There are businesses that make all sorts of gasses into liquids. A
machine similar to an air conditioner is used to cool air until it
becomes a liquid. Look at the question about making liquid nitrogen for
more details.
Liquid Oxygen is used in rockets, liquid Helium
and liquid Nitrogen are used in a variety of experiments. Liquid
Nitrogen as it expands can even be used to power cars!
When
someone needs a liquid, they can buy it from one of the places that
makes it. Because liquids that cold can be dangerous, we have to have
permission to buy it.
EJ
(published on 10/22/2007)
