This episode sponsored by Audible.com Special offer to podictionary listeners: a free audio book and free use of the Audible service for 14 days. In the latter half of the 1700s this guy Antoine Lavoisier had this theory.  He figured that heat was a physical property, a material substance, like water. His thinking was something along the lines that if you take a bowl of water and an empty bowl beside it, and connect the two with a tube, the water will flow from one bowl into the other until they have the same levels of water in each. Similarly, if you take a cold egg and put it in hot water, the water cools down a little, and the egg warms up.  Or alternately if you take a red hot rock and drop it in a pot of cold water, it heats the water up while the stone cools down. Today we know this is wrongheaded as a theory, but Lavoisier was a leading scientific thinker and it took a little while to figure out the holes in his theory. But in the meantime the theory had to have a name and the name it got was caloric because Lavoisier named this invisible substance that flowed heat back and forth between bodies caloric after the Latin word for “heat” calorem. The Romans got calorem from some predecessor language themselves because it’s Indo-European root is kela meaning warm. Yesterday I re-posted the very first podictionary episode on the word chauffeur which is also a word that ultimately traces back to this Indo-European root kela. As you might guess Lavoisier was French and so it took Charles Darwin’s grampa Erasmus Darwin to bring the word caloric into English in 1791. This becomes a truly international story since to break the back of the caloric theory it took an American who was a British loyalist and had run away to Germany after the American Revolution. Benjamin Thompson was working at a cannon factory in Germany and he noticed that although the huge chunk of brass that made up a cannon was cold before its barrel was bored out—and so was the bit used to bore it—things seemed to get damn hot during the proceedings. According to the theory of caloric, where heat must be flowing from one place to another, this was impossible. And yet things sure did get hot when all that grinding was going on. Clearly the theory was wrong. In 1798, only seven years after the word caloric found its way into English Thompson published his study and killed the caloric theory. But a word that has been associated with heat for so very long, doesn’t burn out easily. Scientists needed names for the things they were discovering.  Now that they figured heat was another form of energy, instead of some fluid, they also found that a consistent quantity of heat was needed to raise a certain mass of water one degree centigrade.  So they pasted this unit with the name calorie . And yet the calorie is still oh so misunderstood. People concerned about their waistlines count calories but because a real calorie is a pretty tiny little amount of heat, the calories people do calculations on with respect to food are usually kilocalories; that is one thousand calories. People just can’t get up the energy to say the whole word and so have adopted a convention of inaccurately calling food energy calories even though that’s only one tenth of one percent of what they mean. Less