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black, and gray; and when transient, light, dark, and obscure; the intermedia, or degrees of which, are indefinite or infinite, and are termed shades, as those of colours are hues.

1041. By the latent concurrence of light and shade, Colours are generated or produced; and, as the various states of these principles are relative and convertible, we may deduce our proofs and examples from either. Thus, a white spot upon a black ground, or, vice versa, a black spot upon a white ground, viewed through a Lensic prism, will be refracted into an aureola of the primary colours, as represented surrounding the spot, thus:

Fig. 44.

and in either case the blue will lie toward the

For a description of this instrument, and a more extended account of the nature and relations of Colours, &c., see our "Chromatography," chap. iii. and xxvi., and also our "Chromatics" throughout; in which works the science of Chromatics is practically connected with its art.

VOL. II.

L

passive or dark principle, and the yellow toward the active or light principle, with red between them. Thus Colours, like Figures, are generated in the simplest manner by the extension and expansion of a point in space: to which might be added many other coincidences.

1042. It is not necessary in this experiment that either of these principles should be in their absolute extreme, as black and white, or light and shade, it being sufficient that they should be relatively light and dark to afford this effect; nor is it necessary that they should not be coloured, since a spot of either of the foregoing colours, or of any hue, shade, or compound thereof, being formed upon a ground lighter or darker than itself, will also yield an aureola of the three primary colours, modified or ruled by its own particular hue.

1043. In all these cases of the production of these three primary colours, they may, by an inversion of the experiment, be re-compounded and reduced to the original spot: thus, by the union of positive colours in due subordination, they become neutralized, and the negative colours, black, white, and gray, produced by a transition of their principles from latent to sensible concurrence, and vice versá.

1044. Thus the primary colours produced by analysis, or concurring in the synthesis of these principles or fundamentals in union, are three ; the first and lowest number capable of uniting in

variety, harmony, or system, and the variety of their union can be only three.

SECTION II.

1045. First, from the compounding or union of the primaries blue and red, proceeds the secondary purple on the dark extreme; secondly, from the union of yellow and red, proceeds orange on the light extreme; and, thirdly, from the union of blue and yellow, proceeds, medially, the secondary green.

1046. These correlations of colours, and their elements, may be represented in system in the following diagram, which is coincident with that of numbers [554].

[merged small][graphic][merged small]

1047. Not only does this diagram agree in form with that of numbers, but it agrees, also, with it numerically, the central black corresponding to the

number one, or first power, blue to two, red to three, and yellow to four; purple to five, green to six, and orange to seven; and, finally, white corresponding to zero, or infinity. And as the numbers of the Arithmetical Diagram, taken diametrically from either angle, amount to ten, which is the place of the first zero in numeration, so the colours compounded in the same order from the coloured angles of this Chromatic Diagram, amount to the neutral gray, the first stage in the infinity of shade, and corresponding to ten; in agreement with which analogy we have been enabled to reduce every tint or hue and shade of colours, however varied and compounded, to numerical computation with precision.*

SECTION III.

1048. It further follows, that the Secondary Colours, being also three, are capable of the same variety of combinations as their primaries and no more, and with like relations to the fundamentals of all colour; accordingly, from the pairing of the secondary colours, purple and green, proceeds the tertiary olive, on the dark extreme; from that of green and orange proceeds the tertiary citrine, on the light extreme; and, finally, from the union of purple and orange, proceeds the medial tertiary

russet.

*See Experiments on Colours and the Metrochome in our Chromatography, or Treatise on the Powers of Colours," &c.,

p. 248.

White.

1049. Of these tertiaries, blue predominates in, and gives its relations to, the olive, yellow to the citrine, and red to the russet. And as in each of the secondary colours two primaries meet, so in each of the tertiary colours all the three primaries are united. It follows, therefore, that no new distinctions of these elements can proceed from the like combinations of the tertiaries, although they have, in common with primaries and secondaries, innumerable intermediate and compound hues and shades.

1050. There is also an infinite series of hues, shades, and compounds, between the extremes of the chromatic elements, light and shade, or white and black, in the order of the following scale, in which colours are connected in series.

Fig. 46.

DEFINITIVE SCALE OF COLOURS.

Primaries.

Tertiaries.

Yellow, Red, Blue, Citrine, Russet, Olive.

[blocks in formation]

1051. Such are the distinctions, relations, and

gradations of Colours, as determined by the various

Black.

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