immortal, and instructed him to commit ritual suicide with a poisonous elixir composed of mushrooms and cinnabar. in 517, tao edited the zhoushi mingtong ji 周氏冥通記 (records of mr. zhou's communications with the unseen) detailing his disciples visions. the liang dynasty founder emperor wu (r. 502–549) was cautious about taking elixirs of immortality. he and tao hongjing were old friends, and the history of the southern dynasties says the emperor requested him to study elixir alchemy. after tao had learned the secret art of making elixirs, he was worried about the shortage of materials. "so the emperor supplied him with gold, cinnabar, copper sulphate, realgar, and so forth. when the process was accomplished the elixirs had the appearance of frost and snow and really did make the body feel lighter. the emperor took an elixir and found it effective." tao spent his last years working on different elixirs and presented three to the emperor, who had refused immortality elixirs from deng yu 鄧郁 (who claimed to have lived 30 years without food, only consuming pieces of mica in stream water). emperor wenxuan (r. 550–559) of the northern qi dynasty was an early skeptic about immortality elixirs. he ordered alchemists to make the jiuhuan jindan 九還金丹 (ninefold cyclically transformed elixir), which he kept in a jade box, and explained, "i am still too fond of the pleasures of the world to take flight to the heavens immediately—i intend to consume the elixir only when i am about to die". tang dynasty at least five tang dynasty (618–907) emperors were incapacitated and killed by immortality elixirs. in the 9th century tang imperial order of succession, two father-son emperor pairs died from elixirs: first xianzong (r. 805–820) and muzong (r. 820–824), then wuzong (r. 840–846) and xuanzong (r. 847–859). in historic recurrences, the newly enthroned emperor understandably executed the daoist alchemists whose elixirs had killed his father, and then subsequently came to believe in other charlatans enough to consume their poisonous elixirs. emperor xianzong (r. 805–820) indirectly lost his life due to elixir poisoning. the xu tongzhi (supplement to the historical collections) says, "deluded by the sayings of the alchemists, ingested gold elixirs and his behaviour became very abnormal. he was easily offended by those officials whom he daily met, and thus the prisons were left with little vacant space." in response, an official wrote an 819 memorial to the throne that said: of late years, however, (the capital) has been overrun by a host of pharmacists and alchemists ... recommending one another right and left with ever wilder and more extravagant claims. now if there really were immortals, and scholars possessing the tao, would they not conceal their names and hide themselves in mountain recesses far from the ken of man? ... the medicines of the sages of old were meant to cure bodily illnesses, and were not meant to be taken constantly like food. how much less so these metallic and mineral substances which are full of burning poison! ... of old, as the li chi says, when the prince took physic, his minister tasted it first, and when a parent was sick, his son did likewise. ministers and sons are in the same position. i humbly pray that all those persons who have elixirs made from transformed metals and minerals, and also those who recommend them, may be compelled to consume (their own elixirs) first for the space of one year. such an investigation will distinguish truth from falsehood, and automatically clarify the matter by experiment. after the emperor rejected this appeal, the palace eunuchs wang shoucheng and chen hongzhi 陳弘志 assassinated him in 820. when xianzong's son and successor emperor muzong (r. 820–824) came to the throne, he executed the alchemists who had poisoned his father, but later began to take immortality elixirs himself. an official wrote muzong an 823 memorial that warned: medicines are for use against illnesses, and should not be taken as food. ... even when one is ill medicines must be used with great circumspection; how much more so when one is not ill. if this is true for the common people how much more so will it be for the emperor! your imperial predecessor believed the nonsense of the alchemists and thus became ill; this your majesty already knows only too well. how could your majesty still repeat the same mistake? the emperor appreciated this reasoning but soon afterwards fell ill and died from poisoning. palace eunuchs supposedly used poisonous elixirs to assassinate muzong's young successor emperor jingzong (r. 824–827). the next tang emperor to die from elixir poisoning was wuzong (r. 840–846). according to the old book of tang, "the emperor favoured alchemists, took some of their elixirs, cultivated the arts of longevity and personally accepted (taoist) talismans. the medicines made him very irritable, losing all normal self-control in joy or anger; finally when his illness took a turn for the worse he could not speak for ten days at a time." chancellor li deyu and others requested audiences with the emperor, but he refused and subsequently died in 846. wuzong's successor emperor xuānzong (r. 846–849) astonishingly also died of elixir poisoning. xuānzong made himself the patron of some daoists who concocted immortality elixirs of vegetable origin, possibly because his father wuzong had died from metallic and mineral elixir poisoning. the new book of tang records that the emperor received a wine tincture of ivy (常春藤, hedera helix) that the daoist adept jiang lu 姜攎 claimed would turn white hair black and provide longevity. however, when the emperor heard that many people died a violent death after drinking ivy tincture, he stopped taking it. jiang was publicly shamed and the emperor granted his request to search in the mountains for the right plant, but he never appeared again. according to the 890 dongguan zuoji (record of memorials from the eastern library), "a medical official, li , presented to the emperor cinnabar which had been heated and subdued by fire, in order to gain favour from him. thus the ulcerous disease of the emperor was all attributable to his crime". besides emperors, many tang literati were interested in alchemy. both li bai and bai juyi wrote poems about the cantong qi and alchemical elixirs. other poets, including