How to stop an ice cube melting?
Apart from putting it in the freezer you can insulate it or put it somewhere where it is below 0°C. Alternatively you can do the following (if you have a second cube at your disposal: Take the other one and smash it to small bits. Then mix it with water (cold water works well) and add salt. Stir this and cover it with plastic foil. Then press the icecube to be preserved gently into the ice-water-salt solution through the plastic (not to have the water touch the cube!!). The solution should cool to well below 0°C and thus chilling the cube. It won’t keep it cold ferever but should save you an afternoon.
