The Gaming Den

I'm not quite sure to look for this, so I figured I'd ask here. How does one collect gases from the air and what not? I know we've been doing it since at least the 1870s but I'd like to know how it is and can be done, if possible. The closest I've seen is the entry for cryopumps on wikipedia so far, but I know we have chemists on here so I figured I'd check.

Also, what are some good books for learning chemistry? I know that's rather vague, but I didn't pay a huge amount of attention to it in school and would like to broaden my knowledge in that field. I mean, I find the idea of chemistry fascination in how compounds form and all that; it just boggles my mind so its something I want to learn.

Also related, anybody know how I can get some damn stirling engines? The US Government has them as a restricted device, which makes it awfully hard for me to buy some from the American companies. Yeah, it can be used for cryocooling but srsly, they're a really useful device. My searches online haven't given me much in results.

The basic answer is: it depends. The most simple to explain manner is simple cooling. The air is roughly 78% Nitrogen and 21% Oxygen. Oxygen condenses to a liquid at -183 degrees, Nitrogen at -196 degrees. Other compounds have similarly disparate condensation temperatures. Carbon Dioxide condenses at -78 degrees, Helium for all intents and purposes does not condense.

So if you cool a quantity of air, you'll get fluids at the bottom of your tank, which you can collect into bottles, which will then be pure substances.

-Username17

Hmm, sounds like an interesting process.

The Golden Book of Chemistry Experiments is amusing. I'm pretty sure it's out of copyright, so you can torrent it or something.

Could I get an explanation on why stirling engines are restricted and what exactly that means?

From what I can extract from the Matrix, a stirling engine is a type of high-efficiency heat engine invented to be safer and more efficient than a steam engine. It can accept pretty much any heat source, and runs on air (i.e. no exploding boilers).

Like electric motors, it can also be run in reverse and act as a heat difference "generator". And they can be used that way to make things super cold. Liquid nitrogen cold. If they're restricted, I'd presume it's because the government don't want random people able to make supercooled liquids at will. I'm not entirely clear on the specific things they're trying to avoid, but liquid nitrogen can mess things up pretty bad...

...and apparently some people in Taiwan are working on using them to power CPU fans off excess CPU heat. Huh.

Prak_Anima wrote:Could I get an explanation on why stirling engines are restricted and what exactly that means?

Stirling air engines are not banned. Stirling cryocoolers are banned. That's basically just a stirling engine in reverse - you apply mechanical work and heat leaves the system. Something about not wanting to give foreigners access to the ability to produce pure elements, on account of that being a key component in bomb making and techno-industrial advancement.

-Username17

Indeed. I want one for power generation and another for cooling, but yeah. Fucking export restrictions. Coleman had a stirling powered cooler, but it got taken off the market couple years ago.

That said, Japan sells them, but I think you have to be a company to buy anything, same with Sunpower (the patent holder for the Japanese company).

Heh, I can only imagine how much harder my entrance to the states will be if DHS finds out I'm after Stirling engines/coolers like that. I barely get in as it is...