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of sciences of urss, national science foundation, washington, israel program for scientific translations, jerusalem 1960 winogradsky serge, microbiologie du sol. problemes et methodes. cinquante ans de recherches, masson & c.ie, paris 1949 external links consultative group on international agricultural research (cgiar) agricultural research service indian council of agricultural research international institute of tropical agriculture international livestock research institute the national agricultural library (nal) - the most comprehensive agricultural library in the world. crop science society of america american society of agronomy soil science society of america agricultural science researchers, jobs and discussions information system for agriculture and food research south dakota agricultural laboratories nmsu

alchemy (from arabic: al-kimiya; from ancient greek: khumeia) is an ancient branch of natural philosophy, a philosophical and protoscientific tradition that was historically practiced in china, india, the muslim world, and europe. in its western form, alchemy is first attested in a number of pseudepigraphical texts written in greco-roman egypt during the first few centuries ce. alchemists attempted to purify, mature, and perfect certain materials. common aims were chrysopoeia, the transmutation of "base metals" (e.g., lead) into "noble metals" (particularly gold); the creation of an elixir of immortality; and the creation of panaceas able to cure any disease. the perfection of the human body and soul was thought to result from the alchemical magnum opus ("great work"). the concept of creating the philosophers'

stone was variously connected with all of these projects. islamic and european alchemists developed a basic set of laboratory techniques, theories, and terms, some of which are still in use today. they did not abandon the ancient greek philosophical idea that everything is composed of four elements, and they tended to guard their work in secrecy, often making use of cyphers and cryptic symbolism. in europe, the 12th-century translations of medieval islamic works on science and the rediscovery of aristotelian philosophy gave birth to a flourishing tradition of latin alchemy. this late medieval tradition of alchemy would go on to play a significant role in the development of early modern science (particularly chemistry and medicine). modern discussions of alchemy are generally split into an examination of its

exoteric practical applications and its esoteric spiritual aspects, despite criticisms by scholars such as eric j. holmyard and marie-louise von franz that they should be understood as complementary. the former is pursued by historians of the physical sciences, who examine the subject in terms of early chemistry, medicine, and charlatanism, and the philosophical and religious contexts in which these events occurred. the latter interests historians of esotericism, psychologists, and some philosophers and spiritualists. the subject has also made an ongoing impact on literature and the arts. etymology the word alchemy comes from old french alquemie, alkimie, used in medieval latin as . this name was itself brought from the arabic word al-kimiya ( or ) composed of two parts: the late greek term khemeia (), also

spelled khumeia () and khemia () - see below, and the arabic definite article al- (), meaning 'the'. together this association can be interpreted as 'the process of transmutation by which to fuse or reunite with the divine or original form'. several etymologies have been proposed for the greek term. the first was proposed by zosimos of panopolis (3rd4th centuries), who derived it from the name of a book, the khemeu. hermanm diels argued in 1914 that it rather derived from , used to describe metallic objects formed by casting. others trace its roots to the egyptian name keme (hieroglyphic khmi ), meaning 'black earth', which refers to the fertile and auriferous soil of the nile valley, as opposed to red desert sand. according to the egyptologist wallis budge, the arabic word al-kimiya actually means "the egyptian

[science]", borrowing from the coptic word for "egypt", keme (or its equivalent in the mediaeval bohairic dialect of coptic, kheme). this coptic word derives from demotic kmi, itself from ancient egyptian kmt. the ancient egyptian word referred to both the country and the colour "black" (egypt was the "black land", by contrast with the "red land", the surrounding desert); so this etymology could also explain the nickname "egyptian black arts". history alchemy encompasses several philosophical traditions spanning some four millennia and three continents. these traditions' general penchant for cryptic and symbolic language makes it hard to trace their mutual influences and "genetic" relationships. one can distinguish at least three major strands, which appear to be mostly independent, at least in their earlier

stages: chinese alchemy, centered in china and indian alchemy, centered on the indian subcontinent; and western alchemy, which occurred around the mediterranean and whose center has shifted over the millennia from greco-roman egypt to the islamic world, and finally medieval europe. chinese alchemy was closely connected to taoism and indian alchemy with the dharmic faiths. in contrast, western alchemy developed its philosophical system mostly independent of but influenced by various western religions. it is still an open question whether these three strands share a common origin, or to what extent they influenced each other. hellenistic egypt the start of western alchemy may generally be traced to ancient and hellenistic egypt, where the city of alexandria was a center of alchemical knowledge, and retained

its pre-eminence through most of the greek and roman periods. following the work of andre-jean festugiere, modern scholars see alchemical practice in the roman empire as originating from the egyptian goldsmith's art, greek philosophy and different religious traditions. tracing the origins of the alchemical art in egypt is complicated by the pseudepigraphic nature of texts from the greek alchemical corpus. the treatises of zosimos of panopolis, the earliest historically attested author (fl. c. 300 ce), can help in situating the other authors. zosimus based his work on that of older alchemical authors, such as mary the jewess, pseudo-democritus, and agathodaimon, but very little is known about any of these authors. the most complete of their works, the four books of pseudo-democritus, were probably written in the

first century ad. recent scholarship tends to emphasize the testimony of zosimus, who traced the alchemical arts back to egyptian metallurgical and ceremonial practices. it has also been argued that early alchemical writers borrowed the vocabulary of greek philosophical schools but did not implement any of its doctrines in a systematic way. zosimos of panopolis wrote in the final abstinence (also known as the "final count"). zosimos explains that the ancient practice of "tinctures" (the technical greek name for the alchemical arts) had been taken over by certain "demons" who taught the art only to those who offered them sacrifices. since zosimos also called the demons "guardians of places" ( ) and those who offered them sacrifices "priests" (), it is fairly clear that he was referring to the gods of egypt

and their priests. while critical of the kind of alchemy he associated with the egyptian priests and their followers, zosimos nonetheless saw the tradition's recent past as rooted in the rites of the egyptian temples. mythology zosimos of panopolis asserted that alchemy dated back to pharaonic egypt where it was the domain of the priestly class, though there is little to no evidence for his assertion. alchemical writers used classical figures from greek, roman, and egyptian mythology to illuminate their works and allegorize alchemical transmutation. these included the pantheon of gods related to the classical planets, isis, osiris, jason, and many others. the central figure in the mythology of alchemy is hermes trismegistus (or thrice-great hermes). his name is derived from the god thoth and his greek counterpart

hermes. hermes and his caduceus or serpent-staff, were among alchemy's principal symbols. according to clement of alexandria, he wrote what were called the "forty-two books of hermes", covering all fields of knowledge. the hermetica of thrice-great hermes is generally understood to form the basis for western alchemical philosophy and practice, called the hermetic philosophy by its early practitioners. these writings were collected in the first centuries of the common era. technology the dawn of western alchemy is sometimes associated with that of metallurgy, extending back to 3500bc. many writings were lost when the roman emperor diocletian ordered the burning of alchemical books after suppressing a revolt in alexandria (ad292). few original egyptian documents on alchemy have survived, most notable among them

the stockholm papyrus and the leyden papyrus x. dating from ad250300, they contained recipes for dyeing and making artificial gemstones, cleaning and fabricating pearls, and manufacturing of imitation gold and silver. these writings lack the mystical, philosophical elements of alchemy, but do contain the works of bolus of mendes (or pseudo-democritus), which aligned these recipes with theoretical knowledge of astrology and the classical elements. between the time of bolus and zosimos, the change took place that transformed this metallurgy into a hermetic art. philosophy alexandria acted as a melting pot for philosophies of pythagoreanism, platonism, stoicism and gnosticism which formed the origin of alchemy's character. an important example of alchemy's roots in greek philosophy, originated by empedocles and

developed by aristotle, was that all things in the universe were formed from only four elements: earth, air, water, and fire. according to aristotle, each element had a sphere to which it belonged and to which it would return if left undisturbed. the four elements of the greek were mostly qualitative aspects of matter, not quantitative, as our modern elements are; "...true alchemy never regarded earth, air, water, and fire as corporeal or chemical substances in the present-day sense of the word. the four elements are simply the primary, and most general, qualities by means of which the amorphous and purely quantitative substance of all bodies first reveals itself in differentiated form." later alchemists extensively developed the mystical aspects of this concept. alchemy coexisted alongside emerging christianity.

