Beschreibung
Ann. de Chim. 1, 65-67. - A Prais, Chez Bernard, 1808, 8°, 336 pp., 1 Taf.; 336, 2 Taf.; 336 pp., 1 Taf., 2 abweichende Halbledereinbände der Zeit; frisches Exemplar. First Print - Hassenfratz defined the term "complementary color" ! It was the physics professor Jean Henri Hassenfratz (1755-1827) who gave the most thorough treatment of color and the most radical overhaul of Newtonian theory. His first critique of Newtonian color was given as a lecture at the Cours révolutionnaire in 1794, and was then printed in the Journal de l'École Polytechnique. He began with the same phenomenon as Monge, that is, the blue shadows of sunrise. But then continued on that there was nothing particular about sunrise. Rather, every shadow that one observed was colored in some way, even those of high noon that looked perfectly black. Hassenfratz investigated the shadows produced by various light sources, and found that they took on every color of the prism. Like Monge, he concluded that these colors could not be solely the property of the physical particles. Hassenfratz also noticed that not only were the shadows colored, but also they seemed to come in complementary pairs. He observed the situation when there were multiple light sources in play, competing with the light of the sun or atmosphere. In this case, there were anywhere from two to six different colors visible in the shadows. If there were two colors, Hassenfratz claimed, it was always the case that these two colors were complements of one another. If there were three colors, one of them was always the complement of the two others. And so on for any number of shadows. One of these colors would always depend on the color of whatever object was providing the reflected light. For example, if the room was dominated by light reflecting off of slate surfaces, the shadows would be bluish. If the light was reflected off of plants or trees, the shadows would look green. All of this made sense, and Hassenfratz admitted that it could be easily predicted by current understandings of color and shadows. What was less predictable, however, was the presence of the second complementary color, which existed even in the absence of any body capable of reflecting that color. Hassenfratz was careful to define the term "complementary color," because this was one of the first instances of its use in the French language. He pointed out that the notion of complementary colors did not in any way oppose Newton's claim that white light was made up of an infinite number of homogeneous colors. This part of Newton's work, found in book one of the Opticks, was entirely compatible with his observations. It was the second part of Newton's color theory, found in Book 2 of the Opticks, with which Hassenfratz disagreed. This part had to do with the causes of color generation, and particularly the analogy with Newton's rings. Hassenfratz published the full run of his critique "On the Coloring of Bodies" in the 1808 edition of the Annales. "Optics," he lamented, "has remained stationary since the publication of Newton's experiments on light." The authority of the great man, he claimed, prevented serious research on even the most problematic aspects of the theory. In particular, Hassenfratz proposed to examine the central analogy posited between the natural color of objects and those created in the air gaps of Newton's rings. Hassenfratz proposed to test Newton's theory by looking at the spectra of light that had passed through colored glass. According to Newton's theory, the spectrum of light that has been reflected from a colored body must be the same as the spectrum of a thin film of the same color. As the rules involved in putting these mixtures of light together were very precise, there were only certain ." Theresa Levitt, The Shadow of Enlightenment : Optical and Political Transparency in France . (2009), pp.26-27. Bestandsnummer des Verkäufers 51630
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