989) advised two emperors that they should not worry about elixirs but direct their minds to improving the state administration, chai rong or emperor shizong of later zhou in 956, and then emperor taizu of song in 976. song dynasty after its heyday in the tang dynasty daoist alchemy continued to flourish during the song dynasty (960–1279) period. however, since six tang emperors and many court officials died from elixir poisoning, song alchemists exercised more caution, not only in the composition of the elixirs themselves, but also in attempts to find pharmaceutical methods of counteracting the toxic effects. the number of ingredients used in elixir formulas was reduced and there was a tendency to return to the ancient and difficult terminology of the cantongqi, perhaps to conceal the processes from rash and ignorant operators. psycho-physiological neidan alchemy became steadily more popular than laboratory waidan alchemy. during the song dynasty, the practice of consuming metallic elixirs was not confined to the imperial court and expanded to anyone wealthy enough to pay. the author and official ye mengde (1077–1148) described how two of his friends had died from elixirs of immortality in one decade. first, lin yanzhen, who boasted about his health and muscular strength, took an elixir for three years, "whereupon ulcers developed in his chest, first near the hairs as large as rice-grains, then after a couple of days his neck swelled up so that chin and chest seemed continuous." lin died after ten months of suffering, and his doctors discovered cinnabar powder had accumulated in his pus and blood. second, whenever xie renbo "heard of anyone who had some cinnabar subdued by fire he went after it, caring nothing about the distance, and his only fear was that he would not have enough." he also developed ulcers on the chest. although his friends noticed changes in his appearance and behavior, xie did not recognize that he had been poisoned, "till suddenly it came upon him like a storm of wind and rain, and he died in a single night". the scientist and statesman shen kuo's 1088 dream pool essays suggested that mercury compounds might be medicinally valuable and needed further study—foreshadowing the use of metallic compounds in modern medicine, such as mercury in salvarsan for syphilis or antimony for visceral leishmaniasis. shen says his cousin once transformed cinnabar into an elixir, but one of his students mistakenly ate a leftover piece, became delirious, and died the next day. now cinnabar is an extremely good drug and can be taken even by a newborn baby, but once it has been changed by heat it can kill an (adult) person. if we consider the change and transformation of opposites into one another, since (cinnabar) can be changed into a deadly poison why should it not also be changed into something of extreme benefit? since it can change into something which kills, there is good reason to believe that it may have the pattern-principle of saving life; it is simply that we have not yet found out the art (of doing this). thus we cannot deny the possibility of the existence of methods for transforming people into feathered immortals, but we have to be very careful about what we do. su shi (1037–1101), the song dynasty scholar and pharmacologist, was familiar with the life-prolonging claims of alchemists, but wrote in a letter that, "i have recently received some cinnabar (elixir) which shows a most remarkable colour, but i cannot summon up enough courage to try it". the forensic medical expert song ci was familiar with the effects of metal poisoning, and his c. 1235 collected cases of injustice rectified handbook for coroners gives a test for mercury poisoning: plunge a piece of gold into the intestine or tissues and see if a superficial amalgam forms. he also describes the colic, cramps, and discharge of blood from arsenic poisoning, and gives several antidotes including emetics. ming dynasty chinese woodblock illustration of a neidan practice "putting the miraculous elixir into the ding tripod", 1615 xingming guizhi (pointers on spiritual nature and bodily life) ming dynasty (1368–1644) authorities strongly disapproved of immortality elixirs, but the jiajing emperor (r. 1521–1567) supposedly died from consuming them. the emperor was interested in the art of immortality and put great confidence in daoist physicians, magicians, and alchemists. one named wang jin 王金, who was appointed a physician-in-attendance in the imperial academy of medicine, convinced the emperor that eating and drinking from vessels made of alchemical gold and silver would bring about immortality, but it only resulted in his death. wang fled but was caught and exiled to the frontiers in 1570. li shizhen's classic 1578 compendium of materia medica discusses the historical tradition of producing gold and cinnabar elixirs, and concludes, "(the alchemists) will never realise that the human body, which thrives on water and the cereals, is unable to sustain such heavy substances as gold and other minerals within the stomach and intestines for any length of time. how blind it is, in the pursuit of longevity, to lose one's life instead!". in another section, li criticizes alchemists and pharmacologists for perpetuating the belief in mercury elixirs. i am not able to tell the number of people who since the six dynasties period (3rd to 6th centuries) so coveted life that they took (mercury), but all that happened was that they impaired their health permanently or lost their lives. i need not bother to mention the alchemists, but i cannot bear to see these false statements made in pharmacopoeias. however, while mercury is not to be taken orally, its use as a medicine must not be ignored. qing dynasty the qing dynasty yongzheng emperor (r. 1722–1735) was the last chinese ruler known to die from elixir poisoning. he was a superstitious man, affected by portents and omens, and a firm believer in daoist longevity techniques. taking immortality elixirs is thought to have caused his sudden death in 1735. historical interpretations the chinese tradition of using toxic heavy metals in elixirs of immortality has historical parallels in ayurvedic medicine. rasa shastra is the practice of adding metals and minerals to herbal medicines, rasayana is an alchemical tradition that used mercury and cinnabar for lengthening lifespan, raseśvara is a tradition that advocated the use of mercury to make the body immortal, and samskara is a process