by Janice Willson
Who doesn’t love bubbles? We made the liquid to form these bubbles with water, dish soap, and glycerin with food colouring added for effect. I love the rainbow of colour that is formed on the surface of the bubbles and is constantly moving and changing. These “rainbows” are an optical property caused by the soap molecules rushing around to fill in thin spots on the bubble surface and keep the tension at the surface in equilibrium – it is known as the Marangoni effect.