Sparks are flying. And things are sizzling and flaring up, sending out acrid chemical smells and huge plumes of thick, dark smoke bubbling up like mushrooms. Every now and then, a huge boom makes students jump. You never realise just how many things blow up until you go to John Conkling’s seminar, the Chemistry of Pyrotechnics and Explosives, held every year at Washington College in Chestertown, Maryland, for the past 27 years. A scholar specialising in pyrotechnics, every summer he offers a crash course in the chemistry behind explosions.

It’s for the growing number of people who regulate, control, invent or use volatile materials, including police officers, soldiers and technicians who design fireworks displays. In the lab, students see how to make flames white, red, yellow, blue, even such subtle shades as peach and honeydew melon. They learn how to create thick smoke, ash that squirms and writhes and coils up like a snake, or a quick, brilliant burst of light.

Conkling got into this by accident. He was doing research in organic chemistry at Washington College, where he now teaches, then at Johns Hopkins University, when he realised that studying pyrotechnics could be a lot more fun. Conkling has studied propellants and explosives, but most of his work has been in pyrotechnics, in which the reactions are designed to produce coloured lights, smoke and other effects, either for entertainment such as fireworks, or for defense purposes such as flares. And his speciality has been sensitivity—what sets off a reaction, which could be anything from a heavy impact such as a blow from a hammer to the slightest tap of a finger, or friction or flame, depending on the chemicals involved. His findings have often been used to make the manufacture, transport and use of the materials safer.

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