Water freezes and ice melts at the same point, 32° F., or 0° C. If ice is mixed with salt, the temperature is reduced far below the freezing point, nearly to 0° F. This process reduces any watery substance which it surrounds to its freezing point, the heat being used in the melting of the ice. This is an interesting topic to discuss in the Physics class.

Ice at its ordinary temperature of 32° F. is used for cooling food agreeably. Its most important function in the refrigerator is as preserver of food for a short time at least. For this it is invaluable, and cheap ice is really necessary in summer to the health of a great city.