Indian lake is rich, transparent, and deep,—less brilliant and more durable than the colours of cochineal, but inferior in both respects to those of madder. Used thickly or in strong glazing, as a shadow colour, it is of great body and much permanence; but in thin glazing it changes and flies, as it also does in tint with white lead. In the properties of drying, &c., it resembles other lakes. The pigment may be dispensed with in favour of madder lake and madder brown, whose combinations serve for every purpose to which it can be applied, and are stable.

Lac appears to be the lake which has stood best in old pictures, and was probably employed by the Venetians, who had the trade of India when painting flourished at Venice.

MADDER LAKES.

Rubric Lakes, or Field's Lakes, are derived from the root of "rubia tinctorum," a plant largely grown in France and Holland, whence the bulk of that used in England is obtained. The French madders are in a state of very fine powder, containing one half their weight of gum, sugar, salts, and other soluble substances, which water speedily dissolves. Madder roots in the unground state are imported from the Levant, and called Turkey roots. Good qualities of Turkey madder yield near sixty per cent of extractive matters, a term that includes everything removable by water and dilute alkalis: the woody fibre is therefore about forty per cent. This is presuming the root to be genuine, for madder is often adulterated with brickdust, red ochre, red sand, clay, mahogany sawdust, logwood, sandal and japan-wood, and bran.

Unlike cochineal, madder possesses several colouring matters; the question of which, despite the learned researches of Dr. Schunck and others, is far from settled yet. The following remarks embody our own experience of the root, simply as a pigment-producing product:—

Madder contains five colouring matters—yellow, red, orange, purple, and brown. Of these, the first colour is soluble in cold water. By washing the powdered root quickly with it by decantation, the yellow and brown are extracted in the form of an opaque liquid. If this be decanted and allowed to stand, the brown deposits, leaving a clear buffish-yellow supernatant liquor. In the root from which the extract was poured, the remaining three colours are left. On adding a strong boiling solution of alum, these are dissolved, yielding a fine red liquid. From this there can be thrown down, by the agency of different chemicals, a red, an orange, or a purple precipitate. Or, supposing the whole of the colouring matter to be deposited as a red lake, it is possible to convert this—also by the agency of different chemicals—either into orange or purple. Hence, for all practical purposes, madder contains but three colouring matters: a yellow, soluble in cold water; a brown, not soluble in, but capable of being extracted by cold water; and a red, soluble in boiling alum, and furnishing at will a purple or an orange.

As was observed in the previous chapter, no good pigment is obtained from the yellow, of which the less there is present the better; but the brown affords a valued product, which will be duly noticed. It is essential to the purity of the reds, that the madder should be freed from both these colours; and it was probably due to insufficient aqueous washing of the root, that the old lakes were dull and muddy, mere brick-reds of ochrous hues. For many years, however, lakes have been prepared perfectly transparent, and literally as beautiful and pure in colour as the rose; qualities in which they are unrivalled by the lakes and carmine of cochineal. They have justly been considered as supplying a desideratum, and as among the most valuable acquisitions of the palette in modern times, since permanent transparent red and rose pigments were previously unknown. The red varieties range from rich crimson to a delicate rose, and are known as Madder Carmine, Field's Carmine, Pink Madder, Rose Madder, Madder Lake, and Liquid Rubiate or Liquid Madder Lake.

77. MADDER CARMINE,

Or Field's Carmine, like that of cochineal, is the richest and deepest lake prepared, containing most colouring matter and least base. It differs from the paler products chiefly in transparency and intensity, and is the only durable carmine for painting either in water or oil; for both which it is qualified by texture without previous grinding. In common with the other reds of madder, its faint washes possess greater clearness than those of cochineal. This carmine is a difficult colour to make well, exceeding care and nicety being required to obtain the fullest tint: hence it is apt to vary in hue according to the skill of the manufacturer. Being expensive also, the price increasing according to depth of colour, the lake has been the most liable to adulteration, of all the reds of madder. Mrime states that samples were sent to him from Berlin, under the name of "carmine madder," which evidently owed their brightness to tincture of cochineal. It is certain that madder lakes have been imitated on the Continent with various success by those of lac, cochineal, and carthamus or safflower. The best we have seen is the laque de garance, which was tinged with the rouge of carthamus, and was of course inferior in durability. As, however, liquid ammonia and alkalis generally dissolve the colours of cochineal, lac, and safflower, the test is simple. If the liquid remain uncoloured on adding ammonia to an assumed madder lake, in all probability the pigment is genuine.

78. ROSE MADDER.

The exquisite flowers of Bartholomew, Miss Mutrie, and others, give evidence of the beauty, purity, and stability of the reds of madder, both in water and oil. This variety, less intense than the preceding and without its carmine hue, is of a rich rose colour—a true rose—tending neither to crimson, scarlet, nor purple. Marked by a peculiar softness, and an unusual clearness in its pale washes, rose madder affords the most perfect carnation tints known. Not liable to change by the action of light, impure air, or admixture with white lead and other colours, it resembles all madder lakes in these respects. Like them, too, it is but a tardy dryer in oil unless thoroughly edulcorated, and does not work in water with the entire fulness and facility of cochineal pigments. When, therefore, permanence is of no consideration, the latter may still be preferred. In those works, however, where the hues and tints of nature are to be imitated with stability and pure effect, the rose colours of madder are become indispensable. They have this advantage, moreover, that they possess the property of ultramarine of improving in hue by time—their tendency being to their own specific prismatic red colour. As they are too beautiful and require saddening for the general use of the painter, the addition of manganese brown, cappagh brown, or burnt umber, adds to their powers, and improves their drying in oils; for which last purpose a little japanner's gold size may be likewise employed.

In the light touches of bright clouds or mountains, where a mixture of cadmium yellow and Chinese white is used, rose madder is invaluable for glazing over such touches when dry, should they be required of a warmer hue. The red portion of sunset skies may be improved by a thin wash of this pigment, tinged perhaps with the above yellow, or with gamboge. Most serviceable landscape tints are afforded by admixture of rose madder with cobalt, Indian red, purple madder, yellow ochre, lamp black, &c. In painting flesh, the lake cannot be dispensed with.

