How it is nice to drink something refreshing in a hot day. But this pleasure hides a danger. If temperature difference between a drink and an atmospheric air is quite large, you can catch a cold. So, it is riskily to chill a liquid in a refrigerator. An organism needs more comfortable temperature that differs from outside only on few degrees.
Dr. Ivan Myronyuk suggested solve this issue by dint of pottery. The idea is jug-fridge. The feature is that the special micro-cellular structure was created in the material. A liquid that is kept in a container permeates in a small amount via micro-pores on the outer surface, evaporates and in this way provides self-cooling. A temperature becomes on 3-5 degrees less than one outside. So, a drink gets a nice coolness and, in the same time, risks of cold are minimized.