Color theory primary colors work at all is that the imperfect pigments being used have sloped absorption curves, and thus change color with concentration. A pigment that is pure red at high concentrations can behave more like magenta at low concentrations. This allows it to make purples that would otherwise be impossible. Likewise, a blue that is ultramarine at high concentrations appears cyan at low concentrations, allowing it to be used to mix green. Chromium red pigments can appear orange, and then yellow, as the concentration is reduced. It is even possible to mix very low concentrations of the blue mentioned and
Orange (colour) political and social movements. In the United States Army, orange has traditionally been associated with the dragoons, the mounted infantry units which eventually became the US Cavalry. The 1st Cavalry Regiment was founded in 1833 as the United States Dragoons. The modern coat of arms of the 1st Cavalry features the colour orange and orange-yellow shade called dragoon yellow, the colours of the early US dragoon regiments. The US Signal Corps, founded at the beginning of the American Civil War, adopted orange and white as its official colours in 1872. Orange was adopted because it was the colour of a