79. PINK MADDER

Was a weaker preparation of the preceding, paler in hue and possessing less colour. It was formerly employed in miniature painting, but with the decline of that art became less and less used, until it may now be said to be obsolete. The name, however, still lives, but is applied to rose madder, which is indeed indifferently called Rose Madder, Pink Madder, or Madder Lake. Speaking of pink roses, Mrs. Duffield remarks that "the local colour is best imitated with pink madder," and the Messrs. Rowbotham observe "this heather may be best represented by cobalt and madder lake." In trade catalogues several names are often given, as in this instance, to one and the same pigment. The seeming superfluity is rendered necessary through some artists knowing a pigment by one name and some by another. Hence arises the value of a list of synonyms.

80. LIQUID RUBIATE,

Rose Rubiate, or Liquid Madder Lake, is a concentrated tincture of madder of the most beautiful and perfect rose colour and transparency. It is used as a water colour only in its simple state, diluted with water, and with or without gum. In oil it dries by acting as a siccative. Mixed or ground with all other madder colours, with or without gum, it forms combinations which work freely in water, and produce the most charming and stable effects. The rubiate also furnishes a fine red ink, and is a durable stain for printing on cotton, &c. To the tinting of maps and charts permanently, it is peculiarly suited.

81. MARS RED

Or Rouge de Mars, is an artificial iron ochre, similar in subdued tint and permanence to the native earths. Its chemical affinities, however, are greater than those of the latter, and it therefore requires to be employed cautiously with pigments affected by iron. In this respect the red resembles its compeers, Mars yellow, Mars orange, Mars violet, and Mars brown, all of which are iron ochres artificially prepared. Possessing the richness and depth of Indian red, it is distinguished by the russet-orange hue of light red. Its pale washes are marked by considerable clearness. In keeping the Mars colours separate from the ochres, we have followed the plan of the author.

OCHRES

Comprise Red Ochre, Indian Red, Light Red, Venetian Red, English Red, Persian Red, Prussian Red, Spanish Red, Brown Red, Indian Ochre, Scarlet Ochre, Carnagione, Terra Puzzoli, English Vermilion, Spanish Brown, Majolica, Redding, Ruddle, Bole, Almagra, Sil Atticum, Terra Sinopica, &c. They are rather hues and tints than definite colours, or more properly belong to the tertiary, semi-neutral, and broken colours. As a rule they are native pigments, found in most countries, and very abundantly and fine in our own; but some are products of manufacture, and obtainable in the variety of nature by art.

The colouring matter of these earths is the red oxide of iron, as that of the yellow ochres is the yellow oxide. All the yellow ochres are more or less reddened by being burnt, as yellow oxide of iron itself becomes red on calcination. It was observed in the fourth chapter that time has often the effect of fire, more or less intense; and hence it is that yellow ochres occasionally assume a buffish-red hue, by the gradual peroxidation of the iron. Similarly, if a yellow ochre be but partially calcined, the red so obtained is apt to deepen or darken. Especially do these changes take place when the iron oxides are not associated with an earthy base; when, in fact, the so-called ochres cannot be classed as such. In this case, too, as was lately remarked, the pigments are more chemically active, and more likely to affect those colours to which iron is inimical.

82. RED OCHRE

Is a native earth; sometimes brown ochre burnt, and called Brown Red. It is less pure in hue and clear in its tints than light red, and is best reserved for dark and vigorous shades and touches. For draperies of a dusky red it is well suited, or even for the shadows of bright-red drapery. In dead colouring it is very valuable. Like all ochres, it is characterized by permanence in water, oil, crayons, and fresco; and is, like most of them, available in enamel-painting.

Almagra, the Sil Atticum of the ancients, is a deep red ochre found in Andalusia; as is also their Terra Sinopica or Armenian Bole, dug originally in Cappadocia, and now found in New Jersey and elsewhere under the name of Bloodstone.

83. INDIAN RED,

Once known as Persian Red, is brought from Bengal. It is a natural earth rich in peroxide of iron, of a purple russet hue and good body, and valued when fine for the clearness and soft lakey tone of its tints. In a crude state it is a coarse powder, full of extremely hard and brilliant particles of a dark appearance and sometimes magnetic. It is greatly improved by grinding and washing over, and is very permanent. Neither light, impure air, mixture with other colours, time, nor fire, effects any sensible change in it; but being opaque and not keeping its place well, it is unsuited for glazing. This pigment differs considerably in its hues, that which is most rosy being esteemed the best, and affording the purest tints. Inferior ochres were formerly substituted for Indian red, which procured it a variable character; but the colour being now obtained abundantly can in general be had genuine. It is a good drier.

Mixed with Indian ink, it furnishes useful shadows; and compounded with cobalt or indigo, most serviceable grays. For sunsets, where deep purple lines are louring over the horizon's brink, a mixture of French blue with a little Indian red and lake is admirably adapted. In twilight and stormy clouds, in sails and buildings, in shade carnations of portraits and backgrounds, &c., the red is often employed.

84. LIGHT RED

Is an ochre of an orange-russet hue, chiefly valued for its tints. The principal yellow ochres afford this colour best, and the brighter and clearer the yellow ochre is from which it is prepared, the brighter will the red be, and the better flesh tints will it yield with white. Light red has the good properties common to ochres, dries capitally, and furnishes an excellent crayon. It is much used both in figure and landscape painting, giving fine grays with cobalt, and serviceable compounds with yellow ochre, indigo, lamp black, rose madder, Payne's grey, brown madder, &c.

Terra Puzzoli, a volcanic production, is a species of light red, as is the Carnagione of the Italians.

