Resumo

WISNIAK, Jaime. Conservation of Energy: Readings on the Origins of the First Law of Thermodynamics. Part II. Educ. quím [online]. 2008, vol.19, n.3, pp.216-225. ISSN 0187-893X.

In this second part on the history of the development of the first law of thermodynamics, we describe the contributions of the four principal scientists, Colding, Mayer, Joule, and Helmholtz, which provided the statement of the principle of conservation of energy, as we know it today. In the first part of this paper (Wisniak, 2008) we discussed the general concepts behind the principle of conservation of energy and the impossibility of constructing a perpetuum mobile. We also gave a description of the historical issues that led to the situation that by the end of the first quarter of the nineteenth century the interchangeability between the different forms of mechanical energy, and the equivalence of heat and mechanical work, were already becoming accepted concepts. In the short period between 1840 and 1850 the experimental evidence was ripe enough for the declaration of the general law of conservation of energy. The hypothesis of energy conservation was publicly announced in different forms by four widely scattered European scientists, Ludvig August Colding (1815-1888), Julius Lothar Mayer (1830-1895), James Prescott Joule (1818-1889), and Hermann Ludwig von Helmholtz (1821-1894), all but the last working in complete ignorance of the other (Kuhn, 1959). We will now continue to study of the ideas that culminated in the statement of the first law of thermodynamics, as we know it today.

Palavras-chave : Heat equivalent; conservation of energy; Colding; Mayer; Joule; Helmholtz.

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