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,
Diseases and epidemics of the 19th century and Robert Koch's discovery of micro-organisms as the cause of disease transmission. Thus throughout the majority of the 19th century, there was only the most basic, common sense understanding of the causes, amelioration and treatment of epidemic disease. The late 19th century was the beginning of widespread use of vaccines. The cholera bacterium was isolated in 1854 by Italian anatomist Filippo Pacini, and a vaccine, the first to immunize humans against a bacterial disease, was developed by Spanish physician Jaume Ferran i Clua in 1885, and by Russian-Jewish bacteriologist Waldemar Haffkine in July 1892. Antibiotic drugs did not appear until