title: Chakra

text: These ideas are not unique to Hindu and Buddhist traditions. Similar and overlapping concepts emerged in other cultures in the East and the West, and these are variously called by other names such as subtle body, spirit body, esoteric anatomy, sidereal body and etheric body. According to Geoffrey Samuel and Jay Johnston, professors of Religious studies known for their studies on Yoga and esoteric traditions:


title: Chakra

text: Chakra and related beliefs have been important to the esoteric traditions, but they are not directly related to mainstream yoga. According to the Indologist Edwin Bryant and other scholars, the goals of classical yoga such as spiritual liberation (freedom, self-knowledge, moksha) is "attained entirely differently in classical yoga, and the "cakra / nadi / kundalini" physiology is completely peripheral to it."


title: Chakra

text: The classical eastern traditions, particularly those that developed in India during the 1st millennium AD, primarily describe "nadi" and "chakra" in a "subtle body" context. To them, they are in same dimension as of the psyche-mind reality that is invisible yet real. In the "nadi" and "cakra" flow the "prana" (breath, life energy). The concept of "life energy" varies between the texts, ranging from simple inhalation-exhalation to far more complex association with breath-mind-emotions-sexual energy. This prana or essence is what vanishes when a person dies, leaving a gross body. Some of this concept states this subtle body is what withdraws within, when one sleeps. All of it is believed to be reachable, awake-able and important for an individual's body-mind health, and how one relates to other people in one's life. This subtle body network of "nadi" and "chakra" is, according to some later Indian theories and many new age speculations, closely associated with emotions.


title: Chakra

text: Esoteric traditions in Hinduism mention numerous numbers and arrangements of chakras, of which a classical system of six-plus-one, the last being the Sahasrara, is most prevalent. This seven-part system, central to the core texts of hatha yoga, is one among many systems found in Hindu tantric literature. Hindu Tantra associates six Yoginis with six places in the subtle body, corresponding to the six chakras of the six-plus-one system.


title: Chakra

text: The Chakra methodology is extensively developed in the goddess tradition of Hinduism called Shaktism. It is an important concept along with yantras, mandalas and kundalini yoga in its practice. Chakra in Shakta tantrism means circle, an "energy center" within, as well as being a term for group rituals such as in "chakra-puja" (worship within a circle) which may or may not involve tantra practice. The cakra-based system is a part of the meditative exercises that came to be known as yoga.


title: Chakra

text: The esoteric traditions in Buddhism generally teach four chakras. In some early Buddhist sources, these chakras are identified as: manipura (navel), anahata (heart), vishuddha (throat) and ushnisha kamala (crown). In one development within the Nyingma lineage of the "Mantrayana" of Tibetan Buddhism a popular conceptualization of chakras in increasing subtlety and increasing order is as follows: Nirmanakaya (gross self), Sambhogakaya (subtle self), Dharmakaya (causal self), and Mahasukhakaya (non-dual self), each vaguely and indirectly corresponding to the categories within the Shaiva "Mantramarga" universe, i.e., Svadhisthana, Anahata, Visuddha, Sahasrara, etc. However, depending on the meditational tradition, these vary between three and six. The chakras are considered psycho-spiritual constituents, each bearing meaningful correspondences to cosmic processes and their postulated Buddha counterpart.


title: Chakra

text: A system of five chakras is common among the Mother class of Tantras and these five chakras along with their correspondences are:


title: Chakra

text: Chakras clearly play a key role in Tibetan Buddhism, and are considered to be the pivotal providence of Tantric thinking. And, the precise use of the chakras across the gamut of tantric sadhanas gives little space to doubt the primary efficacy of Tibetan Buddhism as distinct religious agency, that being that precise revelation that, without Tantra there would be no Chakras, but more importantly, without Chakras, there is no Tibetan Buddhism. The highest practices in Tibetan Buddhism point to the ability to bring the subtle pranas of an entity into alignment with the central channel, and to thus penetrate the realisation of the ultimate unity, namely, the "organic harmony" of one's individual consciousness of Wisdom with the co-attainment of All-embracing Love, thus synthesizing a direct cognition of absolute Buddhahood.


title: Chakra

text: According to Samuel, the buddhist esoteric systems developed cakra and nadi as "central to their soteriological process". The theories were sometimes, but not always, coupled with a unique system of physical exercises, called "yantra yoga" or "phrul khor".


title: Chakra

text: Chakras, according to the Bon tradition, enable the gestalt of experience, with each of the five major chakras, being psychologically linked with the five experiential qualities of unenlightened consciousness, the six realms of woe.


title: Chakra

text: The tsa lung practice embodied in the Trul khor lineage, unbaffles the primary channels, thus activating and circulating liberating prana. Yoga awakens the deep mind, thus bringing forth positive attributes, inherent gestalts, and virtuous qualities. In a computer analogy, the screen of one's consciousness is slated and an attribute-bearing file is called up that contains necessary positive or negative, supportive qualities.


title: Chakra

text: Tantric practice is said to eventually transform all experience into clear light. The practice aims to liberate from all negative conditioning, and the deep cognitive salvation of freedom from control and unity of perception and cognition.


title: Chakra

text: The more common and most studied chakra system incorporates six major chakras along with a seventh center generally not regarded as a chakra. These points are arranged vertically along the axial channel (sushumna nadi in Hindu texts, Avadhuti in some Buddhist texts). According to Gavin Flood, this system of six chakras plus the "sahasrara" "center" at the crown first appears in the "Kubjikāmata-tantra", an 11th-century Kaula work.


title: Chakra

text: It was this chakra system that was translated in the early 20th century by Sir John Woodroffe (also called Arthur Avalon) in the text "The Serpent Power". Avalon translated the Hindu text "Ṣaṭ-Cakra-Nirūpaṇa" meaning the examination (nirūpaṇa) of the seven (ṣaṭ) chakras (cakra).


title: Chakra

text: The Chakras are traditionally considered meditation aids. The yogi progresses from lower chakras to the highest chakra blossoming in the crown of the head, internalizing the journey of spiritual ascent. In both the Hindu kundalini and Buddhist candali traditions, the chakras are pierced by a dormant energy residing near or in the lowest chakra. In Hindu texts she is known as Kundalini, while in Buddhist texts she is called Candali or Tummo (Tibetan: "gtum mo", "fierce one").


title: Chakra

text: Below are the common new age description of these six chakras and the seventh point known as sahasrara. This new age version incorporates the Newtonian colors of the rainbow not found in any ancient Indian system.


title: Chakra

text: Kurt Leland, for the Theosophical Society in America, concluded that the western chakra system was produced by an "unintentional collaboration" of many groups of people: esotericists and clairvoyants, often theosophical; Indologists; the scholar of myth, Joseph Campbell; the founders of the Esalen Institute and the psychological tradition of Carl Jung; the colour system of Charles W. Leadbeater's 1927 book "The Chakras", treated as traditional lore by some modern Indian yogis; and energy healers such as Barbara Brennan. Leland states that far from being traditional, the two main elements of the modern system, the rainbow colours and the list of qualities, first appeared together only in 1977.


title: Chakra

text: The concept of a set of seven chakras came to the West in the 1880s; at that time each chakra was associated with a nerve plexus. In 1918, Sir John Woodroffe, alias Arthur Avalon, translated two Indian texts, the "Ṣaṭ-Cakra-Nirūpaṇa" and the "Pādukā-Pañcaka", and in his book "The Serpent Power" drew Western attention to the seven chakra theory.


title: Chakra

text: In the 1920s, each of the seven chakras was associated with an endocrine gland, a tradition that has persisted. More recently, the lower six chakras have been linked to both nerve plexuses and glands. The seven rainbow colours were added by Leadbeater in 1927; a variant system in the 1930s proposed six colours plus white. Leadbeater's theory was influenced by Johann Georg Gichtel's 1696 book "Theosophia Practica", which mentioned inner "force centres".


title: Chakra

text: Psychological and other attributes such as layers of the aura, developmental stages, associated diseases, Aristotelian elements, emotions, and states of consciousness were added still later. A wide range of supposed correspondences such as with alchemical metals, astrological signs and planets, foods, herbs, gemstones, homeopathic remedies, Kabbalistic spheres, musical notes, totem animals, and Tarot cards have also been proposed.


title: Chakra

text: In "Anatomy of the Spirit" (1996), Caroline Myss described the function of chakras as follows: "Every thought and experience you've ever had in your life gets filtered through these chakra databases. Each event is recorded into your cells...". The chakras are described as being aligned in an ascending column from the base of the spine to the top of the head. New Age practices often associate each chakra with a certain colour. In various traditions, chakras are associated with multiple physiological functions, an aspect of consciousness, a classical element, and other distinguishing characteristics; these do not correspond to those used in ancient Indian systems. The chakras are visualised as lotuses or flowers with a different number of petals in every chakra.


title: Chakra

text: The chakras are thought to vitalise the physical body and to be associated with interactions of a physical, emotional and mental nature. They are considered of life energy or prana (which New Age belief equates with "shakti", "qi" in Chinese, "ki "in Japanese, "koach-ha-guf" in Hebrew, "bios "in Greek, and "aether"" "in both Greek and English), which is thought to flow among them along pathways called nadi. The function of the chakras is to spin and draw in this energy to keep the spiritual, mental, emotional and physical health of the body in balance.


title: Chakra

text: Rudolf Steiner considered the chakra system to be dynamic and evolving. He suggested that this system has become different for modern people than it was in ancient times and that it will, in turn, be radically different in future times. Steiner described a sequence of development that begins with the upper chakras and moves down, rather than moving in the opposite direction. He gave suggestions on how to develop the chakras through disciplining thoughts, feelings, and will. According to Florin Lowndes, a "spiritual student" can further develop and deepen or elevate thinking consciousness when taking the step from the "ancient path" of schooling to the "new path" represented by Steiner's "The Philosophy of Freedom".


title: Chakra

text: The not-for-profit Edinburgh Skeptics Society states that despite their popularity, "there has never been any evidence for these meridian lines or chakras". It adds that while practitioners sometimes cite "scientific evidence" for their claims, such evidence is often "incredibly shaky".


title: Gasoline

text: Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. On average, U.S. refineries produce, from a barrel of crude oil, about 19 to 20 gallons of gasoline; 11 to 13 gallons of distillate fuel (most of which is sold as diesel fuel); and 3 to 4 gallons of jet fuel. The product ratio depends on the processing in an oil refinery and the crude oil assay. A barrel of oil is defined as holding 42 US gallons, which is about 159 liters or 35 imperial gallons.


