The brilliant white, sparkling yellow, glowing red and the shimmering blue colours in the fireworks that brighten up a Diwali evening are produced by metals or metal salts present in the fireworks. Metals have the property of emitting light of a particular colour while they burn. For instance, when sodium or its salts burn, yellow light is given out. Similarly, on burning, finely divided aluminium gives out bright white light. Strontium salts give out red colour while copper and barium salts produce intense blue and green colours respectively. Fireworks manufacturers make use of this property of metals and their salts and use them in various combinations in crackers to produce spectacular fireworks display.
