Figure 36 is a photograph of a collection of 11 washing detergent capsules arranged in a small pile. Closer inspection reveals that there are only five different types. The main visual difference between these types is their colour. The capsules are clear so the coloration is due to the detergent they contain. One type of capsule has two colours arranged in a sort of Yin-Yang pattern that makes them stand out from the others. It looks like this capsule contains two different liquids that are kept in separate compartments within the capsule. It is not evident from the picture what the two colours or their pattern are meant to signify. The capsules also vary in size. The two colour capsule is the smallest and the largest is about twice its volume.