Nowadays we say that during the adiabatic expansion stage of the Carnot Cycle the internal energy due to the temperature of the gas gets transformed into work, but Carnot himself supported the caloric theory of heat, concieving that thermodynamic work could only be done by a "fall" of caloric from a body at one temperature to another body at a different temperature. How was adiabatic expansion seen from the caloric theory perspective? Thank you in advance for your time.
Some historians, e.g., La Mer, Truesdell, etc., argue that the word "calorique" as used by Carnot is to be distinguished from the word "chaleur"; the word chute is never used as "chute de chaleur" but always used as "chute de calorique" so that is not "drop of heat" but rather "drop of entropy", see La Mer: "Some Current Misinterpretations of N. L. Sadi Carnot's Memoir and Cycle.", https://doi.org/10.1119/1.1933908, and then it makes sense. Not all historians agree with this interpretation of the historical events, though; see Kuhn: Carnot's Version of "Carnot's Cycle" https://doi.org/10.1119/1.1933907 and the ensuing debate in the same Journal.