Nicolas Clément (12 January 1779 – 21 November 1841) was a French

physicist A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe. Physicists generally are interested in the root or ultimate caus ...

and

chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...

. He was a colleague of Charles Desormes, with whom he conducted the Clément-Desormes experiment. The two chemists are also credited with determining an accurate value of gamma in the gas law (see

Equation of state In physics, chemistry, and thermodynamics, an equation of state is a thermodynamic equation relating state variables, which describe the state of matter under a given set of physical conditions, such as pressure, volume, temperature, or internal ...

) that relates the heat capacity of air when expanded at constant pressure vs. constant temperature. They also conducted research on

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

and played a role in determining that it was an element. This research eventually led others to invent the process of photography, and Clément-Desormes is recognized as a contributor in the early history of that industry. Among their accomplishments was establishing a value for

absolute zero Absolute zero is the lowest limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reach their minimum value, taken as zero kelvin. The fundamental particles of nature have minimum vibration ...

Marriage

Clément married Desormes' daughter and adopted the family surname as Clément-Desormes.

Career

Professor Clément held one of the first chairs in chemistry at the

Conservatoire des Arts et Metiers A music school is an educational institution specialized in the study, training, and research of music. Such an institution can also be known as a school of music, music academy, music faculty, college of music, music department (of a larger ins ...

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, 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 In the history of science, the mechanical equivalent of heat states that motion and heat are mutually interchangeable and that in every case, a given amount of work would generate the same amount of heat, provided the work done is totally converte ...

, and developed formulae for calculating energy efficiency almost 20 years before Mayer and Joule's work on this subject in the 1840s. Evidence concerning the connection between Clément and Carnot is summarized in a book by the historian, Robert Fox. and in an article on th
history of the calorie
Clément was the first man known to define and utilize the

Calorie The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of on ...

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 young 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 disagreement concerning payments that were owed to him for successful introduction of a profitable process.

Marriage

Career

References

See also