19th century in science Carnot captured some of the ideas of thermodynamics in his discussion of the efficiency of an idealized engine. Sadi Carnot's work provided a basis for the formulation of the first law of thermodynamics—a restatement of the law of conservation of energy—which was stated around 1850 by William Thomson, later known as Lord Kelvin, and Rudolf Clausius. Lord Kelvin, who had extended the concept of absolute zero from gases to all substances in 1848, drew upon the engineering theory of Lazare Carnot, Sadi Carnot, and Émile Clapeyron–as well as the experimentation of James Prescott Joule on the interchangeability of mechanical, chemical,
Jim Crow laws early as 1892 in the title of a "New York Times" article about Louisiana requiring segregated railroad cars. The origin of the phrase "Jim Crow" has often been attributed to "Jump Jim Crow", a song-and-dance caricature of blacks performed by white actor Thomas D. Rice in blackface, which first surfaced in 1832 and was used to satirize Andrew Jackson's populist policies. As a result of Rice's fame, "Jim Crow" by 1838 had become a pejorative expression meaning "Negro". When southern legislatures passed laws of racial segregation directed against blacks at the end of the 19th century, these statutes became known