lactantius believed hermes trismegistus had prophesied its birth. staugustine later affirmed this in the 4th & 5th centuries, but also condemned trismegistus for idolatry. examples of pagan, christian, and jewish alchemists can be found during this period. most of the greco-roman alchemists preceding zosimos are known only by pseudonyms, such as moses, isis, cleopatra, democritus, and ostanes. others authors such as komarios, and chymes, we only know through fragments of text. after ad400, greek alchemical writers occupied themselves solely in commenting on the works of these predecessors. by the middle of the 7th century alchemy was almost an entirely mystical discipline. it was at that time that khalid ibn yazid sparked its migration from alexandria to the islamic world, facilitating the translation and preservation

of greek alchemical texts in the 8th and 9th centuries. byzantium greek alchemy is preserved in medieval greek (byzantine) manuscripts, and yet historians have only relatively recently begun to pay attention to the study and development of greek alchemy in the byzantine period. india the 2nd millennium bc text vedas describe a connection between eternal life and gold. a considerable knowledge of metallurgy has been exhibited in a third-century ce text called arthashastra which provides ingredients of explosives (agniyoga) and salts extracted from fertile soils and plant remains (yavakshara) such as saltpetre/nitre, perfume making (different qualities of perfumes are mentioned), granulated (refined) sugar. buddhist texts from the 2nd to 5th centuries mention the transmutation of base metals to gold. according

to some scholars greek alchemy may have influenced indian alchemy but there are no hard evidences to back this claim. the 11th-century persian chemist and physician abu rayhan biruni, who visited gujarat as part of the court of mahmud of ghazni, reported that they the goals of alchemy in india included the creation of a divine body (sanskrit divya-deham) and immortality while still embodied (sanskrit jivan-mukti). sanskrit alchemical texts include much material on the manipulation of mercury and sulphur, that are homologized with the semen of the god siva and the menstrual blood of the goddess devi. some early alchemical writings seem to have their origins in the kaula tantric schools associated to the teachings of the personality of matsyendranath. other early writings are found in the jaina medical treatise

kalyanakarakam of ugraditya, written in south india in the early 9th century. two famous early indian alchemical authors were nagarjuna siddha and nityanatha siddha. nagarjuna siddha was a buddhist monk. his book, rasendramangalam, is an example of indian alchemy and medicine. nityanatha siddha wrote rasaratnakara, also a highly influential work. in sanskrit, rasa translates to "mercury", and nagarjuna siddha was said to have developed a method of converting mercury into gold. scholarship on indian alchemy is in the publication of the alchemical body by david gordon white. a modern bibliography on indian alchemical studies has been written by white. the contents of 39 sanskrit alchemical treatises have been analysed in detail in g. jan meulenbeld's history of indian medical literature. the discussion of these

works in himl gives a summary of the contents of each work, their special features, and where possible the evidence concerning their dating. chapter 13 of himl, various works on rasasastra and ratnasastra (or various works on alchemy and gems) gives brief details of a further 655 (six hundred and fifty-five) treatises. in some cases meulenbeld gives notes on the contents and authorship of these works; in other cases references are made only to the unpublished manuscripts of these titles. a great deal remains to be discovered about indian alchemical literature. the content of the sanskrit alchemical corpus has not yet (2014) been adequately integrated into the wider general history of alchemy. islamic world after the fall of the roman empire, the focus of alchemical development moved to the islamic world.

much more is known about islamic alchemy because it was better documented: indeed, most of the earlier writings that have come down through the years were preserved as arabic translations. the word alchemy itself was derived from the arabic word al-kimiya (). the early islamic world was a melting pot for alchemy. platonic and aristotelian thought, which had already been somewhat appropriated into hermetical science, continued to be assimilated during the late 7th and early 8th centuries through syriac translations and scholarship. in the late ninth and early tenth centuries, the arabic works attributed to jabir ibn hayyan (latinized as "geber" or "geberus") introduced a new approach to alchemy. paul kraus, who wrote the standard reference work on jabir, put it as follows: islamic philosophers also made great

contributions to alchemical hermeticism. the most influential author in this regard was arguably jabir. jabir's ultimate goal was takwin, the artificial creation of life in the alchemical laboratory, up to, and including, human life. he analyzed each aristotelian element in terms of four basic qualities of hotness, coldness, dryness, and moistness. according to jabir, in each metal two of these qualities were interior and two were exterior. for example, lead was externally cold and dry, while gold was hot and moist. thus, jabir theorized, by rearranging the qualities of one metal, a different metal would result. by this reasoning, the search for the philosopher's stone was introduced to western alchemy. jabir developed an elaborate numerology whereby the root letters of a substance's name in arabic, when treated

with various transformations, held correspondences to the element's physical properties. the elemental system used in medieval alchemy also originated with jabir. his original system consisted of seven elements, which included the five classical elements (aether, air, earth, fire, and water) in addition to two chemical elements representing the metals: sulphur, "the stone which burns", which characterized the principle of combustibility, and mercury, which contained the idealized principle of metallic properties. shortly thereafter, this evolved into eight elements, with the arabic concept of the three metallic principles: sulphur giving flammability or combustion, mercury giving volatility and stability, and salt giving solidity. the atomic theory of corpuscularianism, where all physical bodies possess an inner

and outer layer of minute particles or corpuscles, also has its origins in the work of jabir. from the 9th to 14th centuries, alchemical theories faced criticism from a variety of practical muslim chemists, including alkindus, abu al-rayhan al-biruni, avicenna and ibn khaldun. in particular, they wrote refutations against the idea of the transmutation of metals. east asia whereas european alchemy eventually centered on the transmutation of base metals into noble metals, chinese alchemy had a more obvious connection to medicine. the philosopher's stone of european alchemists can be compared to the grand elixir of immortality sought by chinese alchemists. in the hermetic view, these two goals were not unconnected, and the philosopher's stone was often equated with the universal panacea; therefore, the two traditions

may have had more in common than initially appears. black powder may have been an important invention of chinese alchemists. as previously stated above, chinese alchemy was more related to medicine. it is said that the chinese invented gunpowder while trying to find a potion for eternal life. described in 9th-century texts and used in fireworks in china by the 10th century, it was used in cannons by 1290. from china, the use of gunpowder spread to japan, the mongols, the muslim world, and europe. gunpowder was used by the mongols against the hungarians in 1241, and in europe by the 14th century. chinese alchemy was closely connected to taoist forms of traditional chinese medicine, such as acupuncture and moxibustion. in the early song dynasty, followers of this taoist idea (chiefly the elite and upper class)

would ingest mercuric sulfide, which, though tolerable in low levels, led many to suicide. thinking that this consequential death would lead to freedom and access to the taoist heavens, the ensuing deaths encouraged people to eschew this method of alchemy in favor of external sources (the aforementioned tai chi chuan, mastering of the qi, etc.) chinese alchemy was introduced to the west by obed simon johnson. medieval europe the introduction of alchemy to latin europe may be dated to 11 february 1144, with the completion of robert of chester's translation of the arabic book of the composition of alchemy. although european craftsmen and technicians pre-existed, robert notes in his preface that alchemy (though here still referring to the elixir rather than to the art itself) was unknown in latin europe at the

time of his writing. the translation of arabic texts concerning numerous disciplines including alchemy flourished in 12th-century toledo, spain, through contributors like gerard of cremona and adelard of bath. translations of the time included the turba philosophorum, and the works of avicenna and muhammad ibn zakariya al-razi. these brought with them many new words to the european vocabulary for which there was no previous latin equivalent. alcohol, carboy, elixir, and athanor are examples. meanwhile, theologian contemporaries of the translators made strides towards the reconciliation of faith and experimental rationalism, thereby priming europe for the influx of alchemical thought. the 11th-century stanselm put forth the opinion that faith and rationalism were compatible and encouraged rationalism in a christian

