Bleached rose

A piece of sulphur is ignited in a jam jar. Since a pungent vapour is produced, you should do the experiment out of doors. Hold a red rose in the jar. The colour of the flower becomes visibly paler until it is white.
When sulphur is burned, sulphur dioxide is formed. As well as its germicidal action in sterilisation, the gas has a bleaching effect, and the dye of the flower is destroyed by it. Sulphur dioxide also destroys the chlorophyll of plants, which explains their poor growth in industrial areas, where the gas pollutes the air.