At one time I was confused by the fact that temperature increased resistance, since in almost all chemical applications where molecules bond, heat is considered a catalyst.
Then someone explained that it was merely a matter of the atoms getting farther and farther apart from expansion as they heated, thus making the "gap" the electron was required to jump larger and, therefore, increased the resistance.
I guess this could be taken one step further to the point that the atomic structure expands to the point the molecules no longer bond adequately, and go from a rigid state to a molten one.
....or maybe not
[This message has been edited by WFO (edited 03-01-2006).]