Henri Victor Regnault

French physicist and chemist (1800–1878)

Regnault came from a poor background in Aachen (now in Germany) and started work as a draper's assistant. He entered the Ecole Polytechnique in 1830 and later worked under Justus von Liebig at Giessen. He was successively professor of chemistry at the University of Lyons and the Ecole Polytechnique (1840). He became professor of physics at the Collège de France (1841) and finally director of the Sèvres porcelain factory in 1854.

Regnault's main work was in physics on the properties of gases and in particular the more accurate determination of many physical and chemical effects. Through his meticulous studies he showed, for example, that the law of Pierre Dulong and Alexis Petit was only approximately true when pure samples were taken and temperatures carefully measured. He also worked on the properties of gases – Joseph Gay-Lussac had claimed that a gas will increase by 1/266 of its volume for each increase of temperature of 1°C but Regnault showed that the true increase was 1/273. In addition he made accurate measurements of specific and latent heats and reliable determinations of atomic weights. Regnault is credited with the invention of the air thermometer.

In chemistry, Regnault discovered various organic chlorides that have since become important industrially, including vinyl chloride and carbon tetrachloride. He also took samples of air from different parts of the world and demonstrated that wherever it comes from it contains about 21% oxygen.

(b Aix-la-Chapelle, 21 July 1810; d Paris, 19 Jan 1878). Photographer, scientist and physician. He was a self-taught scientist and a member of the Acad?mie des Sciences from 1840. He first approached photography from a scientific viewpoint c. 1845-7, discovering the use of pyrogallic acid as a developing fluid. He was the first president of the Soci?t? Fran?aise de Photographie, founded in 1854. He also collected photographs by French pioneers (album in Paris, Soc. Fr. Phot.) and worked for the photographic printer Louis-D?sir? Blanquart-Evrard.

Part of the Regnault family

See the Abbreviations for further details.

Régnault, Henri-Victor (1810-78), French physicist and a pioneer of French paper photography. Although he conducted experiments as early as 1841, it was not until 1847 that he used the process regularly. From then until the mid-1850s he devoted part of his time to photography, especially at and around the Sèvres porcelain works, of which he was, from 1851, director. His favourite subjects were landscapes, architectural studies, and portraits. He was the first president of the Société Française de Photographie, which houses most of his work.

— Quentin Bajac

Bibliography

• Dahlberg, L., Victor Régnault and the Advance of Photography. The Art of Avoiding Errors (2005)

Henri Victor Regnault
Henri Victor Regnault
Born	July 21, 1810 (1810-07-21) Aachen
Died	January 19, 1878 (1878-01-20)
Nationality	French
Fields	thermodynamics
Alma mater	École Polytechnique
Influences	Justus von Liebig
Influenced	William Thomson

Henri Victor Regnault (July 21, 1810 – January 19, 1878) was a French chemist and physicist best known for his careful measurements of the thermal properties of gases. He was an early thermodynamicist and was mentor to William Thomson in the late 1840s.

Biography

Born in Aachen in 1810, he moved to Paris following the death of his parents at the age of eight. There, he worked for an upholstery firm until he was eighteen. In 1830, he was admitted to the École Polytechnique, and in 1832 he graduated from the École des mines.

Working under Justus von Liebig at Gießen, Regnault distinguished himself in the nascent field of organic chemistry by synthesizing several chlorinated hydrocarbons (e.g. vinyl chloride, polyvinyl chloride, dichloromethane), and he was appointed professor of chemistry at the University of Lyon. In 1840, he was appointed the chair of chemistry of the Ecole Polytechnique, and in 1841, he became a professor of Physics in the College de France.

Beginning in 1843, he began compiling extensive numerical tables on the properties of steam. These were published in 1847, and led to his receiving the Rumford Medal of the Royal Society of London and appointment as Chief Engineer of Mines. In 1851 he was elected a foreign member of the Royal Swedish Academy of Sciences. In 1854 he was appointed director of the porcelain works at Sèvres.

At Sèvres, he continued work on the thermal properties of matter. He designed sensitive thermometers, hygrometers, hypsometers and calorimeters, and measured the specific heats of many substances and the coefficient of thermal expansion of gases. In the course of this work, he discovered that not all gases expand equally when heated and that Boyle's Law is only an approximation, especially at temperatures near a substance's boiling point.

Regnault was also an avid amateur photographer. He introduced the use of pyrogallic acid as a developing agent, and was one of the first photographers to use paper negatives. In 1854, he became the founding president of the Société Française de Photographie.

In 1871, his laboratory at Sèvres was destroyed and his son Alex-Georges-Henri Regnault killed, both as a result of the Franco-Prussian War. He retired from science the next year, never recovering from these losses.

The crater Regnault on the Moon is named after him. Some have suggested that the symbol R for the ideal gas constant is also named after him.^[1]

References

1. ^ Jensen, William B. (July 2003). "The Universal Gas Constant R". Chemical Education Today Vol. 80 (No. 7): p. 731. http://jchemed.chem.wisc.edu/Journal/Issues/2003/Jul/PlusSub/V80N07/p731.pdf. 

Wikisource has the text of the 1913 Catholic Encyclopedia article Henri Victor Regnault.

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