Rudolf Clausius (1822 - 1888) Germany
He was Professor of Physics at Berlin (1850), Zurich (1855), Wurzburg (1867) and Bonn (1869). He worked with results of Joule and Carnot and in an 1865 paper stated the First Law of Thermodynamics and the Second Law of Thermodynamics.
1. The energy of the universe is constant.
2. The entropy of the universe tends to a maximum.
He developed the concept of entropy and coined the term entropy. Clausius-Clapeyron equation expresses P and T relation for solids or liquids in equilibrium with vapor. With Maxwell, he developed the kinetic theory of gases.