meng haoran, liu yuxi, and liu zongyuan also referred to elixir compounding in their works. the influential tang physician and alchemist sun simiao's c. 640 alchemical taiqing zhenren dadan 太清真人大丹 (great purity essentials of elixir manuals for oral transmission) recommends 14 elixir formulas he found successful, most of which seem poisonous, containing mercury and lead, if not arsenic, as ingredients. sun's medical c. 659 qianjin yifang 千金要方 (supplement to the thousand golden remedies) categorically states that mercury, realgar, orpiment, sulphur, gold, silver, and vitriol are poisonous, but prescribed them in much larger amounts for elixirs than for medicines. in contrast to drinking soluble arsenic (as in groundwater), when powdered arsenic is eaten "astonishing degrees of tolerance can be achieved", and sun simiao might have thought that when human beings reached to a level "approaching that of the immortals their bodies would no longer be susceptible to poison". tang alchemists were well aware of elixir poisoning. the c. 8th–9th century zhenyuan miaodao yaolüe 真元妙道要略 (synopsis of the essentials of the mysterious dao of the true origin) lists 35 common mistakes in elixir preparation: cases where people died from eating elixirs made from cinnabar, mercury, lead, and silver; cases where people suffered from boils on the head and sores on the back by ingesting cinnabar prepared by roasting together mercury and sulphur, and cases where people became seriously ill through drinking melted "liquid lead". the c. 850 xuanjie lu 玄解錄 (record of mysterious antidotes)—which is notable as the world's oldest printed book on a scientific subject—recommends a potent herbal composition that serves both as an elixir and as an antidote for common elixir poisoning. the procedure to make shouxian wuzi wan 守仙五子丸 (five-herbs immortality-safeguarding pills) is to take 5 ounces each of indian gooseberry, wild raspberry, dodder, five-flavor berry, and broadleaf plantain and pound them into flour. mix it with boxthorn juice and false daisy juice and dry. heat almonds and good wine in a silver vessel, and add foxglove, tofu, and "deer glue". combine this with the five herbs, and dry into small pills. the usual dosage is 30 pills a day taken with wine, but one should avoid eating pork, garlic, mustard, and turnips when taking the medicine. during the tang period, chinese alchemists divided into two schools of thought about elixir poisoning. the first altogether ignored the poison danger and considered the unpleasant symptoms after taking an elixir as signs of its efficacy. the c. 6th century taiqing shibi ji 太清石壁記 (records of the rock chamber) described away the side effects and recommended methods of bringing relief. after taking an elixir, if your face and body itch as though insects were crawling over them, if your hands and feet swell dropsically, if you cannot stand the smell of food and bring it up after you have eaten it, if you feel as though you were going to be sick most of the time, if you experience weakness in the four limbs, if you have to go often to the latrine, or if your head or stomach violently ache—do not be alarmed or disturbed. all these effects are merely proofs that the elixir you are taking is successfully dispelling your latent disorders. many of these symptoms are characteristic of metallic poisoning: formication, edema, and weakness of the extremities, later leading to infected boils and ulcers, nausea, vomiting, gastric and abdominal pain, diarrhea, and headaches. for relieving the side-effects when the elixir takes effect, the taiqing shibi ji recommends that one should take hot and cold baths, and drink a mixture of scallion, soy sauce, and wine. if that does not bring relief, then one should combine and boil a hornets' nest, spurge, solomon's seal, and ephedra into a medicine and take one dose. the second school of alchemists, admitted that some metal and mineral elixir constituents were poisonous and tried either to neutralize them or to replace them with less dangerous herbal substances. for instance, the 8th-century zhang zhenren jinshi lingsha lun 張真人金石靈沙論 (the adept zhang's discourse on metals, minerals, and cinnabar) emphasized the poisonous nature of gold, silver, lead, mercury, and arsenic, and described witnessing many cases of premature death brought about by consuming cinnabar. zhang believed however that the poisons could be rendered harmless by properly choosing and combining adjuvant and complimentary ingredients; for example gold should always be used together with mercury, while silver can only be used when combined with gold, copper carbonate, and realgar for the preparation of the jindan golden elixir. many tang alchemical writers returned to the fashion of using obscure synonyms for ingredients, perhaps because of the alarming number of elixir poisonings, and the desire to dissuade amateur alchemists from experimenting on themselves. by the end of the yuan dynasty (1271–1368), the more cautious alchemists had generally changed the elixirs ingredients from minerals and metals to plants and animals. the late tang or early song huangdi jiuding shendan jingjue 黄帝九鼎神丹經訣 (explanation of the yellow emperor's manual of the nine-vessel magical elixir) says, "the ancient masters (lit. sages) all attained longevity and preserved their lives (lit. bones) by consuming elixirs. but later disciples (lit. scholars) have suffered loss of life and decay of their bones as the result of taking them." the treatise explains the secret ancient methods for rendering elixir ingredients harmless by treating them with wine made from chastetree leaves and roots, or with saltpeter and vinegar. another method of supposedly removing the poison from mercury was to put it in three-year-old wine, add sal ammoniac and boil it for 100 days. five dynasties two rulers died from elixir poisoning during the five dynasties period (907–979) of political turmoil after the overthrow of the tang dynasty. zhu wen or emperor taizu (r. 907–912), the founder of the later liang dynasty, became seriously incapacitated as a result of elixir poisoning, and fell victim to an assassination plot. li bian or emperor liezu (r. 937–943), the founder of the southern tang kingdom, took immortality elixirs that made him irritable and deathly ill. the daoist adept chen tuan (d.