| Section2 = {{Chembox Properties | Formula = (C₅O₂H₈)_n | MolarMass = varies | Appearance = | Density = 1.18 g/cm³ | Melting_notes = | BoilingPt = | Boiling_notes = | Solubility = | SolubleOther = | Solvent = Chloroform (poor) | LogP = | VaporPressure = | HenryConstant = | Young's Modulus = 1.8–3.1 GPa | AtmosphericOHRateConstant = | pKa = | pKb = | RefractIndex = 1.4914 at 587.6 nm. It has since been sold under many different names including Lucite and Perspex.

PMMA is an economical alternative to polycarbonate (PC) when extreme strength is not necessary. Additionally, PMMA does not contain the potentially harmful bisphenol-A subunits found in polycarbonate. It is often preferred because of its moderate properties, easy handling and processing, and low cost, but behaves in a brittle manner when loaded, especially under an impact force, and is more prone to scratching compared to glass.

History

The first acrylic acid was created in 1843. Methacrylic acid, derived from acrylic acid, was formulated in 1865. The reaction between methacrylic acid and methanol results in the ester methyl methacrylate. The German chemists Fittig and Paul discovered in 1877 the polymerization process that turns methyl methacrylate into polymethyl methacrylate. In 1933 the German chemist Otto Röhm patented and registered the brand name PLEXIGLAS. In 1936 the first commercially viable production of acrylic safety glass began. During World War II acrylic glass was used for submarine periscopes, windshields, canopies, and gun turrets for airplanes.

Names

PMMA has been sold under a variety of brand names and generic names. It is often generically called acrylic glass, although it is chemically unrelated to glass. It is sometimes called simply acrylic, although acrylic can also refer to other polymers or copolymers containing polyacrylonitrile. Other notable trade names include:

Plexiglas Altuglas (Arkema) Lucite Perspex Optix (Plaskolite)

Synthesis

PMMA is routinely produced by emulsion polymerization, solution polymerization and bulk polymerization. Generally radical initiation is used (including living polymerization methods), but anionic polymerization of PMMA can also be performed. To produce of PMMA, about of petroleum is needed.

Processing

The glass transition temperature of PMMA ranges from ; the range is so wide because of the vast number of commercial compositions. The forming temperature starts at the glass transition temperature and goes up from there. All common molding processes may be used, including injection molding, compression molding and extrusion. The highest quality PMMA sheets are produced by cell casting, but in this case, the polymerization and molding steps occur concurrently. The strength of the material is higher than molding grades owing to its extremely high molecular mass. Rubber toughening has been used to increase the strength of PMMA owing to its brittle behavior in response to applied loads.

Handling, cutting, and joining

PMMA can be joined using cyanoacrylate cement, more commonly known as superglue, with heat (melting), or by using solvents such as di- or trichloromethane to dissolve the plastic at the joint which then fuses and sets, forming an almost invisible weld. Scratches may easily be removed by polishing or by heating the surface of the material.

Laser cutting may be used to form intricate designs from PMMA sheets. PMMA vaporizes to gaseous compounds (including its monomers) upon laser cutting, so a very clean cut is made, and cutting is performed very easily. However, the pulsed lasercutting introduces a high internal stresses along the cut edge, which when exposed to solvents produces undesirable "stress-crazing" at the cut edge and several millimetres deep. Even ammonium-based glass-cleaner and almost everything short of soap-and-water produces similar undesirable crazing, sometimes over the entire surface of the cut parts, at great distances from the stressed edge. Annealing the PMMA sheet/parts is therefore an obligatory post-processing step when intending to chemically bond lasercut parts together. This involves heating the parts in an air circulating oven from room temperature up to 90 degrees C (at a rate of no more than 18 degrees per hour) down to room temperature (at a rate of no more than 12 degrees per hour). Temperature should be maintained as follows: One hour for 3mm thickness, two hours for up to 6mm thickness, four hours for up to 12mm thickness, and six hours for up to 20mm thickness. A rapid annealing cycle is reliable for thin sheets and involves placing them in a pre-heated oven to 80 degrees C for one hour, then removing parts from oven and allowing to cool to room temperature. This added time component should be factored into the whole fabrication process, and the alternative Zero-rake sawcutting technique may provide better cost-effectiveness, unless complex non-straight line edges are required. In this respect PMMA has an advantage over competing polymers such as polystyrene and polycarbonate, which require higher laser powers and give more messy and charred laser cuts.

In the majority of applications, it will not shatter. Rather, it breaks into large dull pieces. Since PMMA is softer and more easily scratched than glass, scratch-resistant coatings are often added to PMMA sheets to protect it (as well as possible other functions).

Acrylate resin casting

chemical sample used for teaching. The sample vial of corrosive and poisonous liquid has been cast into an acrylic plastic cube]] Methyl methacrylate "synthetic resin" for casting (simply the bulk liquid chemical) may be used in conjunction with a polymerization catalyst such as MEKP, to produce hardened transparent PMMA in any shape, from a mold. Objects like insects or coins, or even dangerous chemicals in beakable quartz ampules, may be embedded in such "cast" blocks, for display and safe handling.

Properties

that makes up PMMA]]

PMMA is a strong and lightweight material. It has a density of 1.17–1.20 g/cm³, It also has good impact strength, higher than both glass and polystyrene; however, PMMA's impact strength is still significantly lower than polycarbonate and some engineered polymers. PMMA ignites at and burns, forming carbon dioxide, water, carbon monoxide and low molecular weight compounds, including formaldehyde.

