education a rather different process is used for cadavers embalmed for dissection by medical professionals, students, and researchers. here, the first priority is for long-term preservation, not presentation. as such, medical embalmers use anatomical wetting fluids that contain concentrated formaldehyde (37–40%, known as formalin) or glutaraldehyde and phenol, and are made without dyes or perfumes. many embalming chemical companies make specialized anatomical embalming fluids. anatomical embalming is performed into a closed circulatory system. the fluid is usually injected with an embalming machine into an artery under high pressure and flow, and allowed to swell and saturate the tissues. after the deceased is left to sit for a number of hours, the venous system is generally opened and the fluid allowed to drain out, although many anatomical embalmers do not use any drainage technique. anatomical embalmers may choose to use gravity-feed embalming, where the container dispensing the embalming fluid is elevated above the body's level, and fluid is slowly introduced over an extended time, sometimes as long as several days. unlike standard arterial embalming, no drainage occurs, and the body distends extensively with fluid. the distension eventually reduces, often under extended (up to six months) refrigeration, leaving a fairly normal appearance. no separate cavity treatment of the internal organs is given. anatomically embalmed cadavers have a typically uniform grey colouration, due both to the high formaldehyde concentration mixed with the blood and the lack of red colouration agents commonly added to standard, nonmedical, embalming fluids. formaldehyde mixed with blood causes the grey discoloration also known as "formaldehyde grey" or "embalmer's grey". a new embalming technique developed gradually since the 1960s by anatomist walter thiel at the graz anatomy institute in austria has been the subject of various academic papers, as the cadaver retains the body's natural color, texture and plasticity after the process. the method uses 4-chloro-3-methylphenol and various salts for fixation, boric acid for disinfection, and ethylene glycol for the preservation of tissue plasticity. the embalmed cadavers are used in anatomical research, surgical and anaesthesia training, preoperative test procedures, and ct image quality studies. religious practices opinions differ among different faiths as to the permissibility of embalming. a brief overview of some of the larger faiths positions are: most branches and denominations of the christian faith allow embalming. some bodies within eastern orthodoxy profess an absolute ban on embalming except when required by law or other necessity, while others may discourage but do not prohibit it. in most christian denominations, the decision on embalming is the preference of the deceased's family rather than for church policy or theological viewpoint. the church of jesus christ of latter-day saints does not discourage or prohibit embalming. often, due to the custom of church members dressing the deceased, embalming is given preference. some neopagans discourage embalming, believing it unnatural to disrupt the physical recycling of the body to the earth. members of the baháʼí faith are not embalmed. instead, the body is washed and then placed in a cotton, linen, or silk shroud. zoroastrians traditionally hold a type of sky burial within a structure known as a tower of silence in which the body is exposed to weathering and predation to dispose of the remains, thus embalming the body is contrary to their funeral designs. traditional jewish law forbids embalming and burial is to be done as soon as possible – preferably within 24 hours. in islam, embalming of the dead is not practiced by muslims - except in cases of necessity, such as when a body is being transported internationally and the law requires it to be embalmed. muslims bury their deceased as soon as possible (preferably with 24 hours), to allow the soul to transition to the afterlife as soon as possible. notable embalmings lord nelson (1758–1805) was preserved for two months in brandy and spirits of wine mixed with camphor and myrrh after which time the body was found to be in excellent condition and completely plastic. various communist leaders have been embalmed and put on public display. perhaps the most famous embalmed body of the 20th century is that of vladimir lenin, which continues to draw crowds decades after his death in 1924, and is seen in his moscow mausoleum. joseph stalin was also embalmed and placed next to lenin, but his body was buried in 1961 during de-stalinization. klement gottwald of czechoslovakia, who died just five days after attending stalin's funeral, was embalmed and displayed in a mausoleum at national monument in vitkov in prague. however, in 1962 due to political reasons, the body was removed and cremated. bulgarian georgi dimitrov was embalmed and placed on display in the sofia georgi dimitrov mausoleum. after the fall of communism in bulgaria, his body was buried in 1990 in the central cemetery of sofia. mongolia's khorloogiin choibalsan, angola's agostinho neto, romania's gheorghe gheorghiu-dej and guyana's forbes burnham were also embalmed by the same russian team. currently, embalmed communist leaders can also be found in the mausoleum of mao zedong, the ho chi minh mausoleum, and the kumsusan palace of the sun for kim il sung and kim jong il. the botched embalming of pope pius xii (1876–1958; pope 1939–1958) by a charlatan doctor – which only sped up the rate of decomposition – led to his body turning black and his nose falling off while lying in state, and the body disintegrated in the coffin. the swiss guards stationed around pius xii's body were forced to change shifts every 10 to 15 minutes, since the body's odor caused some guards to pass out. the doctor who performed the embalming had also taken photos of the pontiff in his death throes, intending to sell them to tabloids. the italian tabloids refused to buy the photos, and the doctor was banned from entering the vatican city-state by john xxiii, who furthermore prohibited any photography of a deceased pope until the body is properly vested and laid out. charles xii (1682–1718) is one of