Throughout history, forms of art have gone through periodic abrupt changes called artistic revolutions. Movements have come to an end to be replaced by a new movement markedly different in striking ways. Scientific and technological Not all artistic revolutions were political. Sometimes, science and technological innovations have brought about unforeseen transformations in the works of artists. The stylistic revolution known as Impressionism, by painters eager to more accurately capture the changing colors of light and shadow, is inseparable from discoveries and inventions in the mid-19th century in which the style was born. Michel Eugène Chevreul, a French chemist hired as director of dyes at a French tapestry works, began to investigate the optical nature of color in order to improve color in fabrics. Chevreul realized It was the eye, and not the dye, that had the greatest influence on color, and from this, he revolutionized color theory by grasping what came to be called the law of simultaneous contrast: that colors mutually influence one another when juxtaposed, each imposing its own complementary color on the other. The French painter Eugène Delacroix, who had been experimenting with what he called broken tones, embraced Chevreul's book, The Law of Contrast of Color (1839) with its explanations of how juxtaposed colors can enhance or diminish each other, and his exploration of all the visible colors of the spectrum. Inspired by Chevreul’s 1839 treatise, Delacroix passed his enthusiasm on to the young artists who were inspired by him. It was Chevreul who led the Impressionists to grasp that they should apply separate brushstrokes of pure color to a canvas and allow the viewer’s eye to combine them optically. They were aided greatly in this by innovations in oil paint itself. Since the Renaissance, painters had to grind pigment, add oil and thus create their own paints; these time-consuming paints also quickly dried out, making studio painting a necessity for large works, and limiting painters to mix one or two colors at a time and fill in an entire area using just that one color before it dried out. In 1841, a little-known American painter named John G. Rand invented a simple improvement without which the Impressionist movement could not have occurred: the small, flexible tin tube with removable cap in which oil paints could be stored. Oil paints kept in such tubes stayed moist, usable, and portable. For the first time since the Renaissance,