When I was a kid we would ball up a bunch of aluminum foil balls, put them in a pop bottle, pour in some "The works" cleaner which as hydrogen chloride water and some surfactants. Screw the lid in and watch as the bottle gre taller and taller, eventually going BOOOM!!! MY UNDERSTANDING is h+ Cl- (+) al= AlCl(aluminum chloride) + H(gas) why does no one make hydrogen gas this way? It seems like the easiest way. All OTC. Simple, available every where, efficacious...