Hold the bottom end of a test tube full of cold water in your hand. Heat the

Question:

Hold the bottom end of a test tube full of cold water in your hand. Heat the top part in a flame until the water boils. That you can still hold the bottom shows that water (as well as glass) is a poor conductor of heat. This is even more dramatic when you wedge chunks of ice with steel wool at the bottom; then the water above can be brought to a boil without melting the ice! Try it and see.

Boiling water Steel wool Ice