The conductor of the electric power in a tube or discharge lamp is a gas. The first lamp of this kind, made at the beginning of last century, used carbon dioxide or nitrogen. As they were non inert gasses, the tube was empaty in a few weeks, due to the fact that in the excited atmosphere of the luminous tube these were combined with lamp materials, which for the lack of an electric power conductor faded away.
Neon appears when, in 1910, Gorge Claude

used it to enlighten a sign in Paris, which

ha already been done using carbon dioxide. ...