Pierre Curie and Marya Sklodowska Curie discover polonium and radium in 1898.

The French chemists, carrying out radiochemical analysis on a ton of pitchblende, a uranium ore from Joachimsthal, Bohemia, ascribe to a new element the very intense radioactivity not attributable to uranium.

Mme. Curie names the new element, the discovery of which is announced in July 1898, polonium for her native Poland.

It is the first element to be discovered by radiochemical analysis.

The Curies, and an assistant, G. Bélmont, discover radium in 1898 in the pitchblende, given them by Austria after the uranium salts have been removed for use in glass manufacture.

They have earlier found polonium in a similar sample.

Mme. Curie has earlier observed that the radioactivity of pitchblende is four or five times greater than that of the uranium it contains and not fully explained by the presence of radioactive polonium.

The new substance, powerfully radioactive, follows the behavior of barium, but because its chloride is slightly more insoluble, it can be concentrated by fractional crystallization.

Gerhard Carl Schmidt and, independently, Marie Curie, find the radioactivity of thorium in 1898.