PMMA transmits up to 92% of visible light (3 mm thickness), and gives a reflection of about 4% from each of its surfaces on account of its refractive index (1.4914 at 587.6 nm). It filters ultraviolet (UV) light at wavelengths below about 300 nm (similar to ordinary window glass). Some manufacturers add coatings or additives to PMMA to improve absorption in the 300–400 nm range. PMMA passes infrared light of up to 2800 nm and blocks IR of longer wavelengths up to 25 µm. Colored PMMA varieities allow specific IR wavelengths to pass while blocking visible light (for remote control or heat sensor applications, for example).

PMMA swells and dissolves in many organic solvents; it also has poor resistance to many other chemicals on account of its easily hydrolyzed ester groups. Nevertheless, its environmental stability is superior to most other plastics such as polystyrene and polyethylene, and PMMA is therefore often the material of choice for outdoor applications.

PMMA as maximum water absorption ratio of 0.3–0.4% by weight. Tensile strength decreases with increased water absorption. Its coefficient of thermal expansion is relatively high as (5–10)×10⁻⁵ /K.

Modification of properties

Pure poly(methyl methacrylate) homopolymer is rarely sold as an end product, since it is not optimized for most applications. Rather, modified formulations with varying amounts of other comonomers, additives, and fillers are created for uses where specific properties are required. For example,

A small amount of acrylate comonomers are routinely used in PMMA grades destined for heat processing, since this stabilizes the polymer to depolymerization ("unzipping") during processing.

Comonomers such as butyl acrylate are often added to improve impact strength.

Comonomers such as methacrylic acid can be added to increase the glass transition temperature of the polymer for higher temperature use such as in lighting applications.

Plasticizers may be added to improve processing properties, lower the glass transition temperature, or improve impact properties.

Dyes may be added to give color for decorative applications, or to protect against (or filter) UV light.

Fillers may be added to improve cost-effectiveness.

Poly(methyl acrylate)

The polymer of methyl acrylate, PMA or poly(methyl acrylate), is similar to poly(methyl methacrylate), except for the lack of methyl groups on the backbone carbon chain. PMA is a soft white rubbery material that is softer than PMMA because its long polymer chains are thinner and smoother and can more easily slide past each other.

Uses

PMMA is a versatile material and has been used in a wide range of fields and applications.

Transparent glass substitute

, with single conical window of PMMA (Plexiglas) set into sphere hull. The very small black circle (smaller than the man's head) is the inner side of the plastic "window," and is only a few inches in diameter. The larger circular clear black area represents the larger outer-side of the thick one-piece plastic cone "window."]] tank has acrylic windows up to 13 inches thick to withstand the water pressure]]

PMMA acrylic glass is commonly used for constructing residential and commercial aquariums. Designers started building big aquariums when poly(methyl methacrylate) could be used. The spectacular size of both flat panels and tunnels in aquariums such as Monterey Bay, Tokyo Sea Life Park, Osaka, Nagoya, Georgia and Dubai Aquariums were made possible with the introduction of acrylic.

PMMA was used for the window of the bathyscaphe Trieste for all of its dives, including the record-setting dive to the bottom of the Challenger deep in the Mariana Trench in 1960. The conical window set into the 12.7 cm thick wall of the sphere (small end inward) was required to withstand ~ 1100 atmospheres of pressure at the bottom.

Acrylic is used for viewing ports and even complete pressure hulls of submersibles, such as the Alicia submarine's viewing sphere.

PMMA is used in the lenses of exterior lights of automobiles.

The spectator protection in ice hockey rinks is made from PMMA.

It is used in motorcycle helmet visors

Historically, PMMA was an important improvement in the design of aircraft windows, making possible such iconic designs as the bombadier's transparent nose compartment in the Boeing B-17 Flying Fortress.

Polycast acrylic sheet is the most widely used material in aircraft transparencies (windows). In applications where the aircraft is pressurized, stretched acrylic is used. Only in the most advanced modern fighter jets, such as the F-22 Raptor, has traditional acrylic been replaced by polycarbonate (Lexan).

Police vehicles for riot control often have the regular glass replaced with acrylic to protect the occupants from thrown objects.

In some Motor racing championships the glass windows in the cars are replaced with acrylic to prevent glass shattering on the driver and track during a crash. They also help to save some weight making the car lighter and faster.

Acrylic is an important material in the making of certain lighthouse lenses.

Acrylic is also used to make infra-red receptors tamper-proof. Infra red radiation can travel through acrylic material, but its use prevents physical damage to the sensor.

Daylight redirection

Laser cut acrylic panels have been used to redirect sunlight into a light pipe and, from there, to spread it into a room. Their developers Veronica Garcia Hansen, Ken Yeang, and Ian Edmonds were awarded the Far East Economic Review Innovation Award in bronze for this technology in 2003. Attenuation being quite strong for distances over one meter (more than 90% intensity loss for a 3000 K source), acrylic broadband light guides are then dedicated mostly to decorative uses. Pairs of acrylic sheets with a layer of microreplicated prisms between the sheets can have reflective and refractive properties that let them redirect part of incoming sunlight in dependence on its angle of incidence. Such panels act as miniature light shelves. Such panels have been commercialized for purposes of daylighting, to be used as a window or a canopy such that sunlight descending from the sky is directed to the ceiling or into the room rather than to the floor. This can lead to a higher illumination of the back part of a room, in particular when combined with a white ceiling, while having a slight impact on the view to the outside compared to normal glazing.

