Jean Rey (physician)
Encyclopedia
Jean Rey was a French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

 physician and chemist.

Born at Le Bugue
Le Bugue
Le Bugue is a commune in the Dordogne department in southwestern France.-Geography:Le Bugue is located on the banks of the Vézère River a few kilometres before the confluence of the Vézère with the Dordogne River at Limeuil. Le Bugue is also on two national routes .-History:Le Bugue has been...

, in the Périgord
Périgord
The Périgord is a former province of France, which corresponds roughly to the current Dordogne département, now forming the northern part of the Aquitaine région. It is divided into four regions, the Périgord Noir , the Périgord Blanc , the Périgord Vert and the Périgord Pourpre...

 (Dordogne
Dordogne
Dordogne is a départment in south-west France. The départment is located in the region of Aquitaine, between the Loire valley and the High Pyrénées named after the great river Dordogne that runs through it...

 département), he studied medicine at the University of Montpellier
University of Montpellier
The University of Montpellier was a French university in Montpellier in the Languedoc-Roussillon région of the south of France. Its present-day successor universities are the University of Montpellier 1, Montpellier 2 University and Paul Valéry University, Montpellier III.-History:The university...

. He practised medicine in his native town and corresponded with Descartes
René Descartes
René Descartes ; was a French philosopher and writer who spent most of his adult life in the Dutch Republic. He has been dubbed the 'Father of Modern Philosophy', and much subsequent Western philosophy is a response to his writings, which are studied closely to this day...

 and Mersenne
Marin Mersenne
Marin Mersenne, Marin Mersennus or le Père Mersenne was a French theologian, philosopher, mathematician and music theorist, often referred to as the "father of acoustics"...

.

He discovered that the weight of lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...

 and tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...

 increases when they are calcinated
Calcination
Calcination is a thermal treatment process applied to ores and other solid materials to bring about a thermal decomposition, phase transition, or removal of a volatile fraction. The calcination process normally takes place at temperatures below the melting point of the product materials...

, and attributed this phenomenon to the weight of air, which he believed to become denser when heated (Essays, 1630). He explained the greater weight of calcinated lead and tin by supposing that calcination involves the incorporation of air in the metal. This hypothesis would later be confirmed by Lavoisier
Antoine Lavoisier
Antoine-Laurent de Lavoisier , the "father of modern chemistry", was a French nobleman prominent in the histories of chemistry and biology...

, over a century later in 1789.

His discovery of the weight of air also made possible the invention of the barometer
Barometer
A barometer is a scientific instrument used in meteorology to measure atmospheric pressure. Pressure tendency can forecast short term changes in the weather...

 by Torricelli
Evangelista Torricelli
Evangelista Torricelli was an Italian physicist and mathematician, best known for his invention of the barometer.-Biography:Evangelista Torricelli was born in Faenza, part of the Papal States...

 in 1643. He also developed a device called a "Thermoscope", a precursor of the thermometer
Thermometer
Developed during the 16th and 17th centuries, a thermometer is a device that measures temperature or temperature gradient using a variety of different principles. A thermometer has two important elements: the temperature sensor Developed during the 16th and 17th centuries, a thermometer (from the...

.

Jean Rey died at Le Bugue
Le Bugue
Le Bugue is a commune in the Dordogne department in southwestern France.-Geography:Le Bugue is located on the banks of the Vézère River a few kilometres before the confluence of the Vézère with the Dordogne River at Limeuil. Le Bugue is also on two national routes .-History:Le Bugue has been...

, where he had lived all his life.
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