Hi there, This could be absolute nonsense but I just got thinking about this. Say you had a certain metal into which a quantity of hydrogen had diffused, and then you placed it in communication with another hydrogen-free metal (say, titanium), would it be possible that the hydrogen would move into the titanium metal, out of the other metal? Coming from a a biology background I was thinking about osmosis (well, any concentration gradient-type process) - does the same apply to gases in metals i.e. would an equilibrium be reached? Or is there no driving force created by the "empty" metal? Any ideas would be appreciated, thanks!