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.
Never attempt to connect a gas appliance to the wrong type of gas, as it can be extremely hazardous. A bit of background information is helpful. There are two main differences in the way that LPG (Propane) and natural gas (Methane) are burnt. They Have a Different Energy Content.