When did Rudolf Clausius introduce the second law of thermodynamics?
Theory of heat:  Over the next century, with the introduction of the second law of thermodynamics in 1850 by Rudolf Clausius, this theory evolved into the science of thermodynamics. Rudolf Clausius:  His most important paper, "On the Moving Force of Heat", published in 1850, first stated the basic ideas of the second law of thermodynamics.
1850