Clausius, KLOW zee uhs, Rudolf Julius Emmanuel (1822-1888), a German physicist, helped establish thermodynamics as a science. In 1850, he stated the second law of thermodynamics: "Heat cannot of itself pass from a colder to a hotter body" (see Thermodynamics). He derived an equation that relates the saturated vapor pressure of a liquid to the temperature. He also developed a theory to explain electrolysis (see Electrolysis). Clausius was born in Koslin, Germany (now Koszalin, Poland).