Leg press, deadlifts, RDLs, lunges, leg extensions, leg curls, hack squats, split squats. All those will hit your legs, plus there variations. Do some sprints, run hills, stairs, those will hit your legs. Im sure there are more lifts I can't think of this second as well.
While natural gas occurs in nature as a mixture of methane and other gases, propane is actually a byproduct of both petroleum refining and natural gas processing.
something to be aware of when switching from one to the other is that natural gas burns hotter than propane. If you are used to cooking with gas, you will that water, for instance, will take longer to boil on a propane burner than on a natural gas stove burner.