The Curies Announced the Discovery of Radium

In 1898, Marie and Pierre Curie were working through tonnes of pitchblende, a uranium ore from the mines of Bohemia. The ore was far more radioactive than its uranium content alone could explain, which convinced them that unknown elements were hiding inside it. After isolating the earlier element polonium, they kept chasing a second, even more intense source of radiation.

On 26 December 1898, assisted by the chemist Gustave Bémont, they presented a note to the French Academy of Sciences describing a new, strongly radioactive substance in pitchblende. Because it glowed with activity hundreds of times stronger than uranium, they proposed the name radium, from the Latin word for ray.

They had named the element before they had ever held a visible speck of it.

At the announcement they had only chemical evidence, not pure radium. It took until 1902 to extract a tiny, weighable sample of radium chloride, proving the element was real and earning the Curies a lasting place in the history of radioactivity.