<a class="mw-redirect" href="https://en.wikipedia.org/wiki/Timeline_of_chemical_element_discoveries" id="mwdQ" rel="mw:WikiLink" title="Timeline of chemical element discoveries">Discovery of the chemical elements</a>: Sir <a href="https://en.wikipedia.org/wiki/William_Crookes" id="mwdg" rel="mw:WikiLink" title="William Crookes">William Crookes</a> announces his discovery of <a href="https://en.wikipedia.org/wiki/Thallium" id="mwdw" rel="mw:WikiLink" title="Thallium">thallium</a>.