Argon was discovered in 1894 by Lord Rayleigh and William Ramsey by the fractional distillation of liquid air. Their experiments confirmed English scientist Henry Cavendish's prediction of argon 200 years earlier.
Experimenting with the removal of nitrogen and oxygen from air, Henry Cavendish noted that a small amount of air remained. He was unable to identify the remaining gas due to a lack of appropriate equipment. With the invention of spectroscopy, Ramsey and Rayleigh were able to study this gas. Upon inspection they observed the gas was different from any other known element. The gas was unable to react with anything. Rayleigh and Ramsey called this new element argon and categorized it as a noble gas. A whole new group was added to the periodic table to accommodate the properties of noble gases. Discovery of argon led to the discovery of five other noble gases within the next five years. In addition to argon, the noble gases include helium, krypton, neon, radon and xenon.
Argon is colorless, odorless and tasteless. It comprises about 0.93 percent of the Earth's atmosphere and can also be found in small amounts in the Earth's crust. Because argon is inert, it is used as an insulator to protect materials from contact with oxygen and other gases.