85. VENETIAN RED,

Less known as English Red, Prussian Red, and Scarlet Ochre. True Venetian red, that is, the red of the Venetians, was probably brought from India, and similar to our modern Indian red. The Venetian red of the present day, however, is an artificial product, containing no earthy base, and therefore improperly classed among the ochres. It is prepared by calcining sulphate of iron, to which a little nitre may be advantageously added. The result is a peroxide of iron, resembling light red, but more powerful, and of a more scarlet hue. It is very permanent, but being a purely iron pigment, should be cautiously employed with colours affected by that metal. Though not bright, its tints are clear, and it mixes and works kindly with cobalt or French blue, affording fine pearly grays. Heightened by madder lake, it furnishes a glowing red, very useful in some descriptions of skies; and saddened by black, it gives low toned reds of good quality for buildings. With white it produces carnation tints nearly approaching to nature, and much employed by Titian, Vandyke, and others. Compounded with aureolin, Venetian red yields a clear orange of considerable transparency.

Spanish Red is an ochre differing little from the above.

86. PURE SCARLET,

Or Iodine Scarlet, is an iodide of mercury, having the body and opacity of vermilion, and being as much inferior to it in permanence as it is superior in brilliancy. Of all artistic pigments, it is at once the most dazzling and the most fugitive, and should have no place on the palette. If used, it should be with an ivory knife, as iron and most metals change it to colours varying from yellow to black; hence it should never be compounded with metallic pigments. So sensitive, indeed, is it to the slightest touch of metal, that it has been known to turn to a dull brown merely by being washed over with a colour which had been taken out of its saucer with a penknife. In the cake, it must be carefully kept wrapped up in paper, otherwise the presence of metal tubes or a knife in the colour-box may spoil it. By a foul atmosphere, the scarlet is soon utterly destroyed, and even metallized. In contact with the air, it quickly fades away; and has been found to vanish completely, when exposed to light alone. Employed in water, a thick glaze of gum-arabic or gamboge adds to its stability. As a landscape pigment, the colour is out of the general scale of nature; but in flower-painting its charms are almost irresistible. Nothing certainly can approach it as a colour for scarlet geraniums, but its beauty is almost as fleeting as the flowers.

87. RED CHROME,

Also called Scarlet Chrome, is a bright chromate of lead of an orange-red colour, the red being predominant. Rank in tone, it is liable to the changes of the yellow chromes, though in a less degree. The recent introduction of cadmium red renders the use of this unnecessary.

88. RED LEAD,

Minium, or Saturnine Red, is an ancient pigment, by some old writers confounded with cinnabar, and termed Sinoper or Synoper. It is an oxide of uncertain composition, prepared by subjecting massicot to the heat of a furnace with an expanded surface and free accession of air. Of a scarlet colour and fine hue, it is warmer than common vermilion, whose body and opacity it possesses, and with which it was once customary to mix it. Bright, but not so vivid as the iodide of mercury, it is more durable, although far less so than vermilion. When pure and alone, light does not affect its colour, which soon flies, however, on being mixed with white lead or any preparation of that metal. By impure air, red lead is blackened and ultimately metallized.

On account of its extreme fugacity when compounded with white lead, this red cannot be used in tints; but employed, unmixed with other pigments, in simple varnish or oil not rendered drying by any metallic oxide, it may stand a long time under favourable circumstances. It is an excellent dryer in oil, and has often been used as a siccative with other colours, but it cannot safely be so employed except with the ochres, earths, and blacks in general. Oils, varnishes, and, in some measure, strong mucilages, are preventive of chemical action in the compounding of colours, by intervening and clothing the particles of pigments; and hence heterogeneous and injudicious tints and mixtures have sometimes stood well, but are not to be relied upon in practice. Altogether, red lead is a dangerous pigment in any but skilled hands, and has naturally had a variable character for permanence. It is frequently adulterated with earthy substances, such as brickdust, red ochre, and colcotha.

VERMILIONS.

Vermilion is so called from the Italian word vermiglio (little worm,) given to the kermes or "coccus ilicis," which was used as a scarlet dye before the introduction of cochineal. It is a sulphuret of mercury, which previous to levigation is called Cinnabar; and is found native in quicksilver mines, as well as produced artificially. This is an ancient pigment, the [Greek: kinnabari] of the Greeks, and the minium—a term now confined to red lead—of older writers. Pliny states that it was so esteemed by the Romans, as to have its price fixed by express law of state. Among other places, the natural product is met with in California, Spain, and Peru; and in China there is a native cinnabar so pure as only to require grinding to become very perfect vermilion. Whether the natural possesses any advantages over the artificial, appears to admit of doubt: Bouvier thought that the former blackened more than the latter, and others coincide with him. As, however, native vermilion has become commercially obsolete, the question of their comparative permanence is of little importance. Theoretically, it is difficult to assign a reason why there should be any difference between the two.

Vermilion is capable of being made by both wet and dry processes, but the last are almost exclusively adopted on a scale, and are, we believe, preferable. Our opinion, expressed with some diffidence, is, that pigments whose colour depends on the union of sulphur with a metal—such as vermilion and cadmium yellow—are more stable when the sulphur is forced to bite into the base. This can only be effected by a considerable degree of heat, far greater than can be obtained in any moist method. We hold that in pigments so produced, the sulphur is less liable to oxidation by air and light, and that therefore the colour better withstands exposure to those agents. Before now, vermilions have been taxed with fading in a strong light: supposing them genuine, it would be interesting to know by what mode they were manufactured.

There are two kinds of vermilion in common use, European and Chinese, of which the first inclines to orange and the second to purple. These include the several varieties known as—Vermilion, Deep Vermilion, Pale Vermilion, Scarlet Vermilion, Chinese Vermilion, Carmine Vermilion, Extract of Vermilion, Orange Vermilion, and Field's Orange Vermilion.

