The DU Lounge

This leaves the bag of water at a lower temperature than ambient. It was what some folks did back in the last century... even though Glycol-based cooling fluid was commervcially available.

My experience with them:

We drove up to Mt. Palomar Observatory (above Los Angeles) with these unfilled "desert bags" in the trunk. Had to stop at a stream to fill them up when the motor started overheating. . It sort of worked. The car's motor overheated on the way up the mountain. It cooled down when we drove back down. I remember those Desert Bags draped over the radiator and the engine. It reminded me of the "Okies" in their jalopies as they migrated to California. You can see this in the movie, "The Grapes of Wrath."