Fireworks. Multi-coloured aerial firework display at night over Tower Bridge (at centre) in London, Great Britain. Fireworks consist of an inflammable substance, such as charcoal or sulphur, mixed with an oxygen-giving chemical, such as potassium chlorate or perchlorate. This combination leads to a very vigorous combustion which leads to an explosion. The colours of the firework explosions can be altered by adding various metals; these burn with a particular light. Tower Bridge was built during 1886-94 and, because of its distinctive shape, has become a major tourist attraction.