanging will not occur on the last day of the week. However, in order to reproduce the next stage of the argument, which eliminates the penultimate day of the week, the prisoner must argue that his ability to deduce, from statement (A), that the hanging will not occur on the last day, implies that a second-to-last-day hanging would not be surprising. But since the meaning of "surprising" has been restricted to not deducible from the assumption that the hanging will occur during the week instead of not deducible from statement (A), the argument is blocked.

This suggests that a better formulation would in fact be:

 * The prisoner will be hanged next week and its date will not be deducible the night before using this statement as an axiom (B).

Fitch has shown that this statement can still be expressed in formal logic. Using an equivalent form of the paradox which reduces the length of the week to just two days, he proved that although self-reference is not illegitimate in all circumstances, it is in this case because the statement is self-contradictory.

Epistemological school
Various epistemological formulations have been proposed that show that the prisoner's tacit assumptions about what he will know in the future, together with several plausible assumptions about knowledge, are inconsistent.

Chow (1998) provides a detailed analysis of a version of the paradox in which a surprise hanging is to take place on one of two days. Applying Chow's analysis to the case of the unexpected hanging (again with the week shortened to two days for simplicity), we start with the observation that the judge's announcement seems to affirm three things:

 * S1: The hanging will occur on Monday or Tuesday.
 * S2: If the hanging occurs on Monday, then the prisoner will not know on Sunday evening that it will occur on Monday.
 * S3: If the hanging occurs on Tuesday, then the prisoner will not know on Monday evening that it will occur on Tuesday.

As a first step, the prisoner reasons that a scenario in which the hanging occurs on Tuesday is impossible because it leads to a contradiction: on the one hand, by S3, the prisoner would not be able to predict the Tuesday hanging on Monday evening; but on the other hand, by S1 and process of elimination, the prisoner would be able to predict the Tuesday hanging on Monday evening.

Chow's analysis points to a subtle flaw in the prisoner's reasoning. What is impossible is not a Tuesday hanging. Rather, what is impossible is a situation in which the hanging occurs on Tuesday despite the prisoner knowing on Monday evening that the judge's assertions S1, S2, and S3 are all true.

The prisoner's reasoning, which gives rise to the paradox, is able to get off the ground because the prisoner tacitly assumes that on Monday evening, he will (if he is still alive) know S1, S2, and S3 to be true. This assumption seems unwarranted on several different grounds. It may be argued that the judge's pronouncement that something is true can never be sufficient grounds for the prisoner knowing that it is true. Further, even if the prisoner knows something to be true in the present moment, unknown psychological factors may erase this knowledge in the future. Finally, Chow suggests that because the statement which the prisoner is supposed to "know" to be true is a statement about his inability to "know" certain things, there is reason to believe that the unexpected hanging paradox is simply a more intricate version of Moore's paradox. A suitable analogy can be reached by reducing the length of the week to just one day. Then the judge's sentence becomes: You will be hanged tomorrow, but you do not know that.

title: Unexpected hanging paradox


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Feldspar

Feldspar (sometimes spelled felspar) is a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the plagioclase (sodium-calcium) feldspars and the alkali (potassium-sodium) feldspars. Feldspars make up about 60% of the Earth's crust and 41% of the Earth's continental crust by weight.

Feldspars crystallize from magma as both intrusive and extrusive igneous rocks and are also present in many types of metamorphic rock. Rock formed almost entirely of calcic plagioclase feldspar is known as anorthosite. Feldspars are also found in many types of sedimentary rocks.

Compositions
The feldspar group of minerals consists of tectosilicates, silicate minerals in which silicon ions are linked by shared oxygen ions to form a three-dimensional network. Compositions of major elements in common feldspars can be expressed in terms of three endmembers:
 * potassium feldspar (K-spar) endmember KAlSi$3$O$8$
 * albite endmember NaAlSi$3$O$8$
 * anorthite endmember CaAl$2$Si$2$O$8$

Solid solutions between K-feldspar and albite are called alkali feldspar. Solid solutions between albite and anorthite are called plagioclase, or, more properly, plagioclase feldspar. Only limited solid solution occurs between K-feldspar and anorthite, and in the two other solid solutions, immiscibility occurs at temperatures common in the crust of the Earth. Albite is considered both a plagioclase and alkali feldspar.

