Nicolas Clément
Nicolas Clément (1779, Dijon - 1842) was a French physicist and
Clément married Desormes' daughter and adopted the family surname as Clément-Desormes. Clément himself spelled his first name Nicolas, not Nicholas.
Professor Clément held one of the first chairs in chemistry at the Conservatoire des Arts et Metiers in Paris. He taught a course in industrial chemistry that emphasized the thermodynamics of steam in relation to powering steam engines. In about 1819, he befriended Sadi Carnot[[2]], and the two men developed methods for calculating the maximum amount of energy that could be obtained from a kg of coal. Clément and Carnot clearly understood the concept of a mechanical equivalent of heat, and developed formulae for calculating energy efficiency almost 20 years before Mayer [[3]] and Joule's [[4]] work on this subject in the 1840's[[5]]. Evidence concerning the connection between Clément and Carnot is summarized in a book by the historian, Robert Fox, "Reflexions on the Motive Power of Fire, A Critical Edition..." - 1986 - Manchester University Press.
Clément was the first man known to define and utilize the calorie as a unit of heat. The definition was published in the journal,
Le Producteur, in 1824. His calorie was a kg-calorie (modern kcal), and his definition entered French dictionaries as early as
1842. One of his lasting influences was to help the calorie enter the international lexicon. It was defined as heating a kg of
water by 1 degree C until about 1929, but was superseded when a committee of the British Academy of Sciences proposed the
g-calorie as an alternate unit of energy (with the newly defined joule taking precedence). This marked the beginning of "calorie
confusion" because the kilocalorie had to be introduced as a unit in the m-kg-s system. Thus, the reason that U.S. food labels
describe food energy in calories can be traced to Nicolas Clément-Desormes' lectures of 1819-1824.
Clément-Desormes was a successful industrialist who was owner or partner in several chemical companies, including one that made sugar from beets. He was sought after as an industrial consultant. Some speculate that his sudden death was brought on by a business disgreement concerning payments that were owed to him for successful introduction of a profitable process.
See also
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