said to detoxify heavy metals and toxic herbs. the historians of chinese science joseph needham and ho peng-yoke wrote a seminal article about poisonous alchemical elixirs. based upon early chinese descriptions of elixir poisoning, they decisively demonstrated a close correspondence with the known medical symptoms of mercury poisoning, lead poisoning, and arsenic poisoning. compare the historical descriptions of jin emperor ai (d. 365) who "no longer knew what was going on around him" and tang emperor wuzong (d. 846) who was "very irritable, losing all normal self-control in joy or anger ... he could not speak for ten days at a time" with the distinctive psychological effects of mercury poisoning: progressing from "abnormal irritability to idiotic, melancholic, or manic conditions". needham and his collaborators further discussed elixir poisoning in the science and civilisation in china series. although chinese elixir poisoning may lead some to dismiss chinese alchemy as another example of human follies in history, ho peng-yoke and f. peter lisowski note its positive aspect upon chinese medicine. the caution given to elixir poisoning later led chinese alchemy to "shade imperceptibly" into iatrochemistry, the preparation of medicine by chemical methods, "in other words chemotherapy". a recent study found that chinese emperors lived comparatively short lives, with a mean age at death of emperors at 41.3, which was significantly lower than that of buddhist monks at 66.9 and traditional chinese doctors at 75.1. causes of imperial death were natural disease (66.4%), homicide (28.2%), drug toxicity (3.3%), and suicide (2.1%). homicide resulted in a significantly lower age of death (mean age 31.1) than disease (45.6), suicide (38.8), or drug toxicity (43.1, mentioning qin shi huang taking mercury pills of immortality). lifestyles seem to have been a determining factor, and 93.2% of the emperors studied were overindulgent in drinking alcohol, sexual activity, or both. the study does not refer to the chinese belief that the arsenic sulphides realgar and orpiment, frequently used in immortality elixirs, had aphrodisiac properties. hypothetical explanations a significant question remains unanswered. if the insidious dangers of alchemical elixir poisoning were common knowledge, why did people continue to consume them for centuries? joseph needham and his collaborators suggested three hypothetical explanations, and michel strickmann proposed another. initial exhilaration needham and lu's first explanation is that many alchemical mineral preparations were capable of giving an "initial exhilaration" or transient sense of well-being, usually involving weight loss and increased libido. these preliminary tonic effects could have acted as a kind of "bait" inveigling an elixir-taker deeper into substance intoxication, even to the point of death. chinese medical texts recorded that realgar (arsenic disulphide) and orpiment (arsenic trisulphide) were aphrodisiacs and stimulated fertility, while cinnabar and sulphur elixirs increased longevity, averted hunger, and "lightened the body" (namely, qīngshēn 輕身, which is a common description of elixir effects). wine, as mentioned above, was both prescribed to be drunk when taking elixir pills and to relieve the unpleasant side-effects of elixir poisoning. needham and lu further suggest the possibility that elixir alchemy included hallucinogenic drugs, tentatively identifying the busi zhi yao 不死之藥 "drug of deathlessness" as fly-agaric and busi zhi shu 不死之樹 "tree of deathlessness" as birch. the elixir that tao hongjing's disciple zhou ziliang took to commit suicide "probably had hallucinogenic and toxic mushrooms". in the present day, realgar wine is traditionally consumed as part of the dragon boat festival. incorruptibility jade burial suit of nanyue king zhao mo (d. 122 bce) the preserved body of xin zhui (d. 163 bce) the apparent incorruptibility of an elixir-taker's corpse is needham and lu's second explanation for the persistent belief in immortality elixirs. they suggest that in some cases a body did not decompose because the deceased had died from mercury or arsenic poisoning, which is forensically known to often preserve a corpse from decay. for a believer in daoist immortality drugs, even when an elixir-taker had unmistakably died, if the corpse was comparatively undecomposed, that could be interpreted as proof that the adept had become a xian immortal, as well as evidence for the alchemical elixir's efficacy. terminal incorruptibility was an ancient chinese belief associated with jade, gold, and cinnabar. the baopuzi says, "when gold and jade are inserted into the nine orifices, corpses do not decay. when salt and brine are absorbed into flesh and marrow, dried meats do not spoil. so when men ingest substances which are able to benefit their bodies and lengthen their days, why should it be strange that (some of these) should confer life perpetual?" the abolition of decay was believed to demonstrate the power of elixirs, "the corruptible had put on incorruptibility". chinese jade burial suits are a better known example of using a mineral to preserve corpses. there is a possibility that sun simiao (above) died from taking mercury elixirs. according to sun's hagiography in the 10th-century xuxian zhuan 續仙傳 (further biographies of the immortals), after his death in 682 there was no visible sign of putrefaction, "after more than a month had passed there was no change in his appearance, and when the corpse was raised to be placed in the coffin it was as light as (a bundle of) empty clothes". the incorruptibility stories about elixir users were not all myth, and recent archeological evidence showed that the ancient chinese knew how "to achieve an almost perpetual conservation". the 1972 excavation of a tomb at mawangdui discovered the extremely well-preserved body of xin zhui or lady dai, which resembled that of "a person who had died only a week or two before". a subsequent autopsy on her corpse found "abnormally high levels" of mercury and lead in her internal organs. temporary death needham and lu's third justification for taking poisonous elixirs is a drug-induced "temporary death", possibly a trance or coma. in the classic legend (above) about wei boyang drinking an elixir of immortality, he appears to die, subsequently revives, and takes more elixir to achieve immortality. the baopuzi describes a five mineral-based multicolored ninefold radiance elixir