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.
When used for heating or cooking, most people cannot tell much difference between propane and natural gas. Some barbecue enthusiasts prefer natural gas because it is a cleaner burning fuel, meaning that it doesn't release as many pollutants into the air.