The rare gases in the air include argon, helium, neon, krypton, and xenon. Like nitrogen, all these are inert gases. Formerly they were regarded merely as interesting substances or as scientific curiosities.
However, important commercial uses have been found for three of them. Helium is used in dirigible balloons. Nearly all the world’s present supply of this valuable gas is found in the United States.
Argon is used in the globes of electric lamps. Neon finds wide use in electric signs. It is thought that still further uses will be made of these gases.