Jean Rey (; c. 1583 – c. 1645) or (''in English'') John Rey was a French physician and chemist. Born in Le Bugue, in the Périgord (

Dordogne Dordogne ( , or ; ; ) is a large rural departments of France, department in south west France, with its Prefectures in France, prefecture in Périgueux. Located in the Nouvelle-Aquitaine region roughly half-way between the Loire Valley and ...

'' département''), he studied medicine at the University of Montpellier. He practised medicine in his native town and corresponded with

René Descartes René Descartes ( , ; ; 31 March 1596 – 11 February 1650) was a French philosopher, scientist, and mathematician, widely considered a seminal figure in the emergence of modern philosophy and Modern science, science. Mathematics was paramou ...

and

Marin Mersenne Marin Mersenne, OM (also known as Marinus Mersennus or ''le Père'' Mersenne; ; 8 September 1588 – 1 September 1648) was a French polymath whose works touched a wide variety of fields. He is perhaps best known today among mathematicians for ...

. He discovered that the weight of

lead Lead () is a chemical element; it has Chemical symbol, symbol Pb (from Latin ) and atomic number 82. It is a Heavy metal (elements), heavy metal that is density, denser than most common materials. Lead is Mohs scale, soft and Ductility, malleabl ...

and tin increases when they are calcinated, 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

Antoine Lavoisier Antoine-Laurent de Lavoisier ( ; ; 26 August 17438 May 1794), When reduced without charcoal, it gave off an air which supported respiration and combustion in an enhanced way. He concluded that this was just a pure form of common air and that i ...

, over a century later in 1789. His discovery of the weight of air also made possible the invention of the

barometer A barometer is a scientific instrument that is used to measure air pressure in a certain environment. Pressure tendency can forecast short term changes in the weather. Many measurements of air pressure are used within surface weather analysis ...

Evangelista Torricelli Evangelista Torricelli ( ; ; 15 October 160825 October 1647) was an Italian people, Italian physicist and mathematician, and a student of Benedetto Castelli. He is best known for his invention of the barometer, but is also known for his advances i ...

in 1643. He also developed a device called a "Thermoscope", a precursor of the

thermometer A thermometer is a device that measures temperature (the hotness or coldness of an object) or temperature gradient (the rates of change of temperature in space). A thermometer has two important elements: (1) a temperature sensor (e.g. the bulb ...

. Jean Rey died in Le Bugue, where he had lived all his life. The exact date of his death is disputed.

References

1580s births 1640s deaths 17th-century French chemists 17th-century French physicians People from Dordogne {{chem-hist-stub