89. VERMILION,

Deep or pale, when well made and pure is of strict permanence, not sensibly affected by light, time, or foul air; and eligible either in water, oil, or fresco. For an enamel colour it is unsuited, being dissipated at a red heat, a test that detects the presence of any non-volatile adulterant. The best vermilion is a powerful vivid colour, higher in tone than all reds, except the scarlet iodide of mercury. With this it should not be compounded, but with other pigments it may safely be used in admixture, as far as its own colour is concerned. Of great body, weight, and opacity, it is a somewhat slow drier; and does not retain that brilliancy when dry, which is peculiar to it while wet. A want of transparency, and not drying well, prevent its being so generally employed as would be desirable. Pictures should seem to be painted with colour, not with pigment, the material being lost amid the hues, tints, and shades; but with such compounds as vermilion, the art of concealing art becomes difficult indeed. The pigment is apt to predominate over the colour, and the painting to look mechanical rather than natural: particles are apparent where hues alone should be seen, and all sense of reality is destroyed. For these reasons, vermilion is a dangerous pigment in unskilled hands, needing an intimate acquaintance with its physical properties. The extreme weight or specific gravity of the red renders it liable to sink and separate when compounded with other colours; hence the heavier those mixed with it the better. Its almost equal opacity, too, and habit of washing up, militate against its use by young painters. With experience, however, and due care, this is a serviceable colour; yielding with white most delicate flesh tints, and in minute proportion with cobalt or French blue and white, tender arial grays.

Being cheaper than formerly, vermilion is not so much adulterated as it once was; although, even now, brickdust, orpiment, &c. sometimes sophisticate it. The knavish practices to which the pigment has been subjected, have acquired it an ill-fame both with authors and artists. Vermilion has been charged with fading in the light, and with being blackened by impure air; but it was the custom to crimson the colour by means of lake, or tone it to a scarlet hue by red lead. With pigments as with persons, evil communications corrupt good manners—a motto that might be written with advantage on every palette.

90. SCARLET VERMILION

Resembles the preceding in all respects, except in being more scarlet in its tint, and washing better; advantages which render it more useful when the tone is required to be very bright and pure. At one time, the Dutch alone in Europe possessed the secret of giving to vermilion a rich scarlet colour.

91. CHINESE VERMILION,

Or Carmine Vermilion, partakes of a crimson hue, and is adapted, mixed with white, for the rose and lilac-tints of some complexions. Like other vermilions, however, the colour needs much nicety of management; and it must not be attempted to further enrich it by admixture of cochineal lakes. Those colours, as we have remarked, cannot safely be brought into contact with vermilion, either compounded or as a glaze. The reds of madder should be substituted for them.

92. EXTRACT OF VERMILION,

A somewhat curious name for a metallic colour, was a peculiar preparation of the author, possessing in its time certain advantages over other vermilions, and especially distinguished by a more scarlet hue. Now, however, extract of vermilion and scarlet vermilion are synonymous terms.

93. ORANGE VERMILION

Is rather more transparent than ordinary vermilion, with a clear but not bright orange hue. It also washes better, and is for landscape purposes more generally useful. Resembling red-lead in appearance, it is not subject to its changes, being perfectly durable in oil and water. A most powerful tinger of white, its tints are warmer than red-lead's, affording delicate carnations similar to those of Titian and Rubens. This pigment—or, preferably, the succeeding variety—may be employed with excellent results in scumbling of flesh, for which Sir Joshua Reynolds improperly used the so-called red orpiment. It dries in simple linseed oil, but works with best effect in water with a considerable portion of gum. In speaking of sunset and sunrise clouds, Mr. Penley observes—"Orange vermilion if used so thin as to get rid of its opacity, is a fine tone; but it must be remembered that transparency is the character of the sunset or sunrise, and hence arises the difficulty of employing such opaque colour effectively." Before the introduction of cadmium red, this and the following pigment were the best and only unexceptionable orange-reds known. It is probable, however, that the new colour will in a great measure supersede these latter in cases where transparency is sought. Orange vermilion is often a mixture, in which case the yellow employed is apt to separate from the red and float on its surface.

94. FIELD'S ORANGE VERMILION

Is a superior preparation to the preceding, being brighter, purer, and clearer. It possesses also, less opacity, and is not a compound. Both pigments are rather reds with an orange cast than strictly orange colours, and are therefore inserted in this chapter.

* * * * *

95. Antimony Red,

Or Mineral Kermes. We have obtained this colour ranging from light orange to deep carmine, of different degrees of brightness and stability. Some of the tints stood well in a book, but faded on exposure to light and air; and some even vanished when secluded from those agents. It has more than once been recommended as a pigment, but our experience is against its adoption by artists. The colour is not affected by sulphuretted hydrogen.

96. Chica Red

Is extracted from the leaves of a tree growing in central and southern America. A sample examined by Mr. O'Neill was in small irregular lumps, of a bright scarlet colour, adherent to the tongue like indigo, and taking a metallic polish of a greenish reflection, when rubbed against a hard smooth body, as the finger nail. So far it seems to be only employed by the Indians as a paint for their bodies, mixed up with fatty matters. It has doubtless been used in painting: for in the old churches of those parts of America there is a good deal of red colour, which remains brilliant and sound after a couple of centuries; and from the appearance of it, and such accounts as can be collected, it is probably this chica. A portion was forwarded to an eminent artist in England, to ascertain whether it would be of any value as a pigment in the fine arts. His report is stated to have been unfavourable; and the chica, contained in a gourd labelled "Chica d'Andiguez," was then tested as to its capabilities for dyeing and printing. Fine and durable reds were found to be produced by it upon woollen, equal to those of cochineal. To mordanted calico the shades imparted were dull and heavy, but very solid. Chica is described as a very strong colouring matter, a small quantity dyeing a large amount of cloth, and as more nearly resembling lac lake than anything else.

No information existing as to its price, or the quantity that could be obtained if it were wanted, chica remains in the state of an unapplied product. If it really possess, however, the durability assigned to it, this red is worth attention. With regard to the artist's disapproval, the chica sent him may not have been properly or sufficiently prepared to adapt it for a pigment.

97. Coal-Tar Colours.

Our work might be considered incomplete without some allusion to the coal-tar colours, even though they are rather dyes than pigments, not possessing sufficient stability for the palette. To avoid repeated reference, we have preferred grouping them in this chapter, irrespective of hue. Consequently, yellow, red, blue, orange, green, purple, brown, and black, will be all comprised under the heading of coal-tar colours.

