The year 1869 in science and technology involved some significant events, listed below.

Events

• November 4 – The first issue of scientific journal Nature is published in London, edited by Norman Lockyer.

Chemistry

• March 6 – Dmitri Mendeleev makes a formal presentation of his periodic table to the Russian Chemical Society.
• June 15 – John Wesley Hyatt patents celluloid, in Albany, New York.
• July 15 – Hippolyte Mège-Mouriès files a patent for margarine (as oleomargarine) in France as a beef tallow and skimmed milk substitute for butter.
• German chemist Lothar Meyer makes a formal presentation of the revised and expanded version of his independently-created 1864 periodic table, „Die Natur der chemischen Elemente als Funktion ihrer Atomgewichte".
• Publication of Adolphe Wurtz's Dictionnaire de chimie pure et appliquée begins in Paris.

Life sciences

• April 6 – The American Museum of Natural History is founded in New York.
• June 24 – Sea Birds Preservation Act passed in the United Kingdom, preventing killing of designated species during the breeding season, the first Act to offer any protection to British wild birds.^[1]
• Paul Langerhans discovers the pancreatic islets.
• Friedrich Miescher discovers deoxyribonucleic acid (DNA) in the pus of discarded surgical bandages. Found in the nuclei of cells, Miescher names it "nuclein".
• Neurasthenia is first published as a diagnosis in psychopathology by Michigan alienist E. H. Van Deusen of the Kalamazoo asylum^[2] followed a few months later by New York neurologist George Miller Beard.^[3]
• French missionary and naturalist Père Armand David receives the skin of a giant panda from a hunter, the first time this species has become known to a Westerner;^[4] he also first describes a specimen of the "pocket handkerchief tree", which will be named in his honor as Davidia involucrata.
• Alfred Russel Wallace publishes The Malay Archipelago.

Mathematics

• W. Stanley Jevons publishes The Substitution of Similars and has a "Logic Piano" constructed to work out problems in symbolic logic.^[5]
• Hermann Schwarz devises Schwarz–Christoffel mapping.

Technology

• Approximate date – Henry Christopher Mance develops a practical military heliograph in the British Raj.^[6][7][8]

Awards

• Copley Medal: Henri Victor Regnault^[9]
• Wollaston Medal for Geology: Henry Clifton Sorby

Births

• February 14 – C. T. R. Wilson (died 1959), Scottish physicist and meteorologist, recipient of the Nobel Prize in Physics.
• February 27 – Alice Hamilton (died 1970), American physician.^[10]
• April 8 – Harvey Cushing (died 1939), American neurosurgeon.
• April 17 – Robert Robertson (died 1949), Scottish-born chemist.
• June 19 – Christopher Addison (died 1951), English anatomist and politician.
• July 18 – Maria von Linden (died 1936), German bacteriologist and zoologist.
• August 23 – Robert Gunther (died 1940), English historian of science.
• October 3 – Robert W. Paul (died 1943), English pioneer of cinematography.
• November 23 – Valdemar Poulsen (died 1942), Danish audio engineer.
• December 16 – Bertha Lamme (died 1943), American electrical engineer.
• Helen Boyle (died 1957), British physician and psychologist.

Deaths

• July 22 – John A. Roebling (born 1806), German American bridge engineer.
• July 28 – Carl Gustav Carus (born 1789), German physiologist and landscape painter.
• September 11 – Thomas Graham (born 1805), Scottish chemist.