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) century, they organised what they called the Orange Free State. In the United States, the flag of the City of New York has an orange stripe, to remember the Dutch colonists who founded the city. William of Orange is also remembered as the founder of the College of William & Mary, and Nassau County in New York is named after the House of Orange-Nassau. In the 18th century orange was sometimes used to depict the robes of Pomona, the goddess of fruitful abundance; her name came from the "pomon", the Latin word for fruit. Oranges themselves became more common in