Previous to the year 1856 the colouring matters derived from coal-tar were practically unknown. Until then, that black evil-smelling substance was looked upon as almost worthless; but gradually the unsightly grub emerged into a beautiful butterfly, clothed first in mauve and next in magenta. After its long winter of neglect, there sprung from coal-tar the most vivid and varied hues, like flowers from the earth at spring. At a touch of the fairy wand of science, the waste land became a garden of tropic tints, and colour succeeded colour, until the whole gamut had been gone through. Never was transformation more dazzling or more complete. The once despised refuse was now a valued commercial product—indeed a trade in itself. Perfectly fascinated by the study, chemists threw themselves heart and soul into coal-tar, and coal-tar colours were to be seen everywhere.

It were beside our purpose to enter into the various stages through which coal has to pass to become colour. Enough to state that to the introduction of gas-light we are indebted for the acquisition of coal-tar colours, the starting point for the production of mauve, magenta, &c., being the manufacture of coal-gas. From the destructive distillation of coal, coal-tar oil results; and from this are obtained the products which yield the colours in question. Among these products may be mentioned aniline, rosaniline, napthaline, chinoline, carbolic acid, picric acid, &c., with their derivatives.

Of the fifty-one compounds furnished by the distillation of coal, perhaps the most popularly associated with coal-tar colours is aniline, to which we will therefore confine ourselves. Discovered in 1826, this body was formerly prepared from indigo—in Spanish, anil, whence the name; but is now produced on a larger scale from benzol, a coal-tar product. As the source of mauve and magenta, aniline must be considered the parent of coal-tar colours generally. Little was known of it at one time except that on being mixed with a solution of chloride of lime there was formed a splendid purple liquid, which immediately gave place to a dingy reddish precipitate. From the investigation of this simple fact, however, by Mr. W. Perkin, there was created a new and important branch of chemical industry—the manufacture of coal-tar colours. The violet mauve led the way, followed by the red magenta, the blue azuline, the yellow phosphine, the green emeraldine, the orange aurine, by purple, and brown, and black. Such were the hues, with many intermediate tints and shades, which one reaction brought forth. The world rubbed its eyes with astonishment; and truly it seemed almost as wonderful to produce the colours of the rainbow from a lump of coal, as to extract sunshine from cucumbers.

The history of these colours reads more like a romance than a sober story, but to the artist it is of slight practical interest. Sufficiently stable as dyes, though they be, coal-tar colours are not adapted to the palette. Mauve, magenta, with a few others, hare been introduced as pigments and fairly tried, but a want of permanence has been fatal to their success. Mauve is more durable than magenta, and the rest vary in stability, but none of them have proved really fitted for artists' colours. Exposed to light and air, they all more or less fade, especially in thin washes; and they have mostly the objection of staining and permeating the paper or canvas on which they are employed. Used in body, some may be found eligible in portfolio illuminations and the like, where the brilliancy of their colours shows to advantage; but in landscapes and pictures of life, coal-tar pigments are best avoided.

Cakes of red, blue, violet, and other hues, may be prepared for painting, by combining the colours with a mixture of starch and alumina, or with soap and alumina in a moist state—thus: 150 parts of white curd soap, dissolved in 1000 parts of hot water, are mixed with an alcoholic or a methylated spirit solution of six parts of the crystallized or solid coal-tar colour. To this are added 250 parts by weight of washed gelatinous alumina. The whole is then well stirred, collected on a filter, drained, and dried. Several hues, tints, and shades may be obtained by compounding: for instance, an orange is produced on admixture of picric yellow with aniline red, or a green by adding the same yellow to aniline blue.

98. Cobalt Reds.

There are obtainable from cobalt by different processes rose and red colours of more or less beauty and intensity, but all vastly inferior to those of madder, in whose absence alone they could gain a place on the palette. Durable as a rule, they are in general characterized by a fatal chalkiness, and poorness of hue. More expensive than the madder colours, and without their purity, delicacy, depth, or transparency, cobalt reds have often been offered as pigments, and as often declined. A colour may be good in itself, but if there is something better and at the same time cheaper, its introduction into commerce is out of the question.

99. Copper Reds.

A somewhat finely coloured red oxide is produced by exposing to a white heat for twenty minutes, a mixture of certain proportions of blue vitriol, mono-carbonate of soda, and copper filings. The product, however, is affected by impure air, and is otherwise not so desirable as an iron oxide.

An interesting account has lately been given by Professor Church of a new animal pigment, containing copper, found in the feathers of the violet plantain-eater and two species of Turacus, natives respectively of the Gold Coast, the Cape, and Natal. Turacine, the name proposed for it, is noticed here only because it is the first animal or vegetable pigment, with copper as an essential element, which has been hitherto isolated. The colour is extracted by solution in an alkali, and precipitation by an acid, and is changed on long exposure to air and moisture to a green hue. As the entire plumage of a bird yields not more than three grains of pigment, turacine must be looked upon as a mere curiosity.

100. Ferrate of Baryta,

Produced by adding aqueous ferrate of potash to an excess of dilute solutions of baryta salts, has been described as carmine-coloured and permanent. We have not found it to be so—an experience which has evidently not been confined to ourselves; and we cannot help thinking that this is one of those errors which get copied from one chemical work into another, to the special confusion of students. It is but fair, however, to add that in Mr. Watts' Dictionary of Chemistry, the latest and best work of the kind, this ferrate is said to become "brick-red after washing and drying at 100 C.," and to be only "tolerably stable."

101. Gold Reds.

Many organic substances added to gold solutions throw down either the metallic gold or the red oxide, which then unites with the organic compound more or less decomposed and forms a red precipitate. Sugar, gum, the decoctions of cochineal, gamboge, fustic, turmeric, sumach, catechu, and Brazil wood, all afford red pulverulent colours. Boiled with sugar, gold solution gives first a light and then a dark red. Whatever their merits, the excessive costliness of these preparations renders them inadmissible as pigments. At one time, indeed, a gold compound known as purple of Cassius was so employed, but this soon became obsolete on the introduction of madder purple.

