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The resulting release of carbon dioxide is fed to an accelerator mass spectrometer, which measures the decay of radioactive carbon 14the more the carbon 14 has decayed, the older the object is.Over the past 20 years, chemist Marvin Rowe of Texas A&M University has developed a nondestructive method for carbon dioxide extraction.Thus far, hes dated samples of wood, charcoal, animal skin, bone from a mummy, and ostrich eggshell. Taylor, a radiocarbon expert at the University of California, Riverside, says Rowes technique may have limitations, as items older than 10,000 years will have impurities that the technique may not be able to purge.Everything so far that weve tried to do with the nondestructive technique has agreed statistically with regular radiocarbon dating, Rowe says, and you basically dont see any change in the sample. Archaeologists, meanwhile, are hailing the discovery as one of the most important in decades, particularly for issues surrounding the repatriation of human remains from Native American burials, which modern tribes dont want to see harmed.The results will force historians to revise their records for the two millennia when ancient Egypt dominated the Mediterranean world and hopefully end debate once and for all between rival Egyptologists.Led by Professor Christopher Ramsey of Britain's Oxford University, an international team tested seeds, baskets, textiles, plant stems and fruit obtained from museums in the United States and Europe for the landmark study.landmark "For the first time, radiocarbon dating has become precise enough to constrain the history of ancient Egypt to very specific dates," said Ramsey.Precisely dating archaeological artifacts is not as easy or harmless as it might seem.The most common method, radiocarbon dating, requires that a piece of an organic object be destroyedwashed with a strong acid and base at high temperature to remove impurities, and then set aflame.
Willard Libby tested during the radiocarbon dating development process was this wood from an ancient Egyptian coffin.
Other corrections must be made to account for the proportion of throughout the biosphere (reservoir effects).
Additional complications come from the burning of fossil fuels such as coal and oil, and from the above-ground nuclear tests done in the 1950s and 1960s.
Its essentially like slowly burning the sample, so we can just oxidize a little off the surface and collect that carbon dioxide, explains Rowe.
This year he further refined the method so it will work on objects coated in sticky hydrocarbons, such as the resins that cover Egyptian mummy gauze.
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The method was developed by Willard Libby in the late 1940s and soon became a standard tool for archaeologists.