Scientific American 2, 12.1.1861
It would appear, from numerous observations, that soldiers are hit during battle according to the color of their dress, in the following order: Red is the most fatal color; the least fatal, Austrian gray. The proportions are - red, 12; rifle-green 7; brown, 6; Austrian bluish-gray, 5.
A patent has lately been taken out by C. Couper, of London, for a new and beautiful blue color. It consists of soluble Prussian blue and ca[r]mine of indigo mixed together, according to their combining proportions. He has found that these two colorings substances dissolve one another and combine to form a new blue of definite composition, which possesses the property of being applied to fabrics made of both vegetable and animal substances, either with or without mordants. This blue is a clear color, and does not vary in artificial or solar light.