COLOUR, a property inherent in light, by which, according to its various proportions or quantities, or from some other cause, it excites different vibrations in the optic nerve, which, propagated to the sensorium, affect the mind with different sensations. See Chromatics and Optics. Colour, in Dyeing. See Dyeing. Colour, in Heraldry. The colours generally used in heraldry are, red, blue, black, green, and purple, which the heralds call gules., azure, sable, vert or sinople, and pur pure ; tenne or tawny, and sanguine, are not so common; and as to yellow and white, called or and argent, they are metals, not colours.

The metals and colours are sometimes expressed in blazonry by the names of precious stones, and sometimes by those of planets or stars.

Oenomaus is said first to have invented the distinctions of colours, to distinguish the gundillae of combatants at the Circensian games; the green for those who represented the earth, and the blue for those who represented the sea.

Colour, in the Human Species, difference of. See Complexion. Colour, in Painting, is applied both to the drugs, and to the tints produced by those drugs, variously mixed and applied.

The principal colours used by painters are red and white lead or ceruse; yellow and red ochres; several kinds of earth, umber, orpiment, lamp black, burnt ivory, black lead, cinnabar or vermilion, gamboge, lacca, blue and green ashes, verdigris, bistre, bice, smalt, carmine, ultramarine.

Of these colours, some are used tempered with gumwater, some ground with oil, others only in fresco, and others for miniature.

Painters reduce all the colours they use under these two classes, of dark and light colours; dark colours include black, and all others that are obscure and earthy, as umber, bistre, and the like. Under light colours are comprehended white, and all others that approach nearest to it.

Painters also distinguish colours into simple and mineral. Under simple colours they rank all those which are extracted from vegetables, and which will not bear the fire; as the yellow made of saffron, French berries, lacca, and other tinctures extracted from flowers, used by limners, illuminées, and others. The mineral colours are those which, being drawn from metals, <⅛c. are able to bear the fire, and therefore used by enamellers.

_ Changeable and permanent colours form another division of colours. Changeable colours are such as depend on the situation of the objects with respect to the eye, as that of a pigeon’s neck, taffeties, and the like; the first, however, being attentively viewed by the microscope, each fibre of the feathers appears composed of several little squares, alternately red and green, so that they are fixed colours.

Water-Colours are such as are used in painting with gum-water or size, without being mixed with oil. See Painting. Colour, in Plants, is an attribute found to be very variable. Different colours are observed, not only in different individuals of the same species, but likewise in different parts of the same individual. Thus, marvel of Peru and sweet-william have frequently petals of different colours on the same plant. Three or four different colours are frequently found upon the same leaf or flower, as on the leaves of the amaranthus tricoor, and the flowers of the tulip, auricula, three-coloured violet, and others. To produce the most beautiful and striking variety of colours in such flowers, is the principal delight and business of the florist.

The primitive colours, and their intermediate shades or gradations enumerated by botanists, are as follow:
Water-colour, hyalinus.
White.
Lead-colour, cincreus.
Black, niger.
Brown, fuscus.
Pitch-black, ater.
Yellow, luteus.
Straw-colour, flavus.
Flame-colour, fulvus.
Iron-colour, gilvus.
Red.
Flesh-colour, incarnatus.
Scarlet, coccineus.
Purple.
Violet-colour, caeruleo-pwpitreus.
Blue, caeruleus.
Green.

These colours seem to be appropriated to particular parts of the plant. Thus white is most common in roots, sweet berries, and the petals of spring flowers; watercolour in the filaments and styles; black in the roots and seeds, but rarely in the seed-vessel, and scarcely ever to be found in the petals. Yellow is frequent in the antherae, or tops of the stamina; as likewise in the petals of autumnal flowers, and the compound ligulated flowers of Linnaeus. Red is common in the petals of summer flowers, and in the acid fruits; blue and violet-colour in the petals; and green in the leaves and calyx, but rarely in the petals. In the interchanging of colours, which in plants is found to depend upon differences in heat, climate, soil, and culture, a sort of elective attraction is observed to take place. Thus, red is more easily changed into white and blue, blue into white and yellow, yellow into white, and white into purple. A red colour is often changed into a white, in the flowers of heath, mother of thyme, be-tony, pink, viscous campion, cucubalus, trefoil, orchis, foxglove, thistle, cudweed, saw-wort, rose, poppy, fumitory, and geranium. Red passes into blue in pimpernel. Blue is changed into white in bell-flower, greek-valerian, bindweed, columbine, violet vetch, milk-wort, goat’s rue, viper’s bugloss, comfrey, borrage, hyssop, dragon’s head, scabious, blue-bottle, and succory; but it is changed into yellow in crocus. Yellow passes easily into white in melilot, agrimony, mullein, tulip, blattaria, or moth-mulh in, and corn marigold. White is changed into purple in wood-sorrel, thorn-apple, peas, and daisy. ∙

