From the Telegraph:
The mistress of France's 16th century King Henry II was poisoned by a gold elixir she drank to keep herself looking young, scientists have discovered.
Diane de Poitiers was renowned for her youthful looks and porcelain skin and thought the concoction preserved her youth.
Experts say she was up to 20 years older than the king but her appearance made them look the same age. One courtier said she was "as fresh and lovable" in her final years as when aged 30 and had skin "of great whiteness".
But her secret was the elixir she drunk every day made up of gold chloride and diethyl ether.
The breakthrough came when they [the scientists] studied locks of her hair kept at the chateau d'Anet: these were found to contain gold 500 times above normal levels, as well as mercury – used as a "purifier" in the elixir.