Supplies
-
Wide shallow dish
-
Full cream milk
-
Liquid food colouring (3-4 different colours)
-
Dishwashing liquid
Instructions
-
Pour enough milk into the dish so it covers the bottom and add 3-4 drops of each colour of food colouring to the milk.
-
Now add a drop or two of dishwashing liquid to the centre of the milk and watch as the colours swirl around and dance across the surface.
-
Eventually the swirling will slow down, and the colours will become mixed together.
The sciencey bit
Simply put, milk contains fat, and dishwashing liquid contains soap molecules that bond to fat. The swirling effect you see is caused by the water and food colouring being pushed out of the way as the fat and soap molecules bond together.