Exploding Salt
Quote
If a small quantity of powdered charcoal and hyper-oxy-muriate of potash1 be rubbed together in a mortar, an explosion will be produced, and the charcoal inflamed. Three parts of this salt, and one of sulphur, rubbed together in a mortar, produce a violent detonation. If struck with a hammer on an anvil, there is an explosion like the report of a pistol.
When concentrated sulphuric acid is poured upon this salt, there is a considerable explosion; it is thrown about to a great distance, sometimes with a red flame; and there is exhaled a brown vapour, accompanied with a strong odour.>
— Endless Amusement; a Collection of Entertaining Experiments in Various Branches of Science (1820) Thomas Boys, London source
When mixed and ignited, the potassium chlorate decomposes to release oxygen. The carbon in the charcoal reacts with this oxygen to form carbon dioxide (CO2) and release heat.
4KClO3+3C→4KCl+3CO2
Extremely sensitive to heat, friction, and impact. Can ignite spontaneously. Highly exothermic. May contain nuts.