title: Gasoline

text: The characteristic of a particular gasoline blend to resist igniting too early (which causes knocking and reduces efficiency in reciprocating engines) is measured by its octane rating, which is produced in several grades. Tetraethyl lead and other lead compounds, once widely used to increase octane ratings, are no longer used except in aviation, off-road and auto-racing applications. Other chemicals are frequently added to gasoline to improve chemical stability and performance characteristics, control corrosiveness, and provide fuel system cleaning. Gasoline may contain oxygen-containing chemicals such as ethanol, MTBE, or ETBE to improve combustion.


title: Gasoline

text: Gasoline can enter the environment (uncombusted), both as liquid and as vapor, from leakage and handling during production, transport, and delivery (e.g., from storage tanks, from spills, etc.). As an example of efforts to control such leakage, many underground storage tanks are required to have extensive measures in place to detect and prevent such leaks. Gasoline contains known carcinogens. Burning of gasoline emits about of , a greenhouse gas, contributing to human-caused climate change.


title: Gasoline

text: "Gasoline" (often shortened to "gas") is an American word that denotes fuel for automobiles. The term is thought to have been influenced by the trademark "Cazeline" or "Gazeline", named after the surname of British publisher, coffee merchant, and social campaigner John Cassell. On 27 November 1862, Cassell placed an advertisement in "The Times" of London:


title: Gasoline

text: This is the earliest occurrence of the word to have been found. Cassell discovered that a shopkeeper in Dublin named Samuel Boyd was selling counterfeit cazeline and wrote to him to ask him to stop. Boyd did not reply and changed every 'C' into a 'G', thus coining the word "gazeline". The "Oxford English Dictionary" dates its first recorded use to 1863 when it was spelled "gasolene". The term "gasoline" was first used in North America in 1864.


title: Gasoline

text: In most Commonwealth countries (except Canada), the product is called "petrol", rather than "gasoline". The word "petroleum", originally used to refer to various types of mineral oils and literally meaning "rock oil", comes from Medieval Latin ("petra", "rock", and "oleum", "oil"). "Petrol" was used as a product name in about 1870, as the name of a refined mineral oil product sold by British wholesaler Carless, Capel & Leonard, which marketed it as a solvent. When the product later found a new use as a motor fuel, Frederick Simms, an associate of Gottlieb Daimler, suggested to John Leonard, the owner of Carless, that they register the trademark "Petrol", but by that time the word was already in general use, possibly inspired by the French "pétrole", and the registration was not allowed because the word was a general descriptor; Carless was still able to defend its use of "Petrol" as a product name due to their having sold it under that name for many years by then. Carless registered a number of alternative names for the product, but "petrol" nonetheless became the common term for the fuel in the British Commonwealth.


title: Gasoline

text: British refiners originally used "motor spirit" as a generic name for the automotive fuel and "aviation spirit" for aviation gasoline. When Carless was denied a trademark on "petrol" in the 1930s, its competitors switched to the more popular name "petrol". However, "motor spirit" had already made its way into laws and regulations, so the term remains in use as a formal name for petrol. The term is used most widely in Nigeria, where the largest petroleum companies call their product "premium motor spirit". Although "petrol" has made inroads into Nigerian English, "premium motor spirit" remains the formal name that is used in scientific publications, government reports, and newspapers.


title: Gasoline

text: The use of the word "gasoline" instead of "petrol" is uncommon outside North America, although "gasolina" is used in Spanish and Portuguese.


title: Gasoline

text: In many languages, the name of the product is derived from benzene, such as "Benzin" in Persian and German or "benzina" in Italian; but in Argentina, Uruguay, and Paraguay, the colloquial name "nafta" is derived from that of the chemical naphtha.


title: Gasoline

text: Some languages, like French and Italian, use the respective words for gasoline to indicate diesel fuel.


title: Gasoline

text: The first internal combustion engines suitable for use in transportation applications, so-called Otto engines, were developed in Germany during the last quarter of the 19th century. The fuel for these early engines was a relatively volatile hydrocarbon obtained from coal gas. With a boiling point near ("n"-octane boils about higher), it was well-suited for early carburetors (evaporators). The development of a "spray nozzle" carburetor enabled the use of less volatile fuels. Further improvements in engine efficiency were attempted at higher compression ratios, but early attempts were blocked by the premature explosion of fuel, known as knocking.


title: Gasoline

text: In 1891, the Shukhov cracking process became the world's first commercial method to break down heavier hydrocarbons in crude oil to increase the percentage of lighter products compared to simple distillation.


title: Gasoline

text: The evolution of gasoline followed the evolution of oil as the dominant source of energy in the industrializing world. Before World War One, Britain was the world's greatest industrial power and depended on its navy to protect the shipping of raw materials from its colonies. Germany was also industrializing and, like Britain, lacked many natural resources which had to be shipped to the home country. By the 1890s, Germany began to pursue a policy of global prominence and began building a navy to compete with Britain's. Coal was the fuel that powered their navies. Though both Britain and Germany had natural coal reserves, new developments in oil as a fuel for ships changed the situation. Coal-powered ships were a tactical weakness because the process of loading coal was extremely slow and dirty and left the ship completely vulnerable to attack, and unreliable supplies of coal at international ports made long-distance voyages impractical. The advantages of petroleum oil soon found the navies of the world converting to oil, but Britain and Germany had very few domestic oil reserves. Britain eventually solved its naval oil dependence by securing oil from Royal Dutch Shell and the Anglo-Persian Oil Company and this determined from where and of what quality its gasoline would come.


title: Gasoline

text: During the early period of gasoline engine development, aircraft were forced to use motor vehicle gasoline since aviation gasoline did not yet exist. These early fuels were termed "straight-run" gasolines and were byproducts from the distillation of a single crude oil to produce kerosene, which was the principal product sought for burning in kerosene lamps. Gasoline production would not surpass kerosene production until 1916. The earliest straight-run gasolines were the result of distilling eastern crude oils and there was no mixing of distillates from different crudes. The composition of these early fuels was unknown and the quality varied greatly as crude oils from different oil fields emerged in different mixtures of hydrocarbons in different ratios. The engine effects produced by abnormal combustion (engine knocking and pre-ignition) due to inferior fuels had not yet been identified, and as a result, there was no rating of gasoline in terms of its resistance to abnormal combustion. The general specification by which early gasolines were measured was that of specific gravity via the Baumé scale and later the volatility (tendency to vaporize) specified in terms of boiling points, which became the primary focuses for gasoline producers. These early eastern crude oil gasolines had relatively high Baumé test results (65 to 80 degrees Baumé) and were called "Pennsylvania high-test" or simply "high-test" gasolines. These were often used in aircraft engines.


title: Gasoline

text: By 1910, increased automobile production and the resultant increase in gasoline consumption produced a greater demand for gasoline. Also, the growing electrification of lighting produced a drop in kerosene demand, creating a supply problem. It appeared that the burgeoning oil industry would be trapped into over-producing kerosene and under-producing gasoline since simple distillation could not alter the ratio of the two products from any given crude. The solution appeared in 1911 when the development of the Burton process allowed thermal cracking of crude oils, which increased the percent yield of gasoline from the heavier hydrocarbons. This was combined with the expansion of foreign markets for the export of surplus kerosene which domestic markets no longer needed. These new thermally "cracked" gasolines were believed to have no harmful effects and would be added to straight-run gasolines. There also was the practice of mixing heavy and light distillates to achieve the desired Baumé reading and collectively these were called "blended" gasolines.


title: Gasoline

text: Gradually, volatility gained favor over the Baumé test, though both continued to be used in combination to specify a gasoline. As late as June 1917, Standard Oil (the largest refiner of crude oil in the United States at the time) stated that the most important property of a gasoline was its volatility. It is estimated that the rating equivalent of these straight-run gasolines varied from 40 to 60 octane and that the "high-test", sometimes referred to as "fighting grade", probably averaged 50 to 65 octane.


title: Gasoline

text: Prior to the American entry into World War I, the European Allies used fuels derived from crude oils from Borneo, Java, and Sumatra, which gave satisfactory performance in their military aircraft. When the U.S. entered the war in April 1917, the U.S. became the principal supplier of aviation gasoline to the Allies and a decrease in engine performance was noted. Soon it was realized that motor vehicle fuels were unsatisfactory for aviation, and after the loss of several combat aircraft, attention turned to the quality of the gasolines being used. Later flight tests conducted in 1937 showed that an octane reduction of 13 points (from 100 down to 87 octane) decreased engine performance by 20 percent and increased take-off distance by 45 percent. If abnormal combustion were to occur, the engine could lose enough power to make getting airborne impossible and a take-off roll became a threat to the pilot and aircraft.


title: Gasoline

text: On 2 August 1917, the U.S. Bureau of Mines arranged to study fuels for aircraft in cooperation with the Aviation Section of the U.S. Army Signal Corps and a general survey concluded that no reliable data existed for the proper fuels for aircraft. As a result, flight tests began at Langley, McCook and Wright fields to determine how different gasolines performed under different conditions. These tests showed that in certain aircraft, motor vehicle gasolines performed as well as "high-test" but in other types resulted in hot-running engines. It was also found that gasolines from aromatic and naphthenic base crude oils from California, South Texas, and Venezuela resulted in smooth-running engines. These tests resulted in the first government specifications for motor gasolines (aviation gasolines used the same specifications as motor gasolines) in late 1917.


title: Gasoline

text: Engine designers knew that, according to the Otto cycle, power and efficiency increased with compression ratio, but experience with early gasolines during World War I showed that higher compression ratios increased the risk of abnormal combustion, producing lower power, lower efficiency, hot-running engines, and potentially severe engine damage. To compensate for these poor fuels, early engines used low compression ratios, which required relatively large, heavy engines with limited power and efficiency. The Wright brothers' first gasoline engine used a compression ratio as low as 4.7-to-1, developed only from , and weighed . This was a major concern for aircraft designers and the needs of the aviation industry provoked the search for fuels that could be used in higher-compression engines.


title: Gasoline

text: Between 1917 and 1919, the amount of thermally cracked gasoline utilized almost doubled. Also, the use of natural gasoline increased greatly. During this period, many U.S. states established specifications for motor gasoline but none of these agreed and they were unsatisfactory from one standpoint or another. Larger oil refiners began to specify unsaturated material percentage (thermally cracked products caused gumming in both use and storage while unsaturated hydrocarbons are more reactive and tend to combine with impurities leading to gumming). In 1922, the U.S. government published the first specifications for aviation gasolines (two grades were designated as "fighting" and "domestic" and were governed by boiling points, color, sulfur content, and a gum formation test) along with one "motor" grade for automobiles. The gum test essentially eliminated thermally cracked gasoline from aviation usage and thus aviation gasolines reverted to fractionating straight-run naphthas or blending straight-run and highly treated thermally cracked naphthas. This situation persisted until 1929.


