The most common use of a frigorific mixture is to melt ice. When salt is placed on ice when the ambient temperature is greater than −17.8 °C (0°F), then the salt melts some of the ice and the temperature drops to −17.8. Since the mixture is colder than the ambient, heat is absorbed and the temperature rises. This causes the salt to melt more of the ice to drive the temperature down again. The process continues until all of the salt is dissolved in the melted ice. If there is enough salt present, then all of the ice will be melted.

Frigorific mixture – Wikipedia, the free encyclopedia