Did Carnot use "caloric theory". Wikipedia asserts the following: "Though Carnot had developed a compelling analysis of a generalised heat engine, he had employed the clumsy and already unfashionable caloric theory." http://en.wikipedia.org/wiki/Benoît_Paul_Émile_Clapeyron Feynman (FLP Vol I, 44-1) asserts: "But it turned out that Clapeyron assumed, not the conservation of energy in general, but that heat was conserved according to caloric theory, which was later shown to be false. So it has often been said that Carnot's logic was wrong. But his logice was quite correct. Only Clapeyron's simplified version, that everybody read, was incorrect." I note that Feynman doesn't explicitly state that Carnot didn't use caloric theory, but he pretty clearly contradicts what Wikipedia asserts. So what's the real history here? Who did or did not use caloric theory?