Explosive s or combustibles used for display.
Of ancient Chinese origin, fireworks evidently developed out of military rockets and explosive missiles and accompanied the spread of military explosives westward to Europe in the Middle Ages. In force-and-spark compositions, potassium nitrate, sulfur, and ground charcoal are used; additional ingredients produce various types of sparks. In flame compositions, such as the stars that shoot out of rockets, potassium nitrate, salts of antimony, and sulfur may be used; for coloured fire, potassium chlorate or perchlorate is combined with a metal salt that determines the colour. Rockets are lifted by recoil from the jet of fire thrown out by the burning composition.