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Field's Chromatography - or Treatise on Colours and Pigments as Used by Artists
by George Field
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SALTER'S EDITION.

FIELD'S CHROMATOGRAPHY;

OR,

TREATISE ON COLOURS AND PIGMENTS

AS USED BY ARTISTS.

AN ENTIRELY NEW AND PRACTICAL EDITION;

REVISED, REWRITTEN, AND BROUGHT DOWN TO THE PRESENT TIME.

BY

THOMAS W. SALTER, F.C.S.

Ars probat artificem.

LONDON:

WINSOR AND NEWTON, 38, RATHBONE PLACE,

Manufacturing Artists' Colourmen by Special Appointment to Her Majesty, and Their Royal Highnesses the Prince and Princess of Wales.

[The Right of Translation is reserved.]



CONTENTS.

PART I. ON COLOURS AND COLOURING.

Chapter. Page.

I.—On Colouring 3

II.—On the Relations and Harmonies of Colours 13

PART II. ON COLOURS AND PIGMENTS GENERALLY.

III.—On Classes of Colours 27

IV.—On the Durability and Fugacity of Pigments 31

V.—On the General Qualities of Pigments 46

PART III. ON COLOURS AND PIGMENTS INDIVIDUALLY.

VI.—On Colours and Pigments individually 57

VII.—On the Neutral, White 62

VIII.—On the Primary, Yellow 81

IX.—On the Primary, Red 127

X.—On the Primary, Blue 183

XI.—On the Secondary, Orange 239

XII.—On the Secondary, Green 263

XIII.—On the Secondary, Purple 294

XIV.—On the Tertiary, Citrine 310

XV.—On the Tertiary, Russet 320

XVI.—On the Tertiary, Olive 325

XVII.—On the Semi-Neutral, Brown 334

XVIII.—On the Semi-Neutral, Marrone 362

XIX.—On the Semi-Neutral, Gray 372

XX.—On the Neutral, Grey 381

XXI.—On the Neutral, Black 387

Addendum 414

Index 417



NOTICE.

Among the works consulted in this Edition are the following, from most of which extracts have been taken:

Bancroft's Philosophy of Colours.

Brande's Manual of Chemistry.

Chemical News.

Chevreul on Colour.

Fownes' Manual of Chemistry.

Gmelin's Handbook of Chemistry.

Handbooks on Art.

Liebig and Kopp's Annual Report of the Progress of Chemistry.

Mrime's Painting in Oil.

Muspratt's Dictionary of Chemistry.

Normandy's Commercial Handbook of Chemical Analysis.

O'Neill's Chemistry of Calico Printing.

Quarterly Journal of the Chemical Society.

Ruskin's Elements of Drawing.

Watts' Dictionary of Chemistry.



PART I.

* * * * *

ON COLOURS AND COLOURING.



CHROMATOGRAPHY;

OR,

A TREATISE ON COLOURS AND PIGMENTS.

* * * * *



CHAPTER I.

ON COLOURING.

How early, and to what extent, colouring may have attained the rank of science among the ancients, are questions not easily set at rest; but that some progress had been made, even at a very remote period, is proved by the magnificent tombs of the Egyptian kings at Thebes, where the walls of the royal mausoleum are described as being covered with paintings so fresh and perfect, as to require neither restoration nor improvement. So far from this, indeed, that with all care in copying, it was difficult to equal the brilliancy of the originals, which, as far as colours went, threw all others in the background. And yet, in spite of the scale having comprised pure vermilion, ochres, and indigo, it was not gaudy, owing to the judicious balance of the colours, and the artful management of the black. Nor was there an ornament throughout the dresses, wherein the red, yellow, and blue, were not so employed as to produce a delicious harmony.

Moreover, it is stated that in one painting eighty feet high and proportionably broad, which was divided into two ranges of gigantic figures, these were glowing with most exquisite colours, suited to the drapery and naked parts; and in which the azure, yellow, green, &c., were as well preserved as though they had been laid on yesterday. Again, an apartment was discovered among the stupendous ruins at Carnac, on the site of ancient Thebes, one hundred paces wide and sixty deep, completely crowded with pillars, which, together with the ceiling, roof, and walls, were decorated with figures in basso-relievo, and hieroglyphics—all marvellously beautiful and finely painted, and as fresh, splendid and glorious, after so many ages, as if they had just been finished.

In various accounts these colourings of the Egyptians are described in the warmest terms of admiration. The most charming are undoubtedly those on the tombs and temples: others of less merit have been found on the cases and cloths of mummies, and on papyrus rolls; but it is to the patterns on the walls and ceilings of their houses that they seem to have been most partial, and paid the most attention. The ordinary colours employed by them were red, yellow, green, and blue. Of the last there were two tints; black also was common. For white, the finely prepared stone-coloured ground was deemed sufficient. These colours were occasionally modified by mixture with chalk; but were always, or nearly always, applied singly, in an unmixed state. With regard to their composition, chemical analysis has shown several of the blues to be oxide of copper with a small proportion of iron; none containing cobalt. There is little doubt, however, that the most brilliant specimens—those which retain all their original force and beauty in the temples of Upper Egypt after an exposure of three thousand years, consist of ultramarine—the celebrated Armenian blue, possibly, of the ancients. The reds seem for the most part to be composed of oxide of iron mixed with lime, and were probably limited to iron earths and ochres, with a native cinnabar or vermilion. The yellows are said to have been, in many cases, vegetable colours; but it is likely earths and ochres were their chief source. The greens consist of yellow mixed with copper blue. The bluish-green which sometimes appears on Egyptian antiquities, is merely a faded blue. The blacks are both of vegetable and mineral origin, having been obtained from a variety of substances in a variety of ways.

But, as shown by Layard in his discoveries at Nineveh, a knowledge of colouring was not confined to the Egyptians; it was likewise possessed by the Assyrians. The painted ornaments of the latter are stated to have been remarkably elegant; and although the colours were limited to blue, red, white, yellow, and black, yet they were arranged with so much taste and skill, and the contrasts were so judiciously preserved, that the combinations were in general agreeable to the eye. The pale yellowish-white ground on which the designs were painted, resembled the tint on the walls of Egyptian monuments, and a strong well-defined black outline was found to be as peculiar a feature in Assyrian as in Egyptian painting, black frequently combining with white alone, or alternating with other colours. As far as they have been analysed, the pigments employed were mineral, the brightest being a blue derived from copper. No traces of vegetable colours have been found; it is presumed that they existed, but being subject to more rapid decay than the mineral pigments, they have disappeared. That all the colours, indeed, employed by the ancients were not permanent, was proved by the fact of certain blues and reds, brilliant and vivid when the earth was removed from them, fading rapidly when exposed to the air.

From Philocles, the Egyptian, and Gyges, a Lydian, both of whom, according to Pliny, acquired the knowledge of the art of painting in Egypt, the Greeks obtained the knowledge of their Ars Chromatica, which they are said to have carried by gradual advances during several centuries, from the monochromatic of their earlier painters, to the perfection of colouring under Zeuxis and Apelles, 450 to 350 B.C. Unfortunately, not long after, or about 300 B.C., art rapidly deteriorated; the invasion of the Romans commenced; and the principles of light, shade, and colours in painting as understood by the Greeks, together with their valuable treatises on the subject were lost. The early Roman and Florentine painters, so eminent in other respects, were almost destitute of those principles, and of truly refined feeling for the effects of colouring.

The partial restoration of this branch seems to have been coeval with the earliest practice of painting in oil. The glory of it belongs to the Venetians, to whom the art of painting passed with the last remains of the Greek schools after the capture of Constantinople at the beginning of the thirteenth century. Giovanni Bellini laid the foundation of colouring, and Titian carried it to its highest practical perfection. From the Venetian it extended to the Lombard, Flemish, and Spanish schools. In the practice of these, however, there was perhaps as much of instinct as principle, colouring still remaining to be established in its perfection as a science.

