The Secret to Making Ice Cream in the 17th Century

It is unclear who first served ice cream. There are stories about the Roman emperor Nero and Catherine de Medici serving frozen treats, but the first confirmed mention of ice cream was in an account of a feast hosted by English king Charles II in 1671.

The ice cream was flavored with orange blossom. Legend has it that Charles paid the person who made it an annual stipend to keep the recipe a secret. However, the secret was out by the 1680s, when the Grace Countess Granville wrote it down. Orange blossom was the only flavor of ice cream available until the end of the 17th century, when other flavors, including chocolate, lemon, and pumpkin, were introduced.

When making ice cream at home, the secret is to mix salt with ice and add a container filled with cream, eggs, sugar, and flavoring. When the salt mixes with the ice, a chemical reaction lowers the ice’s freezing point. That is the same reason why salt is put on roads in the winter. Ice needs energy from heat to return to a liquid state. It gets that heat from the ice around it and from the cream mixture.

People who made ice cream in the 1600s were not aware of this property of salt. They used saltpeter to lower the temperature of the mixture. Saltpeter was used to make fireworks and gunpowder. It is unclear how people learned about saltpeter’s ability to lower another material’s freezing point.

In 1558, an Italian scholar and playwright named Giambattista della Porta published “Natural Magick,” a book in which he recommended mixing saltpeter and ice and dipping a vial of watered wine in the mixture to create something similar to a wine slushie. The secret spread, and it eventually came to be used to make ice cream for royalty.