context. in the early 12th century, peter abelard followed anselm's work, laying down the foundation for acceptance of aristotelian thought before the first works of aristotle had reached the west. in the early 13th century, robert grosseteste used abelard's methods of analysis and added the use of observation, experimentation, and conclusions when conducting scientific investigations. grosseteste also did much work to reconcile platonic and aristotelian thinking. through much of the 12th and 13th centuries, alchemical knowledge in europe remained centered on translations, and new latin contributions were not made. the efforts of the translators were succeeded by that of the encyclopaedists. in the 13th century, albertus magnus and roger bacon were the most notable of these, their work summarizing and explaining

the newly imported alchemical knowledge in aristotelian terms. albertus magnus, a dominican friar, is known to have written works such as the book of minerals where he observed and commented on the operations and theories of alchemical authorities like hermes and democritus and unnamed alchemists of his time. albertus critically compared these to the writings of aristotle and avicenna, where they concerned the transmutation of metals. from the time shortly after his death through to the 15th century, more than 28 alchemical tracts were misattributed to him, a common practice giving rise to his reputation as an accomplished alchemist. likewise, alchemical texts have been attributed to albert's student thomas aquinas. roger bacon, a franciscan friar who wrote on a wide variety of topics including optics, comparative

linguistics, and medicine, composed his great work () for as part of a project towards rebuilding the medieval university curriculum to include the new learning of his time. while alchemy was not more important to him than other sciences and he did not produce allegorical works on the topic, he did consider it and astrology to be important parts of both natural philosophy and theology and his contributions advanced alchemy's connections to soteriology and christian theology. bacon's writings integrated morality, salvation, alchemy, and the prolongation of life. his correspondence with clement highlighted this, noting the importance of alchemy to the papacy. like the greeks before him, bacon acknowledged the division of alchemy into practical and theoretical spheres. he noted that the theoretical lay outside the

scope of aristotle, the natural philosophers, and all latin writers of his time. the practical confirmed the theoretical, and bacon advocated its uses in natural science and medicine. in later european legend, he became an archmage. in particular, along with albertus magnus, he was credited with the forging of a brazen head capable of answering its owner's questions. soon after bacon, the influential work of pseudo-geber (sometimes identified as paul of taranto) appeared. his summa perfectionis remained a staple summary of alchemical practice and theory through the medieval and renaissance periods. it was notable for its inclusion of practical chemical operations alongside sulphur-mercury theory, and the unusual clarity with which they were described. by the end of the 13th century, alchemy had developed into

a fairly structured system of belief. adepts believed in the macrocosm-microcosm theories of hermes, that is to say, they believed that processes that affect minerals and other substances could have an effect on the human body (for example, if one could learn the secret of purifying gold, one could use the technique to purify the human soul). they believed in the four elements and the four qualities as described above, and they had a strong tradition of cloaking their written ideas in a labyrinth of coded jargon set with traps to mislead the uninitiated. finally, the alchemists practiced their art: they actively experimented with chemicals and made observations and theories about how the universe operated. their entire philosophy revolved around their belief that man's soul was divided within himself after the

fall of adam. by purifying the two parts of man's soul, man could be reunited with god. in the 14th century, alchemy became more accessible to europeans outside the confines of latin speaking churchmen and scholars. alchemical discourse shifted from scholarly philosophical debate to an exposed social commentary on the alchemists themselves. dante, piers plowman, and chaucer all painted unflattering pictures of alchemists as thieves and liars. pope john xxii's 1317 edict, spondent quas non-exhibent forbade the false promises of transmutation made by pseudo-alchemists. in 1403, henry iv of england banned the practice of multiplying metals (although it was possible to buy a licence to attempt to make gold alchemically, and a number were granted by henry vi and edward iv). these critiques and regulations centered

more around pseudo-alchemical charlatanism than the actual study of alchemy, which continued with an increasingly christian tone. the 14th century saw the christian imagery of death and resurrection employed in the alchemical texts of petrus bonus, john of rupescissa, and in works written in the name of raymond lull and arnold of villanova. nicolas flamel is a well-known alchemist, but a good example of pseudepigraphy, the practice of giving your works the name of someone else, usually more famous. although the historical flamel existed, the writings and legends assigned to him only appeared in 1612. flamel was not a religious scholar as were many of his predecessors, and his entire interest in the subject revolved around the pursuit of the philosopher's stone. his work spends a great deal of time describing

the processes and reactions, but never actually gives the formula for carrying out the transmutations. most of 'his' work was aimed at gathering alchemical knowledge that had existed before him, especially as regarded the philosopher's stone. through the 14th and 15th centuries, alchemists were much like flamel: they concentrated on looking for the philosophers' stone. bernard trevisan and george ripley made similar contributions. their cryptic allusions and symbolism led to wide variations in interpretation of the art. renaissance and early modern europe during the renaissance, hermetic and platonic foundations were restored to european alchemy. the dawn of medical, pharmaceutical, occult, and entrepreneurial branches of alchemy followed. in the late 15th century, marsilo ficino translated the corpus hermeticum

and the works of plato into latin. these were previously unavailable to europeans who for the first time had a full picture of the alchemical theory that bacon had declared absent. renaissance humanism and renaissance neoplatonism guided alchemists away from physics to refocus on mankind as the alchemical vessel. esoteric systems developed that blended alchemy into a broader occult hermeticism, fusing it with magic, astrology, and christian cabala. a key figure in this development was german heinrich cornelius agrippa (14861535), who received his hermetic education in italy in the schools of the humanists. in his de occulta philosophia, he attempted to merge kabbalah, hermeticism, and alchemy. he was instrumental in spreading this new blend of hermeticism outside the borders of italy. philippus aureolus paracelsus,

(theophrastus bombastus von hohenheim, 14931541) cast alchemy into a new form, rejecting some of agrippa's occultism and moving away from chrysopoeia. paracelsus pioneered the use of chemicals and minerals in medicine and wrote, "many have said of alchemy, that it is for the making of gold and silver. for me such is not the aim, but to consider only what virtue and power may lie in medicines." his hermetical views were that sickness and health in the body relied on the harmony of man the microcosm and nature the macrocosm. he took an approach different from those before him, using this analogy not in the manner of soul-purification but in the manner that humans must have certain balances of minerals in their bodies, and that certain illnesses of the body had chemical remedies that could cure them. iatrochemistry

refers to the pharmaceutical applications of alchemy championed by paracelsus. john dee (13 july 1527 december, 1608) followed agrippa's occult tradition. although better known for angel summoning, divination, and his role as astrologer, cryptographer, and consultant to queen elizabeth i, dee's alchemical monas hieroglyphica, written in 1564 was his most popular and influential work. his writing portrayed alchemy as a sort of terrestrial astronomy in line with the hermetic axiom as above so below. during the 17th century, a short-lived "supernatural" interpretation of alchemy became popular, including support by fellows of the royal society: robert boyle and elias ashmole. proponents of the supernatural interpretation of alchemy believed that the philosopher's stone might be used to summon and communicate with

angels. entrepreneurial opportunities were common for the alchemists of renaissance europe. alchemists were contracted by the elite for practical purposes related to mining, medical services, and the production of chemicals, medicines, metals, and gemstones. rudolf ii, holy roman emperor, in the late 16th century, famously received and sponsored various alchemists at his court in prague, including dee and his associate edward kelley. king james iv of scotland, julius, duke of brunswick-luneburg, henry v, duke of brunswick-luneburg, augustus, elector of saxony, julius echter von mespelbrunn, and maurice, landgrave of hesse-kassel all contracted alchemists. john's son arthur dee worked as a court physician to michael i of russia and charles i of england but also compiled the alchemical book fasciculus chemicus. although

most of these appointments were legitimate, the trend of pseudo-alchemical fraud continued through the renaissance. betruger would use sleight of hand, or claims of secret knowledge to make money or secure patronage. legitimate mystical and medical alchemists such as michael maier and heinrich khunrath wrote about fraudulent transmutations, distinguishing themselves from the con artists. false alchemists were sometimes prosecuted for fraud. the terms "chemia" and "alchemia" were used as synonyms in the early modern period, and the differences between alchemy, chemistry and small-scale assaying and metallurgy were not as neat as in the present day. there were important overlaps between practitioners, and trying to classify them into alchemists, chemists and craftsmen is anachronistic. for example, tycho brahe

