Anyway, he said that he kept food cool in his cell by wrapping it in wet cloth. That doesn't specifically answer your question, and I don't even know how true it is. But I'm throwing it out there to see if anyone knows anything about this.
If you’re in a dry area the evaporation keeps it cool. People used to come here from California to buy green chile by the pick-up load and they covered it with gunny sacks and wet them regularly on the trip home and it was just like it was refrigerated.
I’ve heard about the wrapping stuff in a wet cloth before.
It makes sense. Evaporation is a cooling process.
Wrapping things in wet cloth cools it by the evaporative process.