A chemical wave was initiated in a system (test tube) containing an aqueous gel of potassium iodide and starch by carefully pouring an excess of bleaching solution (aqueous solution of sodium hypochlorite) over it. A blue disk is formed immediately at the boundary surface, which propagates slowly downwards. Photos (a total of 240) were taken with a digital camera (one snapshot every 20 s), and they were linked to give a video clip that may be used as a time-saving alternative to the classical demonstration.
Petruševski et al. (Thu,) studied this question.