The Dry Ice article was very informative and interesting. However, it still remains to be asked - how exactly is Dry Ice created? Do you simply take a bunch of CO2 floating around in a box and make it really cold - at which point it flashes into ice? What would an observer see as it was being made?
From this site:
Compress the CO2, remove excess heat, send through an expansion valve, then compress the flakes into a block.
Thanks for the reply, Ice Wolf. One thing about the explanation given at the site you recommend baffles me: how does absorption of heat by the evaporating liquid cause it to freeze? Generally, doesn’t the addition of heat do the opposite - that is, melt (or in this case sublimate) a substance?
I continue to harbour a vision of a room full of CO2 in which golf ball-sized chunks of ice materialize in thin air and fall to the ground. 
You can make your own dry ice from compressed CO[sub]2[/sub] in a tank with this device from Edmund Scientific.
mindputty, the outgassing CO2 is removing heat from the liquid part left behind. The standard evaporative chilling effect. Perhaps “absorbs heat” isn’t the best phrase the cited article could have used.
Aha. Gotcha. I was confused there for a while - I got hung up on the notion that dry ice is a solid gas. In actuality, it’s the compressed liquid that is changing into the solid ice flakes, not the evaporating gas, correct?
Could that ever happen? That is, a gas going directly to a solid state? That would be fascinating.
Gaseous CO[sub]2[/sub] will indeed go directly to a solid, at standard pressure and sufficiently low temperature. It’s just that the easiest way to get such temperatures involves pressurizing it first. If, say, you took a sealed container of gaseous CO[sub]2[/sub] (at STP) and dunked it into a resevoir of liquid nitrogen, the gas in the container would go directly to a solid. In this case, I imagine that it would deposit like frost on the walls of the container.
For that matter, I think that ordinary water frost is also an example of transition directly from gas to solid.