1825 in science

• Pierre-Simon Laplace completes his study of gravitation, the stability of the Solar System, tides, the precession of the equinoxes, the libration of the Moon, and Saturn's rings in publishing the fifth and final volume of Mécanique Céleste (Celestial Mechanics).{{Cite journal|date=June 1829|title=Art. III.—Traité de Mecanique Celeste, par M. Le Marquis De Laplace, Pair de France; &c. &c. Tome Cinquime. Paris, Bachelier: 1825. 4to. pp. 420.|url=https://books.google.com/books?id=yNYRAAAAYAAJ|journal=American Quarterly Review|location=Philadelphia|publisher=Carey, Lea & Carey|volume=V|issue=X|pages=310|via=Google Books}}

• Richard Harlan publishes Fauna Americana.{{Cite journal|date=January 1826|title=Harlan's Fauna Americana|url=https://books.google.com/books?id=daNKAAAAcAAJ|journal=The North American Review|publisher=Frederick T. Gray|volume=XXII|issue=L|pages=120–136|via=Google Books}}
• Charles Waterton publishes Wanderings in South America, the North-west of the United States, and the Antilles, in the years 1812, 1816, 1820, and 1824; with original instructions for the perfect preservation of birds, &c. for cabinets of natural history.
• Cox's Orange Pippin apple cultivar first grown, at Colnbrook in Buckinghamshire, England, by horticulturist and retired brewer Richard Cox.

• Michael Faraday isolates benzene as Bicarburet of Hydrogen.{{cite journal|last=Faraday|first=M.|url=http://gallica.bnf.fr/ark:/12148/bpt6k559209/f473.image|title=On New Compounds of Carbon and Hydrogen, and on Certain Other Products Obtained during the Decomposition of Oil by Heat|journal=Philosophical Transactions of the Royal Society of London|volume=115|date=1825-06-16|pages=440–466|doi=10.1098/rstl.1825.0022|jstor=107752|access-date=2012-09-25|doi-access=free|url-access=subscription}}{{cite journal|first=R.|last=Kaiser|title='Bicarburet of Hydrogen': Reappraisal of the Discovery of Benzene in 1825 with the Analytical Methods of 1968|journal=Angewandte Chemie|edition=International|volume=7|issue=5|year=1968|pages=345–350|doi=10.1002/anie.196803451}}
• Hans Christian Ørsted reduces aluminium chloride to produce metallic aluminium in an impure form.
• Friedrich Wöhler and Justus von Liebig perform the first confirmed discovery and explanation of isomers, earlier named by Berzelius. Working with cyanic acid and fulminic acid, they correctly deduce that isomerism is caused by differing arrangements of atoms within a molecular structure.{{cite web|url=https://www.sciencehistory.org/historical-profile/justus-von-liebig-and-friedrich-w%C3%B6hler|title=Justus von Liebig and Friedrich Wöhler|work=Science History Institute|date=June 2016}}{{cite book|last1=Bowden|first1=Mary Ellen|title=Chemical achievers : the human face of the chemical sciences|url=https://archive.org/details/chemicalachiever0000bowd|url-access=registration|date=1997|publisher=Chemical Heritage Foundation|location=Philadelphia, PA|isbn=9780941901123|chapter=Justus von Liebig and Friedrich Wöhler|pages=[https://archive.org/details/chemicalachiever0000bowd/page/83 83–87]}}

• July – Volcanic eruption of Mount Guntur in West Java.
• G. Poulett Scrope publishes Considerations on Volcanoes, the first systematic work on volcanology.{{cite web|url=https://www.britannica.com/biography/George-Julius-Poulett-Scrope|title=Scrope, George Julius Poulett|work=Encyclopædia Britannica Online|year=2009|access-date=22 August 2016}}

• Augustin-Louis Cauchy presents the Cauchy integral theorem for general integration paths—he assumes the function being integrated has a continuous derivative.
• Augustin-Louis Cauchy introduces the theory of residues in complex analysis.
• Peter Gustav Lejeune Dirichlet and Adrien-Marie Legendre prove Fermat's Last Theorem for n = 5.
• André-Marie Ampère discovers Stokes' theorem.
• Benjamin Gompertz formulates the Gompertz function.

