[outofsalt]

I Cuba we buried our milk cans in the ground and it kept for a week. Under ground storage will keep things cool even in very warm areas.

[MrB]

A pioneer trick was to put a silver dollar in the milk can - the silver is a natural anti-biotic and preserved the milk longer.

[JDW11235]

Don’t forget the “Pot-in-pot” technology used for thousands of years. Basically it is two terra cotta pots, one smaller that the other. You take the big pot, put in the small pot, and fall the space between the two with sand. Then you wet the sand, soak a towel and drape it over the pot (it may need re-wetting at some point). You can get the temperature to dip down into the 40’s in the right conditions. It’s also called a “Zeer.” Although it’s noteworthy, that you get more of a cooling effect the hotter and dryer a climate is, but also, that there is a maximum cooling effect that can be reached by evaporation. (Like evaporative coolers/swamp coolers, can only cool air about 30-40º before becoming ineffective.)

Here’s a wiki page for it:

http://en.wikipedia.org/wiki/Pot-in-pot_refrigerator

And a video:

http://www.youtube.com/watch?v=LfKgOpJc7Ps&feature=related