Medical technologies and implants

PMMA has a good degree of compatibility with human tissue, and can be used for replacement intraocular lenses in the eye when the original lens has been removed in the treatment of cataracts. This compatibility was discovered in WWII RAF pilots, whose eyes had been riddled with PMMA splinters coming from the side windows of their Supermarine Spitfire fighters - the plastic scarcely caused any rejection, compared to glass splinters coming from aircraft such as the Hawker Hurricane. Historically, hard contact lenses were frequently made of this material. Soft contact lenses are often made of a related polymer, where acrylate monomers containing one or more hydroxyl groups make them hydrophilic. In orthopedic surgery, PMMA bone cement is used to affix implants and to remodel lost bone. It is supplied as a powder with liquid methyl methacrylate (MMA). When mixed these yield a dough-like cement that gradually hardens. Surgeons can judge the curing of the PMMA bone cement by pressing their thumb on it. Although PMMA is biologically compatible, MMA is considered to be an irritant and a possible carcinogen. PMMA has also been linked to cardiopulmonary events in the operating room due to hypotension. Bone cement acts like a grout and not so much like a glue in arthroplasty. Although sticky, it does not bond to either the bone or the implant, it primarily fills the spaces between the prosthesis and the bone preventing motion. A big disadvantage to this bone cement is that it heats to quite a high temperature while setting, potentially 82.5 deg C and because of this, thermal necrosis of neighbouring tissue can potentially result. A careful balance of initiators and monomers is needed to reduce the rate of polymerisation, and thus the heat generated. A major consideration when using PMMA cement is the effect of stress shielding. Since PMMA has a Young's modulus greater than that of natural bone, the stresses are loaded into the cement and so the bone no longer receives the mechanical signals to continue bone remodelling and so resorbtion will occur.

Dentures are often made of PMMA, and can be color-matched to the patient's teeth & gum tissue.

In cosmetic surgery, tiny PMMA microspheres suspended in some biological fluid are injected under the skin to reduce wrinkles or scars permanently.

A large majority of white Dental filling materials (i.e. composites) have PMMA as their main organic component.

Emerging biotechnology and Biomedical research uses PMMA to create microfluidic lab-on-a-chip devices, which require 100 micrometre-wide geometries for routing liquids. These small geometries are amenable to using PMMA in a biochip fabrication process and offers moderate biocompatibility.

Bioprocess chromatography columns use cast acrylic tubes as an alternative to glass and stainless steel. These are pressure rated and satisfy stringent requirements of materials for biocompatibility, toxicity and extractables.

Artistic and aesthetic uses

Acrylic paint essentially consists of PMMA suspended in water; however since PMMA is hydrophobic, a substance with both hydrophobic and hydrophilic groups needs to be added to facilitate the suspension.

Modern furniture makers, especially in the 1960s and 1970s, seeking to give their products a space age aesthetic, incorporated Lucite and other PMMA products into their designs, especially office chairs. Many other products (for example, guitars) are sometimes made with acrylic glass to make the commonly opaque objects translucent.

Perspex has been used as a surface to paint on, for example by Salvador Dalí.

Diasec is a process which uses acrylic glass as a substitute for normal glass in picture framing. This is done for its relatively low cost, light weight, shatter-resistance, aesthetics and because it can be ordered in larger sizes than standard picture framing glass.

From approximately the 1960s onward, sculptors and glass artists began using acrylics, especially taking advantage of the material's flexibility, light weight, cost and its capacity to refract and filter light.

In the 1950s and 1960s, Lucite was an extremely popular material for jewelry, with several companies specialized in creating high-quality pieces from this material. Lucite beads and ornaments are still sold by jewelry suppliers.

Other uses

shoes made of Lucite]] with its body made out of perspex]]

Sheets of PMMA are commonly used in the sign industry to make flat cut out letters in thicknesses typically varying from . These letters may be used alone to represent a company's name and/or logo, or they may be a component of channel letters which are neon or LED illuminated. Acrylic's attractiveness, durability and resistance to warping make it an ideal interior and exterior sign material. Acrylic is also used extensively throughout the sign industry as a component of wall signs where it may be a backplate, painted on the surface or the backside, a faceplate with additional raised lettering or even photographic images printed directly to it, or a spacer to separate sign components. One of the most popular sheets is a non-glare, translucent which is sold in or in thicknesses.

PMMA was used in laserdisc optical media. (CDs and DVDs use polycarbonate for higher impact resistance.)

It is used as a light guide for the backlights in TFT-LCDs.

Plastic optical fiber used for short distance communication is made from PMMA, and perfluorinated PMMA, clad with fluorinated PMMA, in situations where its flexibility and cheaper installation costs outweigh its poor heat tolerance and higher attenuation over glass fiber.

