It will be useless, may endanger the environment, cause global warming and kill whales. I will take it off your hands for a small fee and ensure it is properly disposed of in accordance with my own local H&S regs.
I bought a large tin in the 1980s from a Ironmonger who was selling up, how long it had been in stock before that I wouldn't know but it still does the job.
What can happen after some years is that the tin can totally rusts away. My stock (bought 19-umpteen) is now in a plastic can., and works like on day one.