The history of noble gases initiated in 1868. Pierre Jansen, a scientist, saw a bright yellow line during a solar eclipse. He thought it was sodium, but later it was identified as helium by William Crookes. The first isolation of noble gases happened in 1875, when Henry Cavendish removed nitrogen and oxygen form a sample of air, and the gases that were unaffected by this process.
lets take an seprated nitrogen and oxygen from gases left are argon,helium etc....(you dont know these are noble gases you only know there is some gases present) now tell me since they are chemically inert hou can you indentify them if they dont respond to any of your experiments....
They were first found in 1875 whn a scientist removed nitrogen and oxygen from a sample of air