title: Gasoline

text: The automobile industry reacted to the increase in thermally cracked gasoline with alarm. Thermal cracking produced large amounts of both mono- and diolefins (unsaturated hydrocarbons), which increased the risk of gumming. Also, the volatility was decreasing to the point that fuel did not vaporize and was sticking to spark plugs and fouling them, creating hard starting and rough running in winter and sticking to cylinder walls, bypassing the pistons and rings, and going into the crankcase oil. One journal stated, "on a multi-cylinder engine in a high-priced car we are diluting the oil in the crankcase as much as 40 percent in a run, as the analysis of the oil in the oil-pan shows".


title: Gasoline

text: Being very unhappy with the consequent reduction in overall gasoline quality, automobile manufacturers suggested imposing a quality standard on the oil suppliers. The oil industry in turn accused the automakers of not doing enough to improve vehicle economy, and the dispute became known within the two industries as "the fuel problem". Animosity grew between the industries, each accusing the other of not doing anything to resolve matters, and their relationship deteriorated. The situation was only resolved when the American Petroleum Institute (API) initiated a conference to address the fuel problem and a cooperative fuel research (CFR) committee was established in 1920, to oversee joint investigative programs and solutions. Apart from representatives of the two industries, the Society of Automotive Engineers (SAE) also played an instrumental role, with the U.S. Bureau of Standards being chosen as an impartial research organization to carry out many of the studies. Initially, all the programs were related to volatility and fuel consumption, ease of starting, crankcase oil dilution, and acceleration.


title: Gasoline

text: With the increased use of thermally cracked gasolines came an increased concern regarding its effects on abnormal combustion, and this led to research for antiknock additives. In the late 1910s, researchers such as A.H. Gibson, Harry Ricardo, Thomas Midgley Jr., and Thomas Boyd began to investigate abnormal combustion. Beginning in 1916, Charles F. Kettering of General Motors began investigating additives based on two paths, the "high percentage" solution (where large quantities of ethanol were added) and the "low percentage" solution (where only 0.53-1.1 g/L or 0.071-0.147 oz / U.S. gal were needed). The "low percentage" solution ultimately led to the discovery of tetraethyllead (TEL) in December 1921, a product of the research of Midgley and Boyd and the defining component of leaded gasoline. This innovation started a cycle of improvements in fuel efficiency that coincided with the large-scale development of oil refining to provide more products in the boiling range of gasoline. Ethanol could not be patented but TEL could, so Kettering secured a patent for TEL and began promoting it instead of other options.


title: Gasoline

text: The dangers of compounds containing lead were well-established by then and Kettering was directly warned by Robert Wilson of MIT, Reid Hunt of Harvard, Yandell Henderson of Yale, and Erik Krause of the University of Potsdam in Germany about its use. Krause had worked on tetraethyllead for many years and called it "a creeping and malicious poison" that had killed a member of his dissertation committee. On 27 October 1924, newspaper articles around the nation told of the workers at the Standard Oil refinery near Elizabeth, New Jersey who were producing TEL and were suffering from lead poisoning. By 30 October, the death toll had reached five. In November, the New Jersey Labor Commission closed the Bayway refinery and a grand jury investigation was started which had resulted in no charges by February 1925. Leaded gasoline sales were banned in New York City, Philadelphia, and New Jersey. General Motors, DuPont, and Standard Oil, who were partners in Ethyl Corporation, the company created to produce TEL, began to argue that there were no alternatives to leaded gasoline that would maintain fuel efficiency and still prevent engine knocking. After several industry-funded flawed studies reported that TEL-treated gasoline was not a public health issue, the controversy subsided.


title: Gasoline

text: In the five years prior to 1929, a great amount of experimentation was conducted on different testing methods for determining fuel resistance to abnormal combustion. It appeared engine knocking was dependent on a wide variety of parameters including compression, ignition timing, cylinder temperature, air-cooled or water-cooled engines, chamber shapes, intake temperatures, lean or rich mixtures, and others. This led to a confusing variety of test engines that gave conflicting results, and no standard rating scale existed. By 1929, it was recognized by most aviation gasoline manufacturers and users that some kind of antiknock rating must be included in government specifications. In 1929, the octane rating scale was adopted, and in 1930, the first octane specification for aviation fuels was established. In the same year, the U.S. Army Air Force specified fuels rated at 87 octane for its aircraft as a result of studies it had conducted.


title: Gasoline

text: During this period, research showed that hydrocarbon structure was extremely important to the antiknocking properties of fuel. Straight-chain paraffins in the boiling range of gasoline had low antiknock qualities while ring-shaped molecules such as aromatic hydrocarbons (for example benzene) had higher resistance to knocking. This development led to the search for processes that would produce more of these compounds from crude oils than achieved under straight distillation or thermal cracking. Research by the major refiners led to the development of processes involving isomerization of cheap and abundant butane to isobutane, and alkylation to join isobutane and butylenes to form isomers of octane such as "isooctane", which became an important component in aviation fuel blending. To further complicate the situation, as engine performance increased, the altitude that aircraft could reach also increased, which resulted in concerns about the fuel freezing. The average temperature decrease is per increase in altitude, and at , the temperature can approach . Additives like benzene, with a freezing point of , would freeze in the gasoline and plug fuel lines. Substituted aromatics such as toluene, xylene, and cumene, combined with limited benzene, solved the problem.


title: Gasoline

text: By 1935, there were seven different aviation grades based on octane rating, two Army grades, four Navy grades, and three commercial grades including the introduction of 100-octane aviation gasoline. By 1937, the Army established 100-octane as the standard fuel for combat aircraft, and to add to the confusion, the government now recognized 14 different grades, in addition to 11 others in foreign countries. With some companies required to stock 14 grades of aviation fuel, none of which could be interchanged, the effect on the refiners was negative. The refining industry could not concentrate on large capacity conversion processes for so many different grades and a solution had to be found. By 1941, principally through the efforts of the Cooperative Fuel Research Committee, the number of grades for aviation fuels was reduced to three: 73, 91, and 100 octane.


title: Gasoline

text: The development of 100-octane aviation gasoline on an economic scale was due in part to Jimmy Doolittle, who had become Aviation Manager of Shell Oil Company. He convinced Shell to invest in refining capacity to produce 100-octane on a scale that nobody needed since no aircraft existed that required a fuel that nobody made. Some fellow employees would call his effort "Doolittle's million-dollar blunder" but time would prove Doolittle correct. Before this, the Army had considered 100-octane tests using pure octane but at , the price prevented this from happening. In 1929, Stanavo Specification Board Inc. was organized by the Standard Oil companies of California, Indiana, and New Jersey to improve aviation fuels and oils and by 1935 had placed their first 100 octane fuel on the market, Stanavo Ethyl Gasoline 100. It was used by the Army, engine manufacturers and airlines for testing and for air racing and record flights. By 1936, tests at Wright Field using the new, cheaper alternatives to pure octane proved the value of 100 octane fuel, and both Shell and Standard Oil would win the contract to supply test quantities for the Army. By 1938, the price was down to , only more than 87 octane fuel. By the end of WWII, the price would be down to .


title: Gasoline

text: In 1937, Eugene Houdry developed the Houdry process of catalytic cracking, which produced a high-octane base stock of gasoline which was superior to the thermally cracked product since it did not contain the high concentration of olefins. In 1940, there were only 14 Houdry units in operation in the U.S.; by 1943, this had increased to 77, either of the Houdry process or of the Thermofor Catalytic or Fluid Catalyst type.


title: Gasoline

text: The search for fuels with octane ratings above 100 led to the extension of the scale by comparing power output. A fuel designated grade 130 would produce 130 percent as much power in an engine as it would running on pure iso-octane. During WWII, fuels above 100-octane were given two ratings, a rich and a lean mixture, and these would be called 'performance numbers' (PN). 100-octane aviation gasoline would be referred to as 130/100 grade.


title: Gasoline

text: Oil and its byproducts, especially high-octane aviation gasoline, would prove to be a driving concern for how Germany conducted the war. As a result of the lessons of World War I, Germany had stockpiled oil and gasoline for its blitzkrieg offensive and had annexed Austria, adding per day of oil production, but this was not sufficient to sustain the planned conquest of Europe. Because captured supplies and oil fields would be necessary to fuel the campaign, the German high command created a special squad of oilfield experts drawn from the ranks of domestic oil industries. They were sent in to put out oilfield fires and get production going again as soon as possible. But capturing oilfields remained an obstacle throughout the war. During the Invasion of Poland, German estimates of gasoline consumption turned out to be vastly too low. Heinz Guderian and his Panzer divisions consumed nearly of gasoline on the drive to Vienna. When they were engaged in combat across open country, gasoline consumption almost doubled. On the second day of battle, a unit of the XIX Corps was forced to halt when it ran out of gasoline. One of the major objectives of the Polish invasion was their oil fields but the Soviets invaded and captured 70 percent of the Polish production before the Germans could reach it. Through the German–Soviet Commercial Agreement (1940), Stalin agreed in vague terms to supply Germany with additional oil equal to that produced by now Soviet-occupied Polish oilfields at Drohobych and Boryslav in exchange for hard coal and steel tubing.


title: Gasoline

text: Even after the Nazis conquered the vast territories of Europe, this did not help the gasoline shortage. This area had never been self-sufficient in oil before the war. In 1938, the area that would become Nazi-occupied produced per day. In 1940, total production under German control amounted to only . By early 1941 and the depletion of German gasoline reserves, Adolf Hitler saw the invasion of Russia to seize the Polish oil fields and the Russian oil in the Caucasus as the solution to the German gasoline shortage. As early as July 1941, following the 22 June start of Operation Barbarossa, certain Luftwaffe squadrons were forced to curtail ground support missions due to shortages of aviation gasoline. On 9 October, the German quartermaster general estimated that army vehicles were short of gasoline requirements.