PMMA, in a purified form, is used as the matrix in dye-doped solid-state gain media for solid state dye lasers. In semiconductor research and industry, PMMA aids as a resist in the electron beam lithography process. A solution consisting of the polymer in a solvent is used to spin coat silicon and other semiconducting and semi-insulating wafers with a thin film. Patterns on this can be made by an electron beam (using an electron microscope), deep UV light (shorter wavelength than the standard photolithography process), or X-rays. Exposure to these creates chain scission or (de-cross-linking) within the PMMA, allowing for the selective removal of exposed areas by a chemical developer, making it a positive photoresist. PMMA's advantage is that it allows for extremely high resolution (nanoscale) patterns to be made. It is an invaluable tool in nanotechnology. Smooth PMMA surface can be easily nanostructured by treatment in oxygen radio-frequency plasma and nanostructured PMMA surface can be easily smoothed by vacuum ultraviolet (VUV) irradiation. and B.C. Rich have also made acrylic guitars.

Ludwig-Musser makes a line of acrylic drums called Vistalites, well known as being used by Led Zeppelin drummer John Bonham.

Artificial fingernails are made of acrylic.

Some modern briar, and occasionally meerschaum, tobacco pipes sport stems made of Lucite, although the vast majority of stems for such pipes are still made with the traditional vulcanized rubber.

See also

Polystyrene

Polycarbonate

References

Bibliography

Category:Plastics Category:Polyacrylates Category:Optical materials Category:Dielectrics Category:Thermoplastics Category:Dental materials Category:Amorphous solids Category:Biomaterials Category:Transparent materials

Name	Albert King
Background	solo_singer
Birth name	Albert Nelson
Born	April 25, 1923Indianola, Mississippi, United States
Died	December 21, 1992Memphis, Tennessee, U.S.
Instrument	Guitar, vocals
Genre	Blues
Occupation	Songwriter, Musician, producer
Years active	1949–1992
Label	Stax
Notable instruments	Gibson Flying V

Albert King (April 25, 1923 – December 21, 1992) was an American blues guitarist and singer.

Career

One of the "Three Kings of the Blues Guitar" (along with B. B. King and Freddie King), Albert King stood 6' 4" (192 cm) (some reports say 6' 7") and weighed 250 lbs (118 kg) and was known as "The Velvet Bulldozer". He was born Albert Nelson on a cotton plantation in Indianola, Mississippi. During his childhood he would sing at a family gospel group at a church. One of 13 children, King grew up picking cotton on plantations near Forrest City, Arkansas where the family moved when he was eight. He began his professional work as a musician with a group called In The Groove Boys in Osceola, Arkansas. He also briefly played drums for Jimmy Reed's band and on several early Reed recordings. Influenced by blues musicians Blind Lemon Jefferson and Lonnie Johnson, but also interestingly Hawaiian music, the electric guitar became his signature instrument, his preference being the Gibson Flying V, which he named "Lucy".

King was a left-handed "upside-down/backwards" guitarist. He was left-handed, but usually played right-handed guitars flipped over upside-down so the low E string was on the bottom. In later years he played a custom-made guitar that was basically left-handed, but had the strings reversed (as he was used to playing). He also used very unorthodox tunings (i.e., tuning as low as C to allow him to make sweeping string bends). Some believe that he was using open E minor tuning (C-B-E-G-B-E) or open F tuning (C-F-C-F-A-D). A "less is more" type blues player, he was known for his expressive "bending" of notes, a technique characteristic of blues guitarists.

He recorded his first disc in 1953 for Parrot Records in Chicago, but it made no impact. His first minor hit came in 1959 with "I'm a Lonely Man" written by Bobbin Records A&R; man and fellow guitar hero Little Milton, responsible for King's signing with the label. However, it was not until his 1961 release "Don't Throw Your Love on Me So Strong" that he had a major hit, reaching number fourteen on the U.S. Billboard R&B; chart. In 1966 he signed with the Stax record label. Produced by Al Jackson, Jr., King with Booker T. & the MGs recorded dozens of influential sides, such as "Crosscut Saw" and "As The Years Go Passing By", and in 1967 Stax released the album, Born Under a Bad Sign. The title track of that album (written by Booker T. Jones and William Bell) became King's best known song and has been covered by many artists (from Cream to Homer Simpson).

in October, 1968 with his Gibson Flying V guitar Photo: Grant Gouldon]] Another landmark album followed in Live Wire/Blues Power from one of many dates King played at promoter Bill Graham's Fillmore venues. It had a wide and long-term influence on Jimi Hendrix, Eric Clapton, Robbie Robertson, and later Gary Moore and Stevie Ray Vaughan ("Criminal World", on David Bowie's 1983 release "Let's Dance", features a guitar solo copied note-for-note from his hero Albert King by young session musician Stevie Ray Vaughan).

In the 1970s, King was teamed with members of The Bar-Kays and The Movement (Isaac Hayes's backing group), including bassist James Alexander and drummer Willie Hall adding strong funk elements to his music. Adding strings and multiple rhythm guitarists, producers Allen Jones and Henry Bush created a wall of sound that contrasted the sparse, punchy records King made with Booker T. & the MGs. Among these was another of King's signature tunes for King with "I'll Play the Blues For You" in 1972.

King influenced others such as Mick Taylor, Derek Trucks, Warren Haynes, Mike Bloomfield and Joe Walsh (the James Gang guitarist spoke at King's funeral). He also had an impact on contemporaries Albert Collins and Otis Rush. Clapton has said that his work on the 1967 Cream hit "Strange Brew" and throughout the album Disraeli Gears was inspired by King.

