• Brainly User
Wed February 19, 2014 The first person to actually isolate and note the presence of these noble gases was Henry Cavendish. He removed all the nitrogen and oxygen chemically from a receptacle containing air. The nitrogen was oxidised to NO2 by electric discharges and absorbed by a sodium hydroxide solution. Remaining oxygen was removed from the mixture by a special adsorber. 1/120 of the gas volume remained unreacted in the receptacle. As we know today, this must have been mainly argon (99.8%) and traces (0.2%) of other noble gases. Two reasons for late discoveries of noble gases are: 1. They are present in extremely low concentrations in our environment. 2. They are very inert.