Using techniques including mass, infrared and atomic-emission spectrometry, experts have proven that remains thought to be of St. Joan of Arc are actually those from an Egyptian mummy. 

The relics kept at a French church and thought to belong to 15th century French heroine Joan of Arc, who was burned at the stake in 1431 in Rouen, Normandy, were found to instead be the remains of an Egyptian mummy after being analyzed by European experts. The story appears in the April 5 edition of the journal Nature.

Philippe Charlier, a forensic scientist who obtained permission to study the relics, said he was "astonished" by the results. "I'd never have thought that it could be from a mummy," he told Nature. 

Charlier and his colleagues didn't have much to work with: The relics comprise a charred-looking human rib, chunks of what seem to be carbonized wood, a 6-in. fragment of linen and a cat femur, consistent with the medieval practice of throwing black cats onto the pyre of supposed witches.

The relics were discovered in 1867 in a jar in the attic of a Paris pharmacy, with the inscription "Remains found under the stake of Joan of Arc, virgin of Orleans." They were recognized by the church, and are now housed in a museum in Chinon that belongs to the Archdiocese of Tours.

The researchers used a range of techniques to investigate the remains, including mass, infrared and atomic-emission spectrometry, electron microscopy, pollen analysis and, unusually, sniff tests conducted by perfume industry leaders.

Microscopic and chemical analysis of the black crust on the rib and on the cat femur showed that they were not in fact burnt, but were impregnated with a vegetal and mineral matrix, with no trace of muscle, skin, fat or hair. "I see burnt remains all the time in my job," said Charlier. "It was obviously not burnt tissue."

The black material was, however, consistent with an embalming mix of wood resins, bitumen and chemicals such as malachite. It was also consistent with gypsum, which gives the mix its plaster smell. The linen cloth had a coating characteristic of mummy wrappings, and large amounts of pine pollen were present. Pine trees did not grow in Normandy at the time that Joan was killed, but pine resin was used widely in Egypt during embalming.

The representatives from the perfume industry smelled "burnt plaster" and "vanilla" in the relics. The plaster smell was consistent with the fact that Joan was burnt on a plaster stake, not a wooden one, to make the spectacle last longer. But vanilla is inconsistent with cremation. Vanillin is produced during decomposition of a body, Charlier said.

The conclusion that the relics were of the mummy origin was reinforced by carbon-14 analysis dating the remains to between the third and sixth centuries BC. And their spectrometry profiles matched those from Egyptian mummies from the period, and not those of burnt bones.

Charlier pointed out that mummies were used in Europe during the Middle Ages in pharmaceutical remedies.

Part of the legend of Joan of Arc springs from the observation, documented in historical records, that some of her organs resisted the fire. Hundreds of pages of surviving manuscripts describe in vivid detail how she was burnt three times over to try to ensure that nothing but ash remained, and so prevent her remains being worshipped. The observation of remaining organs was interpreted as a miracle. But science has another explanation.

"In fact, it is very difficult to totally cremate a body; organs such as the heart and intestines, which have a high water content, are very resistant to fire," said Charlier. "We see it all the time in forensics."

The church is ready to accept the results, according to Charlier.

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