As he hit his mid-sixties King began to muse about retirement, not unreasonable given that he had health problems. Nevertheless, when near to death, he was planning yet another overseas tour.

King died on December 21, 1992 from a heart attack in Memphis, Tennessee.

Discography

DVD and videos

1995 Maintenance Shop Blues (VHS), Yazoo

2001 Godfather Of The Blues: His Last European Tour DVD, P-Vine Records

2004 Live In Sweden, Image Entertainment

References

Sources

Bowman, Rob (1997) Soulsville, U.S.A.: The Story of Stax Records, Schirmer Books. ISBN 0-8256-7227-9

Discography at Lycos Music

External links

Albert King, Greg Johnson, BluesNotes, September 1999

Albert King at Rolling Stone

Category:1923 births Category:1992 deaths Category:People from Sunflower County, Mississippi Category:Soul-blues musicians Category:Electric blues musicians Category:Urban blues musicians Category:American rhythm and blues musicians Category:American blues singers Category:American blues guitarists Category:Blues Hall of Fame inductees Category:Blues musicians from Mississippi Category:African American guitarists Category:African American singer-songwriters Category:Lead guitarists Category:King Records artists Category:Atlantic Records artists Category:Charly Records artists Category:Ace Records artists

In the Hebrew Bible, Aaron ( or ; Ahărōn, Hārūn), sometimes called Aaron the Levite (), was the brother of Moses, (Exodus 6:16-20) and represented the priestly functions of his tribe, becoming the first High Priest of the Israelites. While Moses was receiving his education at the Egyptian royal court, and during his exile among the Midianites, Aaron and his sister Miriam remained with their kinsmen in the eastern border-land of Egypt (Goshen). There, Aaron gained a name for eloquent and persuasive speech, so that when the time came for the demand upon the Pharaoh to release Israel from captivity, Aaron became his brother’s nabi, or spokesman, to his own people (Exodus 7:1) and, after their unwillingness to hear, to the Pharaoh himself (Exodus 7:9). Various dates for his life have been proposed, ranging from approximately 1600 to 1200 BC.

Etymology

The meaning of the name "Aaron" is enlightened, exalted, mountain of strength. Other possible meanings are # Pregnancy: In Hebrew, הריון herayon. In Ancient Egyptian herr is to conceive and hrara is conception. # From the mountain: In Hebrew הר har, which may refer to place of his own death. # High mountain: In Arabic هارون harun. # One of light # From Hebrew (Ahărōn), possibly meaning "bearer of martyrs", # Related to the Ancient Egyptian aha rw ("warrior lion", or possibly "", " " or "high mountain").

Account in the Hebrew Bible

Genealogy

Descended from Abraham, Isaac, and Jacob

Great-grandfather: Levi, third of 12 sons and tribes of Israel

Grandfather: Kohath

Father: Amram

Mother: Jochebed

Sister: Miriam

Brother: Moses

Uncles: Izhar, Hebron, Uzziel

Sons: Nadab, Abihu, Eleazar, Ithamar

Grandson: Phinehas

Function

Aaron’s function included the duties of speaker and implied personal dealings with the Egyptian royal court on behalf of Moses, who was always the central moving figure. The part played by Aaron in the events that preceded the Exodus was, therefore, ministerial, and not directive. He, along with Moses, performed “signs” before his people which impressed them with a belief in the reality of the divine mission of the brothers (Exodus 4:15–16).

At the command of Moses he stretched out his rod in order to bring on the first of three plagues (Exodus 7:19, 8:1,12). In the infliction of the remaining plagues, he appears to have acted merely as the attendant of Moses, whose outstretched rod drew the divine wrath upon the Pharaoh and his subjects (Exodus 9:23, 10:13,22). The potency of Aaron’s rod had already been demonstrated by its victory over the rods of the Egyptian magicians, which it swallowed after all the rods alike had been turned into serpents (Exodus 7:9). During the journey in the wilderness, Aaron is not always prominent or active; and he sometimes appears guilty of rebellious or treasonable conduct. At the battle with Amalek, he is chosen with Hur to support the hand of Moses that held the “rod of God” (Exodus 17:9). When the revelation was given to Moses at Mount Sinai, he headed the elders of Israel who accompanied Moses on the way to the summit. Joshua, however, was admitted with his leader to the very presence of the Lord, while Aaron and Hur remained below to look after the people Exodus 24:9-14. It was during the prolonged absence of Moses that Aaron yielded to the clamors of the people, and made a Golden Calf as a visible image of the divinity who had delivered them from Egypt (Exodus 32:1-6). (It should be noted that in the account given of the same events, in the Qur'an, Aaron is not the idol-maker and upon Moses' return begged his pardon as he had felt mortally threatened by the Israelites (Quran 7:142-152).) At the intercession of Moses, Aaron was saved from the plague which smote the people (Deuteronomy 9:20, Exodus 32:35), although it was to Aaron’s tribe of Levi that the work of punitive vengeance was committed (Exodus 32:26).

Priesthood

At the time when the tribe of Levi was set apart for the priestly service, Aaron was anointed and consecrated to the priesthood, arrayed in the robes of his office, and instructed in its manifold duties (Exodus 28, Exodus 29).

On the very day of his consecration, his sons, Nadab and Abihu, were consumed by fire from the Lord for having offered incense in an unlawful manner (Leviticus 10).