Although plants are sometimes observed to change their colour upon being moistened with coloured juices, yet that quality in vegetables seems not so much owing to the nature of their nourishment, as to the action of the internal and external air, heat, light, and the primitive organiza-tíon[7:7:128] of the parts. In support of this opinion, we may observe, that there is far less variety in the colours of roots, than of the other parts of the plants ,∙ the pulp within the skin being usually white, sometimes yellow, rarely red. That this effect is produced by their small intercourse with the external air, appears from the circumstance, that the upper parts of roots, when they happen to stand naked above the ground, are often dyed with several colours. Thus the tops of sorrel roots turn red; those of turnips, mullein, and radishes, become purple; and many others are converted into green, whilst those parts of the same roots which lie more under ground are commonly white. The green colour is so proper to leaves, that many, as those of sage, the young sprouts of St John’s wort, and others which are reddish when in the bud, acquire a perfect green upon being fully expanded. In like manner, the leaves of the sea-side grape (polygonum), which when young are entirely red, become, as they advance in growth, perfectly green; except the middle and transverse ribs, which retain their former colour.

As flowers gradually open and are exposed to the air, they throw off their old colour and acquire a new one; in fact, no flow er has its proper colour until it is fully expanded. Thus the purple stock-julyflowers are white or pale in the bud; and in like manner bachelor’s buttons, bluebottle, poppy, red daisies, and many other flowers, though of divers colours when blown, are all white in the bud. Nay, many flowers change their colour thrice successively. Thus, the very young buds of lady’s looking-glass, bugloss, and the like, arc all white; the larger buds purple or murrey; and the open flowers blue.

With respect to the colours of the juices of plants, we may observe, that most resinous gums are tinctured; some, however, are limpid; and that which drops from the domestic pine is clear as rock-water. The milk of some plants is pale, as in burdock; of others white, as in dandelion, euphorbium, and scorzonera; and of others yellow, as in lo-vage, and greater celandine. Most mucilages have little colour, taste, or smell. Of all the colours above enumerated, green is the most common to plants, and black is the most rare.

Colour being a quality in plants so apt to change, ought never to be employed in distinguishing their species. These ought to be characterized from circumstances not liable to alteration by culture or other accidents. The same inconstancy of colour observed in the flowers is likewise to be found in the other parts of plants. Berries frequently change from green to red, and from red to white. Even in ripe fruits, the colour, whether white, red, or blue, is apt to vary; particularly in apple, pear., plum, and cherry trees. Seeds are more constant in point of colour than the vessel which contains them. In the seeds, however, of the poppy, oats, pea, bean, and kidneybean, variations are frequently observed. The root, too, although not remarkably subject to change, is found to vary in some species of carrot and radish. Leaves frequently become spotted, as in a species of orchis, hawk-weed, ranunculus, knot-grass, and lettuce; but seldom relinquish their green colour altogether. Those of some species of amaranthus, or flower-gentle, are beautifully coloured. The spots which appear on the surface of the leaves are of different colours, liable to vary, and not unfrequently disappear altogether. The leaves of officinal lung-wort, and some species of sow-bread, sorrel, trefoil, and ranunculus, are covered with white spots; those of dog's-tooth violet, with purple and white; those of several species of ranunculus and orchis, with black and purple; those of amaranthus tricoor, with green, red, and yellow; those of ranunculus acris, and a species of bog bean, with red or purple. The under surface of the leaves of some species of pimpernel and the sea-plantain is marked with a number of dots or points; a white line runs through the leaves of Indian reed, black-berried heath, and a species of Canary grass: and the margin or brim of the leaf, in some species of box, honeysuckle, ground-ivy, and the evergreen oak, is of a silver-white colour. The whole plant is often found to assume a colour that is unnatural or foreign to it. The varieties in some species of eryngo, mug-wort, orrach, amaranthus, purslane, and lettuce, furnish examples of this.

Such being the inconstancy of colours in all the parts of the plant, specific names derived from that quality are very properly deemed erroneous by Linnaeus; whether they respect the colour of the flower, fruit, seeds, roots, leaves, or express in general the beauty or deformity of the entire plant, with a particular view to that circumstance. But of this impropriety, committed by former botanists, Linnaeus himself is not always guiltless. Thus the two species of sarracena, or the side-saddle flower, are distinguished by the colour of their petals into the yellow and purple sarracena; although the shapes and figure of the leaves afford much more constant as well as striking characters. The same may be said of his lupinus albus and luteus ; reseda alba, glauca, and lutea; angelica atro-purpurea ; dictamnus albus ; lamium album ; selago coccinea ; sida alba ; passiflora rubra, lutea, incarnata, and caerulea; and of many others, in which the specific name is derived from a character or quality that is so liable to vary in the same species.

