Caloric versus Kinetic Caloric Theory of Heat: Heat is an invisible fluid called the “caloric” that flows between objects with different temperatures. The caloric naturally flowed from a hot object with a lot of it, to a cold object with only a little of it. The cold object expanded as it warmed because it had absorbed the invisible fluid. The caloric was first proposed by Antoine Lavoisier in the 1770s. (Lavoisier also proposed the conservation of mass and discovered that water was made from oxygen and hydrogen).

Caloric versus Kinetic Caloric Theory of Heat: Heat is an invisible fluid called the “caloric” that flows between objects with different temperatures. The caloric naturally flowed from a hot object with a lot of it, to a cold object with only a little of it. The cold object expanded as it warmed because it had absorbed the invisible fluid. Sadly, Lavoisier was also a shareholder in the company that collected taxes in Paris, and was executed during the French Revolution.

Caloric versus Kinetic Kinetic Theory of Heat: Heat is due to motions inside a material. An object with more internal motion is hotter than an object with less motion, and the “extra” motion can be transferred from the hot object to the cold object. Later, the motions were attributed to the atoms and molecules in the material. The kinetic theory of heat was supported by Benjamin Thompson, aka Count Rumford, who also invented the percolating coffeepot and a better stove.

Caloric versus Kinetic Kinetic Theory of Heat: Heat is due to motions inside a material. An object with more internal motion is hotter than an object with less motion, and the “extra” motion can be transferred from the hot object to the cold object. Later, the motions were attributed to the atoms and molecules in the material. Rumford is also credited with inventing thermal underwear in his quest to trap heat..

Caloric versus Kinetic Rumford Experiment: In 1798, Rumford did an experiment showing that the friction produced while boring a hole in a cannon with a dull bit produced enough heat to boil water — and the heat never ran out. He concluded that heat could NOT be a substance. Even so, the caloric theory dominated science for another hundred years.