Calories (15°C,CIPM, 1950)
The calorie defined as CIPM, 1950 or the "15°C calorie" is a unit of energy that was historically used to quantify the amount of heat required to raise the temperature of one gram of water by one degree Celsius at 15°C. This definition was established by the International Committee for Weights and Measures (CIPM) in 1950.
Btu (I.T.)
The British Thermal Unit (International Table) is a unit of energy commonly used in the United States defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit at a constant pressure of one atmosphere.