title: Gasoline

text: Virtually all of Germany's aviation gasoline came from synthetic oil plants that hydrogenated coals and coal tars. These processes had been developed during the 1930s as an effort to achieve fuel independence. There were two grades of aviation gasoline produced in volume in Germany, the B-4 or blue grade and the C-3 or green grade, which accounted for about two-thirds of all production. B-4 was equivalent to 89-octane and the C-3 was roughly equal to the U.S. 100-octane, though lean mixture was rated around 95-octane and was poorer than the U.S. version. Maximum output achieved in 1943 reached a day before the Allies decided to target the synthetic fuel plants. Through captured enemy aircraft and analysis of the gasoline found in them, both the Allies and the Axis powers were aware of the quality of the aviation gasoline being produced and this prompted an octane race to achieve the advantage in aircraft performance. Later in the war, the C-3 grade was improved to where it was equivalent to the U.S. 150 grade (rich mixture rating).


title: Gasoline

text: Japan, like Germany, had almost no domestic oil supply and by the late 1930s, produced only seven percent of its own oil while importing the rest—80 percent from the U.S.. As Japanese aggression grew in China (USS Panay incident) and news reached the American public of Japanese bombing of civilian centers, especially the bombing of Chungking, public opinion began to support a U.S. embargo. A Gallup poll in June 1939 found that 72 percent of the American public supported an embargo on war materials to Japan. This increased tensions between the U.S. and Japan, and it led to the U.S. placing restrictions on exports. In July 1940, the U.S. issued a proclamation that banned the export of 87 octane or higher aviation gasoline to Japan. This ban did not hinder the Japanese as their aircraft could operate with fuels below 87 octane and if needed they could add TEL to increase the octane. As it turned out, Japan bought 550 percent more sub-87 octane aviation gasoline in the five months after the July 1940 ban on higher octane sales. The possibility of a complete ban of gasoline from America created friction in the Japanese government as to what action to take to secure more supplies from the Dutch East Indies and demanded greater oil exports from the exiled Dutch government after the Battle of the Netherlands. This action prompted the U.S. to move its Pacific fleet from Southern California to Pearl Harbor to help stiffen British resolve to stay in Indochina. With the Japanese invasion of French Indochina in September 1940, came great concerns about the possible Japanese invasion of the Dutch Indies to secure their oil. After the U.S. banned all exports of steel and iron scrap, the next day, Japan signed the Tripartite Pact and this led Washington to fear that a complete U.S. oil embargo would prompt the Japanese to invade the Dutch East Indies. On 16 June 1941 Harold Ickes, who was appointed Petroleum Coordinator for National Defense, stopped a shipment of oil from Philadelphia to Japan in light of the oil shortage on the East coast due to increased exports to Allies. He also telegrammed all oil suppliers on the East coast not to ship any oil to Japan without his permission. President Roosevelt countermanded Ickes's orders telling Ickes that the "I simply have not got enough Navy to go around and every little episode in the Pacific means fewer ships in the Atlantic". On 25 July 1941, the U.S. froze all Japanese financial assets and licenses would be required for each use of the frozen funds including oil purchases that could produce aviation gasoline. On 28 July 1941, Japan invaded southern Indochina.


title: Gasoline

text: The debate inside the Japanese government as to its oil and gasoline situation was leading to invasion of the Dutch East Indies but this would mean war with the U.S., whose Pacific fleet was a threat to their flank. This situation led to the decision to attack the U.S. fleet at Pearl Harbor before proceeding with the Dutch East Indies invasion. On 7 December 1941, Japan attacked Pearl Harbor, and the next day the Netherlands declared war on Japan, which initiated the Dutch East Indies campaign. But the Japanese missed a golden opportunity at Pearl Harbor. "All of the oil for the fleet was in surface tanks at the time of Pearl Harbor", Admiral Chester Nimitz, who became Commander in Chief of the Pacific Fleet, was later to say. "We had about of oil out there and all of it was vulnerable to .50 caliber bullets. Had the Japanese destroyed the oil," he added, "it would have prolonged the war another two years."


title: Gasoline

text: Early in 1944, William Boyd, president of the American Petroleum Institute and chairman of the Petroleum Industry War Council said: "The Allies may have floated to victory on a wave of oil in World War I, but in this infinitely greater World War II, we are flying to victory on the wings of petroleum". In December 1941 the U.S. had 385,000 oil wells producing barrels of oil a year and 100-octane aviation gasoline capacity was at a day. By 1944, the U.S. was producing over a year (67 percent of world production) and the petroleum industry had built 122 new plants for the production of 100-octane aviation gasoline and capacity was over a day—an increase of more than ten-fold. It was estimated that the U.S. was producing enough 100-octane aviation gasoline to permit the dropping of () of bombs on the enemy every day of the year. The record of gasoline consumption by the Army prior to June 1943 was uncoordinated as each supply service of the Army purchased its own petroleum products and no centralized system of control nor records existed. On 1 June 1943, the Army created the Fuels and Lubricants Division of the Quartermaster Corps, and, from their records, they tabulated that the Army (excluding fuels and lubricants for aircraft) purchased over of gasoline for delivery to overseas theaters between 1 June 1943 through August 1945. That figure does not include gasoline used by the Army inside the U.S. Motor fuel production had declined from in 1941 down to in 1943. World War II marked the first time in U.S. history that gasoline was rationed and the government imposed price controls to prevent inflation. Gasoline consumption per automobile declined from per year in 1941 down to in 1943, with the goal of preserving rubber for tires since the Japanese had cut the U.S. off from over 90 percent of its rubber supply which had come from the Dutch East Indies and the U.S. synthetic rubber industry was in its infancy. Average gasoline prices went from a record low of ( with taxes) in 1940 to ( with taxes) in 1945.


title: Gasoline

text: Even with the world's largest aviation gasoline production, the U.S. military still found that more was needed. Throughout the duration of the war, aviation gasoline supply was always behind requirements and this impacted training and operations. The reason for this shortage developed before the war even began. The free market did not support the expense of producing 100-octane aviation fuel in large volume, especially during the Great Depression. Iso-octane in the early development stage cost , and, even by 1934, it was still compared to for motor gasoline when the Army decided to experiment with 100-octane for its combat aircraft. Though only three percent of U.S. combat aircraft in 1935 could take full advantage of the higher octane due to low compression ratios, the Army saw that the need for increasing performance warranted the expense and purchased 100,000 gallons. By 1937, the Army established 100-octane as the standard fuel for combat aircraft and by 1939 production was only a day. In effect, the U.S. military was the only market for 100-octane aviation gasoline and as war broke out in Europe this created a supply problem that persisted throughout the duration.


title: Gasoline

text: With the war in Europe a reality in 1939, all predictions of 100-octane consumption were outrunning all possible production. Neither the Army nor the Navy could contract more than six months in advance for fuel and they could not supply the funds for plant expansion. Without a long-term guaranteed market, the petroleum industry would not risk its capital to expand production for a product that only the government would buy. The solution to the expansion of storage, transportation, finances, and production was the creation of the Defense Supplies Corporation on 19 September 1940. The Defense Supplies Corporation would buy, transport and store all aviation gasoline for the Army and Navy at cost plus a carrying fee.


title: Gasoline

text: When the Allied breakout after D-Day found their armies stretching their supply lines to a dangerous point, the makeshift solution was the Red Ball Express. But even this soon was inadequate. The trucks in the convoys had to drive longer distances as the armies advanced and they were consuming a greater percentage of the same gasoline they were trying to deliver. In 1944, General George Patton's Third Army finally stalled just short of the German border after running out of gasoline. The general was so upset at the arrival of a truckload of rations instead of gasoline he was reported to have shouted: "Hell, they send us food, when they know we can fight without food but not without oil." The solution had to wait for the repairing of the railroad lines and bridges so that the more efficient trains could replace the gasoline-consuming truck convoys.


title: Gasoline

text: The development of jet engines burning kerosene-based fuels during WWII for aircraft produced a superior performing propulsion system than internal combustion engines could offer and the U.S. military forces gradually replaced their piston combat aircraft with jet powered planes. This development would essentially remove the military need for ever increasing octane fuels and eliminated government support for the refining industry to pursue the research and production of such exotic and expensive fuels. Commercial aviation was slower to adapt to jet propulsion and until 1958, when the Boeing 707 first entered commercial service, piston powered airliners still relied on aviation gasoline. But commercial aviation had greater economic concerns than the maximum performance that the military could afford. As octane numbers increased so did the cost of gasoline but the incremental increase in efficiency becomes less as compression ratio goes up. This reality set a practical limit to how high compression ratios could increase relative to how expensive the gasoline would become. Last produced in 1955, the Pratt & Whitney R-4360 Wasp Major was using 115/145 Aviation gasoline and producing at 6.7 compression ratio (turbo-supercharging would increase this) and of engine weight to produce . This compares to the Wright Brothers engine needing almost of engine weight to produce .


title: Gasoline

text: The U.S. automobile industry after WWII could not take advantage of the high octane fuels then available. Automobile compression ratios increased from an average of 5.3-to-1 in 1931 to just 6.7-to-1 in 1946. The average octane number of regular-grade motor gasoline increased from 58 to 70 during the same time. Military aircraft were using expensive turbo-supercharged engines that cost at least 10 times as much per horsepower as automobile engines and had to be overhauled every 700 to 1,000 hours. The automobile market could not support such expensive engines. It would not be until 1957 that the first U.S. automobile manufacturer could mass-produce an engine that would produce one horsepower per cubic inch, the Chevrolet 283 hp/283 cubic inch V-8 engine option in the Corvette. At $485, this was an expensive option that few consumers could afford and would only appeal to the performance-oriented consumer market willing to pay for the premium fuel required. This engine had an advertised compression ratio of 10.5-to-1 and the 1958 AMA Specifications stated that the octane requirement was 96–100 RON. At (1959 with aluminum intake), it took of engine weight to make .


title: Gasoline

text: In the 1950s, oil refineries started to focus on high octane fuels, and then detergents were added to gasoline to clean the jets in carburetors. The 1970s witnessed greater attention to the environmental consequences of burning gasoline. These considerations led to the phasing out of TEL and its replacement by other antiknock compounds. Subsequently, low-sulfur gasoline was introduced, in part to preserve the catalysts in modern exhaust systems.


title: Gasoline

text: Commercial gasoline is a mixture of a large number of different hydrocarbons. Gasoline is produced to meet a host of engine performance specifications and many different compositions are possible. Hence, the exact chemical composition of gasoline is undefined. The performance specification also varies with season, requiring more volatile blends (due to added butane) during winter, in order to be able to start a cold engine. At the refinery, the composition varies according to the crude oils from which it is produced, the type of processing units present at the refinery, how those units are operated, and which hydrocarbon streams (blendstocks) the refinery opts to use when blending the final product.


