The first synthetic dye, mauvine, was created by William Henry Perkin in 1856. He was trying to synthesize quinine. Other dyes followed, including magenta and solferino. Dyes are altered on exposure to light. This appears to have happened to Louise van Loon’s gorgeous turquoise dress seen in the last image.
From fripperiesandfobs.tumblr.com/post/144821505742/worth-evening-dress-worn-by-louise-van-loon-borken. Also posted to The Bustle Periods - 1870 to 1890 Album here.