(15461601), an alchemist better known for his astronomical and astrological investigations, had a laboratory built at his uraniborg observatory/research institute. michael sendivogius (micha sedziwoj, 15661636), a polish alchemist, philosopher, medical doctor and pioneer of chemistry wrote mystical works but is also credited with distilling oxygen in a lab sometime around 1600. sendivogious taught his technique to cornelius drebbel who, in 1621, applied this in a submarine. isaac newton devoted considerably more of his writing to the study of alchemy (see isaac newton's occult studies) than he did to either optics or physics. other early modern alchemists who were eminent in their other studies include robert boyle, and jan baptist van helmont. their hermeticism complemented rather than precluded their practical

achievements in medicine and science. later modern period the decline of european alchemy was brought about by the rise of modern science with its emphasis on rigorous quantitative experimentation and its disdain for "ancient wisdom". although the seeds of these events were planted as early as the 17th century, alchemy still flourished for some two hundred years, and in fact may have reached its peak in the 18th century. as late as 1781 james price claimed to have produced a powder that could transmute mercury into silver or gold. early modern european alchemy continued to exhibit a diversity of theories, practices, and purposes: "scholastic and anti-aristotelian, paracelsian and anti-paracelsian, hermetic, neoplatonic, mechanistic, vitalistic, and moreplus virtually every combination and compromise thereof." robert

boyle (16271691) pioneered the scientific method in chemical investigations. he assumed nothing in his experiments and compiled every piece of relevant data. boyle would note the place in which the experiment was carried out, the wind characteristics, the position of the sun and moon, and the barometer reading, all just in case they proved to be relevant. this approach eventually led to the founding of modern chemistry in the 18th and 19th centuries, based on revolutionary discoveries of lavoisier and john dalton. beginning around 1720, a rigid distinction began to be drawn for the first time between "alchemy" and "chemistry". by the 1740s, "alchemy" was now restricted to the realm of gold making, leading to the popular belief that alchemists were charlatans, and the tradition itself nothing more than a fraud.

in order to protect the developing science of modern chemistry from the negative censure to which alchemy was being subjected, academic writers during the 18th-century scientific enlightenment attempted, for the sake of survival, to divorce and separate the "new" chemistry from the "old" practices of alchemy. this move was mostly successful, and the consequences of this continued into the 19th, 20th and 21st centuries. during the occult revival of the early 19th century, alchemy received new attention as an occult science. the esoteric or occultist school, which arose during the 19th century, held (and continues to hold) the view that the substances and operations mentioned in alchemical literature are to be interpreted in a spiritual sense, and it downplays the role of the alchemy as a practical tradition or

protoscience. this interpretation further forwarded the view that alchemy is an art primarily concerned with spiritual enlightenment or illumination, as opposed to the physical manipulation of apparatus and chemicals, and claims that the obscure language of the alchemical texts were an allegorical guise for spiritual, moral or mystical processes. in the 19th-century revival of alchemy, the two most seminal figures were mary anne atwood and ethan allen hitchcock, who independently published similar works regarding spiritual alchemy. both forwarded a completely esoteric view of alchemy, as atwood claimed: "no modern art or chemistry, notwithstanding all its surreptitious claims, has any thing in common with alchemy." atwood's work influenced subsequent authors of the occult revival including eliphas levi, arthur

edward waite, and rudolf steiner. hitchcock, in his remarks upon alchymists (1855) attempted to make a case for his spiritual interpretation with his claim that the alchemists wrote about a spiritual discipline under a materialistic guise in order to avoid accusations of blasphemy from the church and state. in 1845, baron carl reichenbach, published his studies on odic force, a concept with some similarities to alchemy, but his research did not enter the mainstream of scientific discussion. in 1946, louis cattiaux published the message retrouve, a work that was at once philosophical, mystical and highly influenced by alchemy. in his lineage, many researchers, including emmanuel and charles d'hooghvorst, are updating alchemical studies in france and belgium. women several women appear in the earliest history

of alchemy. michael maier names mary the jewess, cleopatra the alchemist, medera, and taphnutia as the four women who knew how to make the philosopher's stone. zosimos' sister theosebia (later known as euthica the arab) and isis the prophetess also played a role in early alchemical texts. the first alchemist whose name we know was mary the jewess (c. 200 a.d.). early sources claim that mary (or maria) devised a number of improvements to alchemical equipment and tools as well as novel techniques in chemistry. her best known advances were in heating and distillation processes. the laboratory water-bath, known eponymously (especially in france) as the bain-marie, is said to have been invented or at least improved by her. essentially a double-boiler, it was (and is) used in chemistry for processes that require gentle

heating. the tribikos (a modified distillation apparatus) and the kerotakis (a more intricate apparatus used especially for sublimations) are two other advancements in the process of distillation that are credited to her. although we have no writing from mary herself, she is known from the early-fourth-century writings of zosimos of panopolis. due to the proliferation of pseudepigrapha and anonymous works, it is difficult to know which of the alchemists were actually women. after the greco-roman period, women's names appear less frequently in the alchemical literature. women vacate the history of alchemy during the medieval and renaissance periods, aside from the fictitious account of perenelle flamel. mary anne atwood's a suggestive inquiry into the hermetic mystery (1850) marks their return during the nineteenth-century

occult revival. modern historical research the history of alchemy has become a significant and recognized subject of academic study. as the language of the alchemists is analyzed, historians are becoming more aware of the intellectual connections between that discipline and other facets of western cultural history, such as the evolution of science and philosophy, the sociology and psychology of the intellectual communities, kabbalism, spiritualism, rosicrucianism, and other mystic movements. institutions involved in this research include the chymistry of isaac newton project at indiana university, the university of exeter centre for the study of esotericism (exeseso), the european society for the study of western esotericism (esswe), and the university of amsterdam's sub-department for the history of hermetic

philosophy and related currents. a large collection of books on alchemy is kept in the bibliotheca philosophica hermetica in amsterdam. a recipe found in a mid-19th-century kabbalah based book features step by step instructions on turning copper into gold. the author attributed this recipe to an ancient manuscript he located. journals which publish regularly on the topic of alchemy include 'ambix', published by the society for the history of alchemy and chemistry, and 'isis', published by the history of science society. core concepts western alchemical theory corresponds to the worldview of late antiquity in which it was born. concepts were imported from neoplatonism and earlier greek cosmology. as such, the classical elements appear in alchemical writings, as do the seven classical planets and the corresponding

seven metals of antiquity. similarly, the gods of the roman pantheon who are associated with these luminaries are discussed in alchemical literature. the concepts of prima materia and anima mundi are central to the theory of the philosopher's stone. magnum opus the great work of alchemy is often described as a series of four stages represented by colors. nigredo, a blackening or melanosis albedo, a whitening or leucosis citrinitas, a yellowing or xanthosis rubedo, a reddening, purpling, or iosis modernity due to the complexity and obscurity of alchemical literature, and the 18th-century disappearance of remaining alchemical practitioners into the area of chemistry, the general understanding of alchemy has been strongly influenced by several distinct and radically different interpretations. those focusing

on the exoteric, such as historians of science lawrence m. principe and william r. newman, have interpreted the 'decknamen' (or code words) of alchemy as physical substances. these scholars have reconstructed physicochemical experiments that they say are described in medieval and early modern texts. at the opposite end of the spectrum, focusing on the esoteric, scholars, such as george calian and anna marie roos, who question the reading of principe and newman, interpret these same decknamen as spiritual, religious, or psychological concepts. new interpretations of alchemy are still perpetuated, sometimes merging in concepts from new age or radical environmentalism movements. groups like the rosicrucians and freemasons have a continued interest in alchemy and its symbolism. since the victorian revival of alchemy,

