Colloid chemistry at the coffee shop

Tired after your walk, you head for a coffee and doughnut. This introduces us to colloids, tiny particles of one substance (gas, liquid or solid - the disperse phase) suspended (or floating) in another (the continuous phase - gas, liquid or solid). All combinations are possible, except gas in gas, eight in all. Colloids account for a surprisingly high proportion of the substances we come across in everyday life, as a visit to a coffee shop demonstrates.