But what if you want to preserve something, such as milk, that will not keep for a long time and does not lend itself to one of these methods? Or what if you have some food you want to store for a short time, or you don’t have the time or materials to dry it, smoke it, cure it, or salt it? What will you do then? You’ll just put it in the refrigerator!

Early refrigerators were similar to today’s ice chests. People would mine ice and snow in the mountains, transport it to their locations, and place it either in a cave or in an underground chamber. Often, they would line the location with straw before putting the ice and snow in. This would insulate it and make the ice and snow last longer. These storage locations were the first “refrigerators.”

The World of Mechanical Refrigeration

Hauling ice and snow into caves and underground chambers is great if you have the ice and snow to bring in, but that is not the case in all places. People began to look at ways to create “cold.” This area of study falls under the discipline of mechanical engineering and is called “thermodynamics.” The term “thermo” means heat, and the term “dynamics” means motion. Thermodynamics is the study of controlling the motion of heat.

Scientists understood that heat was a form of energy. The more energy something had, the more heat it generated. In order for something to become cold, it must lose some of its energy. Refrigeration, as it turns out, is not a matter of creating cold, but rather of taking away heat. It is a thermodynamic process. The heat moves from one object to another. The first object gets colder, while the second object gets hotter.

God built a refrigeration system into each one of us. It’s called “sweat.” When we sweat, beads of perspiration build up on our bodies. Here’s the ingenious part: When the sweat evaporates off of our skin, it causes heat to transfer from our bodies into the atmosphere! Sweating is a thermodynamic process.

Scientists began experimenting with ways to control evaporation. They learned that there were some materials that, when properly controlled, could move a lot of heat, resulting in a lot of cooling. This led to early refrigerating devices. A classic example, which was used into the early 1900s and still shows up on occasion at flea markets, is called the “Icy Ball.”

The Icy Ball was invented in the early 20th century as an affordable refrigeration system for the average household. It used two metal spheres connected by an inverted, U-shaped metal tube. One of the spheres was called the “cold” side, and the other was called the “hot” side. The Icy Ball worked on a principle known as “gas-absorption.” It had no moving parts and required no electricity! Here’s how it worked.