William Ramsay

William Ramsay was a Scottish chemist born on October 2, 1852. He is best known for discovering the noble gases. In 1892, Ramsay, working with Lord Rayleigh, noticed that the nitrogen that was extracted from the air was denser than nitrogen released during different chemical reactions. He was able to identify this unknown gas that seemed to be mixed with nitrogen as being argon. While working to isolate argon from various minerals, he stumbled upon helium, which, at the time, was thought to only exist on the sun. From there, he was able to methodically discover the rest of the nobel gasses including xenon, neon, and krypton. For his work in discovering the nobel gasses, Ramsay was awarded the Nobel Prize in 1904.

http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1904/ramsay-bio.html

https://www.chemheritage.org/historical-profile/william-ramsay