"occultists reinterpreted alchemy as a spiritual practice, involving the self-transformation of the practitioner and only incidentally or not at all the transformation of laboratory substances", which has contributed to a merger of magic and alchemy in popular thought. esoteric interpretations of historical texts in the eyes of a variety of modern esoteric and neo-hermeticist practitioners, alchemy is fundamentally spiritual. in this interpretation, transmutation of lead into gold is presented as an analogy for personal transmutation, purification, and perfection. according to this view, early alchemists such as zosimos of panopolis (c. ad 300) highlighted the spiritual nature of the alchemical quest, symbolic of a religious regeneration of the human soul. this approach is held to have continued in the middle

ages, as metaphysical aspects, substances, physical states, and material processes are supposed to have been used as metaphors for spiritual entities, spiritual states, and, ultimately, transformation. in this sense, the literal meanings of 'alchemical formulas' were like a veil, hiding their true spiritual philosophy. in the neo-hermeticist interpretation, both the transmutation of common metals into gold and the universal panacea are held to symbolize evolution from an imperfect, diseased, corruptible, and ephemeral state toward a perfect, healthy, incorruptible, and everlasting state, so the philosopher's stone then represented a mystic key that would make this evolution possible. applied to the alchemist himself, the twin goal symbolized his evolution from ignorance to enlightenment, and the stone represented

a hidden spiritual truth or power that would lead to that goal. in texts that are held to have been written according to this view, the cryptic alchemical symbols, diagrams, and textual imagery of late alchemical works are supposed to contain multiple layers of meanings, allegories, and references to other equally cryptic works; which must be laboriously decoded to discover their true meaning. in his 1766 alchemical catechism, theodore henri de tschudi denotes that the usage of the metals was merely symbolic: psychology alchemical symbolism has been important in depth and analytical psychology and was revived and popularized from near extinction by the swiss psychologist carl gustav jung. initially confounded and at odds with alchemy and its images, after being given a copy of the translation of the secret

of the golden flower, a chinese alchemical text, by his friend richard wilhelm, jung discovered a direct correlation or parallels between the symbolic images in the alchemical drawings and the inner, symbolic images coming up in dreams, visions or imaginations during the psychic processes of transformation occurring in his patients. a process, which he called "process of individuation". he regarded the alchemical images as symbols expressing aspects of this "process of individuation" of which the creation of the gold or lapis within were symbols for its origin and goal. together with his alchemical mystica soror, jungian swiss analyst marie-louise von franz, jung began collecting all the old alchemical texts available, compiled a lexicon of key phrases with cross-references and pored over them. the volumes of

work he wrote brought new light into understanding the art of transubstantiation and renewed alchemy's popularity as a symbolic process of coming into wholeness as a human being where opposites brought into contact and inner and outer, spirit and matter are reunited in the hieros gamos or divine marriage. his writings are influential in psychology and for people who have an interest in understanding the importance of dreams, symbols and the unconscious archetypal forces (archetypes) that influence all of life. both von franz and jung have contributed greatly to the subject and work of alchemy and its continued presence in psychology as well as contemporary culture. jung wrote volumes on alchemy and his magnum opus is volume 14 of his collected works, mysterium coniunctionis. literature alchemy has had a long-standing

relationship with art, seen both in alchemical texts and in mainstream entertainment. literary alchemy appears throughout the history of english literature from shakespeare to j. k. rowling, and also the popular japanese manga fullmetal alchemist. here, characters or plot structure follow an alchemical magnum opus. in the 14th century, chaucer began a trend of alchemical satire that can still be seen in recent fantasy works like those of the late sir terry pratchett. visual artists had a similar relationship with alchemy. while some of them used alchemy as a source of satire, others worked with the alchemists themselves or integrated alchemical thought or symbols in their work. music was also present in the works of alchemists and continues to influence popular performers. in the last hundred years, alchemists

have been portrayed in a magical and spagyric role in fantasy fiction, film, television, novels, comics and video games. science one goal of alchemy, the transmutation of base substances into gold, is now known to be impossible by chemical means but possible by physical means. although not financially worthwhile, gold was synthesized in particle accelerators as early as 1941. see also alchemical symbol biological transmutation in corentin louis kervran cupellation historicism history of chemistry list of alchemists nuclear transmutation outline of alchemy porta alchemica renaissance magic spagyric superseded theories in science synthesis of precious metals western esotericism notes references citations bibliography further reading general lawrence principe, the secrets of alchemy, chicago, 2013. jennifer

m. rampling. 2020. the experimental fire: inventing english alchemy, 1300-1700. university of chicago press. greco-egyptian alchemy texts marcellin berthelot and charles-emile ruelle (eds.), collection des anciens alchimistes grecs (caag), 3 vols., 18871888, vol 1: https://gallica.bnf.fr/ark:/12148/bpt6k96492923, vol 2: https://gallica.bnf.fr/ark:/12148/bpt6k9680734p, vol. 3: https://gallica.bnf.fr/ark:/12148/bpt6k9634942s. andre-jean festugiere, la revelation d'hermes trismegiste, paris, les belles lettres, 2014 (, oclc 897235256). robert halleux and henri-dominique saffrey (eds.), les alchimistes grecs, t. 1 : papyrus de leyde papyrus de stockholm recettes, paris, les belles lettres, 1981. otto lagercrantz (ed), papyrus graecus holmiensis, uppsala, a.b. akademiska bokhandeln, 1913, https://archive.org/details/papyrusgraecusho00lage/page/n8.

michele mertens and henri-dominique saffrey (ed.), les alchimistes grecs, t. 4.1 : zosime de panopolis. memoires authentiques, paris, les belles lettres, 1995. andree collinet and henri-dominique saffrey (ed.), les alchimistes grecs, t. 10 : l'anonyme de zuretti ou l'art sacre and divin de la chrysopee par un anonyme, paris, les belles lettres, 2000. andree collinet (ed), les alchimistes grecs, t. 11 : recettes alchimiques (par. gr. 2419; holkhamicus 109) cosmas le hieromoine chrysopee, paris, les belles lettres, 2000. matteo martelli (ed), the four books of pseudo-democritus, maney publishing, 2014. studies dylan m. burns, : alchemical metaphor in the paraphrase of shem (nhc vii,1) , aries 15 (2015), p.79106. alberto camplani, procedimenti magico-alchemici e discorso filosofico ermetico in giuliana

lanata (ed.), il tardoantico alle soglie del duemila, ets, 2000, p.7398. alberto camplani and marco zambon, il sacrificio come problema in alcune correnti filosofice di eta imperiale , annali di storia dell'esegesi 19 (2002), p.5999. regine charron and louis painchaud, 'god is a dyer,' the background and significance of a puzzling motif in the coptic gospel according to philip (cg ii, 3), le museon 114 (2001), p. 41-50. regine charron, the apocryphon of john (nhc ii,1) and the greco-egyptian alchemical literature , vigiliae christinae 59 (2005), p. 438-456. philippe derchain, "l'atelier des orfevres a dendara et les origines de l'alchimie," chronique d'egypte, vol. 65, no 130, 1990, p. 219242. korshi dosoo, a history of the theban magical library , bulletin of the american society of papyrologists 53

