Passage:
In 1824, the French chemist Michel Eugène Chevreul was appointed director of the dye works at the Manufacture des Gobelins, a royal tapestry workshop in Paris. Soon after his arrival, weavers and overseers lodged formal complaints regarding the perceived inferiority of the workshop's black and deep violet dyes, asserting that these pigments lacked chemical saturation and appeared dingy when integrated into complex figurative compositions. Chevreul undertook systematic chemical analyses of the mordants and organic colorants used in the vats, but found no evidence of pigment degradation, improper binding, or chemical impurity. Instead, he observed that the perceived lack of vigor in the dark wools occurred exclusively when those threads were bordered by adjacent, highly luminous hues or complementary tones.
Through a sequence of controlled experiments using juxtaposed swatches of colored paper and woven textiles, Chevreul deduced that the perceived hue and brightness of any given color are altered by the simultaneous perception of adjacent colors—a phenomenon he formalized as the law of simultaneous contrast. He demonstrated that when two distinct colors are viewed side by side, the human visual system involuntarily shifts each tone toward the complementary color of its neighbor. Consequently, a neutral black thread placed alongside a brilliant blue thread does not simply appear black; rather, the adjacent blue induces its complementary tone (an orange-yellow cast), making the black appear muted, brownish, or faded. Chevreul concluded that the apparent defect was an optical illusion arising from retinal and neural processing rather than a flaw in the workshop's chemical formulations, and he advised weavers to modify the juxtaposition of neighboring colored threads rather than reformulating the dye vats.
Statement: According to the passage, Chevreul's chemical investigations revealed that the black and violet dyes used at the Gobelins workshop showed no evidence of pigment degradation or chemical impurity.
Answer: Answer