Scholarly consensus is that in Aaron's high priesthood the sacred writer intended to describe a model, the prototype, so to say, of the Jewish high priest. God, on Mount Sinai instituting a worship, also instituted an order of priests. According to the patriarchal customs, the firstborn son in every family used to perform the functions connected with God's worship. It might have been expected, consequently, that Reuben's family would be chosen by God for the ministry of the new altar. However, according to the biblical narrative it was Aaron who was the object of God's choice. To what jealousies this gave rise later, has been indicated above. The office of the Aaronites was at first merely to take care of the lamp which was to burn perpetually before the veil of the tabernacle Exodus 27:21. A more formal calling soon followed (Exodus 28:1). Aaron and his sons, distinguished from the commoners by their sacred functions, were also to receive holy garments suitable to their office.

Aaron offered the various sacrifices and performed the many ceremonies of the consecration of the new priests, according to the divine instructions (Exodus 29), and repeated these rites for seven days, during which Aaron and his sons were entirely separated from the rest of the people. When, on the eighth day, the high priest had inaugurated his office of sacrifice by killing the animals, he blessed the people (very likely according to the prescriptions of Numbers 6:24-26), and, with Moses, entered into the tabernacle to possess it. They "came forth and blessed the people. And the glory of the Lord appeared to all the multitude: And behold a fire, coming forth from the Lord, devoured the holocaust, and the fat that was upon the altar: which when the multitude saw, they praised the Lord, falling on their faces" (Leviticus 9:23-24). In this way the institution of the Aaronic priesthood was established. In the present instance it is made clear by the express words of the oracle (Numbers 12:6-8) that Moses was unique among men as the one with whom the Lord spoke face to face. The failure to recognize or concede this prerogative of their brother was the sin of Miriam and Aaron.

The validity of the exclusive priesthood of the family of Aaron was attested after the ill-fated rebellion of Korah, who was a first cousin of Aaron. When the earth had opened and swallowed up the leaders of the insurgents (Numbers 16:25-35), Eleazar, the son of Aaron, was commissioned to take charge of the censers of the dead priests. And when the plague had broken out among the people who had sympathized with the rebels, Aaron, at the command of Moses, took his censer and stood between the living and the dead till the plague was stayed (Numbers 17:1-15, 16:36-50).

Another memorable transaction followed. Each of the tribal princes of Israel took a rod and wrote his name upon it, and the twelve rods were laid up over night in the tent of meeting. The next morning Aaron’s rod was found to have budded and blossomed and produced ripe almonds (Numbers 17:8). The miracle proved merely the prerogative of the tribe of Levi; but now a formal distinction was made in perpetuity between the family of Aaron and the other Levites. While all the Levites (and only Levites) were to be devoted to sacred services, the special charge of the sanctuary and the altar was committed to the Aaronites alone (Numbers 18:1-7). The scene of this enactment is unknown, as is the time mentioned.

Death

Aaron, like Moses, was not permitted to enter Canaan with the others. The reason alleged is that the two brothers showed impatience at Meribah (Kadesh) in the last year of the desert pilgrimage (Numbers 20:12-13), when Moses brought water out of a rock to quench the thirst of the people. Thus Aaron, the first priest, ranks below Moses: he is his mouthpiece, and the executor of the will of God revealed through Moses, although it is pointed out that it is said fifteen times in the Pentateuch that “the Lord spoke to Moses and Aaron.” Under the influence of the priesthood which shaped the destinies of the nation under Persian rule, a different ideal of the priest was formed, as is learned from Malachi 2:4–7; and the prevailing tendency was to place Aaron on a footing equal with Moses. Accompanied by Moses, his brother, and by Eleazar, his son, Aaron went to the summit of Mount Hor, where the rock suddenly opened before him and a beautiful cave lit by a lamp presented itself to his view.

The rabbis also dwell with special laudation on the brotherly sentiment which united Aaron and Moses.

When Moses poured the oil of anointment upon the head of Aaron, Aaron modestly shrank back and said: "Who knows whether I have not cast some blemish upon this sacred oil so as to forfeit this high office."

Moses

According to Tanhuma, Aaron’s activity as a prophet began earlier than that of Moses. Hillel held Aaron up as an example, saying: “Be of the disciples of Aaron, loving peace and pursuing peace; love your fellow creatures and draw them nigh unto the Law!” This is further illustrated by the tradition preserved in Abot de-Rabbi Natan 12, Sanhedrin 6b, and elsewhere, according to which Aaron was an ideal priest of the people, far more beloved for his kindly ways than was Moses. Moses was bewailed by “the sons of Israel” only (). His fortitude and silent submission to the will of God on the loss of his two sons are referred to as an excellent example to men how to glorify God in the midst of great affliction. Especially significant are the words represented as being spoken by God after the princes of the Twelve Tribes had brought their dedication offerings into the newly reared Tabernacle: “Say to thy brother Aaron: Greater than the gifts of the princes is thy gift; for thou art called upon to kindle the light, and, while the sacrifices shall last only as long as the Temple lasts, thy light shall last forever.”

Christianity

icon of Aaron (18th century, Iconostasis of Kizhi monastery, Karelia, Russia).]] While Aaron and his descendants were the high priests of Judaism, Melchizedek, a mystical figure who appeared over 700 years before Moses, is considered a type of Christ, the high priest of the new dispensation(see the Book of Hebrews).