According to the true, natural, and philosophical classification of painting, there are but three principal classes or schools; viz.: the gross and material which is content with mere nature, and to which belong the Dutch and Flemish schools; the sensible, which aims at refined and select nature, and accords with the Venetian school; and the intellectual, which aspires to the ideal in beauty, grandeur, and sublimity, and corresponds with the Greek, Roman, and Florentine schools. Modern art as founded upon the intellectual school of the ancient Greeks, became grand, scientific, and severe in the practice of Michael Angelo, and Leonardo da Vinci; graceful, beautiful and expressive in Raphael, Correggio, Dominichino, and Guido; and, aiming at sensible perfection, it attained harmony of colouring and effect in the works of Titian and Tintoret; but it sunk into grossness and sensuality while perfecting itself materially among the Flemish and Dutch.

In the practice of the individual in painting, as well as in all revolutions of pictorial art, in ancient Greece as in modern Italy, colouring in its perfection has been the last attainment of excellence in every school. It has been justly observed, indeed, that for near three hundred years, since painting was revived, we could hardly reckon six painters that had been good colourists, among the thousands who had laboured to become such. But there is reason to hope that as Zeuxis succeeded and excelled Polygnotus, and Titian Raphael, the artists of Britain will transcend all preceding schools in the chromatic department of painting. It is even probable that they may surpass them in all other branches, and in every mode and application of the art, as they have already more particularly done in an original and unrivalled use of water-colours.

Happily, too, there has arisen among us a school of colouring that confirms this expectation, strengthened as it is, by the suitableness of our climate to perfect vision. For in it we have that mean degree of light which is best adapted to the distinguishing of colours, a boundless diversity of hue in nature relieved by those fine effects of light and shade which are denied to more vertical suns, besides those beauties of complexion and feature in our females peculiar to England; respects in which at least our country is not unfavourable to art.

Even now it is urged by some to the disparagement of the British school, that it excels in colouring; as if this were incompatible with any other excellence, or as if nature, the great prototype of art, ever dispensed with it. The graphic branches of painting, owe everything to colour, which, if it does not constitute a picture, is its flesh and blood. Without it, the finest performances remain lifeless skeletons, and yield no pleasure. Painting is the art of representing visible things by light, shade, form, and colour; but of these, colour—and colour alone—is the immediate object which attracts the eye. Colouring is, therefore, the first requisite—the one thing imparting warmth and life—the chief quality engaging attention; in short, the best introduction to a picture, and that which continues to give it value so long as it is regarded. It is a power, too, which is with the most difficulty retained, being the first to leave the artist himself, and the first to quit a school on its decline. Graphic art without colouring, is as food without flavour; and it was the deficiency of colouring in the great works of the Roman and Florentine schools that caused Sir Joshua Reynolds to confess a certain want of attraction in them. To relish and estimate truly their greatness, required, he said, a forced and often-repeated attention, and "it was only those persons incapable of appreciating such divine performances, who made pretensions to instantaneous raptures on first beholding them." Gainsborough also, with a candour similar to that of Reynolds, upon viewing the cartoons at Hampton Court, acknowledged that their beauty was of a class he could neither appreciate nor enjoy.

Colouring, then, is a necessity; but there is in it a vicious extreme; that in which it is rendered so principal as, by want of subordination, to overlay the subject. There is also a negative excellence which consists in not always employing pleasing tints, but of sometimes taking advantage of the effects to be derived from impure hues, as Poussin did in his "Deluge." In this work, neither black nor white, blue, red, nor yellow appears; the whole mass being, with little variation, of a sombre grey, the true resemblance of a dark and humid atmosphere, by which every object is rendered indistinct and almost colourless. This absence of colour, however, is a merit, and not a fault. Vandyke employed such means with admirable effect in the background of a Crucifixion, and in his Pieta; and the Phaton of Giulio Romano is celebrated for a suffusion of smothered red, which powerfully excites the idea of a world on fire.

Of the rank and value of this department of painting, there will be, as there has been, difference of judgment and opinion, as there is variety in the powers of the eye and understanding. But take from Rubens, Rembrandt, Titian, and other distinguished masters, the estimation of their colouring, and we fear all that is left to them would hardly preserve their names from oblivion. Art cannot, indeed, attain its appropriate end, that of pleasing, without excellence in colouring. It is colour which the true artist most loves, and it is colouring in all its complex and high relations, that he ever seeks to attain. Looking above, and around, and beneath him, with the intelligent eye of the colourist, he finds a boundless source of never-ceasing enjoyment. With harmonies and accordances lost to the untutored gaze, colour meets him in every stone he treads on—in the mineral, vegetable, and animal creation—in the heavens, sea, and earth. For him, in truth, colour is as equally diffused as light, spreading itself over the entire face of nature, and clothing the whole world with beauty.



CHAPTER II.

ON THE RELATIONS AND HARMONY OF COLOUR.

Assured as we must be of the importance of colouring as a branch of art, colours in all their bearings become interesting to the artist, and on their use and arrangement his reputation as a colourist must depend.

Colour, remarks Ruskin, is wholly relative; each hue throughout a work is altered by every touch added in other places. Thus, to place white beside a colour is to heighten its tone; to set black beside a colour is to weaken its tone; while to put grey beside a colour, is to render it more brilliant. If a dark colour be placed near a different, but lighter colour, the tone of the first is heightened, while that of the second is lowered. An important consequence of this principle is, that the first effect may neutralize the second, or even destroy it altogether. What was cold before, becomes warm when a colder colour is set near it, and what was in harmony before, becomes discordant as other colours are put beside it. For example, to place a light blue beside a yellow, tinges it orange, and consequently heightens its tone. Again, there are some blues so dark relatively to the yellow that they weaken it, and not only hide the orange tint, but even cause sensitive eyes to feel that the yellow is rather green than orange—a very natural result when it is considered that the paler the yellow becomes, the more it tends to appear green.

We learn from these relations of colours, why dapplings of two or more produce effects in painting so much more clear and brilliant than uniform tints obtained by compounding the same colours: and why hatchings, or a touch of their contrasts, thrown as it were by accident upon local tints, have the same effect. We see, too, why colours mixed deteriorate each other, which they do more—in many cases—by imperfectly neutralizing or subduing each other chromatically, than by any chemical action. Finally, we are impressed with the necessity, not only of using colours pure, but of using pure colours; although pure colouring and brilliancy differ as much from crudeness and harshness, as tone and harmony from murkiness and monotony.

The powers of colours in contrasting each other agree with their correlative powers of light and shade, and are to be distinguished from their powers individually on the eye, which are those of light alone. Thus, although orange and blue are equal powers with respect to each other, as regards the eye they are totally different and opposed. Orange is a luminous colour, and has a powerfully irritating effect, while blue is a shadowy colour, possessing a soothing quality—and it is the same, in various degrees, with other colours.

There are yet further modes of contrast or antagonism in colouring, which claim the attention and engage the skill of the colourist. Of the contrast of hues, upon which depend the brilliancy, force, and harmony of colouring, we have just spoken; but there is, secondly, the contrast of shades. To this belong all the powers of chiaroscuro, by which term the painter denotes the harmonious effects of light and shade; and though they form the simplest part of colouring, yet they cannot be separated from it—light and shade, the chiaroscuro, being a distinct and important branch of painting. A third mode of contrast in colouring is that of warmth and coolness, upon which depend the toning and general effect of a picture. Fourthly, there is the contrast of colour and neutrality, the chromatic and achromatic, or hue and shade. By the right management of this, local colours acquire value, gradation, keeping, and connection: whence come breadth, arial perspective, and the due distribution of greys and shadows in a picture.

This principle of contrast applies even to individual colours, and conduces greatly to good colouring. It may be carried with advantage into the variety of hue and tint in the same colour, not only as regards light and shade, but likewise with respect to warmth and coolness, as well as to colour and neutrality. Hence the judicious landscape-painter knows how to avail himself of warmth and coolness in the juxtaposition of his greens, in addition to their lightness and darkness, or brilliancy and brokenness, in producing the most beautiful and varied effects; effects which spring in other cases from a like management of blue, white, &c. These powers of a colour upon itself are highly important to the artist, and lead to that gratification from fine colouring, which a good eye ever enjoys.

In landscape we see nature employing broken colours in harmonious consonance and variety, while, equally true to picturesque relations, she uses also broken forms and figures, in conjoint harmony with colours; occasionally throwing into the composition a regular form, or a primary colour, for the sake of animation and contrast. And if we inspect her works more closely, we shall find that they have no uniform tints. Whether in the animal, vegetable or mineral creation—flesh or foliage, earth or sky, flower or stone—however uniform the colour may appear at a distance, it will, when examined nearly, be found to consist of a variety of hues and shades, compounded with harmony and intelligence.

