Sodium Chloride

[Robert_Brenchley]

You could have done worse with it. We used to fill lengths of pipe with a chlorate/sugar mix, bury them, and let them off. The craters were most impressive. These days half the class would probably be spirited off to some torture chamber in Afghanistan, but back then, the worst that happened was a visit from a constable inquiring about mysterious explosions in the school shrubbery. That time it was thunderflashes, not chemistry experiments.

[Robert_Brenchley]