Liquid nitrogen cocktail in the preparation of frozen desserts, such as ice cream, which can be created within moments at the table because of the speed at which it cools food. Similarly, liquid nitrogen has become popular in the preparation of cocktails because it can be used to quickly chill glasses or freeze ingredients. It is also added to drinks to create a smoky effect, which is created by the cold nitrogen vapour (liquid nitrogen boils at -195.8 Celsius at normal atmospheric pressure) condensing the moisture (i.e., water vapor) in the surrounding air above. Because of its low temperature liquid nitrogen can be
Ice cream maker firm consistency. Some machines—such as certain lower-priced countertop models—require the resulting mixture to be frozen for additional time after churning is complete. Nancy Johnson patented the first hand-cranked model in 1843. She then sold the patent to William Young, who marketed the machine as the "Johnson Patent Ice-Cream Freezer". Hand-cranked machines' ice and salt mixture must be replenished to make a new batch of ice cream. Usually, rock salt is used. The salt causes the ice to melt and lowers the temperature in the process, below fresh water freezing, but the water does not freeze due to the salt content.