Calories (15 °C, NBS 1939)
Abbreviation/Symbol:
cal(NBS)
Worldwide use:
As part of the metric system but not an SI unit, calories still have widespread use but are being superceded by the Joule
Definition:
The National Bureau of Standards (NBS, now known as The National Institute of Standards and Technology) defined the cal15 as being the ammount of energy needed to warm 1g of water from 14.5°C to 15.5°C
Origin:
The calorie was defined in 1824 by Nicolas Clément as a unit of heat. It is a metric unit that has been superceeded in the SI units by the Joule