102. Iodine Pink.

There may be obtained from iodine and mercury a very pretty pink colour, analogous in composition to pure scarlet. It is apt to pass into the scarlet modification, and is in other respects even less to be depended on than that variety.

103. Kermes Lake

Is an ancient pigment, perhaps the earliest of the European lakes, and so called from the Arabic Alkermes. It is sometimes spelt cermes, whence probably cermosin and crimson, and kermine and carmine. In old books it is named vermilion, in allusion to the insect, or vermes, from which it is prepared. This insect is the "coccus ilicis," which feeds upon the leaves of the prickly oak in the south of Europe. Like the "coccus cacti," it is covered with a whitish dust, and yields a tinctorial matter soluble in water and alcohol. Kermes and the lac of India doubtless afforded the lakes of the Venetians, and appear to have been used by the earliest painters in oil of the school of Van Eyck. The former, under the appellation [Greek: kurno kokino], is said to be employed by the modern Greeks for dyeing their caps red.

Some old specimens of this pigment which the author obtained were in drops of a powdery texture and crimson colour, warmer than cochineal lakes, and having less body and brilliancy. They worked well, however, and withstood the action of light better than the latter, though the sun ultimately discoloured and destroyed them. In other respects, they resembled the lakes of cochineal. As a colouring matter, kermes is only about one-twelfth part as powerful as that substance.

104. Lawson's Red.

In 1861 it was stated that Professor Lawson had prepared a new dye of great richness, in the laboratory of Queen's College, Canada, from an insect, a species of coccus, found the previous summer for the first time on a tree of the common black spruce (Abies nigra), in the neighbourhood of Kingston. Having been but recently observed, a sufficient quantity had not been obtained for a complete series of experiments as to its nature and uses; but the habits of the insect, as well as the properties of the dye, seemed to indicate that it might become of practical importance. In colour it closely resembled ordinary cochineal, but was rather more scarlet in hue. It was described as capable of being produced in temperate countries. The colouring matter had not then been thrown upon a base, nor do we know that it has since been introduced as a pigment. If it possessed greater stability than cochineal, with equal brilliancy and depth, this dye might form one of those colours of the future, to whose possible sources we would direct attention.

105. Manganese Red.

Bisulphide of arsenic combines with basic metallic sulphides forming a class of sulphur-salts, called by Berzelius, hyposulpharsenites. The hyposulpharsenite of manganese is a dark red precipitate, uninjured by sulphuretted hydrogen, and so far applicable as a pigment. Containing arsenic, it would of course be poisonous; and would probably be found to fade on exposure to air and light.

106. Murexide.

The red obtained from this substance created a great deal of interest among printers and dyers on its introduction in 1857, or thereabouts. For purity and brilliancy of shade it was not excelled by any other colour, but not being able to stand the effects of air and light, its employment was limited. We are not aware that murexide has yet been brought forward as a pigment, and judging from its character as a dye, it would scarcely enrich the palette. Dyes and pigments have much in common, and a fugitive dye cannot be expected to furnish a permanent pigment.

Murexide is produced by the action of ammonia on alloxan, which is itself derived from the uric acid of guano by treatment with nitric acid, and was known nearly forty years back to stain the fingers and nails red. The first murexide sent into the market was a reddish-purple powder, dissolving in water with a fine purple tint, leaving a little residue undissolved. Owing to improvements in manufacture, it is now capable of being prepared almost chemically pure, and with that green metallic reflection peculiar to several coal-tar salts and the wings of certain insects. When sulphuretted hydrogen is passed through a concentrated solution of murexide, it is immediately decoloured; a fact which renders it likely that murexide pigments would be as liable to suffer from an impure atmosphere, as from exposure to light and air.

When an alkaline solution of murexide is precipitated by an acid, a light shining powder results, called purpuric acid. This dissolves in alkalies, and combines with metalline bases to form various coloured compounds, termed Purpurates. Among them may be mentioned a red purpurate of lead, a purple-red and a rose-coloured purpurate of mercury, a purple-red purpurate of silver, a dark red-brown purpurate of strontia, a crystalline red purpurate of cobalt, a scarlet purpurate of platinum, a yellow purpurate of zinc, and a green purpurate of baryta. All of these, however, being more or less soluble in water, and owing their colours to murexide, would be ill adapted for pigments.

107. Paille de Mil,

Or African Cochineal, is a substance obtained from Africa. Whether it has received its name of cochineal from its appearance or origin is not clear, but it behaves more like galls and sumac than cochineal, though it does give a kind of red with alumina mordants. The colours it yields are deficient in brightness, and it has otherwise been reported unfavourably of.

108. Peganum Harmala,

The seeds of which afford a red colour, has been investigated by the French, but described as inferior to existing reds both in brilliancy and stability.

109. Persulphomolybdates.

The metallic compounds formed by the combination of persulphomolybdic acid with a base are pulverulent, in many cases of a red colour, and for the most part insoluble in water. With barium, the acid furnishes a yellowish-red powder, insoluble in, but made denser by water, which imparts to it a cinnabar colour. With calcium it is said to yield a scarlet, sparingly soluble in water. With chromium, uranium, lead, platinum, and copper, it gives a dark red; that from the last metal turning brown when collected on a filter. It likewise produces reds with zinc, cadmium, iron, mercury, and tin; of which the last is slightly soluble in water.

Molybdenum being a rare metal, and persulphomolybdate of potash, the salt used in the foregoing reactions, difficult to prepare, it is unlikely that the colours named will rank among the pigments of this generation. Nevertheless, as we have observed before, such fancy products should not be altogether ignored, it being quite as well to have some knowledge of our resources, even though those resources be not at present available. All the rare metals afford coloured compounds: tantalum, niobium, pelopium, vanadium, tellurium, titanium, yttrium, lanthanum, didymium, glucinum, cerium, thorinum, zirconium, palladium, rhodium, iridium, ruthenium, osmium, indium, thallium, &c.; and it is just possible that some of these may one day scrape acquaintance with the palette.