• Jean-Baptiste Sarlandière's Mémoires sur L'Électro-Puncture introduces Western medicine to electroacupuncture.{{cite book|first1=Lu|last1=Gwei-Djen|first2=Joseph|last2=Needham|title=Celestial Lancets: A History and Rationale of Acupuncture and Moxa|publisher=Cambridge University Press|year=1980|isbn=978-0-521-21513-8|pages=295–7}}

• Georges Cuvier proposes his catastrophe theory as the cause of extinctions of large groups of animals.
• Étienne Geoffroy Saint-Hilaire identifies Cuvier's fossil 'crocodile' as a teleosaurus.

• August – The wire-cable suspension bridge between Tournon-sur-Rhône and Tain-l'Hermitage, designed by Marc Seguin, opens.{{cite book|url=https://archive.org/details/amemoirsuspensi01drewgoog|title=A Memoir of Suspension Bridges, Comprising the History of their Origin and Progress|last=Drewry|first=Charles Stewart|year=1832|publisher=Longman, Rees, Orme, Brown, Green & Longman|location=London|pages=[https://archive.org/details/amemoirsuspensi01drewgoog/page/n128 110]–114|access-date=2011-04-18}}
• September 27 – The world's longest railway to be worked by steam locomotives at this date, the Stockton and Darlington Railway, opens in northern England.
• October 26 – The Erie Canal officially opens over {{convert|363|mi|km}} from Albany, New York, to Lake Erie.{{citation|title=The Story of the New York State Canals|first=Roy G.|last=Finch|year=1925|access-date=2012-09-25|publisher=New York State Canal Corporation|url=http://www.canals.ny.gov/history/finch_history.pdf|format=PDF}}
• English inventor William Sturgeon describes the first electromagnet.{{cite journal|first1=William|last1=Gee|first2=Frank A. J. L.|last2=James|title=Sturgeon, William (1783–1850)|journal=Oxford Dictionary of National Biography|year=2004|url=http://www.oxforddnb.com/view/article/26748|access-date=2012-01-05|doi=10.1093/ref:odnb/26748|url-access=subscription}} {{ODNBsub}}

• December 19 – First of the annual Royal Institution Christmas Lectures in London, which will continue for two centuries.

• Copley Medal: François Arago; Peter Barlow{{cite web |title=Copley Medal {{!}} British scientific award |url=https://www.britannica.com/science/Copley-Medal |website=Encyclopedia Britannica |access-date=22 July 2020 |language=en}}

• January 18 – Edward Frankland (died 1899), English chemist.
• March 25 – Max Schultze (died 1874), German physiologist.
• March 30 – Theodor Kjerulf (died 1888), Norwegian geologist.
• May 1 – Johann Balmer (died 1898), Swiss mathematician.
• May 4 – Thomas Henry Huxley (died 1895), English biologist.
• May 9 – George Davidson (died 1911), English-born geodesist, astronomer, geographer, surveyor and engineer in the United States.
• June 6 – Friedrich Bayer (died 1880), German manufacturing chemist.
• September 4 – Richard Maack (died 1886), Russian naturalist, geographer, and anthropologist.
• November 29 – Jean-Martin Charcot (died 1893), French neurologist.
• December 26 – Felix Hoppe-Seyler (died 1895), German physiologist.

• April 19 – Marc-Auguste Pictet (born 1752), Swiss scientific journalist and natural philosopher.{{cite book|url=https://www.royalsoced.org.uk/cms/files/fellows/biographical_index/fells_indexp2.pdf|title=Biographical Index, Part Two|date=July 2006|publisher=The Royal Society of Edinburgh|isbn=0 902 198 84 X|series=Former Fellows of The Royal Society of Edinburgh 1783–2002|pages=736|access-date=2019-03-18|archive-url=https://web.archive.org/web/20160304074135/https://www.royalsoced.org.uk/cms/files/fellows/biographical_index/fells_indexp2.pdf|archive-date=2016-03-04|url-status=dead}}
• June – William Higgins (born 1763), Irish chemist.{{cite web|url=http://www.encyclopedia.com/topic/William_Higgins.aspx|title=William Higgins|website=Complete Dictionary of Scientific Biography|publisher=Encyclopedia.com|access-date=18 March 2019}}
• July 25 – John Gough (born 1757), blind English natural philosopher.
• October 6 – Bernard Germain Étienne (born 1756), French naturalist.
• Maria Angela Ardinghelli (born 1730), Italian mathematician and physicist.
• John Templeton (born 1766), "father of Irish botany".

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Category:19th century in science

Category:1820s in science