The origin of cryogenics can be traced back to 1714 when Gabriel Fahrenheit invented the
Fahrenheit scale, which was based on a process of reaching temperatures slightly lower than 0
degrees Fahrenheit (called cryohydrate). This process involved mixing ice with rock salt (which
eventually led to the mixing of ice and calcium chloride), which produced temperatures as low
as -67 degrees Fahrenheit ("Cryogenics" 1970).