AirProperties depends on ConstantProperties, but does nothing if you don't have it.

[aeslaughter]

AirProperties requires the use of properties defined in ConstantProperties but doesn't check that they exist. This check needs to be implemented in the constructor.

[aeslaughter]

All of the properties need to be wrapped up into a single Action that controls all of the materials from one location. This action should automatically create the ChemicalPotentialUserObject as well.