It is for this reason that no two colours are ever found discordant in nature, however much so they may be in art. Blue and green have been termed discordant, and in painting they may undoubtedly be made so. Yet those are two colours which nature seems to intend never to be separated, and never to be felt, either of them, in its full beauty, without the other—a blue sky through green leaves, or a blue wave with green lights through it, being precisely the loveliest things, next to clouds at sunrise, in this coloured world of ours. A good eye for colour will soon discover how constantly nature puts green and purple together, purple and scarlet, green and blue, yellow and neutral grey, and the like; and how she strikes these colour-concords for general tones, before working into them with innumerable subordinate ones.

Upon the more intimate union, or the blending and gradience of contrasts from one to another mutually, depend some of the most fascinating effects of colouring. The practical principle employed in producing them is important, and consists in the blending and gradating by mixture, while we avoid the compounding of contrasting colours. That is, the colours must be kept distinct in the act of blending them, or otherwise they will run into dusky neutrality and defile each other. This is the case in blending and gradating from green to red, or from hue to hue—from blue to orange, or to and from coldness and warmth—from yellow to purple, or to and from advancing and retiring colours. It is the same in light and shade, or white and black, which mix with clearness. Now, there are only two ways in which this distinctness in union of contrasts can be effected in practice: the one is by hatching or breaking them together in mixture, without compounding them uniformly; and the other is by glazing, in which the colours unite and penetrate mutually, without monotonous composition.

The former process may be said to be the carrying out of the principle of separate colours to the utmost possible refinement, by using atoms of colour in juxtaposition, instead of in large spaces. And it is to be noted, in filling up minute interstices of this kind, that if the colour with which they are filled be wanted to show brightly, a rather positive point of it had better be put, with a little white left beside or round it in the interstice. This plan is preferable to laying a pale tint of the colour over the whole interstice. Yellow or orange, for instance, will hardly show, if pale, in small spaces; but they show brightly in free touches, however small, with white beside them. The latter mode is founded on the fact, that if a dark colour be laid first, and a little blue or white body-colour struck lightly over it, a more beautiful gray will be obtained than by mixing the colour and the blue or white. Similarly, if over a solid and perfectly dry touch of vermilion there be quickly washed a little very wet carmine, a much more brilliant red will be produced than by mixing the two colours.

Transparency and opacity constitute another contrast of colouring, the former of which belongs to shade and blackness, the latter to light and whiteness. Even contrast has its contrast, for gradations or intermedia are opposed to contrasts or extremes; and, upon the right management of contrasts and gradations depend the harmony and melody, the tone, effect, and general expression of a picture. Thus, painting is an affair of judicious contrasting so far as regards colour, if even it be not such altogether.

Colour, it has already been observed, is wholly relative. In contrasting, therefore, any colour, if we wish it to have light or brilliancy, we cast its opposite into the shade; if we would have it warm, we cool its antagonist; and if transparent, we oppose it by an opaque contrary, and vice vers: indeed, in practice, all these must be in some measure combined.

Such are some of the powers of contrast in colouring alone, and such is the diversity of art upon which skill in colouring depends. It must not be forgotten, however, that contrasts or extremes, whether of light and shade, or of colours, become violent and offensive when they are not reconciled by the interposition of their media, or intermediates, which partake of both extremes of the contrasts. Thus blue and orange in contrast become reconciled, softened in effect, and harmonized, when a broken colour composed of the two intervenes. The same may be said of other colours, shades, and contrasts.

Seeing that the management and mastery of colours are to a great extent dependent on the same principles as light and shade, it might become a point of good discipline, after acquiring the use of black and white in the chiaroscuro, to paint designs in contrast; that is, with two contrasting colours only, in conjunction with black and white—for example, with blue and orange, before attempting the whole. Indeed, black can be dispensed with in these cases, because it may be compounded, since the neutral grey and third colours always arise from the compounding of contrasting colours. In this way, even flesh may be painted—for instance, with red and green alone, as Gainsborough is said at one period to have done.

Some artists have produced pictures in the above hot and cold colours only; which, although captivating to the eye, and true in theory with respect to colour, light and shade, are generally false in practice with regard to nature, which rarely employs such extreme accordances. Colouring like this, therefore, is more beautiful than true. It is as though a painter were to execute a landscape in the full light of day, as he saw it looking through a prism, so that every object glowed with rainbow hues. Such a picture would present a beautiful fairy scene, and be true as regards colours, but as respects nature, it would be false.

Colour, and what in painting is called transparency, belong chiefly to shade. It has been a common error to ascribe those properties to light only, and hence many have employed a uniform shade tint, regarding shadows as simply darkness, blackness, or the mere absence of light; when, in truth, shadows are infinitely varied by colour, and always so by the colours of the lights which produce them. But while we incline attention toward the relation of colour to shade, both light and shade being strictly co-essential to colour, a vicious extreme must be avoided. For although, as transparent, colour inclines to shade, and, as opaque, it partakes of light; yet the general tendency of colour is to transparency and shade, all colour being a departure from light. Hence it becomes a maxim, which he who aspires to good colouring must never lose sight of, that the colour of shadow is always transparent, and only that of extreme light objects opaque. It follows, that white is to be kept as much as possible out of shadow, and black, for the same reason, out of colour. In their stead, whenever it is necessary to cover, opaque tints may be employed, glazed over with transparent colours. Such practice would also be more favourable to durability of the tones of pictures, than the shades and tints produced with black and white. The hues and shadows of nature are in no ordinary case either black or white, which, except as local colours, are always poor and frigid. The perfection of colouring is to combine harmony with brilliancy, unity with variety, and freshness with force, without violating the laws of nature.

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 arial perspective or the perspective of light and shade. This 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 ancient painters seem to have known little of either; and linear perspective was established as science before the arial, 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 point at which red would disappear; yet blue preserves its hue better than yellow, because colours are cooled in the distance. In this respect, the compound colours partake of the powers of their components, in obedience to a general rule, by which local colours closely connected with black are first lost in the distance, and those nearly related to white disappear last. The same may be said of local light and shade, the latter of which is totally lost at great distances; and it is for this reason 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 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 a simple scumbling or uniform degradation of local colours will not effect a true perspective—for this will be the arial of light and shade only—but such a subordination of hues and tints, as the various powers of colours require, and as is always observable in nature.

In furnishing or setting the palette philosophically and upon principle, it is necessary to supply it with pure blue, red, and yellow; to oppose to these an orange, of a hue that will neutralise the blue—green, of a hue that will neutralise the red—and purple, of a hue that will neutralise the yellow; and so on to black and white, which will neutralise each other. As in nature, the general colour of the sky is blue, and the colour of light is always opposite to that of the sky and shade, so the white which is to represent light should be tinged with the orange of the palette sufficiently to neutralise the predominant coldness of black. Pure neutral white may thus be reserved as a "local" colour, which is a technical term for the natural colour of an object, unvaried by distance, reflection, or anything interfering with distinct vision; although, properly speaking, local colours are subject to all the relations and effects of the places they occupy in a composition—whether of light, shade, reflection, or distance.

From what we have said, it will be seen that the relations and harmony of colours form a complex subject, requiring constant and careful study; one, indeed, into which he who would become a colourist must enter heart and soul. For as colouring is the beginning and end of a painter's craft, so colour in all its aspects must be the chief lesson of his life. And this lesson can only be learnt, by ever watching with a loving eye those wondrous colourings of nature, in which there is nothing inharmonious or out of place.



PART II.

* * * * *

ON COLOURS AND PIGMENTS GENERALLY.



CHAPTER III.

ON CLASSES OF COLOURS.

By mixing his colours with white, the artist obtains his tints. By mixing colours with colours, he produces compound colours, or hues. And by mixing colours or tints with black, he gets shades. It is a common error to confound these distinctions.

The above classification of colours enables us to understand the simplicity of relation which exists among an infinity of tints, hues, and shades of colour. Also, it is calculated to give precision to language respecting colours, the nomenclature of which has too often been vague and uncertain.

