What could be more common than the household refrigerator? It is the most-used appliance in America with more than 99.5% of homes having one. How did this come about, and what does heat treatment have to do with cooling things?
The process of keeping food cold by using evaporative cooling goes back to ancient times. The Romans used terra-cotta pots in water fanned by slaves to cool their food. Likewise, around 500 B.C. the Egyptians and Indians made ice on cold nights by setting water out in earthenware pots and keeping the pots wet. In relatively modern times, the icebox was used for about 150 years until the invention of the mechanical refrigerator in the late 1800s.