The ratio of alkali feldspar to plagioclase feldspar, together with the proportion of quartz, is the basis for the QAPF classification of igneous rock. Calcium-rich plagioclase is the first feldspar to crystallize from cooling magma, but the plagioclase becomes increasingly sodium-rich as crystallization continues. This defines the continuous Bowen's reaction series. K-feldspar is the final feldspar to crystallize from the magma.

Alkali feldspars
Alkali feldspars are grouped into two types: those containing potassium in combination with sodium, aluminium, or silicon; and those where potassium is replaced by barium. The first of these include:
 * orthoclase (monoclinic) KAlSi3O8
 * sanidine (monoclinic) (K,Na)AlSi3O8
 * microcline (triclinic) KAlSi3O8
 * anorthoclase (triclinic) (Na,K)AlSi3O8

Potassium and sodium feldspars are not perfectly miscible in the melt at low temperatures, therefore intermediate compositions of the alkali feldspars occur only in higher temperature environments. Sanidine is stable at the highest temperatures, and microcline at the lowest. Perthite is a typical texture in alkali feldspar, due to exsolution of contrasting alkali feldspar compositions during cooling of an intermediate composition. The perthitic textures in the alkali feldspars of many granites can be seen with the naked eye. Microperthitic textures in crystals are visible using a light microscope, whereas cryptoperthitic textures can be seen only with an electron microscope.

Ammonium feldspar
Buddingtonite is an ammonium feldspar with the chemical formula: NH4AlSi3O8. It is a mineral associated with hydrothermal alteration of the primary feldspar minerals.

Barium feldspars
Barium feldspars form as the result of the substitution of barium for potassium in the mineral structure. Barium feldspars are sometimes classified as a separate group of feldspars, and sometimes they are classified as a sub-group of alkali feldspars.

The barium feldspars are monoclinic and include the following:
 * celsian BaAl2Si2O8
 * hyalophane (K,Ba)(Al,Si)4O8

Plagioclase feldspars
The plagioclase feldspars are triclinic. The plagioclase series follows (with percent anorthite in parentheses):
 * albite (0 to 10) NaAlSi3O8
 * oligoclase (10 to 30) (Na,Ca)(Al,Si)AlSi2O8
 * andesine (30 to 50)
 * labradorite (50 to 70) (Ca,Na)Al(Al,Si)Si2O8
 * bytownite (70 to 90) (NaSi,CaAl)AlSi2O8
 * anorthite (90 to 100) CaAl2Si2O8

Intermediate compositions of exsolve to two feldspars of contrasting composition during cooling, but diffusion is much slower than in alkali feldspar, and the resulting two-feldspar intergrowths typically are too fine-grained to be visible with optical microscopes. The immiscibility gaps in the plagioclase solid solutions are complex compared to the gap in the alkali feldspars. The play of colours visible in some feldspar of labradorite composition is due to very fine-grained exsolution lamellae known as Bøggild intergrowth. The specific gravity in the plagioclase series increases from albite (2.62) to anorthite (2.72–2.75).

Structure
The structure of a feldspar crystal is based on aluminosilicate tetrahedra. Each tetrahedron consists of an aluminium or silicon ion surrounded by four oxygen ions. Each oxygen ion, in turn, is shared by a neighbouring tetrahedron to form a three-dimensional network. The structure can be visualized as long chains of aluminosilicate tetrahedra, sometimes described as crankshaft chains because their shape is kinked. Each crankshaft chain links to neighbouring crankshaft chains to form a three-dimensional network of fused four-member rings. The structure is open enough for cations (typically sodium, potassium, or calcium) to fit into the structure and provide charge balance.

Etymology
The name feldspar derives from the German Feldspat, a compound of the words Feld ("field") and Spat ("flake"). Spat had long been used as the word for "a rock easily cleaved into flakes"; Feldspat was introduced in the 18th century as a more specific term, referring perhaps to its common occurrence in rocks found in fields (Urban Brückmann, 1783) or to its occurrence as "fields" within granite and other minerals (René-Just Haüy, 1804). The change from Spat to -spar was influenced by the English word spar, meaning a non-opaque mineral with good cleavage. Feldspathic refers to materials that contain feldspar. The alternate spelling, felspar, has fallen out of use. The term 'felsic', meaning light coloured minerals such as quartz and feldspars, is an acronymic word derived from feldspar and silica, unrelated to the obsolete spelling 'felspar'.

