Want to know why the sky is blue during the daytime and red during the evening and morning? A simple experiment is all that is needed. The ingredients required for the experiment are simply hydrochloric acid solution, sodium thiosulphate, a torch which produces white light, water and a few beakers and tubes. By carefully adding measured quantities of the chemicals above in water to form a suspension of sulphur particles, and then focusing the white light through the mixture at proper angles, a blue sky like effect can be produced. The principle behind this experiment is simply the way in which light is scattered by the constituent particles of the mixture.