There are five classes of colours, viz.:—the Neutral, the Primary, the Secondary, the Tertiary, and the Semi-neutral.

Neutral Colours are three only, white, black, and grey. According to the laws of Optics, the two first comprise all other colours synthetically, and afford them all by analysis. These are sometimes called "extreme" colours, grey being their intermediate.

Primary Colours are three only, yellow, red, and blue. They are such as yield others by being compounded, but are not themselves capable of being produced by composition of other colours. By way of distinction, they are occasionally designated "entire" colours.

Secondary Colours, are three only, orange, green, and purple. Each of these is composed of, or can be resolved into, two primaries. Thus, orange is composed of red and yellow; green, of yellow and blue; and purple, of blue and red.

Tertiary Colours are three only, citrine, russet, and olive. Each of these is composed of, or can be resolved into, either two secondary colours, or the three primaries. Thus, citrine consists of green and orange, or of a predominant yellow with blue and red; russet is compounded of orange and purple, or of a predominant red with blue and yellow; and olive is composed of purple and green, or of a predominant blue with yellow and red.

The last three genera of colours comprehend in an orderly gradation all those which are positive or definite; and the three colours of each genus, united or compounded in such subordination that neither of them predominates to the eye, constitute the negative or neutral colours, of which black and white have been stated to be the opposed extremes, and greys their intermediates. Thus black and white are constituted of, and comprise latently, the principles of all colours, and accompany them in their depth and brilliancy as shade and light.

Semi-neutral Colours belong to a class of which brown, marrone, and gray may be considered types. They are so called, because they comprehend all the combinations of the primary, secondary, and tertiary colours, with the neutral black. Of the various combinations of black, those in which yellow, orange, or citrine predominates, have obtained the name of brown, &c. A second class in which the compounds of black are of a predominant red, purple, or russet hue, comprises marrone, chocolate, &c. And a third class, in which the combinations of black have a predominating hue of blue, green, or olive, includes gray, slate, &c.

While treating of the classes of colours, it may not be out of place to note here the difference between gray as spelt with an a, and grey as spelt with an e, the two names being occasionally confounded. Gray is semi-neutral, and denotes a class of cool cinereous colours, faint of hue; whence we have blue grays, olive grays, green grays, purple grays, and grays of all hues in which blue predominates; but no yellow or red grays, the predominance of such hues carrying the compounds into the classes of brown and marrone, of which gray is the natural opposite. Grey is neutral, and is composed of or can be resolved into black and white alone, from a mixture of which two colours it springs in an infinite series.

It must be observed that each colour may comprehend an indefinite series of shades between the extremes of light and dark, as each compound colour also may comprise a similar series of hues between the extremes of the colours composing it. And as the relations of colours have been deduced regularly, from white or light to black or shade; so the same may be done, inversely, from black to white. On this plan the tertiaries, olive, russet, and citrine, take the place of the primaries, blue, red, and yellow; while the secondaries still retain their intermediate station and relation to both.

Thus, russet and olive compose or unite in dark purple; citrine and olive in dark green; russet and citrine in dark orange. The tertiaries have, therefore, the same order of relation to black that the primaries have to white; and we have black primaries, secondaries, and tertiaries, inversely, as we have white primaries, secondaries, and tertiaries, directly. In other words, we have light and dark colours in all classes.



CHAPTER IV.

ON THE DURABILITY AND EVANESCENCE OF PIGMENTS.

Pigments may be defined as colours in a solid or insoluble state, prepared for the artists' use. Hitherto, we have treated of colours in the abstract sense, as appealing to the eye only: we have now to consider them as material bodies.

As colour itself is relative, so is durability of colour relative. For the reason that all material substances are changeable and in perpetual action and reaction, no pigment is so permanent as that nothing will alter its colour. On the other hand, none is so fugitive as not to last under some favouring circumstances. Time, of long or short continuance, has often the effect of fire, more or less intense. Indeed, it is some sort of criterion of the stability and changes of colour in pigments, that time and fire are apt to produce similar effects thereon. Thus, if fire deepen, or cool, or warm a colour, so may time; if it vary its hues, so may time; if it destroy a colour altogether, so may time ultimately. The power of time, however, varies extremely with regard to the period in which it produces those effects, that are instantly accomplished by fire.

That there is no absolute but only relative durability of colour may be proved from the most celebrated pigments. For instance, the colour of native ultramarine, which will endure a hundred centuries under ordinary circumstances, may be at once destroyed by a drop of lemon juice; and the generally fugitive and changeable carmine of cochineal will, when secluded from light and air, continue fifty years or more; while fire or time, which merely deepen the former colour, will completely dissipate the latter. Again, there have been works of art in which the white of lead has retained its freshness for ages in a pure atmosphere, but has been changed to blackness after a few days' or even hours' exposure to foul air. These and other peculiarities of colours will be noticed, when we come to speak of pigments individually; not for the purpose of destroying the artist's confidence, but as a caution, and a guide to the availing himself of their powers properly.

It is, therefore, the lasting under the usual conditions of painting, and the common circumstances to which works of art are exposed, that entitles a colour to the character of permanency; and it is the not-so-enduring which attaches to it rightly the opposite character of evanescence: while a pigment may obtain a false repute for either, by accidental preservation or destruction under unusually favourable or fatal circumstances.

Many have imagined that colours vitrified by intense heat are consequently durable when levigated for painting in oil or water. Had this been the case, the artist need not have looked farther for the furnishing of his palette than to a supply of well-burnt and levigated enamel pigments. But though such colours for the most part stand well when fluxed on glass, or in the glazing of enamel, they are nearly, without exception, subject to the most serious changes when ground to the degree of fineness necessary to their application as pigments, and become liable to all the chemical changes and affinities of the substances which compose them. These remarks even apply in a measure to native products, such as coloured earths and metallic ores.

Others have not unreasonably supposed that when pigments are locked up in varnishes and oils, they are safe from all possibility of change. The assumption would be more warranted if we had an impenetrable varnish—and even that would not resist the action of light, however well it might exclude the influence of air and moisture. But, in fact, varnishes and oils themselves yield to changes of temperature, to the action of a humid atmosphere, and to other influences: their protection of colour from change is therefore far from perfect.

Want of attention to the unceasing mutability of all chemical substances, as well as to their reciprocal actions, has occasioned those changes of colour to be ascribed to fugitiveness of the pigment, which belong to the affinities of other substances with which it has been improperly mixed and applied. It is thus that the best pigments have suffered in reputation under the injudicious processes of the painter; although, owing to a desultory practice, the effects and results have not been uniform. If a colour be not extremely permanent, dilution will render it in some measure more weak and fugitive; and this occurs in several ways—by a too free use of the vehicle; by complex mixture in the formation of tints; by distribution, in glazing or lackering, of colours upon the lights downward, or scumbling colours upon the shades upward; or by a mixed mode very common among the Venetian painters, in which opaque pigments are combined, as umber and lake.

The fugitive colours do less injury in the shadows than in the lights of a picture, because they are employed pure, and in greater body in shadows, and are therefore less liable to decay by the action of light, and by mixture. Through partially fading, moreover, they balance any tendency to darken, to which the dead colouring of earthy and metallic pigments is disposed.

The foregoing circumstances, added to the variableness of pigments by nature, preparation, and sophistication, have often rendered their effects equivocal, and their powers questionable. These considerations enforce the expediency of using colours as pure and free from unnecessary mixture as possible; for simplicity of composition and management is equally a maxim of good mechanism, good chemistry, and good colouring. Accordingly, in respect to the latter, Sir Joshua Reynolds remarks, "Two colours mixed together will not preserve the brightness of either of them single, nor will three be as bright as two: of this observation, simple as it is, an artist who wishes to colour bright will know the value."

There prevail, notwithstanding, two principles of practice on the palette, opposed to each other—the one, simple; the other, multiple. The first is that of having as few pigments as possible; and consists, when carried to the extreme, in employing the three primary colours only. The second is that of having a number of pigments; and consists, also when carried to the extreme, of employing as many, if possible, as there are hues and shades of colour.

