From a paper on the science of color, by W. Benson, an abstract of which appears in the Building News, we collate the following statements relative to the effect produced by the juxtaposition of colors, which are of great value to all engaged in decorative arts. These statements are based upon deductions from the study of prismatic colors, and are confirmed by all sorts of experiments made with the colors of pigments. We may test the colors of pigments with the prism in a beautifully simple way. We have merely to cover a small part of a strip of white paper with the pigment, and view it over a dark cavity, through the prism, and we see the spectrum of the pigment color adjoining to that of the white, and detect at once the rays which are absorbed or extinguished by the pigment, and those which it sends to the eye, to which its color is due. Thus, with respect to yellow, which many will still maintain to be a primary color, unconvinced by the experiments on the combination of the prismatic rays (which show that the best yellow is produced by throwing together all from the first red to the last green ray); if we analyze the color of aureolin, of chrome yellow, or of king's yellow, or the petal of any bright yellow flower, we uniformly find that, the better and clearer the yellow, the more perfectly the object reflects all the red and all the gren rays, absorbing only the blue. Hence, if blue is a primary color, it is difficult to see how it can be supposed that a color produced by all the other rays of the spectrum, is not made up of both the other primaries combined, whatever those primaries are. Colors intermediate between two pigments cannot be obtained by their admixture. Gamboge and Prussian blue, for instance, make, by admixture or superposition, a green, darker than either the yellow or the blue of those pigments ; the scientific method gives, as their intermediate color, a gray of mean brightness, in agreement with the results obtained by experiments on the combination of the prismatic rays. So, also, it does the colors of king's yellow and cobalt, or lemon yellow and French blue or ultramarine. Mr. Benson claims that facts determined by his experiments on the combination of prismatic rays, as well as those upon pigments, confirm the opinion that red, green, and blue are the primary, and sea-green, pink, and yellow the secondary colors. In perfect agreement with these facts, are all those apparent changes of color which are perceived when the retina, having been strongly excited by some one or other color, becomes less sensible to it than usual, and every object to which we direct the eye appears, therefore, more or less tinged with the complementary color, as if a wash had been laid over it. For it is .always found that in an eye excited by red, by green, or by blue, objects appear tinged with sea-green, with pink, or with yellow, and the reverse; and that by intermediate colors intermediate effects are produced. Some of these effects have been otherwise described by sev eral writers; it is usual, for instance, to hear it said that red tinges the adjoining colors with green ; but this is not correct, I unless the one be a pink-red, or crimson, and the other a sea-green green. So again, it is usual to say, that blue and orange mutually deepen each other; but, for this to be true, the blue must be of a sea-green blue or azure hue, and the orange must be yellowish. The most careful experiments, made by looking steadfastly at spots colored with those pigments which best represent the principal compounds of the prismatic colors, and brilliantly illuminated upon a black ground, and then suddenly directing the eye to a perfectly neutral gray ground, will always clearly show the gray surface darkened and modified in hue in ac~ cordance with what I have already pointed out as the real or natural complementaries. Thus, an eye affected with bright red or scarlet, like that of vermilion, turns the gray into a grayish sea-green of the hue of verdigris ; one affected with green, like that of emerald green, turns it a grayish pink, of about the hue of rose madder; one affected with blue, like that of cobalt, turns it into a grayish yellow, of the hue of king's yellow, and the reverse. The same effects are seen in the shadows cast by a sunbeam which has passed through strongly-colored glass, upon a gray surface otherwise illuminated by a neutral light; and in many other ways, if due precautions are used. And no doubt the peculiar improvement in depth, which is evident in truly complementary colors when viewed in juxtaposition, the eye glancing rapidly from one to the other of them, arises from the same cause. It is evident, therefore, that the eye itself is so constituted as to agree, in this respect, with the deductions of science concerning the actual relations of colors. The attempt to reconcile these obvious ocular effects with the common doctrine as to what colors are complementary to each other has led some to regard the deep prismatic blue, which Newton called indigo, as being violet in hue, and the deep prismatic red as being an orange red. The terms used to distinguish colors are among the most