several swedish kings to have been embalmed. when charles xii's sarcophagus was opened in 1917, his features were still recognizable, almost 200 years after his death. photographs of his remains clearly show the gunshot wound to his head leading to his death. the body of pope john xxiii (1881–1963; pope 1958–1963) is on display on an altar on the main floor of the basilica of saint peter after having been exhumed from the grottoes beneath the main altar and has retained an extremely well-preserved state. if a body's remains do not decompose, contrary to expectations, it is often treated as a miracle. however, the case of john xxiii's body did not enjoy the same acclamation, as it was held to have been due to embalming and adipocere formation. the body of pope pius x (1835–1914; pope 1903–1914) lies in a crystal coffin, in the chapel of the presentation of the virgin mary. on 17 february 1952, pius x's body was transferred from the crypt of the vatican grotto. the body is dressed in pontifical robes, while the face and hands are covered with silver. he lies within a glass and bronze-work sarcophagus for the faithful to see. papal physicians had been in the habit of removing organs to aid the embalming process. pius x expressly prohibited this, however, and none of his successors has allowed the practice to be reinstituted. murdered civil rights activist medgar evers was so well embalmed that a valid autopsy was able to be performed on his corpse decades after his death, and this helped secure the conviction of his killer. abraham lincoln, detail from a carte de visite (photo caption from book, retouched post mortem photograph by john b. bachelder, washington, dc, 16 april 1865) famous russian surgeon and scientist n. i. pirogov was embalmed after his death in 1881. he was embalmed using the technique he himself developed. his body rests in a church in vinnitsa, ukraine. in contrast to the corpse of lenin, which undergoes thorough maintenance in a special underground clinic twice a week, the body of pirogov rests untouched and unchanging – reportedly only dust has to be brushed off of it. it rests at room temperature in a glass-lid coffin (while lenin's body is preserved at a constant low temperature). abraham lincoln was embalmed after his assassination in 1865. to prevent anyone stealing lincoln's body, lincoln's eldest son robert called for lincoln's exhumation in 1901 to be buried in a concrete vault in the burial room of his tomb in springfield, illinois. fearing that his body would have been stolen in the interim, lincoln's coffin was opened, and his features were still recognizable, 36 years after his death. rosalia lombardo, who died at age one on 6 december 1920, was one of the last corpses to be interred in the capuchin catacombs of palermo, sicily before the local authorities banned the practice. nicknamed the 'sleeping beauty', rosalia's body is still perfectly intact. embalmed by alfredo salafia, she is in a glass case, looking very much like a surreal doll. eva perón was embalmed by dr. pedro ara, as ordered by her husband juan perón. the body was preserved to look like it was in a sleep-like state. the procedure worked and the body showed no signs of decomposition when eva was interred at her final resting place many years after the initial procedure. kemal atatürk was embalmed. his remains were originally laid to rest in the ethnography museum of ankara from 10 november 1938 to 10 november 1953. he was subsequently moved to anıtkabir in ankara, turkey, buried in a 42-ton sarcophagus. chiang kai-shek and chiang ching-kuo were embalmed and rest at cihu mausoleum and touliao mausoleum in daxi district, taoyuan city, taiwan. francisco franco was embalmed. his remains were originally laid to rest in the valley of the fallen from 1975 to 2019. he was subsequently moved to mingorrubio cemetery, el pardo, madrid, spain. ferdinand marcos was embalmed in hawaii upon his death. his body was flown home and is on display at marcos museum and mausoleum in batac, ilocos norte, philippines from 1993 to 18 november 2016. diana, princess of wales was embalmed shortly after her death in france in august 1997. the decision to embalm her provoked conspiracy theories that she was pregnant; conspiracists claimed, incorrectly, that the embalming fluid would have destroyed any evidence of fetal presence in her womb. the official explanation for the embalming was that the warm conditions in the chapel of rest where her body was laid out would have sped up the decomposition of the remains. when the basilica of saint-denis was desecrated by french revolutionaries in 1793, the body of henry iv was so well preserved it was displayed two days before being thrown in a mass grave, and a new death mask was able to be made. likewise, louis xiii was still recognisable thanks to his well preserved moustache. turenne was so well preserved that looters first thought he was still alive. maria ii of portugal died in childbirth on 15 november 1853 at the age of 34. she was embalmed the following day. in a letter dated 28 november 1853, the duchess of ficalho, the queen's lady-in-waiting, reported the outcome to her brother, the 2nd count of lavradio: "sad embalming, which took place on november 16th, i was always there. the infante's and the queen's lasted seven hours. once that affliction was over, it was time to put the clothes on, which was almost impossible due to the state of dissolution of her majesty, but it was done as well as possible, bearing the orders and the royal mantle, but it was necessary to close the coffin, because its not possible to describe the state of dissolution." between february and september 2012, researchers at the university of são paulo in brazil exhumed the remains of emperor pedro i of brazil (also king of portugal as pedro iv; 1798–1834) and his two wives empress maria leopoldina (1797–1826) and empress amélie (1812–1873). they were surprised to find that the body of the latter had been mummified. skin, hair and internal organs were preserved. examinations at the hospital das clínicas found an incision in the empress' jugular vein. aromatics such as camphor and myrrh were injected into the incision during the embalming process. "it certainly helped to nullify the