On the former plan, every tint requires to be compounded; on the latter, one pigment supplies the place of two or more. Now, the more pigments are mixed, the more they are deteriorated in colour, attenuated, and chemically set at variance. Original pigments, that is, such as are not made up of two or more colours, are purer in hue and generally more durable than those compounded. Hence pure intermediate tints in single, permanent, original pigments, are to be preferred to pigments compounded, often to the dilution and injury of their colours. Cadmium Orange, for instance, which is naturally an orange pigment and not composed of red and yellow, is superior to many mixtures of those colours in a chemical sense, and to all such mixtures in an artistic sense. At the same time, it is quite possible for the artist to multiply his pigments unnecessarily. Colours are sometimes brought out under new names which have no claim to be regarded as new colours, being, indeed, mere mixtures. Compound pigments like these may most frequently be dispensed with, in favour of hues and tints composed extemporaneously of original colours upon the palette.

It may be inferred from the foregoing that, between the modes of employing as few pigments as possible, and of having as many as there are hues and shades of colour, a middle course is the best. But, whatever the practice adopted, permanent original pigments should be used as often as the case will admit; it being borne in mind, that a pigment may be compound, although its colour may be primary. As a rule, the less colours are mixed, the purer, brighter, and more lasting they will be found.

To the practice of producing tints and hues by grinding pigments together, instead of blending them on the palette, may be attributed some of the peculiarities of the tints and textures of the Flemish school; they being, perhaps, results of intimate combination from grinding, and consequently of a more powerful chemical action among the ingredients compounded. This method has, in a great measure, fallen into disuse, and undoubtedly it conduced to foulness when the colours of the pigments ground were not pure and true, and did not assimilate well in mixture chemically.

The superiority of Rubens and the Flemings, and of Titian and the Venetian school, in colouring and effect, is due in a considerable degree to their sketching their designs in colours experimentally with a full palette. This practice, as derived from Reynolds, is common with the best masters of our own school, who, in executing their works, resort also to nature, with an improved knowledge of colours and colouring. Such attention to colouring and effect, from the first study and ground of a picture to the finishing, contributes a beauty to the painting no superinduced colouring can accomplish.

The durability of colour in substances is to a great extent dependent upon the condition in which they exist chemically. If pigments, for example, be in a state which chemists have termed protoxide, they are liable to absorb oxygen on exposure to light, air, or moisture, and becoming what is called peroxidized, may, by consequence, change or fade. In like manner, lakes and carmines thrown down upon a base, may owe some of their fugacity to the oxidation of that base, as well as to the natural infirmity of their colouring matter. On the other hand, pigments and bases are subject to deoxidation, or to a loss of oxygen, in which case the colour is apt to deepen. Pigments generally are more affected by oxidation and fading in a water vehicle, and by deoxidation and darkening in one of oil.

A principal test of permanency in pigments is the impunity with which they bear exposure to light and air, an artistic proof of their stability the mere chemist is apt to neglect. Provided the colour remain unaffected by sulphuretted hydrogen, &c., he seldom hesitates to pronounce it safe. But a pigment may be fast in one sense and fugitive in another, believed in by the laboratory, and found wanting by the studio. It has happened before now that the same colour has been dubbed durable and the reverse, by the man of science and the man of art. The former, we take it, looks upon a pigment as a coloured substance of a certain composition, possessing maybe an acid and a base, either, or neither, or both of which, gases and other reagents may injure or destroy. The latter views a colour chiefly as part and parcel of his picture—that picture which may meet with foul exhalations, but must be exposed to light and air. And he too often thinks as little of the effects of an impure atmosphere or injudicious admixture, as the chemist considers the action of air and light.

With the exception of madder, those colours mostly affected by light and air are of organic origin, such as gallstone, Indian yellow, and the yellow dye-wood lakes; the red and purple lakes of cochineal; indigo; and sap green. To these may be added the semi-organic Prussian blue; and the inorganic yellows and orange of arsenic.

The pigments liable to injury from sulphuretted hydrogen, &c., are notably those obtained from lead and copper; and that treacherous compound of iodine and mercury, known as pure scarlet.

Many colours are apt to change from the action of white lead and other lead pigments, &c., principally those which are altered by light and air.

Many, too, cannot safely come into contact with iron, or ferruginous pigments; especially the yellows of arsenic, the lakes of cochineal, and the blues and greens of copper. With these an iron palette knife is best avoided, one of ivory or horn being used instead. The latter, indeed, is preferable in all cases, several pigments being slightly affected by iron, cadmium yellow among the number.

Numerous colours are likewise injured by lime and fire, and cannot therefore be employed in fresco, or enamel painting.

Of substances which may act deleteriously on colours, there remain the vehicles and varnishes with which they are mixed. Many of these have been blamed, and often with justice, for their injurious effects on pigments. The reputation of the most permanent colour may be ruined, if the vehicle, &c., employed with it be untrustworthy. The presence of lead, for instance, in such materials renders them liable to be blackened by foul air, and by consequence the pigments used therewith.

Time produces in many cases a mellow and harmonious change in pictures, but occasionally alterations altogether unfavourable. To ensure the former and prevent the latter, the attention of the artist in the course of his colouring should be to the employment of such pigments and colours as are prone to adapt themselves, in changing, to the intended key of his colouring, and the right effect of his picture. Thus, if he design a cool effect, ultramarine has a tendency through time to predominate and aid the natural key of blue. He will, therefore, compromise the permanence of this effect, if in such case he employ a declining or changeable blue, or if he introduce such reds and yellows as have a tendency to warmth or foxiness, by which the colouring of many pictures has been destroyed. In a glowing or warm key, the case is in some measure reversed—not wholly so, for it is observable that those pictures have best preserved their colouring and harmony in which the blue has been most lasting, by the pigment counteracting the change of colour in the vehicle, and that suffusion of dusky yellow which time is wont to bestow upon pictures even of the best complexion.

Unless introduced and guaranteed by houses of acknowledged reputation, newly discovered pigments are to be used with caution. Good colours have ever been prized with so true an estimation of their value, that to produce such, after so many ages of research is no ordinary accomplishment. But too many resplendent pigments, fruits of the fecundity of modern chemistry, have been found deficient. The yellow and orange chromates of lead, for instance, withstanding as they do the action of the sunbeam, become by time, foul air, and the influence of other pigments, inferior to the ochres. So the dazzling scarlet of iodine and mercury must yield the palm of excellence to the more sober vermilion, being a chameleon colour, subject to the most sudden and opposite changes. And the blues of cobalt, as always tending to greenness and obscurity, cannot rank beside ultramarine.

We are far from asserting, however, that all modern pigments are inferior, or that pigments should be looked upon with suspicion because they are modern. Several most valuable colours have lately claimed attention, notably the permanent transparent yellow called Aureolin. Seeing that, until its introduction, a yellow combining transparency with a perfect stability was unknown to the palette, the importance of such an addition, so long wanted and wished for, cannot be overrated. Equal in beauty and durability with the preceding, but possessing greater richness and depth, and of a semi-opacity, another yellow of the highest order merits regard, Orient Yellow, distinguished for its lustrous golden hue, resembling a bright Indian yellow. Dazzling in brilliancy, and absolute in permanency. Cadmium Red next attracts notice. This new aspirant for artistic fame is a most vivid orange-scarlet, the latter colour predominating, of intense fire, but with no approach to rankness or harshness, yielding delicate pale washes, and blending happily with white in the formation of flesh tints. With it may be coupled Cadmium Orange, a colour equally brilliant and stable, and equally without rankness or harshness, but of a true orange hue, admirably adapted for sunsets and the like. Last of all the fresh pigments of whose thorough durability there is no doubt, comes the splendid Viridian, a green nothing but fire will change, and no mixture of blue and yellow will afford. Clear, bright, and transparent as the emerald, it rivals velvet in its soft gorgeous richness. With this and Aureolin a series of beautiful foliage tints may be formed, sparkling with sunshine, as it were.

Other colours there are which have been brought forward within the last few years, not possessing the absolute permanency of the five foregoing, but equal, or superior, to many formerly used. It were folly, therefore, and a silly conservatism on the part of the artist to limit himself to such pigments only as were employed by his forefathers, especially as their merits were often more than doubtful. New colours, it is true, have to be learnt, for each pigment has its own peculiar habitudes, chemical, physical, artistic; but if they be good and durable, no amount of time and study spent upon them is thrown away. To think less of the quality of one's materials than of the effects which can be produced with them is mistaken policy; and to be content with that quality when better can be had, shows no real love of art, but rather indolence and apathy.

