Mike_MC:
Well, what more can I say? Maybe, you’ve heard of liquid nitrogen, or liquid oxygen, just to name a few of the “liquefied gases” that are manufactured by compressing air? Just about all constituents of air, that have a commercial value, can be purchased as a “liquid”. Also, don’t be confused, I’m not at all talking about the moisture (aka water vapor) in the air, I’m only talking about the “gas” components. The water vapor must be removed before the liquefaction of the gas components can start or the water vapor will turn to ice and plug-up the equipment. Well, I’ll just have to let you live in your world while I live in mine.

But if you want more information go to AIR LIQUIDE (a French company) web site and you’ll see lots of liquefied gas products they produce and each come from the air you breath.

Miles.
PS I’m not trying to be contentious or argumentative, I spent a large portion of my 25 years as an engineer in the gas measurement and compression industry sometimes as a consultant and sometime as an in-insult-ant. Just joking about the last.