title: Gasoline

text: Gasoline is produced in oil refineries. Roughly of gasoline is derived from a barrel of crude oil. Material separated from crude oil via distillation, called virgin or straight-run gasoline, does not meet specifications for modern engines (particularly the octane rating; see below), but can be pooled to the gasoline blend.


title: Gasoline

text: The bulk of a typical gasoline consists of a homogeneous mixture of small, relatively lightweight hydrocarbons with between 4 and 12 carbon atoms per molecule (commonly referred to as C4–C12). It is a mixture of paraffins (alkanes), olefins (alkenes), and cycloalkanes (naphthenes). The usage of the terms "paraffin" and "olefin" in place of the standard chemical nomenclature "alkane" and "alkene", respectively, is particular to the oil industry. The actual ratio of molecules in any gasoline depends upon:


title: Gasoline

text: The various refinery streams blended to make gasoline have different characteristics. Some important streams include the following:


title: Gasoline

text: Currently, many countries set limits on gasoline aromatics in general, benzene in particular, and olefin (alkene) content. Such regulations have led to an increasing preference for alkane isomers, such as isomerate or alkylate, as their octane rating is higher than n-alkanes. In the European Union, the benzene limit is set at one percent by volume for all grades of automotive gasoline. This is usually achieved by avoiding feeding C6, in particular cyclohexane, to the reformer unit, where it would be converted to benzene. Therefore, only (desulfurized) heavy virgin naphtha (HVN) is fed to the reformer unit


title: Gasoline

text: Gasoline can also contain other organic compounds, such as organic ethers (deliberately added), plus small levels of contaminants, in particular organosulfur compounds (which are usually removed at the refinery).


title: Gasoline

text: The specific gravity of gasoline ranges from 0.71 to 0.77, with higher densities having a greater volume fraction of aromatics. Finished marketable gasoline is traded (in Europe) with a standard reference of , and its price is escalated or de-escalated according to its actual density. Because of its low density, gasoline floats on water, and therefore water cannot generally be used to extinguish a gasoline fire unless applied in a fine mist.


title: Gasoline

text: Quality gasoline should be stable for six months if stored properly, but can degrade over time. Gasoline stored for a year will most likely be able to be burned in an internal combustion engine without too much trouble. However, the effects of long-term storage will become more noticeable with each passing month until a time comes when the gasoline should be diluted with ever-increasing amounts of freshly made fuel so that the older gasoline may be used up. If left undiluted, improper operation will occur and this may include engine damage from misfiring or the lack of proper action of the fuel within a fuel injection system and from an onboard computer attempting to compensate (if applicable to the vehicle). Gasoline should ideally be stored in an airtight container (to prevent oxidation or water vapor mixing in with the gas) that can withstand the vapor pressure of the gasoline without venting (to prevent the loss of the more volatile fractions) at a stable cool temperature (to reduce the excess pressure from liquid expansion and to reduce the rate of any decomposition reactions). When gasoline is not stored correctly, gums and solids may result, which can corrode system components and accumulate on wet surfaces, resulting in a condition called "stale fuel". Gasoline containing ethanol is especially subject to absorbing atmospheric moisture, then forming gums, solids, or two phases (a hydrocarbon phase floating on top of a water-alcohol phase).


title: Gasoline

text: The presence of these degradation products in the fuel tank or fuel lines plus a carburetor or fuel injection components makes it harder to start the engine or causes reduced engine performance. On resumption of regular engine use, the buildup may or may not be eventually cleaned out by the flow of fresh gasoline. The addition of a fuel stabilizer to gasoline can extend the life of fuel that is not or cannot be stored properly, though removal of all fuel from a fuel system is the only real solution to the problem of long-term storage of an engine or a machine or vehicle. Typical fuel stabilizers are proprietary mixtures containing mineral spirits, isopropyl alcohol, 1,2,4-trimethylbenzene or other additives. Fuel stabilizers are commonly used for small engines, such as lawnmower and tractor engines, especially when their use is sporadic or seasonal (little to no use for one or more seasons of the year). Users have been advised to keep gasoline containers more than half full and properly capped to reduce air exposure, to avoid storage at high temperatures, to run an engine for ten minutes to circulate the stabilizer through all components prior to storage, and to run the engine at intervals to purge stale fuel from the carburetor.


title: Gasoline

text: Gasoline stability requirements are set by the standard ASTM D4814. This standard describes the various characteristics and requirements of automotive fuels for use over a wide range of operating conditions in ground vehicles equipped with spark-ignition engines.


title: Gasoline

text: A gasoline-fueled internal combustion engine obtains energy from the combustion of gasoline's various hydrocarbons with oxygen from the ambient air, yielding carbon dioxide and water as exhaust. The combustion of octane, a representative species, performs the chemical reaction:


title: Gasoline

text: By weight, combustion of gasoline releases about or by volume , quoting the lower heating value. Gasoline blends differ, and therefore actual energy content varies according to the season and producer by up to 1.75 percent more or less than the average. On average, about of gasoline are available from a barrel of crude oil (about 46 percent by volume), varying with the quality of the crude and the grade of the gasoline. The remainder is products ranging from tar to naphtha.


title: Gasoline

text: A high-octane-rated fuel, such as liquefied petroleum gas (LPG), has an overall lower power output at the typical 10:1 compression ratio of an engine design optimized for gasoline fuel. An engine tuned for LPG fuel via higher compression ratios (typically 12:1) improves the power output. This is because higher-octane fuels allow for a higher compression ratio without knocking, resulting in a higher cylinder temperature, which improves efficiency. Also, increased mechanical efficiency is created by a higher compression ratio through the concomitant higher expansion ratio on the power stroke, which is by far the greater effect. The higher expansion ratio extracts more work from the high-pressure gas created by the combustion process. An Atkinson cycle engine uses the timing of the valve events to produce the benefits of a high expansion ratio without the disadvantages, chiefly detonation, of a high compression ratio. A high expansion ratio is also one of the two key reasons for the efficiency of diesel engines, along with the elimination of pumping losses due to throttling of the intake airflow.


title: Gasoline

text: The lower energy content of LPG by liquid volume in comparison to gasoline is due mainly to its lower density. This lower density is a property of the lower molecular weight of propane (LPG's chief component) compared to gasoline's blend of various hydrocarbon compounds with heavier molecular weights than propane. Conversely, LPG's energy content by weight is higher than gasoline's due to a higher hydrogen-to-carbon ratio.


title: Gasoline

text: Molecular weights of the species in the representative octane combustion are CH 114, O 32, CO 44, HO 18; therefore of fuel reacts with of oxygen to produce of carbon dioxide and of water.


title: Gasoline

text: Spark-ignition engines are designed to burn gasoline in a controlled process called deflagration. However, the unburned mixture may autoignite by pressure and heat alone, rather than igniting from the spark plug at exactly the right time, causing a rapid pressure rise that can damage the engine. This is often referred to as engine knocking or end-gas knock. Knocking can be reduced by increasing the gasoline's resistance to autoignition, which is expressed by its octane rating.


title: Gasoline

text: Octane rating is measured relative to a mixture of 2,2,4-trimethylpentane (an isomer of octane) and n-heptane. There are different conventions for expressing octane ratings, so the same physical fuel may have several different octane ratings based on the measure used. One of the best known is the research octane number (RON).


title: Gasoline

text: The octane rating of typical commercially available gasoline varies by country. In Finland, Sweden, and Norway, 95 RON is the standard for regular unleaded gasoline and 98 RON is also available as a more expensive option.


title: Gasoline

text: In the United Kingdom, over 95 percent of gasoline sold has 95 RON and is marketed as Unleaded or Premium Unleaded. Super Unleaded, with 97/98 RON and branded high-performance fuels (e.g., Shell V-Power, BP Ultimate) with 99 RON make up the balance. Gasoline with 102 RON may rarely be available for racing purposes.


title: Gasoline

text: In the U.S., octane ratings in unleaded fuels vary between 85 and 87 AKI (91–92 RON) for regular, 89–90 AKI (94–95 RON) for mid-grade (equivalent to European regular), up to 90–94 AKI (95–99 RON) for premium (European premium).


title: Gasoline

text: As South Africa's largest city, Johannesburg, is located on the Highveld at above sea level, the Automobile Association of South Africa recommends 95-octane gasoline at low altitude and 93-octane for use in Johannesburg because "The higher the altitude the lower the air pressure, and the lower the need for a high octane fuel as there is no real performance gain".


title: Gasoline

text: Octane rating became important as the military sought higher output for aircraft engines in the late 1930s and the 1940s. A higher octane rating allows a higher compression ratio or supercharger boost, and thus higher temperatures and pressures, which translate to higher power output. Some scientists even predicted that a nation with a good supply of high-octane gasoline would have the advantage in air power. In 1943, the Rolls-Royce Merlin aero engine produced using 100 RON fuel from a modest displacement. By the time of Operation Overlord, both the RAF and USAAF were conducting some operations in Europe using 150 RON fuel (100/150 avgas), obtained by adding 2.5 percent aniline to 100-octane avgas. By this time, the Rolls-Royce Merlin 66 was developing using this fuel.


title: Gasoline

text: Gasoline, when used in high-compression internal combustion engines, tends to auto-ignite or "detonate" causing damaging engine knocking (also called "pinging" or "pinking"). To address this problem, tetraethyl lead (TEL) was widely adopted as an additive for gasoline in the 1920s. With a growing awareness of the seriousness of the extent of environmental and health damage caused by lead compounds, however, and the incompatibility of lead with catalytic converters, governments began to mandate reductions in gasoline lead.


title: Gasoline

text: In the U.S., the Environmental Protection Agency issued regulations to reduce the lead content of leaded gasoline over a series of annual phases, scheduled to begin in 1973 but delayed by court appeals until 1976. By 1995, leaded fuel accounted for only 0.6 percent of total gasoline sales and under () of lead per year. From 1 January 1996, the U.S. Clean Air Act banned the sale of leaded fuel for use in on-road vehicles in the U.S. The use of TEL also necessitated other additives, such as dibromoethane.


title: Gasoline

text: European countries began replacing lead-containing additives by the end of the 1980s, and by the end of the 1990s, leaded gasoline was banned within the entire European Union. The UAE started to switch to unleaded in the early 2000s.


