When was argon discovered as a new element?

Argon was discovered in 1894 by Lord Rayleigh and William Ramsay. They found that nitrogen made from air was slightly denser than nitrogen produced from chemical compounds, which suggested that air contained an unknown component. That mysterious gas turned out to be argon, an inert noble gas that makes up about 0.93% of Earth’s atmosphere. Its discovery helped lead to the identification of the noble gases as a whole group.