There are, however, some anomalous popular names of classes, which, being shades nearly allied to the tertiary colours, have been confounded therewith, and being also of great practical importance, merit the consideration of the colourist. These denominations comprehend all the combinations of the primary, secondary, and tertiary colours, with the neutral, black, or shade, and therefore may be appropriately called semi-neutral colours; and they comport themselves precisely according to the preceding relations and arrangement throughout.

Of the various combinations of black, those in which yellow, orange, or citrine predominates, have obtained the name of brown, etc. A second class, in which the compounds of black are of a predominant red, purple, or russet hue, includes the denomination of makrone, chocolate, etc.; and a third class, in which the combinations of black have a predominating hue of blue, green, or olive, comprehends the colours termed grey, slate, etc. Brown, marrone, and grey may, therefore, be properly adopted as distinguishing appellations of the three classes of semi-neutral colours.*

These colours are of importance in practice, as following, deepening, or shading colours of the primaries, secondaries, and tertiaries, under which they are to be classed, and not to be confounded therewith as legitimate compounds and relatives. Nevertheless, we know an ingenious and eminent artist, who, confounding; shades with hues, and practice with theory, imagines he can always produce his third colours by the addition of black with unusual simplicity, harmony, and force; and a late professor of painting, upon alike supposition, talked of harmonizing his discordant colours by black. The same principle has probably prevailed upon many palettes: it must indeed be that upon which engravings in black are to be coloured, but would require transcendent skill in the painter to escape murkiness; and it may be presumed to have led many of the old masters into obscurity: so that the horror Rubens expressed at white in shadows ought powerfully to prevail against black in colours. A greater horror than either is a partiality for a particular colour; but, to put these horrors out of question, the painter ought to dread only the improper use of any colour. Black is, however, to be guarded against in another respect, that as colours or hues in pictures vanish or decay, blackness takes their place; and, for this, some allowance of freshness and force of colour should be made in painting. Nevertheless, the contrary of this is practised, when an artist, as he is too apt to do, looks at Nature with a prejudiced eye, and sees her objects not in their true colours, but of the hues he has seen in pictures, or of the colours he has been accustomed to paint them. Fearing to look upon her impracticably, or to raise himself up to Nature, he gets over the difficulty by deceiving himself, and pulling her down to his own level. Or demands, perhaps, with the poet, "Who can paint Like Nature? Can imagination boast, Amid her gay creation, hues like these? What hand can mix them with that matchless skill, And lay them on so delicately fine, And lose them in each other, as appears In every bud that blows? " Yet, by following Nature assiduously, the artist has power not only to approach, but to give permanence to her transitory beauties.

* See Note D.

Black is the absolute unity of the triad of colours, and hence has, in a degree, a uniting, monotonizing, or harmonizing power upon them, while it softens their discordances by obscuring them, which is the only rational defence of a practice wherein obscurity, monotony, or shade, is substituted for harmony: the perfection of colouring is, however, to combine harmony with brilliancy, unity with variety, and freshness with force, without violating the truth of nature. In cases, however, where the artist is constrained to represent his principal objects of given local or offensive colours, as in military dresses, etc, or is otherwise compelled by his subject to paint in a difficult key, this power of light and shade over colour stands him as an important aid. By an illegitimate practice in music, similar to the above, the discords of sound are tolerated by the ear when low in the scale, or thrown, unresolved by their proper consonances, growling into shade, the eye and ear being alike more sensible of high and brilliant relations of colours and sounds than of the low and deep.

If any of the preceding denominations of colours, or classes, should be objected against, others more significant or analogous may be substituted, if there be such; for we contend not for terms, content in the present case if those we have adopted convey our meaning to the reader.

With regard to the perspective of colours, or the manner in which they affect the eye, according to position and distance, it is a branch of aerial perspective, or the perspective of light and shade, and both are governed by similar laws. This perspective of light and colours is distinguished from linear perspective, or the perspective of drawing, as drawing is from colouring; and they have progressed alike in the art. The most antient painters seem to have known little of either; and linear perspective was established as science before the aerial, as drawing and composition preceded colouring.

The perspective of colours depends upon their powers to reflect the elements of light, - powers which are by no means uniform; accordingly, blue is lost in the distance before red, and yellow is seen at a distance at which red would disappear; yet blue preserves its hue better than red, and red better than yellow, because colours are cooled by distance. In this respect, the compound colours partake of the powers of their components, according to a general rule, by which local colours nearly related to black are first lost in the distance, and those nearly related to white disappear last. It is the same with local light and shade, the latter of which is totally lost at great distances; and hence it is that the shadowed side of the moon is not generally seen. These powers of colours are, however, varied by mist, air, altitude, and mixture, which produce evanescence; and by contrast, which preserves the force of colours by distinguishing them. Colours do not decline in force so much by height as by horizontal distance, because the upper atmosphere is less dense and less clouded with vapour; and hence it is that mountains of great elevation appear much nearer than they really are. From all these circumstances it is evident, that it is not a simple scumbling, or uniform degradation of local colours, that will effect a true perspective therein; for this will he the aerial of light and shade only; but such a subordination of hues and tints as the various powers of colours require, and is always observable in nature.