title: Gasoline

text: Reduction in the average lead content of human blood may be a major cause for falling violent crime rates around the world including South Africa. A study found a correlation between leaded gasoline usage and violent crime. Other studies found no correlation.()


title: Gasoline

text: In August 2021, the UN Environment Programme announced that leaded petrol had been eradicated worldwide, with Algeria being the last country to deplete its reserves. UN Secretary-General António Guterres called the eradication of leaded petrol an "international success story". He also added: "Ending the use of leaded petrol will prevent more than one million premature deaths each year from heart disease, strokes and cancer, and it will protect children whose IQs are damaged by exposure to lead". Greenpeace called the announcement "the end of one toxic era". However, leaded gasoline continues to be used in aeronautic, auto racing, and off-road applications. The use of leaded additives is still permitted worldwide for the formulation of some grades of aviation gasoline such as 100LL, because the required octane rating is difficult to reach without the use of leaded additives.


title: Gasoline

text: Different additives have replaced lead compounds. The most popular additives include aromatic hydrocarbons, ethers(MTBE and ETBE), and alcohols, most commonly ethanol.


title: Gasoline

text: Lead replacement petrol (LRP) was developed for vehicles designed to run on leaded fuels and incompatible with unleaded fuels. Rather than tetraethyllead, it contains other metals such as potassium compounds or methylcyclopentadienyl manganese tricarbonyl (MMT); these are purported to buffer soft exhaust valves and seats so that they do not suffer recession due to the use of unleaded fuel.


title: Gasoline

text: LRP was marketed during and after the phaseout of leaded motor fuels in the United Kingdom, Australia, South Africa, and some other countries. Consumer confusion led to a widespread mistaken preference for LRP rather than unleaded, and LRP was phased out 8 to 10 years after the introduction of unleaded.


title: Gasoline

text: Leaded gasoline was withdrawn from sale in Britain after 31 December 1999, seven years after EEC regulations signaled the end of production for cars using leaded gasoline in member states. At this stage, a large percentage of cars from the 1980s and early 1990s which ran on leaded gasoline were still in use, along with cars that could run on unleaded fuel. However, the declining number of such cars on British roads saw many gasoline stations withdrawing LRP from sale by 2003.


title: Gasoline

text: Methylcyclopentadienyl manganese tricarbonyl (MMT) is used in Canada and the U.S. to boost octane rating. Its use in the U.S. has been restricted by regulations, although it is currently allowed. Its use in the European Union is restricted by Article 8a of the Fuel Quality Directive following its testing under the Protocol for the evaluation of effects of metallic fuel-additives on the emissions performance of vehicles.


title: Gasoline

text: Gummy, sticky resin deposits result from oxidative degradation of gasoline during long-term storage. These harmful deposits arise from the oxidation of alkenes and other minor components in gasoline (see drying oils). Improvements in refinery techniques have generally reduced the susceptibility of gasolines to these problems. Previously, catalytically or thermally cracked gasolines were most susceptible to oxidation. The formation of gums is accelerated by copper salts, which can be neutralized by additives called metal deactivators.


title: Gasoline

text: This degradation can be prevented through the addition of 5–100 ppm of antioxidants, such as phenylenediamines and other amines. Hydrocarbons with a bromine number of 10 or above can be protected with the combination of unhindered or partially hindered phenols and oil-soluble strong amine bases, such as hindered phenols. "Stale" gasoline can be detected by a colorimetric enzymatic test for organic peroxides produced by oxidation of the gasoline.


title: Gasoline

text: Gasolines are also treated with metal deactivators, which are compounds that sequester (deactivate) metal salts that otherwise accelerate the formation of gummy residues. The metal impurities might arise from the engine itself or as contaminants in the fuel.


title: Gasoline

text: Gasoline, as delivered at the pump, also contains additives to reduce internal engine carbon buildups, improve combustion and allow easier starting in cold climates. High levels of detergent can be found in Top Tier Detergent Gasolines. The specification for Top Tier Detergent Gasolines was developed by four automakers: GM, Honda, Toyota, and BMW. According to the bulletin, the minimal U.S. EPA requirement is not sufficient to keep engines clean. Typical detergents include alkylamines and alkyl phosphates at a level of 50–100 ppm.


title: Gasoline

text: In the EU, 5 percent ethanol can be added within the common gasoline spec (EN 228). Discussions are ongoing to allow 10 percent blending of ethanol (available in Finnish, French and German gasoline stations). In Finland, most gasoline stations sell 95E10, which is 10 percent ethanol, and 98E5, which is 5 percent ethanol. Most gasoline sold in Sweden has 5–15 percent ethanol added. Three different ethanol blends are sold in the Netherlands—E5, E10 and hE15. The last of these differs from standard ethanol–gasoline blends in that it consists of 15 percent hydrous ethanol (i.e., the ethanol–water azeotrope) instead of the anhydrous ethanol traditionally used for blending with gasoline.


title: Gasoline

text: The Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP) requires gasoline for automobile use to have 27.5 percent of ethanol added to its composition. Pure hydrated ethanol is also available as a fuel.


title: Gasoline

text: Legislation requires retailers to label fuels containing ethanol on the dispenser, and limits ethanol use to 10 percent of gasoline in Australia. Such gasoline is commonly called E10 by major brands, and it is cheaper than regular unleaded gasoline.


title: Gasoline

text: The federal Renewable Fuel Standard (RFS) effectively requires refiners and blenders to blend renewable biofuels(mostly ethanol) with gasoline, sufficient to meet a growing annual target of total gallons blended. Although the mandate does not require a specific percentage of ethanol, annual increases in the target combined with declining gasoline consumption have caused the typical ethanol content in gasoline to approach 10 percent. Most fuel pumps display a sticker that states that the fuel may contain up to 10 percent ethanol, an intentional disparity that reflects the varying actual percentage. Until late 2010, fuel retailers were only authorized to sell fuel containing up to 10 percent ethanol (E10), and most vehicle warranties (except for flexible fuel vehicles) authorize fuels that contain no more than 10 percent ethanol. In parts of the U.S., ethanol is sometimes added to gasoline without an indication that it is a component.


title: Gasoline

text: In October 2007, the Government of India decided to make five percent ethanol blending (with gasoline) mandatory. Currently, 10 percent ethanol blended product (E10) is being sold in various parts of the country. Ethanol has been found in at least one study to damage catalytic converters.


title: Gasoline

text: Though gasoline is a naturally colorless liquid, many gasolines are dyed in various colors to indicate their composition and acceptable uses. In Australia, the lowest grade of gasoline (RON 91) was dyed a light shade of red/orange and is now the same color as the medium grade (RON 95) and high octane (RON 98), which are dyed yellow. In the U.S., aviation gasoline (avgas) is dyed to identify its octane rating and to distinguish it from kerosene-based jet fuel, which is clear. In Canada, the gasoline for marine and farm use is dyed red and is not subject to sales tax.


title: Gasoline

text: Oxygenate blending adds oxygen-bearing compounds such as MTBE, ETBE, TAME, TAEE, ethanol, and biobutanol. The presence of these oxygenates reduces the amount of carbon monoxide and unburned fuel in the exhaust. In many areas throughout the U.S., oxygenate blending is mandated by EPA regulations to reduce smog and other airborne pollutants. For example, in Southern California fuel must contain two percent oxygen by weight, resulting in a mixture of 5.6 percent ethanol in gasoline. The resulting fuel is often known as reformulated gasoline (RFG) or oxygenated gasoline, or, in the case of California, California reformulated gasoline. The federal requirement that RFG contain oxygen was dropped on 6 May 2006 because the industry had developed VOC-controlled RFG that did not need additional oxygen.


title: Gasoline

text: MTBE was phased out in the U.S. due to groundwater contamination and the resulting regulations and lawsuits. Ethanol and, to a lesser extent, ethanol-derived ETBE are common substitutes. A common ethanol-gasoline mix of 10 percent ethanol mixed with gasoline is called gasohol or E10, and an ethanol-gasoline mix of 85 percent ethanol mixed with gasoline is called E85. The most extensive use of ethanol takes place in Brazil, where the ethanol is derived from sugarcane. In 2004, over of ethanol was produced in the U.S. for fuel use, mostly from corn and sold as E10. E85 is slowly becoming available in much of the U.S., though many of the relatively few stations vending E85 are not open to the general public.


title: Gasoline

text: The use of bioethanol and bio-methanol, either directly or indirectly by conversion of ethanol to bio-ETBE, or methanol to bio-MTBE is encouraged by the European Union Directive on the Promotion of the use of biofuels and other renewable fuels for transport. Since producing bioethanol from fermented sugars and starches involves distillation, though, ordinary people in much of Europe cannot legally ferment and distill their own bioethanol at present (unlike in the U.S., where getting a BATF distillation permit has been easy since the 1973 oil crisis).


title: Gasoline

text: The safety data sheet for a 2003 Texan unleaded gasoline shows at least 15 hazardous chemicals occurring in various amounts, including benzene (up to five percent by volume), toluene (up to 35 percent by volume), naphthalene (up to one percent by volume), trimethylbenzene (up to seven percent by volume), methyl "tert"-butyl ether (MTBE) (up to 18 percent by volume, in some states), and about 10 others. Hydrocarbons in gasoline generally exhibit low acute toxicities, with LD50 of 700–2700 mg/kg for simple aromatic compounds. Benzene and many antiknocking additives are carcinogenic.


title: Gasoline

text: People can be exposed to gasoline in the workplace by swallowing it, breathing in vapors, skin contact, and eye contact. Gasoline is toxic. The National Institute for Occupational Safety and Health (NIOSH) has also designated gasoline as a carcinogen. Physical contact, ingestion, or inhalation can cause health problems. Since ingesting large amounts of gasoline can cause permanent damage to major organs, a call to a local poison control center or emergency room visit is indicated.


title: Gasoline

text: Contrary to common misconception, swallowing gasoline does not generally require special emergency treatment, and inducing vomiting does not help, and can make it worse. According to poison specialist Brad Dahl, "even two mouthfuls wouldn't be that dangerous as long as it goes down to your stomach and stays there or keeps going". The U.S. CDC's Agency for Toxic Substances and Disease Registry says not to induce vomiting, lavage, or administer activated charcoal.


title: Gasoline

text: Inhaled (huffed) gasoline vapor is a common intoxicant. Users concentrate and inhale gasoline vapor in a manner not intended by the manufacturer to produce euphoria and intoxication. Gasoline inhalation has become epidemic in some poorer communities and indigenous groups in Australia, Canada, New Zealand, and some Pacific Islands. The practice is thought to cause severe organ damage, along with other effects such as intellectual disability and various cancers.


