Today, that is, on the 26th of December, Marie Curie, her husband Pierre, and Gustavé Bemont announced in the Comptes rendus de l’Académie des Sciences in 1898 that they discovered a new element which they proposed to name radium.
Nowadays, an isotope of radium is of medical use against metastatic bone cancer, relying on the isotope’s release of helium nuclei (so-called α-decay) which destroy cells within a relatively small volume of tissue.
An English translation of the original article is available online. The original can be read here (pp. 1215-1217):