110. Red Chalk,

The colouring matter of which is sesquioxide of iron, is used as a crayon. Some specimens are excessively hard, so much so that they are difficult to crush, even in an iron mortar; while others have the consistence of the softest iron-ochres. They vary too in tint from a fawn colour to the softest brick-red, occasionally being almost as bright as a mixture of equal weights of vermilion and Venetian red. The amount of iron oxide present has been found to range from four to thirty-seven per cent, according to the depth and hardness of the samples. When a specimen of red chalk tolerably rich, but not too rich, in iron oxide is finely powdered and strongly ignited, it offers a remarkable change of colour, becoming a dull sage-green. Perhaps this, if it were permanent, might prove useful in foliage tints.

111. Red Precipitate,

Or mercuric oxide, may be obtained either of a brick-red or orange-yellow colour. It is destroyed by impure air, and on exposure to sunshine gradually turns black, being superficially decomposed into oxygen and metallic mercury or mercurous oxide.

112. Rose Pink

Is a coarse kind of lake, produced by dyeing chalk or whitening with decoction of Brazil wood, peachwood, sapan, bar, camwood, &c. It is a pigment much used by paper-stainers, and in the commonest distemper painting, &c., but is too perishable to merit the attention of the artist.

Chevreul obtained a crystalline substance from Brazil wood, which he looked upon as the pure colouring matter, or as containing the pure colouring matter, and which gave red and crimson precipitates with many salts. Possibly some of these might prove more durable than the roughly made rose pink.

113. Rouge,

The rouge vgtale of the French, is a species of carmine, prepared from safflower or carthamus, which is the flower of a plant growing in the north of Africa, India, and other warm climates. Safflower yields two colours—a valueless yellow which dissolves in cold water, and about five per cent of red, insoluble in water but dissolved by alkalies. The red, or carthamin, furnishes a pigment of exquisite beauty, marked by richness, transparency, and free working. Its extreme fugacity, however, militates against its employment by artists. As a dye, its manner of fixing upon fibre is different from that of any other colouring matter; requiring no mordant, like madder or cochineal, and needing no solution, like indigo or anotta, but fixing at once as soon as the cloth is brought into contact with it. But even for a dye the colour is fugitive, fading after a few hours' exposure to sunshine, and sometimes being quite bleached in the course of a day. It is when combined with levigated talc to form the paint of the toilette that the red becomes most serviceable. Possessing a peculiar softness and velvety glow, rouge is an unrivalled—and a most harmless—aid to beauty.

Chinese Rouge and Pink Saucers have much of the qualities of, and appear to be also prepared from, the safflower.

114. Rufigallic Red.

When a duly proportioned mixture of gallic acid and oil of vitriol is carefully and gradually heated to 140, a viscid wine-red liquid results. If this be poured into cold water, after cooling, a heavy brown-red granular precipitate is formed, soluble in 3333 parts of boiling water. It dissolves in potash-ley, and to fabrics impregnated with alum or iron mordants, imparts the same shades of colour as madder; the colours so produced withstanding soap but not chlorine.

Whether brilliant lakes could be obtained from the potash solution of the red, and whether those reds would be stable, it might be worth while to ascertain.

115. Sandal Red.

We have kept this separate from other reds derived from woods, because it is said (by Professor H. Dussance) to be obtainable not only equal in beauty and brightness to carmine, but of greater permanence. The process of preparation is as follows:—The powdered root exhausted by alcohol gives a solution to which hydrated oxide of lead is added in excess. The combination of colouring matter and lead oxide is then collected on a filter, washed with alcohol, dried, dissolved in acetic acid, and mixed with a quantity of water. The red being insoluble therein is precipitated, while the acetate of lead remains dissolved. After being washed, the colour is dried at a low temperature. The Professor affirms that the red so produced is unaffected by sulphuretted hydrogen, or by light and air; and it is stated that the colour which was used to paint the carriages of the Emperor Napoleon, remained as bright at the end of nine years as when it was put on. Possessing such properties, it is curious that the red has never been—in this country at least—introduced as an artistic pigment, the more especially as seventeen years have elapsed since its discovery.

116. Silver Red.

By adding monochromate of potash to an acid solution of nitrate of silver, a particularly fine ochre-red is obtained. It is, however, apt to be injured both by foul air and exposure.

117. Sorgho Red.

Some nine years back there was found to be a carmine colouring matter in most parts of the Chinese sorgho, chiefly in the unpressed stem. The red, which is extracted in an impure state, is dissolved in weak potash-ley, thrown down by sulphuric acid, and washed with water. This purified product, soluble in alcohol, caustic alkalies, and dilute acids, has been employed in Austria, Baden, &c., for the dyeing of silks and woollens with the common tin mordants. The colours produced from it are unchanged, they say, by warm soapsuds or light. We do not know whether the red found its way to England, but it has certainly not appeared here as a pigment.

118. Thallium Red.

The orange-yellow precipitate formed by mixing a neutral salt of protoxide of thallium with bichromate of potash, is converted by nitric acid into an orange-red. The latter compound, which is a terchromate, is almost insoluble in cold water, 2814 parts being required to dissolve it. If the colour be boiled in a large excess of moderately strong nitric acid it is dissolved, yielding magnificent cinnabar red crystals on the solution cooling. These crystals likewise seem to be the terchromate.

119. Tin Pink.

By igniting strongly for some hours a mixture of stannic oxide, chalk, chromate of potash, and a little silica and alumina, a dingy red mass is obtained, which acquires a beautiful rose-red colour on being washed with water containing hydrochloric acid. For the same reason that the pinks of cobalt are superfluous as artistic pigments, this tin product is commercially ineligible. Having, however, the advantage of being cheap, and being probably durable, it would be well adapted for the common purposes of painting, in place of the fugitive rose pink.

