Prepare to be amazed as this 1937 newsreel clip shows California consulting engineer Otto H. Mohr demonstrating how he was able to make ice cubes in only two hours’ time without electricity. Requiring only conventional mechanical parts, Mohr’s apparatus boils ammonia, then allows it to evaporate through coiled tubes as it returns to its tank. The process creates the cooling effect still used in refrigerators today.
Unlike solar panels, which require constant turning to maximize sun exposure, Mohr’s refrigerator uses the arcing shape of a crystal ball to capture the sun’s rays at all times of the day for channeling solar radiation into the ammonia tank. Inside the cabinet, ammonia rises in the evaporation coils, sucking heat out of the air, cooling food and drinks, and making it possible for water to freeze in a box under the hot summer sun. It’s wild to think of this technology being around in 1937!