title: Gasoline

text: In Canada, Native children in the isolated Northern Labrador community of Davis Inlet were the focus of national concern in 1993, when many were found to be sniffing gasoline. The Canadian and provincial Newfoundland and Labrador governments intervened on several occasions, sending many children away for treatment. Despite being moved to the new community of Natuashish in 2002, serious inhalant abuse problems have continued. Similar problems were reported in Sheshatshiu in 2000 and also in Pikangikum First Nation. In 2012, the issue once again made the news media in Canada.


title: Gasoline

text: Australia has long faced a petrol (gasoline) sniffing problem in isolated and impoverished aboriginal communities. Although some sources argue that sniffing was introduced by U.S. servicemen stationed in the nation's Top End during World War II or through experimentation by 1940s-era Cobourg Peninsula sawmill workers, other sources claim that inhalant abuse (such as glue inhalation) emerged in Australia in the late 1960s. Chronic, heavy petrol sniffing appears to occur among remote, impoverished indigenous communities, where the ready accessibility of petrol has helped to make it a common substance for abuse.


title: Gasoline

text: In Australia, petrol sniffing now occurs widely throughout remote Aboriginal communities in the Northern Territory, Western Australia, northern parts of South Australia, and Queensland. The number of people sniffing petrol goes up and down over time as young people experiment or sniff occasionally. "Boss", or chronic, sniffers may move in and out of communities; they are often responsible for encouraging young people to take it up. In 2005, the Government of Australia and BP Australia began the usage of Opal fuel in remote areas prone to petrol sniffing. Opal is a non-sniffable fuel (which is much less likely to cause a high) and has made a difference in some indigenous communities.


title: Gasoline

text: Gasoline is extremely flammable due to its low flash point of . Like other hydrocarbons, gasoline burns in a limited range of its vapor phase, and, coupled with its volatility, this makes leaks highly dangerous when sources of ignition are present. Gasoline has a lower explosive limit of 1.4 percent by volume and an upper explosive limit of 7.6 percent. If the concentration is below 1.4 percent, the air-gasoline mixture is too lean and does not ignite. If the concentration is above 7.6 percent, the mixture is too rich and also does not ignite. However, gasoline vapor rapidly mixes and spreads with air, making unconstrained gasoline quickly flammable.


title: Gasoline

text: The exhaust gas generated by burning gasoline not only does serious harm to the environment but also to people's health. After CO is inhaled into the human body, it is very easy to combine with hemoglobin in the blood, and its affinity is 300 times that of oxygen. Therefore, the hemoglobin in the lungs does not combine with oxygen but with CO, causing the human body to be hypoxic, causing headaches, dizziness, vomiting, and other poisoning symptoms. In severe cases, it may lead to death. Hydrocarbons only affect the human body when their concentration is quite high, and their toxicity level depends on the chemical composition. The hydrocarbons produced by incomplete combustion include alkanes, aromatics, and aldehydes. Among them, a concentration of methane and ethane over will cause loss of consciousness or suffocation, a concentration of pentane and hexane over will have an anesthetic effect, and aromatic hydrocarbons will have more serious effects on health, blood toxicity, neurotoxicity, and cancer. If the concentration of benzene exceeds 40 ppm, it can cause leukemia, and xylene can cause headache, dizziness, nausea, and vomiting. Human exposure to large amounts of aldehydes can cause eye irritation, nausea, and dizziness. In addition to carcinogenic effects, long-term exposure can cause damage to the skin, liver, kidneys, and cataracts. After NO enters the alveoli, it has a severe stimulating effect on the lung tissue. It can irritate the conjunctiva of the eyes, cause tearing, and cause pink eyes. It also has a stimulating effect on the nose, pharynx, throat, and other organs. It can cause acute wheezing, breathing difficulties, red eyes, sore throat, and dizziness causing poisoning.


title: Gasoline

text: In recent years, with the rapid development of the motor vehicle economy, the production and use of motor vehicles have increased dramatically, and the pollution by motor vehicle exhaust to the environment has become more and more serious. The air pollution in many large cities has changed from coal-burning pollution to "motor vehicle pollution". In the U.S., transportation is the largest source of carbon emissions, accounting for 30 percent of the total carbon footprint of the U.S. Combustion of gasoline produces of carbon dioxide, a greenhouse gas.


title: Gasoline

text: Unburnt gasoline and evaporation from the tank, when in the atmosphere, react in sunlight to produce photochemical smog. Vapor pressure initially rises with some addition of ethanol to gasoline, but the increase is greatest at 10 percent by volume. At higher concentrations of ethanol above 10 percent, the vapor pressure of the blend starts to decrease. At a 10 percent ethanol by volume, the rise in vapor pressure may potentially increase the problem of photochemical smog. This rise in vapor pressure could be mitigated by increasing or decreasing the percentage of ethanol in the gasoline mixture. The chief risks of such leaks come not from vehicles, but gasoline delivery truck accidents and leaks from storage tanks. Because of this risk, most (underground) storage tanks now have extensive measures in place to detect and prevent any such leaks, such as monitoring systems (Veeder-Root, Franklin Fueling).


title: Gasoline

text: Gasoline use causes a variety of deleterious effects to the human population and to the climate generally. The harms imposed include a higher rate of premature death and ailments, such as asthma, caused by air pollution, higher healthcare costs for the public generally, decreased crop yields, missed work and school days due to illness, increased flooding and other extreme weather events linked to global climate change, and other social costs. The costs imposed on society and the planet are estimated to be $3.80 per gallon of gasoline, in addition to the price paid at the pump by the user. The damage to the health and climate caused by a gasoline-powered vehicle greatly exceeds that caused by electric vehicles.


title: Gasoline

text: About of carbon dioxide (CO) are produced from burning gasoline that does not contain ethanol. Most of the retail gasoline now sold in the U.S. contains about 10 percent fuel ethanol (or E10) by volume. Burning E10 produces about of CO that is emitted from the fossil fuel content. If the CO emissions from ethanol combustion are considered, then about of CO are produced when E10 is combusted.


title: Gasoline

text: Worldwide 7 liters of gasoline are burnt for every 100 km driven by cars and vans. Despite increasing sales of electric cars and falling sales of gasoline cars, those gasoline cars that are sold tend to be larger and heavier as more are SUVs, thus gasoline combustion and carbon dioxide emissions per km have not fallen significantly.


title: Gasoline

text: Also the International Energy Agency said in 2021 that: "To ensure fuel economy and CO2 emissions standards are effective, governments must continue regulatory efforts to monitor and reduce the gap between real-world fuel economy and rated performance."


title: Gasoline

text: Gasoline enters the environment through the soil, groundwater, surface water, and air. Therefore, humans may be exposed to gasoline through methods such as breathing, eating, and skin contact. For example, using gasoline-filled equipment, such as lawnmowers, drinking gasoline-contaminated water close to gasoline spills or leaks to the soil, working at a gasoline station, inhaling gasoline volatile gas when refueling at a gasoline station is the easiest way to be exposed to gasoline.


title: Gasoline

text: The International Energy Agency said in 2021 that "road fuels should be taxed at a rate that reflects their impact on people’s health and the climate".


title: Gasoline

text: Countries in Europe impose substantially higher taxes on fuels such as gasoline when compared to the U.S. The price of gasoline in Europe is typically higher than that in the U.S. due to this difference.


title: Gasoline

text: From 1998 to 2004, the price of gasoline fluctuated between . After 2004, the price increased until the average gasoline price reached a high of in mid-2008 but receded to approximately by September 2009. The U.S. experienced an upswing in gasoline prices through 2011, and, by 1 March 2012, the national average was . California prices are higher because the California government mandates unique California gasoline formulas and taxes.


title: Gasoline

text: In the U.S., most consumer goods bear pre-tax prices, but gasoline prices are posted with taxes included. Taxes are added by federal, state, and local governments. , the federal tax was for gasoline and for diesel (excluding red diesel).


title: Gasoline

text: About nine percent of all gasoline sold in the U.S. in May 2009 was premium grade, according to the Energy Information Administration. "Consumer Reports" magazine says, "If [your owner's manual] says to use regular fuel, do so—there's no advantage to a higher grade." The "Associated Press" said premium gas—which has a higher octane rating and costs more per gallon than regular unleaded—should be used only if the manufacturer says it is "required". Cars with turbocharged engines and high compression ratios often specify premium gasoline because higher octane fuels reduce the incidence of "knock", or fuel pre-detonation. The price of gasoline varies considerably between the summer and winter months.


title: Gasoline

text: There is a considerable difference between summer oil and winter oil in gasoline vapor pressure (Reid Vapor Pressure, RVP), which is a measure of how easily the fuel evaporates at a given temperature. The higher the gasoline volatility (the higher the RVP), the easier it is to evaporate. The conversion between the two fuels occurs twice a year, once in autumn (winter mix) and the other in spring (summer mix). The winter blended fuel has a higher RVP because the fuel must be able to evaporate at a low temperature for the engine to run normally. If the RVP is too low on a cold day, the vehicle will be difficult to start; however, the summer blended gasoline has a lower RVP. It prevents excessive evaporation when the outdoor temperature rises, reduces ozone emissions, and reduces smog levels. At the same time, vapor lock is less likely to occur in hot weather.


title: Gasoline

text: Below is a table of the energy density (per volume) and specific energy (per mass) of various transportation fuels as compared with gasoline. In the rows with gross and net, they are from the Oak Ridge National Laboratory's Transportation Energy Data Book.


title: Aryan

text: Aryan or Arya (, Indo-Iranian *"arya") is a term originally used as an ethnocultural self-designation by Indo-Iranians in ancient times, in contrast to the nearby outsiders known as 'non-Aryan' (*"an-arya"). In Ancient India, the term "ā́rya" was used by the Indo-Aryan speakers of the Vedic period as an endonym (self-designation) and in reference to the geographic region known as "Āryāvarta" ('abode of the Aryas'), where the Indo-Aryan culture emerged. In the "Avesta" scriptures, ancient Iranian peoples similarly used the term "airya" to designate themselves as an ethnic group, and in reference to their mythical homeland, "Airyanem Waēǰō" ('stretch of the Aryas'). The root also forms the etymological source of place names such as "Iran" (*"Aryānām") and "Alania" (*"Aryāna-").


title: Aryan

text: Although the root "*arya-" may be of Proto-Indo-European (PIE) origin, its use as an ethnocultural self-designation is only attested among Indo-Iranian peoples, and it is not known if PIE speakers had a term to designate themselves as a group. In any case, scholars point out that, even in ancient times, the idea of being an "Aryan" was religious, cultural and linguistic, not racial.