(2016), p.251274. olivier dufault, early greek alchemy, patronage and innovation in late antiquity, california classical studies, 2019, https://escholarship.org/uc/item/2ks0g83x. sergio knipe, sacrifice and self-transformation in the alchemical writings of zosimus of panopolis , in christopher kelly, richard flower, michael stuart williams (eds.), unclassical traditions. volume ii: perspectives from east and west in late antiquity, cambridge university press, 2011, p.5969. andre-jean festugiere, la revelation d'hermes trismegiste, paris, les belles lettres, 2014 , . kyle a. fraser, zosimos of panopolis and the book of enoch: alchemy as forbidden knowledge , aries 4.2 (2004), p.125147. kyle a. fraser, baptized in gnosis: the spiritual alchemy of zosimos of panopolis , dionysius 25 (2007), p.3354. kyle

a. fraser, distilling natures secrets: the sacred art of alchemy , in john scarborough and paul keyser (eds.), oxford handbook of science and medicine in the classical world, oxford university press, 2018, p.721742. 2018. https://www.oxfordhandbooks.com/view/10.1093/oxfordhb/9780199734146.001.0001/oxfordhb-9780199734146-e-76. shannon grimes, becoming gold: zosimos of panopolis and the alchemical arts in roman egypt, auckland, rubedo press, 2018, paul t. keyser, greco-roman alchemy and coins of imitation silver , american journal of numismatics 78 (19951996), p.209234. paul keyser, the longue duree of alchemy , in john scarborough and paul keyser (eds.), oxford handbook of science and medicine in the classical world, oxford university press, 2018, p.409430. jean letrouit, "chronologie des alchimistes grecs,"

in didier kahn and sylvain matton, alchimie: art, histoire et mythes, seha-arche, 1995, p. 1193. lindsay, jack. the origins of alchemy in greco-roman egypt. barnes & noble, 1970. paul magdalino and maria mavroudi (eds.), the occult sciences in byzantium, la pomme d'or, 2006. matteo martelli, the alchemical art of dyeing: the fourfold division of alchemy and the enochian tradition in sven dupre (ed.), laboratories of art, springer, 2014, . matteo martelli, alchemy, medicine and religion: zosimus of panopolis and the egyptian priests , religion in the roman empire 3.2 (2017), p.202220. gerasimos merianos, alchemy , in a. kaldellis & n. siniossoglou (eds.), the cambridge intellectual history of byzantium (pp.234251). cambridge: cambridge university press, 2017, . efthymios nikolaidis (ed.), greek alchemy

from late antiquity to early modernity, brepols, 2019, . daniel stolzenberg, unpropitious tinctures: alchemy, astrology & gnosis according to zosimos of panopolis , archives internationales d'histoire des sciences 49 (1999), p.331. cristina viano, byzantine alchemy, or the era of systematization , in john scarborough and paul keyser (eds.), oxford handbook of science and medicine in the classical world, oxford university press, 2018, p.943964. c. vlachou and al., experimental investigation of silvering in late roman coinage , material research society symposium proceedings 712 (2002), p.ii9.2.1-ii9.2.9, . early modern principe, lawrence and william newman. alchemy tried in the fire: starkey, boyle, and the fate of helmontian chymistry. university of chicago press, 2002. external links shac: society

for the history of alchemy and chemistry esswe: european society for the study of western esotericism association for the study of esotericism the alchemy website. adam mclean's online collections and academic discussion. dictionary of the history of ideas: alchemy book of secrets: alchemy and the european imagination, 15002000 a digital exhibition from the beinecke rare book and manuscript library at yale university othmer ms 2 alchemical miscellany at openn alchemy featured topic page on science history institute digital collections featuring selected manuscripts, rare books, paintings, and ephemera relating to alchemical topics and experimentation. esotericism hermeticism history of philosophy history of science

alien primarily refers to: alien (law), a person in a country who is not a national of that country enemy alien, the above in times of war extraterrestrial life, life which does not originate from earth specifically, intelligent extraterrestrial beings; see list of alleged extraterrestrial beings introduced species, a species not native to its environment alien(s), or the alien(s) may also refer to: science and technology alien (alice environment), a grid framework alien (file converter), a linux program alien technology, a manufacturer of rfid technology arts and entertainment alien (franchise), a media franchise alien (creature in alien franchise) films alien (film), a 1979 film by ridley scott aliens (film), second film in the franchise from 1986 by james cameron alien 3, third film in the

franchise from 1992 by david fincher alien resurrection, fourth film in the franchise from 1997 by jean-pierre jeunet alien vs. predator (film), fifth film in the franchise from 2004 by paul w. s. anderson aliens vs. predator: requiem, sixth film in the franchise from 2007 by the brothers strause prometheus (2012 film), seventh film in the franchise from 2012 by ridley scott alien: covenant, eighth film in the franchise from 2017 by ridley scott alien 2: on earth, a 1980 unofficial sequel of the 1979 alien film alien visitor (also titled epsilon) (1995 film) australianitalian science fiction film by rolf de heer the alien (2016 film), a 2016 mexican film the alien (unproduced film), an incomplete 1960s indianamerican film literature alien novels, an extension of the alien franchise aliens (tappan

wright novel), a 1902 novel by mary tappan wright the alien (animorphs), the eighth book in the animorphs series the aliens (play), a 2010 play by annie baker music performers alien (band), a 1980s swedish rock group the aliens (australian band), a 1970s new wave group the aliens (scottish band), a 20052008 rock group albums alien (soundtrack), 1979 alien (beam album), 2022 alien (northlane album), 2019 alien (strapping young lad album), 2005 alien, a 1989 ep by tankard aliens (soundtrack), 1987 songs "alien" (britney spears song), 2013 "alien" (jonas blue and sabrina carpenter song), 2018 "alien", a song by third day from the album conspiracy no. 5, 1997 "alien", a song by pennywise from the album straight ahead, 1999 "alien", a song by bush from the album sixteen stone, 1994 "alien",

a song by erasure from the album loveboat, 2000 "alien", a song by japan from the album quiet life, 1979 "alien", a song by lamb from the album fear of fours, 1999 "alien", a song by nerina pallot from the album dear frustrated superstar, 2001 "alien", a song by p-model from the album landsale, 1980 "alien", a song by thriving ivory from the album thriving ivory, 2003 "alien", a song by tokio hotel from the album humanoid, 2009. fans of the band call themselves "aliens". "alien", a song by atlanta rhythm from the album quinella, 1981 "alien", a 2020 song by lee suhyun "aliens" (song), a 2017 song by coldplay "aliens", a 1984 song by warlord "the alien", a song by dream theater from the album a view from the top of the world, 2021 video games alien (1984 video game), based on the film alien (atari

2600), a 1982 maze game based on the 1979 film alien: isolation, a 2014 video game based on the alien science fiction horror film series aliens (1982 video game), a text-only clone of space invaders written for the cp/m operating system on the kaypro computer aliens (1990 video game), a game by konami, based on the sequel of the film other media alien (armenian tv series), a 2017 melodrama series alien (sculpture), a 2012 work by david breuer-weil, in mottisfont, hampshire, england aliens (dark horse comics line) the aliens (tv series), 2016 british sci-fi television series "aliens" (roseanne), a 1992 television episode other uses alien (shipping company), a russian company alien sun (born 1974), singaporean actress alien, a perfume by thierry mugler see also alians, an islamic order alien

project (disambiguation) alien vs. predator (disambiguation) astrobiology, the study of hypothetical alien life atliens, a 1996 album by outkast predator (disambiguation) ufo (disambiguation) unidentified flying object (disambiguation)

an astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of earth. they observe astronomical objects such as stars, planets, moons, comets and galaxies in either observational (by analyzing the data) or theoretical astronomy. examples of topics or fields astronomers study include planetary science, solar astronomy, the origin or evolution of stars, or the formation of galaxies. a related but distinct subject is physical cosmology, which studies the universe as a whole. types astronomers usually fall under either of two main types: observational and theoretical. observational astronomers make direct observations of celestial objects and analyze the data. in contrast, theoretical astronomers create and investigate models of things that cannot

be observed. because it takes millions to billions of years for a system of stars or a galaxy to complete a life cycle, astronomers must observe snapshots of different systems at unique points in their evolution to determine how they form, evolve, and die. they use these data to create models or simulations to theorize how different celestial objects work. further subcategories under these two main branches of astronomy include planetary astronomy, galactic astronomy, or physical cosmology. academic historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using physical laws. today, that distinction has mostly disappeared and the terms "astronomer" and "astrophysicist"

are interchangeable. professional astronomers are highly educated individuals who typically have a phd in physics or astronomy and are employed by research institutions or universities. they spend the majority of their time working on research, although they quite often have other duties such as teaching, building instruments, or aiding in the operation of an observatory. the american astronomical society, which is the major organization of professional astronomers in north america, has approximately 7,000 members. this number includes scientists from other fields such as physics, geology, and engineering, whose research interests are closely related to astronomy. the international astronomical union comprises almost 10,145 members from 70 different countries who are involved in astronomical research at the

