The Caloric Theory of Heat and Carnot's Principle

Abstract

that so small a quantity of powder could not possibly account for all the heat generated, and that the supply of heat appeared to be inexhaustible.Heat could not, therefore, be a material substance, but must be something of the nature of motion, as Newton and Bacon had surmised.The argument was not quite conclusive, because he was unable t o show that the powder really contained the same total amount of heat as the solid metal.But the experiments must have satisfied every reasonable philosopher of the extreme improbability of the explanation then generally accepted.Davy's experiment (described in a n essay " On Heat, Light and Combinations of Light," 1799), in which he melted two blocks of ice by rubbing them together, was more conclusive, since as he remarks " it is a well-known fact that the capacity of water for heat is greater than that of ice, and ice must have an absolute quantity of heat imparted to it before it can be converted into water.Friction consequently does not diminish the capacities of bodies for heat."In stigmatising the " last eleven words " as " a lame and impotent conclusion," Lord Kelvin (Ency.Brit., ' $ Heat," 1882) inadvertently does Davy an injustice, because Davy evidently uses the phrase '( capacity for heat " in both