Perhaps one reason why freshly introduced pigments have not as fair a chance as they are entitled to, is due to the fashion which prevails of exclaiming against the fugacity of modern colours. If their detractors would confine themselves to certain colours, there could be no denial; but to assert, as is often done, that the cause of modern pictures not standing is owing to modern pigments generally, is unjust. It is not the materials which should be blamed, but those who use them. The fact is, that the artist's knowledge has not increased in proportion to the greater variety of colours at his command. In the early periods of art, when the palette was chiefly confined to native pigments, the painter could not very well go wrong. Now-a-days but too many, wanting the skill of the old masters, seek to make amends for it by brilliancy of colouring: with imperfect knowledge of their materials the result is obvious. The palette, we admit, wants weeding; not only of the bad new colours, but of the bad old colours. This, however, must be a work of time, and depend, not upon the colourman—for where there is a demand there will be a supply—but upon the artists themselves. To this end an increased acquaintance with the properties of pigments is required, whereby they may be able to choose the fast from the fugitive. It may be fairly assumed that the painter will be assisted in his task by the progress of chemical science, which will doubtless add from time to time to the list of stable pigments. We have heard it remarked that there are too many colours already—to which we reply, there are not too many good colours, and scarcely can be. The more crowded the palette is with reliable pigments, the more likely are the worthless to be pushed from their places. In our opinion, there is ample room for fresh colours, provided they be durable; and we have as little sympathy with the stereotyped cry of there being too many, as with the fashionable unbelief in modern pigments. Certainly, the artist who seeks for permanence among the whites, reds, or blues, will not be troubled with a superfluity. Certainly, too, colours are as good as ever they were, and better—better made, better ground, better prepared for use. But, fast and fugitive, pigments are more numerous, and for that reason need more careful selection.



CHAPTER V.

ON THE GENERAL QUALITIES OF PIGMENTS.

The general attributes of a perfect pigment are beauty of colour, comprehending pureness and richness, brilliancy and intensity, delicacy and depth,—truth of hue—transparency or opacity, well-working, crispness, setting up, or keeping its place, and desiccation, or drying well. To all of these must be superadded durability when used, a quality to which the health and vitality of a picture belong, and one so essential that all other properties put together without it are of no esteem with the artist who merits reputation. We have, therefore, given it a previous distinct consideration.

It must be observed that no pigment possesses all the foregoing qualifications in perfection, some being naturally at variance or opposed; nor is there any, perhaps, that cannot boast excellence in one or more of them.

Beauty commonly comprises in the same pigment delicacy, purity, and brilliancy; or depth, richness, and intensity. Delicacy and depth in the beauty of colours are at variance in the production of all pigments, so that perfect success in producing the one is attended with more or less of failure in the other, and when they are united—as they occasionally are—it is with some sacrifice of both. Hence the judicious artist purveys for his palette at least two pigments of each colour, one eminent for delicate beauty, the other for richness and depth.

Truth of hue is a relative quality in all colours, except the extreme primaries, in the relations of which, blue, being of nearest affinity to black or shade, has properly but one other relation, in which it inclines to red and becomes purple-blue: it is, therefore, faulty or false, when, tending to yellow, it becomes of a green hue. But red, which is of equal affinity to light and shade, has two relations, by one of which it verges upon blue and becomes a purple-red or crimson; and by the other it leans to yellow, and becomes an orange-red or scarlet, neither of which is individually false or discordant. Yet yellow, which is of nearest affinity to white or light, has strictly but one true relation, by which it inclines to red, and becomes a warm or orange yellow, for by uniting with blue it becomes a defective green-yellow. The best example of true yellow in a pigment, tending neither to red nor blue, is furnished by Aureolin, alluded to in the last chapter. The secondary and tertiary colours, having all duplex relations, may incline without default to either of their relatives.

Transparency is an essential property of all glazing pigments, and adds greatly to the value of dark or shading colours; indeed it is the prime quality upon which depth and darkness depend, as whiteness, or light, does upon opacity or reflecting power. Opacity is, therefore, the antagonist of transparency, and qualifies pigments to cover in dead-colouring, or solid painting, as well as to combine with transparent colours in forming tints; and hence it is that semi-transparent pigments are suited in a mean degree both for dead colouring and for finishing. As excellencies, therefore, transparency and opacity are relative only—the first being as indispensable to shade in all its gradations, as the latter is to light. With regard to transparent and opaque colours generally, it is worthy of attention in the practice of the oil-painter, that the best effects of the former are produced when they are used with a resinous varnish; as opaque pigments are best employed in oil, and the two become united with best effect in a mixture of these vehicles. The natural and artificial powers, or depth and brilliancy, of every colour lie within the extremes of black and white; hence it follows that the most powerful effects of transparent colours are obtained by glazing them over black and white. As, however, few transparent pigments have sufficient body, or tinging power for this, it is often necessary to glaze them over tints, or deep opaque colours of the required hues. There is a charm in transparent colours which frequently leads to an undue use thereof in glazing; but glazing, scumbling, and their combined process must be employed with discretion, according to the objects and effects of a picture.

Working well is a quality which depends principally upon fineness of texture, and what is called body in colours; yet every pigment has its peculiarities in respect to working both in water and oil, and these must become matter of every artist's special experience. Some of the best pigments are most difficult of management, while some ineligible colours are rich in body and free in working. Accidental circumstances, however, may influence all pigments in these respects, according to the painter's particular mode of operation, and his vehicle; upon the affinities of colours with which depend their general faculties of working—such as keeping their place, crispness or setting up, and drying well. These latter, with other properties and accidents of pigments, will be particularly considered in treating of their individual characters; but it may be remarked that crispness or setting up, as well as keeping their place and form in which they are applied, are contrary to the nature of many pigments, and depend in painting with them upon a gelatinous mixture of their vehicle. For example, mastic and other resinous varnishes impart this texture to oils which have been rendered drying by the acetate, or sugar of lead:—simple water, also albumen, and animal jelly made of glue and isinglass, give the same quality to oils and colours; and bees-wax has a similar effect in pure oils. Whitelac varnish, and other spirit varnishes, rubbed into the colours on the palette likewise enable them to keep their place very effectually in most instances. This is important, because glazing cannot be performed except with a vehicle which keeps its place, or with pigments which lend this property to the vehicle, as some lakes and transparent colours do.

Fineness of texture is produced by extreme grinding and levigation. Pigments ground in water in the state of a thick paste, are miscible in oil and dry therein firmly; and in case of utility or necessity, any water-colour in cake, being rubbed off thick in water may be diffused in oil, the gum acting as a medium of union between the two. Thus, pigments which cannot otherwise be employed in oil, or varnish, may be forced into the service and add to the resources of the oil-painter, care being taken to use the palette-knife, if of steel, with caution.

Desiccation or drying. The well-known additions of the acetate, or sugar of lead, litharge, and sulphate of zinc, either mechanically ground, or in solution, for light colours; and japanner's gold size, or oils boiled upon litharge, for lakes; or, in some cases, manganese and verdigris for dark colours, are resorted to when the pigments or vehicles are not sufficiently good dryers alone. It would be well if lead and copper could be banished from the list of siccatives altogether: assuredly, no artist with any regard for the permanent texture of his work should employ them except in extreme cases, and in the smallest possible quantity. The best of pigments may be ruined by their injudicious use, and obtain a character for fugacity which they in no way deserve. It requires attention that an excess of dryer renders oil saponaceous, is inimical to drying, and is otherwise injurious. Some colours dry badly from not being sufficiently edulcorated or washed. Sulphate of zinc, as a siccative, is less powerful than acetate of lead, but is far preferable in a chemical sense. It is supposed erroneously to set the colours running; which is not positively the case, though it will not retain those disposed to move, because it wants the property the acetate of lead possesses, of gelatinizing the mixture of oil and varnish. These two dryers should not be employed together, since they counteract and decompose each other, forming two new substances—acetate of zinc, which is a bad siccative, and sulphate of lead, which is insoluble and opaque. The inexperienced ought here to be guarded against the highly improper practice of some artists, who strew their pictures while wet with acetate of lead, or use that substance in some other mode, without grinding or solution; which, though it may promote present drying, will ultimately effloresce on the surface of the work, throw off the colour in sandy spots, and expose the paintings to peculiar risk from the damaging influence of impure air.