indefinite in all languages ; and the loose way in which they are applied, and the different meanings attached to them by different authors, would lead one to suppose that our color-sensations are so different in different persons, and so variable in the same, that they are more fanciful than real, and that no certainity is attainable in them. Yet, in fact, if we except the comparatively few persons who are only capable of the sensations of yellow and blue, and those whose eyes are less sensible than they should be to red, there is a wonderful uniformity and certainity in the sensations excited by light. Only let the rays which enter the eye be the same in quality and quantity, and let the eye be in the same normal condition, without any present or very recent strong excitement, and we may rely upon the results being the same. But the difference between the new doctrine and the old is more than a difference of terms, for the utmost latitude of interpretation cannot reconcile them. Sir J. G. Wilkinson asserts in his work on " Color and Taste" that though red and blue in juxta-position have the appearance of purple, and yellow placed next to red gives it an orange hue, the same illusion is not caused by the contact of the other two primary colors, blue and yellow, and these do not look green when in juxtaposition, except in certain cases. Nor is the change then so marked as when blue and red, or yellow and red, are in contact. And this is one of many proofs that all the three primary colors are not under the same conditions, in relation to each other. It is not, therefore, necessary to lay down the same general and invariable rule respecting the three primaries, that " in making new patterns or ornaments, red and blue sliould not join, nor yellow and red, nor yellow and blue," as though the three combinations were exactly similar, and subject to the same laws. For yellow and blue do not deceive the eye to the same extent as the others, when in juxtaposition. Nor has red with green the same effect as red with blue and yellow, and still less have red blue and yellow the same effect as these three colors when united in one, that is, according to the theory which the author received, they have not the same effect as white. Such anomalies as those noticed in this extract are the necessary consequences of an erroneous theory. Of course, blue and yellow cannot be treated in the composition by the same rules as blue and red; for blue is complementary to yellow and not to( red. Still less can yellow and red be treated by the same rules as yellow and blue; for yellow harmonizes with red, itself containing the full red in conjunction with the full green, while it contrasts as the opposite color to blue. No wonder that red, yellow, and blue together have not the same effect as red and green together, nor yet the same effect as white ; for the mean of the first combination is always reddish, and of the second yellowish, and neither of them white or netural, whatever proportions are taken. We ought, in the opinion of Mr. Benson, to treat red, green, and blue under the same rules as primary colors, and sea-green, pink, and yellow under the same rules as secondaries, if only we bear in mind the differences in the depth and clearness of the pigments we use to represent them; these, of course, modifying the effects in a large degree. Two primaries of similar depth may please the eye when side by side, while the same two, equally true in hue, but not alike in depth, may fail to do so. A great step will assuredly be gained if we establish correctly the hues of the three simple color-sensations, and of their complementaries ; for these, together with black and white, will give us the eight principal colors upon which to work, and will enable us to determine all the intermediate colors correctly, and to arrange them all with due regard to their natural gradations and contrast of every kind. Tolling Great Sells. A new method of hanging very large bells has been tried at Worcester, England, it would appear with perfect success. The bell upon which the experiment was tried weighed four jtnd one-half tuns. The plan is to make the gudgeons upon which the bell is hung, V-shaped, like tlie bearings of an ordinary scale beam. These rest on brasses very slightly hollowed. The friction was so greatly reduced by this method, that, according to the Builder, this ponderous bell was tolled for afternoon service on Sunday, 17th January, by the Rev. H. T. Ellacombe, that gentleman using only one hand, although a small man and nearly 80 years of age. It is said to be easier than pulling the clapper by a rope, beside being less likely to .crack the bell. Another great advantage is that the tone of the bell comes out much more grandly than by clappering. No wheel is required in this mode of bell hanging, the power being applied by a lever fixed to the stock. The gudgeons must not be lower than the top of the bell. The diameter of the mouth of the bell alluded to was seventy-six and one-half inches.
This article was originally published with the title "Contrast and Admixture of Colors" in Scientific American 20, 17, 257-258 (April 1869)