I was a member of that UK Chemistry Set generation, who had the (good?) fortune to be taught by the original mad scientist. He was always willing to allow us to perform experiments with a hefty boom in the tail, culminating with producing almost industrial quantities of Ammonium Tri-iodide.

Produced as a wet paste and spread on sheets of paper, once it dries it is as unstable as an inverted pyramid, exploding if you scratch the surface lightly with a fingernail.

We took six A4 sheets, still wet, and wadded them into the lock keepers of six classroom doors which we carefully left open. After assembly the following morning we trooped into our classes and the teachers, last in, closed the doors, turning six latches into firing pins.

There were six unexpectedly loud bangs and six door locks landed in the middle of the classroom floors.

Chaos ensued, followed by swift and effective retribution. Dinner was consumed standing,.........oh, but it was worth it.

Don T.