The Zeer pot is an African cooling gadget which, for less than $2US in local materials and without electricity, can extend the storage lifetime of fresh produce by as much as 18 days. It is of staggeringly simple design: Two clay pots are nested with a relatively thin layer of sand between them. The sand […]
The Crosley IcyBall (wikipedia) is a commercial early-twentieth century portable chemical refrigerator that runs without moving parts or electricity. Cooling is caused by the evaporation and re-adsorption of ammonia into a water-based solution, which is a spontaneous process that can be reversed by applying heat, as from a campfire. Authentic IcyBalls are valuable antiques, but […]
