Of the disposition of the mind of the spectator in respect to the judg- ment he forms of an object of art which attracts his eye Historical review of my researches, and final conclusion of the work Concluding remarks on contrast § 1. Of contrast considered in connection with the observation of ib. § 2. Of contrast considered with respect to the size of two con- tiguous objects of unequal size § 3. Are the senses of hearing, taste, and smell submitted to con- § 4. The light which the study of contrast appears to be sus- ceptible of shedding upon several other phenomena of the under- TRANSLATOR'S INTRODUCTION, Explanatory of M, CHEVREUL'S Principles. IN entering upon the study of the Principles of Harmony and Contrast of Colours as established by M. Chevreul, it will be necessary for the reader to forget much that he may have learned from other sources. The notions hitherto prevalent on this important subject were very vague and empirical, not to say fanciful. They had no foundation in observation or experiment, consequently no formula or law could be deduced from them wherewith to guide the inquirer. M. Chevreul's work is based on strict scientific investigation; his observations and experiments can be repeated by every one, and their validity tested and verified. He has established the existence of a law which governs the phenomena of contrast of Colours, and this book develops the process by which he arrived at it, and the numerous applications to the arts of which it is susceptible. As the facts and principles by which this subject is developed are necessarily scattered over a wide space, it is thought that the reader's progress will be greatly facilitated if he be presented with a summary of them, so as to afford a bird's-eye view, as it were, by which the various influences and modifications bearing upon the general law may be seen, and more readily appreciated. There is an arrangement and a sequence in which these facts and principles must of necessity be placed. But it may be convenient to anticipate some of them; to bring them nearer together, by which their mutual connexion and reciprocal influence may be made more apparent. Among the principles which govern the harmony and contrast of colours, few can be taken absolutely or independently of others. By adopting one principle hastily before we have ascertained what other principles modify it, we fall into the errors attendant upon hasty generalisation and false conclusions. A careful study of this Introduction will save the reader from so unprofitable a course. Primary Colours Luminous Colours . Sombre Colours. Warm Colours. Cold Colours. Pigments Coloured Greys DEFINITIONS. Blue, Red, and Yellow. Colours in which all three primaries exist. Yellow, Orange, Red, Light Green, and the light tones of sombre colours. Blue, Violet, and the broken tones of the luminous colours. The same as Luminous colours. The same as Sombre colours. Normal Grey, to which a primary or a se- Tertiary Colours . . . Coloured Greys. Russet is red-grey. Olive Tones. Hue. Scale. Tints Shades is blue-grey. Citrine is yellow-grey. The series of gradations of a colour from its greatest intensity, weakened by the addition of white, or deepened by the addition of black. The change produced in a Colour by the addition to it of another colour. The original colour must always be in the ascendancy, otherwise it becomes a hue of the colour added to it. The series of hues and tones of any given colour. The tones of a colour produced by the addition of white added to the normal colour. The tones of a colour produced by the addition of black to the normal colour. Prismatic Spectrum. . The image of a ray of light when decomposed by a prism. It consists of Blue, Red, and Yellow, and the combinations produced by their mixture or blending with each other, (secondaries) Orange, Green, Violet and its hues, purple, indigo, lavender, &c. ANALYSIS OF LIGHT AND COLOUR. THE SOURCE OF COLOUR. As Light is the source of Colour, it is necessary to commence with an examination of its composition, as the laws of contrast of colours are entirely dependent upon it. When a ray of sunshine, or white light, as it is termed, passes through a glass prism, it is decomposed, or separated, and if the image formed, called the prismatic spectrum, is received upon a white screen, placed at a suitable distance from the prism, it will be found to consist of various colours, arranged in a certain order, like those of the rainbow. These colours are six in number: three of which are simple; and three which are compound, resulting from the mixture of the simple colours in pairs. Blue, Red, and Yellow are simple, or primary colours. Green, Violet, and Orange are compound, or secondary colours. These compound colours vary in hue according to the proportions of the simple colours of which they are formed: thus, by increasing the quantity of blue in the mixture of blue and red, we produce purple, indigo, &c. The same effect takes place with Greens. The primary colours are simple and pure, they cannot, like the secondaries, be produced by the mixture of other colours. It is evident that the colour of the primaries cannot vary as colour (or in hue), but only in intensity, at least so long as they are kept pure, but the hues of the secondaries may vary infinitely, according as one or the other predominates. |