Tyrian purple by ancient authors. Not much is known about the subsequent steps, and the actual ancient method for mass-producing the two murex dyes has not yet been successfully reconstructed; this special "blackish clotted blood" colour, which was prized above all others, is believed to be achieved by double-dipping the cloth, once in the indigo dye of "H. trunculus" and once in the purple-red dye of "B. brandaris". The Roman mythographer Julius Pollux, writing in the 2nd century AD, asserted ("Onomasticon" I, 45–49) that the purple dye was first discovered by the philosopher Heracles of Tyre, or rather, by his dog, whose
George Palmer (colour theorist) the complementary nature of the successive contrast effect by stating that it is due to fatiguing of one or two of the light sensor types, an explanation that continues to be accepted as valid, as does his conjecture that the different kinds of sensors take different time intervals to recover upon exposure to strong light. George Palmer (colour theorist) George Palmer (ca. 1746 – March 3, 1826), also known as George Giros de Gentilly, named Palmer) was an English dye chemist, colour theorist, inventor, and soldier. He is best known for his conjectures about colour vision and colour blindness. According