title: Aryan

text: The term "Arya" was first rendered into a modern European language in 1771 as "Aryens" by French Indologist Abraham-Hyacinthe Anquetil-Duperron, who rightly compared the Greek "arioi" with the Avestan "airya" and the country name "Iran." A German translation of Anquetil-Duperron's work led to the introduction of the term "Arier" in 1776. The Sanskrit word "ā́rya" is rendered as 'noble' in William Jones' 1794 translation of the Indian "Laws of Manu", and the English "Aryan" (originally spelt "Arian") appeared a few decades later, first as an adjective in 1839, then as a noun in 1851.


title: Aryan

text: The Sanskrit word "ā́rya" (आर्य) was originally an ethnocultural term designating those who spoke Vedic Sanskrit and adhered to Vedic cultural norms (including religious rituals and poetry), in contrast to an outsider, or "an-ā́rya" ('non-Arya'). By the time of the Buddha (5th–4th century BCE), it took the meaning of 'noble'. In Old Iranian languages, the Avestan term "airya" (Old Persian "ariya") was likewise used as an ethnocultural self-designation by ancient Iranian peoples, in contrast to an "an-airya" ('non-Arya'). It designated those who belonged to the 'Aryan' (Iranian) ethnic stock, spoke the language and followed the religion of the 'Aryas'.


title: Aryan

text: These two terms derive from the reconstructed Proto-Indo-Iranian stem "*arya"- or "*āryo-", which was probably the name used by the prehistoric Indo-Iranian peoples to designate themselves as an ethnocultural group. The term did not have any racial connotation, which only emerged later in the works of 19th-century Western writers. According to David W. Anthony, "the "Rigveda" and "Avesta" agreed that the essence of their shared parental Indo-Iranian identity was linguistic and ritual, not racial. If a person sacrificed to the right gods in the right way using the correct forms of the traditional hymns and poems, that person was an Aryan."


title: Aryan

text: Since Adolphe Pictet (1799–1875), a number of scholars have proposed to derive the Indo-Iranian stem "arya"- from the reconstructed Proto-Indo-European (PIE) term "*h₂erós" or "*h₂eryós", variously translated as 'member of one's own group, peer, freeman'; as 'host, guest; kinsman'; or as 'lord, ruler'. However, the proposed Anatolian, Celtic and Germanic cognates are not universally accepted. In any case, the Indo-Iranian ethnic connotation is absent from the other Indo-European languages, which rather conceived the possible cognates of *"arya"- as a social status, and there is no evidence that Proto-Indo-European speakers had a term to refer to themselves as 'Proto-Indo-Europeans'.


title: Aryan

text: The term "*h₂er(y)ós" may derive from the PIE verbal root "*h₂er-", meaning 'to put together'. Oswald Szemerényi has also argued that the stem could be a Near-Eastern loanword from the Ugaritic "ary" ('kinsmen'), although J. P. Mallory and Douglas Q. Adams find this proposition "hardly compelling". According to them, the original PIE meaning had a clear emphasis on the in-group status of the "freemen" as distinguished from that of outsiders, particularly those captured and incorporated into the group as slaves. In Anatolia, the base word has come to emphasize personal relationship, whereas it took a more ethnic meaning among Indo-Iranians, presumably because most of the unfree (*"anarya") who lived among them were captives from other ethnic groups.


title: Aryan

text: The term *"arya" was used by Proto-Indo-Iranian speakers to designate themselves as an ethnocultural group, encompassing those who spoke the language and followed the religion of the "Aryas" (Indo-Iranians)"," as distinguished from the nearby outsiders known as the *"Anarya" ('non-Arya'). Indo-Iranians ("Aryas") are generally associated with the Sintashta culture (2100–1800 BCE), named after the Sintashta archaeological site in Chelyabinsk Oblast, Russia. Linguistic evidence show that Proto-Indo-Iranian (Proto-Aryan) speakers dwelled in the Eurasian steppe, south of early Uralic tribes; the stem *"arya"- was notably borrowed into the Pre-Saami language as *"orja"-, at the origin of "oarji" ('southwest') and "årjel" ('Southerner'). The loanword took the meaning 'slave' in other Finno-Permic languages, suggesting conflictual relations between Indo-Iranian and Uralic peoples in prehistoric times.


title: Aryan

text: The stem is also found in the Indo-Iranian god *"Aryaman," translated as 'Arya-spirited', 'Aryanness', or 'Aryanhood'; he was known in Vedic Sanskrit as "Aryaman" and in Avestan as "Airyaman". The deity was in charge of welfare and the community, and connected with the institution of marriage. Through marital ceremonies, one of the functions of "Aryaman" was to assimilate women from other tribes to the host community. If the Irish heroes "Érimón" and "Airem" and the Gaulish personal name "Ariomanus" are also cognates (i.e. linguistic siblings sharing a common origin), a deity of Proto-Indo-European origin named "*h₂eryo-men" may also be posited.


title: Aryan

text: Vedic Sanskrit speakers viewed the term "ā́rya" as a religious–linguistic category, referring to those who spoke the Sanskrit language and adhered to Vedic cultural norms, especially those who worshipped the Vedic gods (Indra and Agni in particular), took part in the sacrifices and festivals, and practiced the art of poetry.


title: Aryan

text: The 'non-Aryas' designated primarily those who were not able to speak the "āryā" language correctly, the "Mleccha" or "Mṛdhravāc." However, "āryā" is used only once in the Vedas to designate the language of the texts, the Vedic area being defined in the "Kauṣītaki Āraṇyaka" as that where the "āryā vāc" ('Ārya speech') is spoken. Some 35 names of Vedic tribes, chiefs and poets mentioned in the "Rigveda" were of 'non-Aryan' origin, demonstrating that cultural assimilation to the "ā́rya" community was possible, and/or that some 'Aryan' families chose to give 'non-Aryan' names to their newborns. In the words of Indologist Michael Witzel, the term "ārya" "does not mean a particular "people" or even a particular 'racial' group but all those who had joined the tribes speaking Vedic Sanskrit and adhering to their cultural norms (such as ritual, poetry, etc.)".


title: Aryan

text: In later Indian texts and Buddhist sources, "ā́rya" took the meaning of 'noble', such as in the terms "Āryadésa"- ('noble land') for India, "Ārya-bhāṣā"- ('noble language') for Sanskrit, or "āryaka"- ('honoured man'), which gave the Pali "ayyaka"- ('grandfather'). The term came to incorporate the idea of a high social status, but was also used as an honorific for the Brahmana or the Buddhist monks. Parallelly, the Mleccha acquired additional meanings that referred to people of lower castes or aliens.


title: Aryan

text: In the words of scholar Gherardo Gnoli, the Old Iranian "airya" (Avestan) and "ariya" (Old Persian) were collective terms denoting the "peoples who were aware of belonging to the one ethnic stock, speaking a common language, and having a religious tradition that centred on the cult of Ahura Mazdā", in contrast to the 'non-Aryas', who are called "anairya" in Avestan, "anaryān" in Parthian, and "anērān" in Middle Persian.


title: Aryan

text: By the late 6th–early 5th century BCE, the Achaemenid king Darius the Great and his son Xerxes I described themselves as "ariya" ('Arya') and "ariya čiça" ('of Aryan origin'). In the Behistun inscription, authored by Darius during his reign (522 – 486 BCE), the Old Persian language is called "ariya", and the Elamite version of the inscription portrays the Zoroastrian deity Ahura Mazdā as the "god of the Aryas" ("ura-masda naap harriia-naum"). In the sacred "Avesta" scriptures, the stem can also be found in poetic expressions such as the 'glory of the Aryas' ("airyanąm xᵛarənō" ), the 'most swift-arrowed of the Aryas' ("xšviwi išvatəmō airyanąm"), associated with the mythical archer Ǝrəxša, or the 'hero of the Aryas' ("arša airyanąm"), attached to Kavi Haosravō.


title: Aryan

text: The self-identifier was inherited in ethnic names such as the Parthian "Ary" ( "Aryān"), the Middle Persian "Ēr" ( "Ēran"), or the New Persian "Irāni" ( "Irāniyān"). The Scythian branch has "Alān" or *"Allān" (from *"Aryāna"; modern "Allon"), "Rhoxolāni" ('Bright Alans'), "Alanorsoi" ('White Alans'), and possibly the modern Ossetian "Ir" ( "Iron"), spelled "Irä" or "Erä" in the Digorian dialect. The Rabatak inscription, written in the Bactrian language in the 2nd century CE, likewise uses the term "ariao" for 'Iranian'. The name "Arizantoi", listed by Greek historian Herodotus as one of the six tribes composing the Iranian Medes, is derived from the Old Iranian *"arya-zantu"- ('having Aryan lineage'). Herodotus also mentions that the Medes once called themselves "Arioi", and Strabo locates the land of "Arianē" between Persia and India. Other occurrences include the Greek "áreion" (Damascius), "Arianoi" (Diodorus Siculus) and "arian" ( "arianōn"; Sasanian period), as well as the Armenian expression "ari" (Agathangelos), meaning 'Iranian'.


title: Aryan

text: Until the demise of the Parthian Empire (247 BCE–224 CE), the Iranian identity was essentially defined as cultural and religious. Following conflicts between Manichean universalism and Zoroastrian nationalism during the 3rd century CE, however, traditionalistic and nationalistic movements eventually took the upper hand during the Sasanian period, and the Iranian identity ("ērīh") came to assume a definite political value. Among Iranians ("ērān"), one ethnic group in particular, the Persians, were placed at the centre of the "Ērān-šahr" ('Kingdom of the Iranians') ruled by the "šāhān-šāh ērān ud anērān" ('King of Kings of the Iranians and non-Iranians').


title: Aryan

text: Ethical and ethnic meanings may also intertwine, for instance in the use of "anēr" ('non-Iranian') as a synonymous of 'evil' in "anērīh ī hrōmāyīkān" ("the evil conduct of the Romans, i.e. Byzantines"), or in the association of "ēr" ('Iranian') with good birth ("hutōhmaktom ēr martōm", 'the best-born Arya man') and the use of "ērīh" ('Iranianness') to mean 'nobility' against "labor and burdens from poverty" in the 10th-century "Dēnkard". The Indian opposition between "ārya"- ('noble') and "dāsá"- ('stranger, slave, enemy') is however absent from the Iranian tradition. According to linguist Émile Benveniste, the root "*das-" may have been used exclusively as a collective name by Iranian peoples: "If the word referred at first to Iranian society, the name by which this enemy people called themselves collectively took on a hostile connotation and became for the Aryas of India the term for an inferior and barbarous people."