It was a revolutionary device because rather than using expensive chemicals to produce electricity like ordinary batteries, it used common gases — oxygen and hydrogen — instead. (scientificamerican.com)
Common gas pains have two major causes, while a few other less common causes can also be the problem. (diaperjunction.com)
Maintenance anesthetic drugs or gases are numerous; however, the most common gas used in veterinary medicine is isoflourane. (texvetpets.org)