However, in the Eastern Orthodox Church and the Maronite Church Aaron is venerated as a saint, with a feast day celebrated on September 4, together with Moses (for those churches which follow the traditional Julian Calendar, September 4 falls on September 17 of the modern Gregorian Calendar). He is also commemorated, together with other righteous saints from the Old Testament on the Sunday of the Holy Fathers (the Sunday before Christmas).

He is commemorated as one of the Holy Forefathers in the Calendar of Saints of the Armenian Apostolic Church on July 30. He is commemorated on July 1 in the modern Latin calendar and in the Syriac Calendar.

Latter-day Saints

In the LDS church, the Aaronic order is the lesser order of priesthood, comprising the grades (from lowest to highest) of deacon, teacher, and priest. The chief office of the Aaronic priesthood is the presiding bishopric; the head of the priesthood is the bishop. Each ward has one or more quora of each office of the Aaronic priesthood.

Aaron in Islam

Caption	Gustave Dore's engraving Moses and Aaron appear before Pharaoh.
Honorific prefix	Prophet
Name	HarunProphet, Messenger, Helper of Moses, Patriarch
Birth date	16th-12th Century B.C. (?)
Parents	Amran and Jochebed
Relatives	Brother of Moses and Miriam
Resting place	Tomb of Aaron, Petra, Jordan
Other names	Bible: Aaron
Known for	Prophesying to the Israelites with Moses using the Law, Preaching against the creation of the Golden Calf, Being the helper of Moses

Harun (Arabic: هارون; meaning Mountain of strength) (circa 1439 BC - 1317 BC?), is an Islamic prophet and messenger mentioned in the Qur'an. In the Bible he is known as Aaron (Aharōn in Hebrew). It is believed that Aaron lived for 122 years.}}

Aaron is also important for being a patriarch the ancestor of the priestly lineage of the family of Amram. The figures mentioned in the Qur'an who came from Aaron's lineage were Mary and Jesus. Furthermore, the other figures present in the household - such as the high priest Zachariah and his wife Elizabeth - are also mentioned as coming through the same bloodline.

Aaron in the Qur'an

The Qur'an's version of Aaron's life was written 2000 years after the original account in the Torah, and is strongly influenced by the Biblical narrative. Aaron was the brother of Moses and like his brother he too was a prophet who was tasked by God with saving the Israelites from the tyrannical Pharaoh. In the Qur'an God says:

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Moses prays to God to grant Aaron as a helper

Aaron was a gifted speaker. He was largely responsible with teaching the Israelites the way of worship as it was laid out in the Torah (Tawrat) of that time. According to the Qur'an, Moses prayed to God to grant him his brother Aaron as a helper to be with him in all his tasks ahead. God, in the Qur'an, says that Moses said:

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God grant's Moses his request

God granted Moses his request and told him that he could take his brother along with him. God says:

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Aaron is given the Law

Aaron, being a prophetic messenger, was also given the law by God, to preach to the Children of Israel according to the Torah. The Qur'an mentions the holy scripture as a light and guidance for those who would accept the Message. God says in the Qur'an:

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The Golden Calf

When Moses led his people on the Exodus to Mount Sinai, he told them that he would be gone for a few days to receive the Tablets of the Law. He informed the Israelites that Aaron would be their leader in his absence. However, the moment Moses left, an evil man, Samiri, fashioned an idol calf out of the people's gold and jewelery and he made the Israelites succumb to idolatry.

Aaron preached with powerful zeal to his people, but they refused to listen to him. It is here that the Qur'anic narrative of the incident sharply contrasts with the Biblical story, which puts blames Aaron for making the golden calf. Aaron was overpowered and was threatened with being killed by his people. When Moses returned from Mount Sinai, he blamed Aaron for allowing the Israelites to worship this idol and seized his brother by his beard, but Aaron then gave his explanation, after which Moses prayed to God to forgive both of them. As God says in the Qur'an:

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Aaron in Muhammad's time

Muhammad, in many of his sayings, speaks of Aaron. In the event of the Mi'raj, his miraculous ascension through the Heavens, Muhammad is said to have encountered Aaron in the fifth heaven. According to old scholars, including Ibn Hisham, Muhammad, in particular, mentioned the beauty of Aaron when he encountered him in Heaven. Martin Lings, in his biographical Muhammad, speaks of Muhammad's wonderment at seeing fellow prophets in their heavenly glory:

Aaron was also mentioned by Muhammad in likeness to Ali. Muhammad had left Ali to look after his family, but the hypocrites of the time begun to spread the rumor that the prophet found Ali a burden and was relieved to be rid of his presence. Ali, grieved at hearing this wicked taunt, told Muhammad what the local people were saying. In reply, the prophet said: "They lie, I bade thee remain for the sake of what I had left behind me. So return and represent me in my family and in thine. Art thou not content, O Ali, that thou should be unto me as Aaron was unto Moses, save that after me there is no prophet."

Burial Place

, Jordan.]] According to Islamic tradition the tomb of Aaron is located on Jabal Harun, or Aaron's Mountain, near Petra in Jordan. At 1350 meters above sea-level it is the highest peak in the area; and it is a place of great sanctity to the local people for here. A 14th century Jordanian mosque stands here with its white dome visible from most areas in and around Petra.

