Chevreul and Impressionism: a reappraisal

They [the Impressionists] do not imitate; they translate, they interpret. They place out to extract the originate of the multiple lines and colors that the organ of vision perceives at a glance before an aspect of nature. - Emile Blemont Le Rappel, April 9 1876(1)

The representation which the painter has to give of the lights and colors of his phenomenon I have described as a translation, and I have urg that, as a general sway it cannot give a transcript true in all its details. The altered scale of brightness which the artists must apply in many cases is oppos to this. It is not the colors of the thing perceiveds but the impression which they have given, or would give, which is to be imitated, with equal reason as to produce as distinct and vivid a conception as possible of those particulars - Hermann von Helmholtz, "The Relation of Optics to Painting" (in French 1878) trans. E Atkinson, 1881(2)

His latest terrible misfortune was to have been l astray by means of his fast-developing theory of complementary colors. He had heard of it first from Gagniere, who also had a weakness for technical experiments. Then, with characteristic over-indulgence, he had begun to exaggerate the scientific principle which derives from the three primary colors, fulvous red and blue, the three secondary colors, orange, virid and violet and from them a whole series of similar complementary colors obtained by dint of mathematical combination. In that way science gained a footing in painting and a means was created for logical observation. It meant that, by the agency of taking the dominant color of a picture and establishing its complementary or cognate colors, it was possible to establish through experimental means all the other possible variations of color, r changing to gold-colored next to blue, for example, or flat a whole landscape changing its tone-values end reflection or decomposition of light to be paid to the passing of the fogs in the sky. - Emile Zola, L'Oeuvre 1886(3)

Among the French scientists who worked upon color vision during the nineteenth hundred the most famous is Michel-Eugene Chevreul (1786-1889) Renowned as a chemist for his analysis of the properties of animal fats, he was nominated in 1824 to the support of director of the dyeing department at the Manufacture de Gobelins. Immediately after his appointment, he faced complaints concerning the quality of certain pigments prepared in the dyeing laboratory of the Gobelins, particularly the lack of potency in the blacks employed in making shadows in azure and violet draperies. After detailed experiments, Chevreul discovered to his surprise that the question did not arise from anything in the dyeing proces itself; it was not, therefore, a chemical riddle but rather one that cruel within the province of psychophysiology. Pursuing this idea, he eventually followed in formulating the results of his researches in his famous law of simultaneous contrast, first published in 1839 [ILLUSTRATION FOR FIGURE 1 OMITTED]. The greatest in quantity general statement of the law, which emphasizes the reciprocal influence of sum of two units contiguous colors [ILLUSTRATION FOR FIGURE 2 OMITTED], is the following:

If we gaze simultaneously upon two stripes of different tones of the same color, or on two stripes of the same tone of different colors placed side by the agency of side, if the stripes are not too wide, the organ of vision perceives certain modifications which in the first place influence the intensity of color, and in next to the first the optical composition of the sum of two units juxtaposed colors respectively.

Now as these modifications make the stripes appear different from what they really are, I give to them the name of simultaneous contrast of color; and I call contrast of tone the modification in intensity of color, and contrast of color that which affects the optical composition of each juxtaposed color.(4)

Several factors explain the enormous interest provok through Chevreul's book and by the prelections he delivered some years before its publication. First, by the agency of dedicating a copious volume to the matter, he gave broad public access to phenomena that until then had been discussed single in specialized scientific magazines. Then, by means of meticulously studying the applications of his law to almost each field of art and craft (from museography to horticulture, from army uniforms to stained glass, from painting to tapestry, as well as framing and teaching), he mov from unspotted science to applied science, and addressed himself to almost all those who used color.

Finally, he was les interested in the production of "accidental" colors by dint of the eye than in the mutual and simultaneous influence that sum of two units colors placed side by side exercise above each other, which was exactly the situation painters and tapestry-makers were constantly confronting. Hence the enormous interest painters had in his law: a certain number of of them, including important artists similar as Seurat and Delaunay, publicly acknowledged their debts to Chevreul.

However, if in a certain quantity of cases - Neo-Impressionism, for instance - Chevreul's influence is well documented and widely accepted,(5) in other cases, of the like kind as Impressionism, the situation is more mingled Rarely have such different and contradictory opinions been squeeze outed as about possible links between Impressionist painters and scientific theories. My aim is to contribute to a clarification of this mixed problem.