Weathering
Chemical weathering of feldspars happens by hydrolysis and produces clay minerals, including illite, smectite, and kaolinite. Hydrolysis of feldspars begins with the feldspar dissolving in water, which happens best in acidic or basic solutions and less well in neutral ones. The speed at which feldspars are weathered is controlled by how quickly they are dissolved. Dissolved feldspar reacts with H+ or OH− ions and precipitates clays. The reaction also produces new ions in solution, with the variety of ions controlled by the type of feldspar reacting.

The abundance of feldspars in the Earth's crust means that clays are very abundant weathering products. About 40% of minerals in sedimentary rocks are clays and clays are the dominant minerals in the most common sedimentary rocks, mudrocks. They are also an important component of soils. Feldspar that has been replaced by clay looks chalky compared to more crystalline and glassy unweathered feldspar grains.

Feldspars, especially plagioclase feldspars, are not very stable at the Earth's surface due to their high formation temperature. This lack of stability is why feldspars are easily weathered to clays. Because of this tendency to weather easily, feldspars are usually not prevalent in sedimentary rocks. Sedimentary rocks that contain large amounts of feldspar indicate that the sediment did not undergo much chemical weathering before being buried. This means it was probably transported a short distance in cold and/or dry conditions that did not promote weathering, and that it was quickly buried by other sediment. Sandstones with large amounts of feldspar are called arkoses.

Applications
Feldspar is a common raw material used in glassmaking, ceramics, and to some extent as filler and an extender in paint, plastics, and rubber. In the US, about 66% of feldspar is consumed in glassmaking, including glass containers and glass fibre. Ceramics (including electrical insulators, sanitaryware, tableware and tile) and other uses, such as fillers, accounted for the remainder.

Glass: Feldspar provides both K2O and Na2O for fluxing, and Al2O3 and CaO as stabilizers. As an important source of Al2O3 for glassmaking, feldspar is valued for its low iron and refractory mineral content, a low cost per unit of Al2O3, no volatiles and no waste.

Ceramics: Feldspars are used in the ceramic industry as a flux to form a glassy phase in bodies during firing, and thus promote vitrification. They also are used as a source of alkalies and alumina in glazes. The composition of feldspar used in different ceramic formulations varies depending on various factors, including the properties of the individual grade, the other raw materials and the requirements of the finished products. However, typical additions include: tableware, 15% to 30% feldspar; high-tension electrical porcelains, 25% to 35%; sanitaryware, 25%; wall tile, 0% to 10%; and dental porcelain up to 80% feldspar.

Earth sciences: In earth sciences and archaeology, feldspars are used for potassium-argon dating, argon-argon dating and luminescence dating.

Minor use: Some household cleaners (such as Bar Keepers Friend and Bon Ami) use feldspar to give a mild abrasive action.

Production
The USGS estimated global production of feldspar in 2020 to be 26 million tonnes, with the top four producing countries being: China 2 million tonnes; India 5 million tonnes; Italy 4 million; Turkey 7.6 million tonnes.

Commercial grades
Typical mineralogical and chemical analyses of three commercial grades used in ceramics are:

Extraterrestrial
In October 2012, the Curiosity rover found high feldspar content in a Mars rock.

title: Feldspar


text:
Best, worst and average case

In computer science, best, worst, and average cases of a given algorithm express what the resource usage is at least, at most and on average, respectively. Usually the resource being considered is running time, i.e. time complexity, but could also be memory or some other resource. Best case is the function which performs the minimum number of steps on input data of n elements. Worst case is the function which performs the maximum number of steps on input data of size n. Average case is the function which performs an average number of steps on input data of n elements.

In real-time computing, the worst-case execution time is often of particular concern since it is important to know how much time might be needed in the worst case to guarantee that the algorithm will always finish on time.

Average performance and worst-case performance are the most used in algorithm analysis. Less widely found is best-case performance, but it does have uses: for example, where the best cases of individual tasks are known, they can be used to improve the accuracy of an overall worst-case analysis. Computer scientists use probabilistic analysis techniques, especially expected value, to determine expected running times.