It is not always that ill drying is to be attributed to the pigments or vehicles, the states of the weather and atmosphere have great influence thereon. The direct rays of the sun are powerfully active in rendering oils and colours siccative, and were probably resorted to before dryers were—not always wisely—added to oils, particularly in the warm climate of Italy. The ground may also advance or retard drying, because some pigments united by mixing or glazing, become either more or less siccative by their conjunction. Many other accidental circumstances may likewise affect drying; and among these none is to be more guarded against by the artist than the presence of soap and alkali, too often left in the washing of his brushes, and which, besides other bad results, decompose and are decomposed by acetate of lead and most siccatives. In such cases desiccation is retarded, streaks and patches are formed on the painting, and the odium of ill drying falls upon some unlucky pigment. To free brushes from this disadvantage, they should be cleansed with linseed oil and turpentine. Dryers should be added to colours only at the time of using them, because they exercise their drying property while chemically combining with the oils employed, during which the latter become thick or fatten. Too much of the siccative will, as before noticed, often retard drying.

The various affinities of pigments occasion each to have its more or less appropriate dryer; and it would be a matter of useful experience if the habits of every colour in this respect were ascertained. It is probable that siccatives of less power generally than the compounds of lead and copper might come into use in particular cases, such as the oxides of manganese, to which umber and the Cappagh browns owe their drying quality.

To other good attributes of pigments, it would be well if we could in all cases add the property of being innoxious. As this, however, cannot be, and colours are by no means to be sacrificed on that account, cleanliness and avoiding the habit of putting the brush unnecessarily to the mouth, so common in water-painting, are sufficient guards against any possibly pernicious effects from the use of any pigment. No colour which is not imbibed by the stomach will in the slightest degree injure the health of the artist.



PART III.

* * * * *

ON COLOURS AND PIGMENTS INDIVIDUALLY.



CHAPTER VI.

ON COLOURS AND PIGMENTS INDIVIDUALLY.

Having briefly discussed the relations and attributes of colours and pigments generally, we come to their powers and properties individually—a subject pregnant with materials and of unlimited connexions, every substance in nature and art possessing colour, the first quality of pigments.

With regard to colours individually, it is a general law of their relations, confirmed by nature and the impressions of sense, that those colours which lie nearest in nature to light have their greatest beauty in their lightest tints: and that those which tend similarly towards shade are most beautiful in their greatest depth or fulness, a rule of course applying to black and white particularly. Thus, the most beautiful yellow, like white, is that which is lightest and most vivid; blue is most beautiful when deep and rich; while red is of greatest beauty when of intermediate depth, or somewhat inclined to light; and their compounds partake of these relations. We speak here only of the individual beauty of colours, and not of that relative beauty by which every tint, hue, and shade of colour become pleasing, or otherwise according to space, place, and reference; for this latter beauty belongs to the general nature and harmony of colours.

In respect to pigments individually, it may be observed that—other things being equal—those pigments are the most beautiful which possess the most colour, whether they be light or dark, opaque or transparent, bright or subdued. There are some which exhibit all their colour at a glance: there are others that the more they are looked into the more colour they are found to have—containing, as they do, an amount of latent colour, not immediately apparent. Apart from the beauty which a wealth of colour imparts, those pigments imbued with it are, as a rule, the most permanent. And not unnaturally so, for the more colour there is present, the longer it takes to be affected, either by exposure or impure air. Colour within colour, therefore, not only lends charm to a pigment, but contributes to its safety.

There is often a vicious predilection of some artists in favour of a particular colour, from which many of our best colourists have not been totally free, and which arises from organic defect, or mental association. Such predilection is greatly to be guarded against by the colourist, who is every way surrounded by dangers. On the one hand, there is fear lest he fall into whiteness or chalkiness; on the other, into blackness or gloom: in front he may run into fire and foxiness, or he may slide backward into cold and leaden dulness: all of which are extremes he must avoid. There are also other important prejudices to which the eye is liable in regard to colours individually, that demand his particular attention. These are occasioned by the various specific powers of single colours acting on the eye according to their masses and the activity of light, or the length of time they are viewed. By consequence, vision becomes over-stimulated, unequally exhausted, and endued, even before it is fatigued, with a spectrum which not only clouds the colour itself, but gives a false brilliancy by contrast to surrounding hues, so as totally or partially to throw the eye off its balance, and mislead the judgment. This derangement of the organ may be caused by a powerful tint on the palette, a mass of drapery, the colour of a wall, the light of a room, or other accidental circumstance; and the remedy is to refresh the eye with a new object—of nature, if possible—or to give it rest. The powers of colours in these respects, as well as of pigments individually, together with their reciprocal action and influence chemically, will be adverted to under their distinct heads.

The attention of the artist to the individual powers of pigments, although it may be of less concern than the attention to general effect in colouring, is by no means less necessary in practice. For he who would excel in colouring must study it from several points of view, in respect to the whole and the parts of a picture, as regards mind and body, and concerning itself alone. To this end, is needed a knowledge of his pigments individually.

If nature has arrayed herself in all the colours of the rainbow, she has not been niggardly in offering man the materials wherewith to copy them. The mineral, animal, vegetable kingdom—each helps him to realize, however faintly, her many manifold beauties: to give some idea, however slight, of that glorious flood of colour, which light lets loose upon the world. Metal, ore, earth, stone; root, plant, flower, fruit; beast, fish, insect—in turn aid the arduous task. The painter's box is a very museum of curiosities, from every part of the universe. For it, the mines yield their treasures, as well as the depths of the sea: to it come Arab camel, and English ox, cuttle-fish and crawling coccus: in it the Indian indigo lies next the madder of France, and the gaudy vermilion of China brightens the mummy of Egypt. Varied, indeed, are the sources whence we derive our pigments; and if they still leave much to desire, improvement is clearly manifest. Slowly but surely, year by year, we are advancing. With the growth of science, the exhaustless stores of creation, will there at last be attained—step by step, though it be—that summit of the artist's hopes, a perfect palette?



CHAPTER VII.

ON THE NEUTRAL, WHITE.

The term "colour" is equivocal when applied to the neutrals, yet the artist is bound to consider them as colours; for a thing cannot but be that of which it is composed, and neutrals are composed of, or comprehend, all colours.

With regard to colour, then, white in a perfect state should be neutral in hue, and absolutely opaque; that white being the best which reflects light most brilliantly. This property in white is called body; by which in other pigments, especially those that are transparent, is meant tingeing power. White, besides its uses as a colour, is the instrument of light in painting, and compounds when pure with all colours, without changing their class. Yet it dilutes and cools all colours except blue, which is specifically cold; and, though it does not change nor defile any colour, it is changed and defiled by all colours. This pureness of white, if it be not in some degree broken or tinged, will cast down or degrade every other colour in a picture, and itself become harsh and crude. Hence the lowness of tone which has been thought a necessity in painting, but is such only because our other colours do not approach to the purity of white. Had we all necessary colours thus relatively pure as white, colouring in painting might be carried up to the full brilliancy of nature; and, in fact, more progress has already been made in that respect, than the prejudice for dulness is disposed to tolerate.

Locally, white is the most advancing of all colours in a picture, and produces the effect of throwing others back in different degrees, according to their specific retiring and advancing powers. These latter, however, are not absolute qualities of colours, but depend on the relations of light and shade, which are variously appropriate to all colours. Hence it is that a white object rightly adapted, appears to detach, distribute, and put in keeping; as well as to give relief, decision, distinctness, and distance to every thing around it: hence, too, the use and requirement of a white or light object, in each separate group of a composition. White itself is advanced or brought forward, unless indeed white surround a dark object, in which case they retire together. In mixture, white communicates these properties to its tints, and harmonizes in conjunction with, or in opposition to all colours; but lies nearest in series to yellow, and remotest from blue, of which, next to black, it is the most thorough contrast. It is correlative with black, which is the opposite extreme of neutrality.

