I recently bought one of those model steam engines, which came with a box of fuel tablets which I can't figure out how to light. I've put them over my cigarette lighter until they snap, crackle, and pop but they just won't catch and my engine won't go. How do you light these things? The box describes the substance of the tablets as Methenamine, and it gives a warning that says they're "highly flammable". Yeah, I wish!