phd level and beyond. contrary to the classical image of an old astronomer peering through a telescope through the dark hours of the night, it is far more common to use a charge-coupled device (ccd) camera to record a long, deep exposure, allowing a more sensitive image to be created because the light is added over time. before ccds, photographic plates were a common method of observation. modern astronomers spend relatively little time at telescopes usually just a few weeks per year. analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers' time. astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes. most universities also have outreach programs including public telescope

time and sometimes planetariums as a public service to encourage interest in the field. those who become astronomers usually have a broad background in maths, sciences and computing in high school. taking courses that teach how to research, write, and present papers are also invaluable. in college/university most astronomers get a phd in astronomy or physics. amateur astronomers while there is a relatively low number of professional astronomers, the field is popular among amateurs. most cities have amateur astronomy clubs that meet on a regular basis and often host star parties. the astronomical society of the pacific is the largest general astronomical society in the world, comprising both professional and amateur astronomers as well as educators from 70 different nations. like any hobby, most people who

think of themselves as amateur astronomers may devote a few hours a month to stargazing and reading the latest developments in research. however, amateurs span the range from so-called "armchair astronomers" to the very ambitious, who own science-grade telescopes and instruments with which they are able to make their own discoveries and assist professional astronomers in research. see also list of astronomers list of women astronomers list of muslim astronomers list of french astronomers list of hungarian astronomers list of russian astronomers and astrophysicists list of slovenian astronomers references sources external links american astronomical society european astronomical society international astronomical union astronomical society of the pacific space's astronomy news astronomy science

ascii ( ), abbreviated from american standard code for information interchange, is a character encoding standard for electronic communication. ascii codes represent text in computers, telecommunications equipment, and other devices. most modern character-encoding schemes are based on ascii, although they support many additional characters. the internet assigned numbers authority (iana) prefers the name us-ascii for this character encoding. ascii is one of the ieee milestones. overview ascii was developed from telegraph code. its first commercial use was as a seven-bit teleprinter code promoted by bell data services. work on the ascii standard began in may 1961, with the first meeting of the american standards association's (asa) (now the american national standards institute or ansi) x3.2 subcommittee. the

first edition of the standard was published in 1963, underwent a major revision during 1967, and experienced its most recent update during 1986. compared to earlier telegraph codes, the proposed bell code and ascii were both ordered for more convenient sorting (i.e., alphabetization) of lists and added features for devices other than teleprinters. the use of ascii format for network interchange was described in 1969. that document was formally elevated to an internet standard in 2015. originally based on the english alphabet, ascii encodes 128 specified characters into seven-bit integers as shown by the ascii chart above. ninety-five of the encoded characters are printable: these include the digits 0 to 9, lowercase letters a to z, uppercase letters a to z, and punctuation symbols. in addition, the original

ascii specification included 33 non-printing control codes which originated with teletype machines; most of these are now obsolete, although a few are still commonly used, such as the carriage return, line feed, and tab codes. for example, lowercase i would be represented in the ascii encoding by binary 1101001 = hexadecimal 69 (i is the ninth letter) = decimal 105. history the american standard code for information interchange (ascii) was developed under the auspices of a committee of the american standards association (asa), called the x3 committee, by its x3.2 (later x3l2) subcommittee, and later by that subcommittee's x3.2.4 working group (now incits). the asa later became the united states of america standards institute (usasi), and ultimately became the american national standards institute (ansi). with

the other special characters and control codes filled in, ascii was published as asa x3.4-1963, leaving 28 code positions without any assigned meaning, reserved for future standardization, and one unassigned control code. there was some debate at the time whether there should be more control characters rather than the lowercase alphabet. the indecision did not last long: during may 1963 the ccitt working party on the new telegraph alphabet proposed to assign lowercase characters to sticks 6 and 7, and international organization for standardization tc 97 sc 2 voted during october to incorporate the change into its draft standard. the x3.2.4 task group voted its approval for the change to ascii at its may 1963 meeting. locating the lowercase letters in sticks 6 and 7 caused the characters to differ in bit pattern

from the upper case by a single bit, which simplified case-insensitive character matching and the construction of keyboards and printers. the x3 committee made other changes, including other new characters (the brace and vertical bar characters), renaming some control characters (som became start of header (soh)) and moving or removing others (ru was removed). ascii was subsequently updated as usas x3.4-1967, then usas x3.4-1968, ansi x3.4-1977, and finally, ansi x3.4-1986. revisions of the ascii standard: asa x3.4-1963 asa x3.4-1965 (approved, but not published, nevertheless used by ibm 2260 & 2265 display stations and ibm 2848 display control) usas x3.4-1967 usas x3.4-1968 ansi x3.4-1977 ansi x3.4-1986 ansi x3.4-1986 (r1992) ansi x3.4-1986 (r1997) ansi incits 4-1986 (r2002) ansi incits 4-1986 (r2007)

(ansi) incits 4-1986[r2012] (ansi) incits 4-1986[r2017] in the x3.15 standard, the x3 committee also addressed how ascii should be transmitted (least significant bit first), and how it should be recorded on perforated tape. they proposed a 9-track standard for magnetic tape, and attempted to deal with some punched card formats. design considerations bit width the x3.2 subcommittee designed ascii based on the earlier teleprinter encoding systems. like other character encodings, ascii specifies a correspondence between digital bit patterns and character symbols (i.e. graphemes and control characters). this allows digital devices to communicate with each other and to process, store, and communicate character-oriented information such as written language. before ascii was developed, the encodings in use included

26 alphabetic characters, 10 numerical digits, and from 11 to 25 special graphic symbols. to include all these, and control characters compatible with the comite consultatif international telephonique et telegraphique (ccitt) international telegraph alphabet no. 2 (ita2) standard of 1924, fieldata (1956), and early ebcdic (1963), more than 64 codes were required for ascii. ita2 was in turn based on the 5-bit telegraph code that emile baudot invented in 1870 and patented in 1874. the committee debated the possibility of a shift function (like in ita2), which would allow more than 64 codes to be represented by a six-bit code. in a shifted code, some character codes determine choices between options for the following character codes. it allows compact encoding, but is less reliable for data transmission, as an

error in transmitting the shift code typically makes a long part of the transmission unreadable. the standards committee decided against shifting, and so ascii required at least a seven-bit code. the committee considered an eight-bit code, since eight bits (octets) would allow two four-bit patterns to efficiently encode two digits with binary-coded decimal. however, it would require all data transmission to send eight bits when seven could suffice. the committee voted to use a seven-bit code to minimize costs associated with data transmission. since perforated tape at the time could record eight bits in one position, it also allowed for a parity bit for error checking if desired. eight-bit machines (with octets as the native data type) that did not use parity checking typically set the eighth bit to 0. internal

organization the code itself was patterned so that most control codes were together and all graphic codes were together, for ease of identification. the first two so-called ascii sticks (32 positions) were reserved for control characters. the "space" character had to come before graphics to make sorting easier, so it became position 20hex; for the same reason, many special signs commonly used as separators were placed before digits. the committee decided it was important to support uppercase 64-character alphabets, and chose to pattern ascii so it could be reduced easily to a usable 64-character set of graphic codes, as was done in the dec sixbit code (1963). lowercase letters were therefore not interleaved with uppercase. to keep options available for lowercase letters and other graphics, the special and numeric

codes were arranged before the letters, and the letter a was placed in position 41hex to match the draft of the corresponding british standard. the digits 09 are prefixed with 011, but the remaining 4 bits correspond to their respective values in binary, making conversion with binary-coded decimal straightforward. many of the non-alphanumeric characters were positioned to correspond to their shifted position on typewriters; an important subtlety is that these were based on mechanical typewriters, not electric typewriters. mechanical typewriters followed the de facto standard set by the remington no. 2 (1878), the first typewriter with a shift key, and the shifted values of 23456789- were "#$%_&'() early typewriters omitted 0 and 1, using o (capital letter o) and l (lowercase letter l) instead, but 1! and 0)