Genetics

Recently, the tradition that Kohanim (the Jewish priesthood) are actually descended from a single patriarch, Aaron, was found to be apparently consistent with genetic testing. The majority of Jewish men with the tradition of being Kohanim, but not all, share a direct male lineage with a common Y chromosome, and testing was done across sectors of the Jewish population to see if there was any commonality between the Y chromosomes of Kohanim. The results were found to cluster rather closely around a specific DNA signature, found in the Semitic Haplogroup J1, which the researchers named the Cohen modal haplotype, implying that many of the Kohanim do share a distinctive common ancestry. This information was also used to support the claim that the Lemba (a sub-Saharan tribe) are in fact descendant from a group of Jewish priests.

The Cohen Modal Haplotype or CMH is found in haplogroup J1, which geneticists estimate originated in the Southern Levant (modern day Israel, Jordan; biblical Canaan) or North Africa (Egypt) approximately 10,000–15,000 years ago. Biblical tradition holds that Abraham and his ancestors, the Semitic tribes, originated from Southern Arabia or East Africa (Genesis 10); Aaron and Moses were 7th generation descendants from Abraham (Exodus 6). An estimated 20% of the modern Jewish community fall into haplogroup J1. The traditional date for Abraham is circa 2200–2000 BC. Behar, et al., found Kohanim in a variety of haplogroups (E3b, G2, H, I1b, J, K2, Q, R1a1, R1b), which included those which originated in the Levant (J1, J2) and those from Southern Arabia, East Africa, or another geographic region.

Dr. Karl Skorecki, the founder of CMH, reported during a Conference for Kohanim in Jerusalem 2007, that he and his research team have discovered not one but two Cohen Modal Haplotypes, which he called J1 and J2. “Pinchas the zealot mentioned in the Bible may be the origin of J2” said Skorecki. According to the observed mutations rates, certain J2 haplotypes found on FTDNA database projects share a common ancestor who lived 3100+/-200 years bp, as Skorecki revealed to the public.

Descendants

Aaron married Elisheba, daughter of Amminadab and sister of Nahshon (Exod 6:23). The sons of Aaron were Eleazar, Ithamar, Nadab and Abihu. A descendant of Aaron is an Aaronite, or Kohen, meaning Priest. Any non-Aaronic Levite descended from Levi but not of the priestly division would be assigned to assist the Levitical priests of the family of Aaron in the care of the tabernacle and later of the temple.

Art history

Depictions of Aaron within art history are rare. Other than Aaron's inclusion in the crowd of revelers around the Golden Calf ceremony—most notably in Nicolas Poussin’s “The Adoration of the Golden Calf” (ca. 1633–34, National Gallery London)—there is little else. The recent discovery in 1991 of Pier Francesco Mola’s “Aaron, Holy to the Lord” (ca. 1650, Private Collection, New York: image available for study at Fred R. Kline Gallery Archives) adds significantly to the Aaronic mythos. The painting offers a dramatic, deeply psychological portrayal of the single figure of Aaron in his priestly garments celebrating Yom Kippur in the wilderness Tabernacle. The Mola “Aaron” is considered, quite surprisingly, the unique single figure of Aaron to have been painted by a European old master artist, circa 15th–18th centuries (A.Pigler, "Barockthemen" Vol. 1; although unknown to Pigler). The carefully rendered Judaic iconographic details in the Mola painting are rare and the subject itself may have importance in relationship to mid-17th century Jewish history, characterized by a controversial messianic movement involving a serious contender for a new Messiah, Shabtai Zvi, whose influence was felt in Jewish communities worldwide (Harris Lenowitz, "The Jewish Messiahs"). It is highly probable that the Zvi messianic phenomenon was noted by the Catholic Church as a possible threat to Jesus, their sanctified Messiah. It may be significant to note, in considering the possible influence of the Roman Catholic Church in choices of lay-commissioned religious art during this period and considering as well the importance of Aaron in the Christian tradition, that "Aaron, Holy to the Lord" was originally commissioned along with a now lost pendant of Moses (both from Mola) by the nobel Colonna family, wealthy Catholic art patrons living in Rome (Getty Museum Archives).

See also

Tomb of Aaron

Harun

Kohen

Y-chromosomal Aaron

Moses in rabbinic literature

References

Further reading

McCurdy, J. F. and Kaufmann Kohler. "Aaron". Jewish Encyclopedia. Funk and Wagnalls, 1901–1906; which cites

* Numbers Rabbah 9

* Leviticus Rabbah 10

in Jellinek’s Bet ha-Midrash, 1:91–95

764

* Baring-Gould, Legends of Old Testament Characters

* Chronicles of Jerahmeel, ed. M. Gaster, pp. cx1:130–133

* Holweck, F. G., A Biographical Dictionary of the Saint. St. Louis, MO: B. Herder Book Co. 1924.

References in the Qur'an

Aaron's prophecy: , , Aaron is made helper of Moses: , , , , Aaron and Moses sent to Pharaoh: , , , Praise for Aaron: , , , , , The Golden Calf: ,

External links

MFnames.com - Origin and Meaning of Aaron

Category:Ancient Jewish Egyptian history Category:High Priests of Israel Category:Torah people Category:Old Testament saints Category:Moses Category:Kohanim *Main Category:Book of Exodus