What is its composition?
Other compositions include #"town gas"# or #"coal gas"#, a mixture of #H_2# and #CO# which used to be used to fire gas cookers. So-called #"beer gas"#, a mixture of food-grade carbon-dioxide, and dinitrogen, is used in the hotel industry to dispense drinks.
There is also #"heliox"#, a dioxygen/helium gas mix that is used for deep-sea diving. I read here that this mix is currently being used (with some success!) for chronic asthma attack. Anaesthetists also probably have access to a range of specialty gas mixtures for their patients.