pairs became standard once 0 and 1 became common. thus, in ascii !"#$% were placed in the second stick, positions 15, corresponding to the digits 15 in the adjacent stick. the parentheses could not correspond to 9 and 0, however, because the place corresponding to 0 was taken by the space character. this was accommodated by removing _ (underscore) from 6 and shifting the remaining characters, which corresponded to many european typewriters that placed the parentheses with 8 and 9. this discrepancy from typewriters led to bit-paired keyboards, notably the teletype model 33, which used the left-shifted layout corresponding to ascii, differently from traditional mechanical typewriters. electric typewriters, notably the ibm selectric (1961), used a somewhat different layout that has become de facto standard on

computers following the ibm pc (1981), especially model m (1984) and thus shift values for symbols on modern keyboards do not correspond as closely to the ascii table as earlier keyboards did. the /? pair also dates to the no. 2, and the ,< .> pairs were used on some keyboards (others, including the no. 2, did not shift , (comma) or . (full stop) so they could be used in uppercase without unshifting). however, ascii split the ;: pair (dating to no. 2), and rearranged mathematical symbols (varied conventions, commonly -* =+) to :* ;+ -=. some then-common typewriter characters were not included, notably , while ^ ` ~ were included as diacritics for international use, and < > for mathematical use, together with the simple line characters \ | (in addition to common /). the @ symbol was not used in continental

europe and the committee expected it would be replaced by an accented a in the french variation, so the @ was placed in position 40hex, right before the letter a. the control codes felt essential for data transmission were the start of message (som), end of address (eoa), end of message (eom), end of transmission (eot), "who are you?" (wru), "are you?" (ru), a reserved device control (dc0), synchronous idle (sync), and acknowledge (ack). these were positioned to maximize the hamming distance between their bit patterns. character order ascii-code order is also called asciibetical order. collation of data is sometimes done in this order rather than "standard" alphabetical order (collating sequence). the main deviations in ascii order are: all uppercase come before lowercase letters; for example, "z" precedes

"a" digits and many punctuation marks come before letters an intermediate order converts uppercase letters to lowercase before comparing ascii values. character groups control characters ascii reserves the first 32 codes (numbers 031 decimal) for control characters: codes originally intended not to represent printable information, but rather to control devices (such as printers) that make use of ascii, or to provide meta-information about data streams such as those stored on magnetic tape. for example, character 10 represents the "line feed" function (which causes a printer to advance its paper), and character 8 represents "backspace". refers to control characters that do not include carriage return, line feed or white space as non-whitespace control characters. except for the control characters that prescribe

elementary line-oriented formatting, ascii does not define any mechanism for describing the structure or appearance of text within a document. other schemes, such as markup languages, address page and document layout and formatting. the original ascii standard used only short descriptive phrases for each control character. the ambiguity this caused was sometimes intentional, for example where a character would be used slightly differently on a terminal link than on a data stream, and sometimes accidental, for example with the meaning of "delete". probably the most influential single device affecting the interpretation of these characters was the teletype model 33 asr, which was a printing terminal with an available paper tape reader/punch option. paper tape was a very popular medium for long-term program storage

until the 1980s, less costly and in some ways less fragile than magnetic tape. in particular, the teletype model 33 machine assignments for codes 17 (control-q, dc1, also known as xon), 19 (control-s, dc3, also known as xoff), and 127 (delete) became de facto standards. the model 33 was also notable for taking the description of control-g (code 7, bel, meaning audibly alert the operator) literally, as the unit contained an actual bell which it rang when it received a bel character. because the keytop for the o key also showed a left-arrow symbol (from ascii-1963, which had this character instead of underscore), a noncompliant use of code 15 (control-o, shift in) interpreted as "delete previous character" was also adopted by many early timesharing systems but eventually became neglected. when a teletype 33 asr

equipped with the automatic paper tape reader received a control-s (xoff, an abbreviation for transmit off), it caused the tape reader to stop; receiving control-q (xon, "transmit on") caused the tape reader to resume. this so-called flow control technique became adopted by several early computer operating systems as a "handshaking" signal warning a sender to stop transmission because of impending buffer overflow; it persists to this day in many systems as a manual output control technique. on some systems, control-s retains its meaning but control-q is replaced by a second control-s to resume output. the 33 asr also could be configured to employ control-r (dc2) and control-t (dc4) to start and stop the tape punch; on some units equipped with this function, the corresponding control character lettering on the

keycap above the letter was tape and tape respectively. delete vs backspace the teletype could not move its typehead backwards, so it did not have a key on its keyboard to send a bs (backspace). instead, there was a key marked that sent code 127 (del). the purpose of this key was to erase mistakes in a manually-input paper tape: the operator had to push a button on the tape punch to back it up, then type the rubout, which punched all holes and replaced the mistake with a character that was intended to be ignored. teletypes were commonly used with the less-expensive computers from digital equipment corporation; these systems had to use what keys were available, and thus the del code was assigned to erase the previous character. because of this, dec video terminals (by default) sent the del code for the key marked

"backspace" while the separate key marked "delete" sent an escape sequence; many other competing terminals sent a bs code for the backspace key. the unix terminal driver could only use one code to erase the previous character, this could be set to bs or del, but not both, resulting in recurring situations of ambiguity where users had to decide depending on what terminal they were using (shells that allow line editing, such as ksh, bash, and zsh, understand both). the assumption that no key sent a bs code allowed control+h to be used for other purposes, such as the "help" prefix command in gnu emacs. escape many more of the control codes have been assigned meanings quite different from their original ones. the "escape" character (esc, code 27), for example, was intended originally to allow sending of other

control characters as literals instead of invoking their meaning, a so-called "escape sequence". this is the same meaning of "escape" encountered in url encodings, c language strings, and other systems where certain characters have a reserved meaning. over time this interpretation has been co-opted and has eventually been changed. in modern usage, an esc sent to the terminal usually indicates the start of a command sequence usually in the form of a so-called "ansi escape code" (or, more properly, a "control sequence introducer") from ecma-48 (1972) and its successors, beginning with esc followed by a "[" (left-bracket) character. in contrast, an esc sent from the terminal is most often used as an out-of-band character used to terminate an operation or special mode, as in the teco and vi text editors. in graphical

user interface (gui) and windowing systems, esc generally causes an application to abort its current operation or to exit (terminate) altogether. end of line the inherent ambiguity of many control characters, combined with their historical usage, created problems when transferring "plain text" files between systems. the best example of this is the newline problem on various operating systems. teletype machines required that a line of text be terminated with both "carriage return" (which moves the printhead to the beginning of the line) and "line feed" (which advances the paper one line without moving the printhead). the name "carriage return" comes from the fact that on a manual typewriter the carriage holding the paper moved while the position where the typebars struck the ribbon remained stationary. the entire

carriage had to be pushed (returned) to the right in order to position the left margin of the paper for the next line. dec operating systems (os/8, rt-11, rsx-11, rsts, tops-10, etc.) used both characters to mark the end of a line so that the console device (originally teletype machines) would work. by the time so-called "glass ttys" (later called crts or "dumb terminals") came along, the convention was so well established that backward compatibility necessitated continuing to follow it. when gary kildall created cp/m, he was inspired by some of the command line interface conventions used in dec's rt-11 operating system. until the introduction of pc dos in 1981, ibm had no influence in this because their 1970s operating systems used ebcdic encoding instead of ascii, and they were oriented toward punch-card

input and line printer output on which the concept of "carriage return" was meaningless. ibm's pc dos (also marketed as ms-dos by microsoft) inherited the convention by virtue of being loosely based on cp/m, and windows in turn inherited it from ms-dos. unfortunately, requiring two characters to mark the end of a line introduces unnecessary complexity and ambiguity as to how to interpret each character when encountered by itself. to simplify matters, plain text data streams, including files, on multics used line feed (lf) alone as a line terminator. unix and unix-like systems, and amiga systems, adopted this convention from multics. on the other hand, the original macintosh os, apple dos, and prodos used carriage return (cr) alone as a line terminator; however, since apple has now replaced these obsolete operating