1815 in science

The year 1815 in science and technology involved some significant events, listed below.

Astronomy and space science

Jean-Baptiste Lamarck begins publication of Histoire naturelle des animaux sans vertèbres.

William Prout anonymously publishes his hypothesis that the atomic weight of every element is an integer multiple of that of hydrogen.
Dutch chemist Coenraad van Houten introduces alkaline salts to chocolate to reduce its bitterness.

April 5 – Volcanic eruption of Mount Tambora on the Indonesian island of Sumbawa. About 92,000 people die as a direct consequence of this disaster, the largest volcanic eruption in recorded history. The eruption sends so much volcanic ash into the atmosphere that weather patterns around the world are altered, causing 1816 to be the "Year Without A Summer".
August 1 – William Smith publishes the first national geological map of the United Kingdom, A Delineation of the Strata of England and Wales, with part of Scotland.

July 10 – Apothecaries Act prohibits unlicensed medical practitioners in the United Kingdom.
Cholesterol is discovered by French chemist Michel E. Chevreul, who analyzes it in human gall stones, but its causal relationship with atherosclerosis remains unknown.

Experiments by Jean Baptist Biot reveal polarimetry in the polarization of light in liquids.
Atomic decay is discovered by Swedish chemist Jöns Jakob Berzelius in gadolinite, a radioactive mineral damaged by alpha particles released in its own activity.

November 3 – Sir Humphry Davy announces his discovery of the Davy lamp as a coal mining safety lamp.
Dental floss is invented by Levi Spear Parmly.