Perfect white is opaque, and perfect black transparent; hence when added to black in minute proportion, white gives it solidity; and from a like small proportion of black combined with white, the latter acquires locality as a colour, and better preserves its hue in painting. Both white and black communicate these properties to other colours, in proportion to their lightness or depth; while they cool each other in mixture, and equally contrast each other when opposed. These extremes of the chromatic scale are each in its way most easily denied, as green, the mean of the scale, is the greatest defiler of all colours. Rubens regarded white as the nourishment of light, and the poison of shadow.

In a picture, white should not be merely glittering or brilliant, but tender as well as bright. The eye should seek it for rest, brilliant though it may be; and feel it as a space of strange heavenly paleness in the midst of the flushing of the colours. This effect can only be reached by general depth of middle tint, by the perfect absence of any white, save where it is needed, and by keeping the white itself subdued by grey, except at a few points of chief lustre.

White, as a pigment, is of more extensive use than any other colour in oil painting and fresco, owing to its local quality, its representing light, and its entering into composition with all colours in the formation of tints. The old masters have been supposed by some to possess whites superior to our own, but this may be questioned. The pureness of whites in some celebrated old pictures is rather to be attributed to a proper method of using, careful preservation of the work, and in many instances to the introduction of ultramarine or a permanent cold colour into the white—such as plumbago—helped also by judicious contrast.

Notwithstanding white pigments are tolerably numerous, a thoroughly unexceptionable white is still a desideratum—one combining the perfect opacity or body of white lead with the perfect permanency of zinc white. The nearest approach to it that has yet been made, is Chinese white, which possesses in a great measure the property of the former, and, being a preparation of zinc, has wholly that of the latter. Unfortunately Chinese white is a water-colour pigment only, not retaining its several advantages, stability excepted, when employed in oil.

1. CONSTANT WHITE,

Also called Permanent white, and Barytic white, is, when well prepared, of superior body in water, but has less opacity in oil. It works in a somewhat unsatisfactory and unpleasant manner, and is considerably lower in its tone while wet than when dry, a fault which subjects even an experienced artist to great uncertainty where he uses it in compound tints. The semi-transparency of the white, while wet, prevents his judging of the true tint until his colour has dried, when he frequently finds it harsh and chalky, and out of tone with the rest of his painting. As little gum as possible should be employed with it, gum being inimical to its body, or whiteness. The best way of preparing this pigment, as well as other terrene whites, so as to preserve their opacity, is to grind them in simple water, and to add towards the end of the grinding sufficient only of clear cold jelly of gum tragacanth as will connect them into a body, and attach them to the paper in painting. Cold starch will answer the same purpose.

Constant white is a sulphate of baryta, found native and known under the name of heavy-spar, or prepared artificially by adding sulphuric acid, or a soluble sulphate, to a solution of a barytic salt. In the first mode, if the white be not well purified from free acid, it is apt to act injuriously on some pigments. Sulphate of baryta is often used for the purpose of adulterating white lead, the native salt being ground to fine powder, and washed with dilute sulphuric acid, by which its colour is improved, and a little oxide of iron probably dissolved out. Whether native or artificial, the compound is quite unaffected by impure air, and is not poisonous.

LEAD WHITES

Comprise and are known under the names of:—White lead, Flake white and Body-white, Cremnitz, or Kremnitz, Crems or Krems white, London and Nottingham white, Flemish white, Pattison's white, Blanc d'argent or Silver white, Ceruse, Dutch white, French white, Venetian white, Hamburgh white, Kremser white, Sulphate of lead, &c.

The heaviest and whitest of these are the best, and in point of colour and body, are superior to all other whites. When pure and properly applied in oil and varnish, they are comparatively safe and durable, drying well without addition; but excess of oil discolours them, and in water-painting they are changeable even to blackness. Upon all vegetable lakes, except those of madder, they have a destructive effect; and are injurious to gamboge, as well as to those almost obsolete pigments, red and orange leads, king's and patent yellow, massicot, and orpiment. With ultramarine, however, red and orange vermilions, yellow and orange chromes, yellow and orange and red cadmiums, aureolin, the ochres, viridian and other oxides of chromium, Indian red &c., they compound with little or no injury. Lead colours must not be employed in water-colour or crayon painting, distemper, or fresco. The whites of lead are carbonates of that metal, with two exceptions:—Flemish white or the sulphate, and Pattison's white or the oxychloride. In using all pigments of which lead is the basis, cleanliness is essential to health.

White lead, by which we must be understood to mean the carbonate, always contains when commercially prepared a certain proportion of hydrated oxide. The less of the latter there is present, the better does the white cover, and the less liable is it to turn brown. The products formed by precipitation have proved to be inferior in body: otherwise, pure mono-carbonate of lead-oxide, obtained by mixing solutions of carbonate of potash and a lead-salt, might be best adapted for a pigment. However, such a carbonate has been lately produced by Mr. Spence's process of passing carbonic acid gas into a caustic soda or potash solution of lead, and for this white an opacity is claimed equal to that of the ordinary compound.

Great as is the opacity of white lead, it is apt to lose that property in some measure in course of time, and become more or less transparent. If, over a series of dry oil-colour rubs of varied hues, there were brushed sufficient white lead paint to utterly obscure them, after some years those rubs would indistinctly appear, and by degrees become more and more visible, until at last their forms—if not their very colours—could be recognised. From this it would seem that white lead must slowly but surely part with some of its carbonic acid, and be at length converted into dicarbonate, a compound possessing less carbonic acid, and less coating power.

Impure air, or sulphuretted hydrogen, browns or blackens white lead, converting it partially or wholly into sulphide. It would appear from the recent investigations of Dr. D. S. Price, that white lead is less liable to be thus affected, when the pictures in which it is used are exposed to a strong light; also, that when such pictures have so suffered, a like exposure will restore them. We have ourselves noticed the rapidity with which an oil rub of white lead that has been damaged by foul gas, regains its former whiteness when submitted to air and sunshine. The action of drying oils has been likewise proved to be very powerful upon sulphide of lead, an exposure to light for a few days only being sufficient to change a surface of it, coated with a thin layer of boiled linseed oil, into a white one. Probably, these agents may have a similar effect upon other pigments injured by sulphuretted hydrogen, and many of the colours in paintings may be restored by treating them with boiled linseed oil, and submitting them to a strong light. That the result is due to oxidation, there can be no doubt. Indeed, the eminent French chemist, M. Thnard, was consulted some years back upon the means of bringing to their original whiteness the black spots which had formed upon a valuable drawing, by the changing of the white lead, and employed for that purpose oxygenated water. He had ascertained its power of converting the black sulphide of lead into the white sulphate, and, by touching the spots with a brush dipped in the fluid, soon succeeded in restoring the drawing to its primitive state. Here, again, the use of the agent might doubtless be extended to other colours, to which foul air is inimical.

In oil painting white lead is essential in the ground, in dead colouring, in the formation of tints of all colours, and in scumbling, either alone or mixed with other pigments. It is also the best local white, when neutralized with ultramarine or black; and it is the true representative of light, when warmed with Naples yellow, or orange vermilion or cadmium, or with a mixture of the yellow and either of the orange pigments, according to the light.

Ordinary white lead is often mixed with considerable quantities of heavy spar, gypsum, or chalk. These injure it in body and brightness, dispose it to dry more slowly, keep its place less firmly, and discolour the oil with which it is applied, as well as prevent it dissolving completely in boiling dilute potash-ley, a test by which pure white lead may be known.

The adulteration of pigments, which we have in some instances found practised to a large extent abroad, is comparatively unfrequent in our own country, so far at least as regards the superior class of colours employed by artists. As a rule, such colours when manufactured in England may be fairly assumed to be genuine; and certainly the respectable colourmen of the present day are not in the habit of sophisticating them. We must bear testimony, indeed, to the zeal with which they purvey, regardless of necessary expense, the choicest and most perfect materials. This should be a matter of congratulation to the painter, who must of necessity rely on the faith and honesty of his colour-dealer; for if he were ever so good a chemist, it would be impossible for him to analyse each pigment before proceeding to use it. The fault must rest with himself, therefore, if, through a mistaken economy, he do not frequent the best houses and pay the best prices. Of a surety, the colours of the artist are not among those things in which quality can, or should, be sacrificed to cheapness.

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