The Eiffel Tower and the Trocadero.
Image: Library of Congress
These postcards of France in the last years of the 19th century were created using the Photochrom process, a technique by which black-and-white photos were imbued with vibrant and lifelike color.
Invented in the 1880s by a Swiss printer, the Photochrom process began with coating a tablet of lithographic limestone with a light-sensitive emulsion and exposing it to sunlight under a photo negative for several hours.
The emulsion would then harden in proportion to the tones of the negative, resulting in a fixed lithographic image on the tablet. Read more...
More about History, Retronaut, France, Paris, and Photochromvia Zero Tech Blog
