@bms, You got me curious and I got these quotes from the US Patent and Trademark Office. I don't think this would apply in this case. This one would apply. Apparently, gas has the energy required. I had always thought that to have a patent, an item must be functional or as they say 'useful'. I guess, without thinking about it, that is what made me think "it functions!? and they gave it a patent!!"DL Put your thinking caps on and start inventing! Bring your ideas to my office at 'Dewey, Cheatham and Howe' and I will file your patent application for you. (yeah, yeah, I stole it from the 'Three Stooges')