Scientists have found that the heart of King Richard I, who ruled England in the 12th-Century, was preserved using mercury, mint and frankincense, among other sweet-smelling plants.
The king's heart was removed and mummified separately from the rest of his body when he died in 1199. It rested in a reliquary at Notre Dame in Rouen for centuries before its rediscovery in 1838.
Now, scientists have found the chemical composition of the substances used to preserve the heart, LiveScience reported.
"These substances were directly inspired by Biblical texts. The aim was to approach the odour of sanctity," study leader Philippe Charlier of University Hospital R Poincare told the website.
Richard I of England began his rule in 1189. He spent two years in captivity in Europe, much of that time being held for ransom by the Holy Roman Emperor.
On March 25, 1199, years after the kidnapping, Richard sustained a crossbow wound in Chalus, France, and died 12 days later of gangrene. His abdominal organs were removed and interred in Chalus, while his body went to rest at Fontevraud Abbey in France.
His heart was embalmed and placed in its own casket and taken to Notre Dame in Rouen. This division of the body was used to symbolise and mark Richard I's territory, Charlier said.
However, no ancient texts remain to record how the embalming process was done.
The heart rested in Rouen until July 1838, when a local historian discovered a lead box inscribed, "Here is the heart of Richard, King of England." The heart had been reduced to dust by the time it was rediscovered in 1838.
It was this brownish-white powder that Charlier and his colleagues tested. They found a variety of compounds, including traces of the proteins found in human heart muscle. They also observed tiny fragments of linen, suggesting that the heart was wrapped before placement in the box. Some metal compounds, including lead and tin, likely seeped into the powder from the lead box. Others were probably used in the embalming process. In particular, the researchers detected mercury, which has been found in other medieval burials and was probably used as an embalming agent.
Frankincense, a tree resin, would also have been useful for both its preservation and its symbolic properties.
"This symbolic substance appeared at both extremities of the Christ life. Presented by the Biblical Magi at His birth, and used during His external embalming after the Passion," the researchers wrote in the journal Scientific Reports.
Preserving the heart would have been important, because the journey to Rouen from Chalus was about 530 kilometres, the researchers wrote.
But Richard I's contemporaries may have also seen the process as one of theological transformation, Charlier said.