The terms are used in other contexts; for example the worst- and best-case outcome of an epidemic, worst-case temperature to which an electronic circuit element is exposed, etc. Where components of specified tolerance are used, devices must be designed to work properly with the worst-case combination of tolerances and external conditions.

Best-case performance for algorithm
The term best-case performance is used in computer science to describe an algorithm's behavior under optimal conditions. For example, the best case for a simple linear search on a list occurs when the desired element is the first element of the list.

Development and choice of algorithms is rarely based on best-case performance: most academic and commercial enterprises are more interested in improving average-case complexity and worst-case performance. Algorithms may also be trivially modified to have good best-case running time by hard-coding solutions to a finite set of inputs, making the measure almost meaningless.

Worst-case versus amortized versus average-case performance
Worst-case performance analysis and average-case performance analysis have some similarities, but in practice usually require different tools and approaches.

Determining what typical input means is difficult, and often that average input has properties which make it difficult to characterise mathematically (consider, for instance, algorithms that are designed to operate on strings of text). Similarly, even when a sensible description of a particular "average case" (which will probably only be applicable for some uses of the algorithm) is possible, they tend to result in more difficult analysis of equations.

Worst-case analysis gives a safe analysis (the worst case is never underestimated), but one which can be overly pessimistic, since there may be no (realistic) input that would take this many steps.

In some situations it may be necessary to use a pessimistic analysis in order to guarantee safety. Often however, a pessimistic analysis may be too pessimistic, so an analysis that gets closer to the real value but may be optimistic (perhaps with some known low probability of failure) can be a much more practical approach. One modern approach in academic theory to bridge the gap between worst-case and average-case analysis is called smoothed analysis.

When analyzing algorithms which often take a small time to complete, but periodically require a much larger time, amortized analysis can be used to determine the worst-case running time over a (possibly infinite) series of operations. This amortized cost can be much closer to the average cost, while still providing a guaranteed upper limit on the running time. So e.g. online algorithms are frequently based on amortized analysis.

The worst-case analysis is related to the worst-case complexity.

Practical consequences
Many algorithms with bad worst-case performance have good average-case performance. For problems we want to solve, this is a good thing: we can hope that the particular instances we care about are average. For cryptography, this is very bad: we want typical instances of a cryptographic problem to be hard. Here methods like random self-reducibility can be used for some specific problems to show that the worst case is no harder than the average case, or, equivalently, that the average case is no easier than the worst case.

On the other hand, some data structures like hash tables have very poor worst-case behaviors, but a well written hash table of sufficient size will statistically never give the worst case; the average number of operations performed follows an exponential decay curve, and so the run time of an operation is statistically bounded.

Sorting algorithms

 * Insertion sort applied to a list of n elements, assumed to be all different and initially in random order. On average, half the elements in a list A1 ... Aj are less than element Aj+1, and half are greater. Therefore, the algorithm compares the (j + 1)th element to be inserted on the average with half the already sorted sub-list, so tj = j/2. Working out the resulting average-case running time yields a quadratic function of the input size, just like the worst-case running time.
 * Quicksort applied to a list of n elements, again assumed to be all different and initially in random order. This popular sorting algorithm has an average-case performance of O(n log(n)), which contributes to making it a very fast algorithm in practice. But given a worst-case input, its performance degrades to O(n2). Also, when implemented with the "shortest first" policy, the worst-case space complexity is instead bounded by O(log(n)).
 * Heapsort has O(n) time when all elements are the same. Heapify takes O(n) time and then removing elements from the heap is O(1) time for each of the n elements. The run time grows to O(nlog(n)) if all elements must be distinct.
 * Bogosort has O(n) time when the elements are sorted on the first iteration. In each iteration all elements are checked if in order. There are n! possible permutations; with a balanced random number generator, almost each permutation of the array is yielded in n! iterations. Computers have limited memory, so the generated numbers cycle; it might not be possible to reach each permutation. In the worst case this leads to O(∞) time, an infinite loop.

Data structures

 * Linear search on a list of n elements. In the absolute worst case, the search must visit every element once. This happens when the value being searched for is either the last element in the list, or is not in the list. However, on average, assuming the value searched for is in the list and each list element is equally likely to be the value searched for, the search visits only n/2 elements.

title: Best, worst and average case