In the 1890s the French physicist Gabriel Lippmann devised a new method of taking photographs that led to the first photographic recording of color:
Lippmann’s color photography process involved projecting the optical image as usual onto a photographic plate. The projection was done through a glass plate coated with a transparent emulsion of very fine silver halide grains on the other side. There was also a liquid mercury mirror in contact with the emulsion, so the projected light traveled through the emulsion, hit the mirror, and was reflected back into the emulsion.
The resulting plates are pretty cool looking, as seen in the video — very similar to the discovery of holography decades later — and technically they record a wider spectrum of color than our standard modern imaging techniques. He won the Nobel Prize in 1908 for his research, but the method was largely shelved due to the complexity of the process and the inability to make color prints, which also didn’t appear commercially until much later.
In 2021 researchers at the Ecole Polytechnique Fédérale de Lausanne published a paper on their research into Lippmann’s images, including a new method that lets us see the images closer to the original color captured in the photographic scene.
Side trivia: among Lippmann’s doctoral students at the Sarbonne was Maria Sklodowska, later a winner of multiple Nobel prizes herself, under her better-known married name: Marie Curie!