We shall conclude this article with observing, that of all sensible qualities, colour is the least useful in indicating the virtues and powers of vegetables. The following general positions on this subject are laid down by Linnaeus, and seem sufficiently confirmed by experiment :—A yellow colour generally indicates a bitter taste; as in gentian, aloe, celandine, turmeric, and other yellow flowers. Red indicates an acid or sour taste; as in cranberries, barberries, currants, raspberries, mulberries, cherries, the fruit of the rose, sea-bŉckthorn, and service-tree. Herbs which turn red towards autumn have likewise a sour taste; as sorrel, wood-sorrel, and bloody dock. Green indicates a crude alkaline taste, as in leaves and unripe fruits. A pale colour denotes an insipid taste; as in endive, asparagus, and lettuce. White promises a sweet luscious taste; as in white currants and plums, sweet apples, &c. Lastly, black indicates a harsh, nauseous, disagreeable taste; as in the berries of deadly night-shade, myrtle-leaved sumach, herb-christopher, and others, many of which are not only unpleasant to the taste, but pernicious and deadly in their effects.

Colours, Incapacity of distinguishing. Of this extraordinary defect in vision we have several instances in the Philosophical Transactions for 1777. One of the persons there mentioned lived at Maryport in Cumberland. The account was communicated by Mr Huddart to Dr Priestley, and is as follows: “His name was Harris, by trade a shoemaker. I had often heard from others that he could discern the form and magnitude of all objects very distinctly, but could not distinguish colours. This report having excited my curiosity, I conversed with him frequently on this subject. The account he gave was this: that he had reason to believe other persons saw something in objects which he could not see; that their language seemed to mark qualities with precision and confidence, which he could only guess at with hesitation, and frequently with error. His first suspicion of this arose when he was about four years old. Having by accident found in the street a child’s stocking, he carried it to a neighbouring house to inquire for the owner; he observed the people called it a red stocking, though he did not understand why they gave it that denomination, as he himself thought it completely[7:7:129] described by being called a slocking. This circumstance, however, remained in his memory, and, together with subsequent observations, led him to the knowledge of his defect.

« He also observed, that when young, other children could discern cherries on a tree, by some pretended difference of colour, though he could only distinguish them from the leaves by the difference of their size and shape. He observed also, that by means of this difference of colour they could see the cherries at a greater distance than he could, though he could see other objects at as great a distance as they, that is, where the sight was not assisted by the colour. Large objects he could see as well as other persons; and even the smaller ones, if they were not enveloped in other things, as in the case of cherries among the leaves.

« I believe he could never do more than guess the name of any colour; yet he could distinguish white from black, or black from any light or bright colour. Dove or straw colour he called white, and different colours he frequently called by the same name; yet he could discern a difference between them when placed together. In general, colours of an equal degree of brightness, however they might otherwise differ, he confounded together. Yet a striped ribbon he could distinguish from a plain one; but he could not tell what the colours were with any tolerable exactness. Dark colours, in general, he often mistook for black; but never imagined white to be a dark colour, nor dark to be a white colour.

« He was an intelligent man, and very desirous of understanding the nature of light and colours; for which end he had attended a course of lectures on natural philosophy.

“He had two brothers in the same circumstances as to sight, and two other brothers and sisters, who, as well as their parents, had nothing of this defect.

“One of the first mentioned brothers, who is now living, I met with at Dublin, and wished to try his capacity to distinguish the colours in a prism; but not having one by me, I asked him whether he had ever seen a rainbow: Jιe replied, he had often, and could distinguish the different colours; meaning only that it was composed of different colours, for he could not tell what they were.

“I then procured and show ed him a piece of ribbon; he immediately, and without any difficulty, pronounced it a striped, and not a plain ribbon. He then attempted to name the different stripes: the several stripes of white he uniformly and without hesitation called white; the four black stripes he was deceived in; for three of them he thought brown, though they were exactly of the same shade with the other, which he properly called black. He spoke, however, with diffidence as to all those stripes; and it must be owned that the black was not very distinct. The light green he called yellow; but he was not very positive; he said, “I think this is what you call yellow.” The middle stripe, which had a slight tinge of red, he called a sort of blue. But he was most of all deceived by the orange colour, of which he spoke very confidently, saying, “This is the colour of grass; this is green.” I also showed him a great variety of ribbons, the colour of which he sometimes named rightly, and sometimes as differently as possible from the true colour.

“I asked him whether he imagined it possible for all the various colours he saw to be mere difference of light and shade, and that all colours could be composed of these two mixtures only. With some hesitation he replied, no, he did imagine there was some other difference.

. “It is proper to add, that the experiment of the striped ribbon was made in the day time, and in a good light.”

Colours, in the Latin and Greek churches, are used to distinguish several mysteries and feasts celebrated therein.

Five colours only are regularly admitted into the Latin church; namely, white, green, red, violet, and black. The white represents the mysteries of our Saviour, the feast of the Virgin, those of the angels, saints, and confessors; the red, the mysteries and solemnities of the holy sacrament, the feasts of the apostles and martyrs; the green, the time between pentecost and advent, and from epiphany to septuagesima; the violet denotes advent and Christmas, vigils, rogations, and votive masses in time of war; lastly, the black is for the dead, and the ceremonies thereto belonging.

In the Greek church the use of colours is almost abolished, as well as among us. Red was, in the Greek church, the colour for Christmas and the dead.