Abd ul-Rahman Lomax wrote:
A stoichiometric mixture of hydrogen and oxygen gas at room temperature the mixture is stable, the gases do not combine. However, given an ignition source, the mixture will rapidly combine (if it's dense enough). It explodes.
As I said, with ordinary palladium hydride exposed to air, the palladium acts as a catalyst and causes the emerging gas to ignite. It does not explode; it glows.
To stop the reaction with the cigarette lighter, they simply covered it up. I assume the gas kept leaking out, under the cover, but there was no air so it did not ignite. Not sure I would want to carry around something like that, but people used to carry "Lucifer" strike-anywhere wooden matches that would occasionally rub together and ignite. That's not what you want rubbing together in your pants pocket.
I think they formed the hydride in those cigarette lighters by exposing them to high pressure hydrogen gas, which would only achieve low loading.
I have not seen a photo or detailed description of a German palladium cigarette lighters. I did a very rough estimate of the amount of palladium needed simply by making some assumptions: they wanted a lighter that had roughly as many lights as a book of matches; loading was low from gas only (maybe 30%); they wanted it small enough to fit in a pocket; and they did not want it to cost too much. Palladium has always been expensive. Anyway, I figure that takes something like 30 to 100 g of palladium.
- Jed