120. Ultramarine Red?

In Gmelin's Handbook of Chemistry it is remarked that "Hydrogen gas passed over ignited ultramarine, colours it light red, from formation of liver of sulphur, hydrosulphuric acid gas and water being evolved at the same time." On most carefully making the experiment with a sample of native blue (the variety referred to) we did not succeed in effecting this change: no alteration to red or even to purple took place, the only result being that the colour was entirely spoilt, having assumed a leaden slate-gray hue. At our request, the trial was kindly repeated by well-known chemists, who took every precaution to ensure success. Several specimens of ultramarine were acted upon, but in no case was a red or anything like a red obtained, the products ranging from a slate-gray to a drab-grey. Sufficient hydrosulphuric acid gas was evolved to blacken paper moistened with acetate of lead, a fact which proved that the blue had lost some of its sulphur. Seeing that not only no red was produced, but that no tendency to red was imparted, is it possible the change described by Gmelin occurred under exceptional circumstances? All conversant with chemical matters will admit that results are obtained occasionally which cannot be repeated, owing it may be to some slight difference in the materials employed, or some slight variation of the process. Perhaps a link, considered of no importance at the time and overlooked, has been lost, and thus the whole chain of proceeding becomes useless. It is, therefore, within the bounds of probability that the red ultramarine of the great German chemist was furnished either by a peculiar specimen of blue, or by a modified form of the method he gives. We have noticed the subject at some length because if a red ultramarine, brilliant and durable, could be obtained, the colour might prove of value. A permanent artificial compound corresponding to French blue would certainly be an acquisition.

121. Uranium Red.

By treating the yellow sulphite of uranium with a prolonged current of sulphuretted hydrogen, and saturating gradually with ammonia, a red finally results. This colour is insoluble in water, and it has the objection of remaining partially suspended for an almost indefinite time, colouring the liquid light red. The product is brighter and more beautiful while moist; when dried and powdered, its tone—slightly approaching vermilion—is duller. The colour may be obtained of several degrees of brilliancy, but, apart from the question of expense, it would be inadmissible in oil, the red gradually altering by contact therewith. The most persistent tint at length resembles burnt Sienna.

122. Wongshy Red.

There was imported a few years ago from Batavia a new colouring principle, under the name of wongshy, and consisting of the seed-capsule of a species of gentian. The aqueous extract, freed from the pectin which it contains, yields with baryta- and lime-water yellow precipitates, from which acids separate the colouring matter of a vermilion hue. When thus prepared it is insoluble in water, and would so far be adapted for a pigment. The red has not, however, been employed as such, and we are unacquainted with its habitudes.

* * * * *

The concluding remarks appended to the chapter on yellow apply equally to red, and indeed to all other colours. It is not assumed that the list is exhausted: there are other reds, but they are, like some we have mentioned, ineligible as pigments, either by reason of their fugacity, their costliness, the difficulty of producing them on a scale, or the sources whence they are derived being commercially unavailable. While endeavouring throughout the work to render complete the collection of pigments actually in use, it is our object to give a selection only of numbered italicised colours; ample enough, however, to include those which have become obsolete or nearly so, and full enough to afford some insight into our resources. The nearer we approach perfection, the more eager we are to arrive at it: the path before us, therefore, cannot fail to be of interest.

Looking back, and noting those pigments commonly employed, we find that the reds like the yellows are divisible into three classes—the good, bad, and indifferent; or the permanent, the semi-stable, and the fugitive.

Among permanent reds, rank cadmium red, madder reds, Mars red, the ochres, and vermilions.

In the second or semi-stable class, must be placed cochineal lakes, Indian lake, and red chrome.

To the third division, or the fugitive, belong dragon's blood, pure scarlet, red lead, and the coal-tar reds.

With regard to the foregoing classification, it must be borne in mind that the properties and effects of pigments are much influenced by adventitious circumstances. Sometimes pigments are varied or altogether changed by the grounds on which they are employed, the vehicles in which they are used, the siccatives and colours with which they are mixed, and the varnishes by which they are covered. And as there is no exact and constant agreement in different specimens of like pigments, so there is no exact and constant result in their use. Artists vary as much as the pigments they employ: some resemble the old masters in the delicacy with which they treat their colours, the cleanliness with which they surround them, and the care with which they compound them: in the hands of such artists pigments have every chance. Some, however, are characterized by a careless manipulation, a dirty mode of working, an utter disregard for all rules of admixture: with such painters the best colours may be ruined. And here, indeed, it may be asked, whether these latter are not more properly termed painters than artists, chiefly belonging as they do to that slap-dash school which manufactures pictures simply to sell them. Duly subordinated, the commercial side of art has a value which it were affectation to ignore; but to paint merely for the present, heedless of the future, is to sink art to the level of a trade, not the most honest. For it is the purchaser who suffers from the want of thought bestowed on the materials, the sloppy manipulation, the careless compounding; sins of omission and commission that cause him, on finding his picture becoming chaos, to join the detractors of modern pigments. In classifying colours therefore, those also should be classified who use them:—into artists, whose love for art would render it more lasting than themselves; and into painters, whose motto is Vita brevis est, Ars quoque.



CHAPTER X.

ON THE PRIMARY, BLUE.

The third and last of the primary or simple colours is blue, which bears the same relation to shade as yellow to light. Hence it is the most retiring and diffusive of all colours, except purple and black; and all colours have the power of throwing it back in painting, to a greater or less extent, in proportion to the intimacy of their relations to light—first white, then yellow, orange, red, &c.

Blue alone possesses entirely the quality technically called 'coldness' in colouring, and it communicates this property variously to all other colours with which it happens to be compounded. Most powerful in a strong light, it seems to become neutral and pale in a declining light, owing to its ruling affinity with black or shade, and its power of absorbing light. Consequently, the eye of the artist is liable to be deceived when painting with blue in too low a light, or toward the close of day, to the endangering of the warmth and harmony of his picture. Entering into combination with yellow in the composition of all greens, and with red in all purples, blue characterizes the tertiary olive, and is also the prime colour or archeus of the neutral black, &c., as well as of the semi-neutral gray, &c.: it therefore is changed in hue less than any other colour by mixture with black, as it is likewise by distance. Blue is present subordinately in all tertiary and broken colours, and being nearest in the scale to black, breaks and contrasts powerfully and agreeably with white, as in pale blues, skies, &c. Being less active than the other primaries in reflecting light, it is sooner lost as a local colour by assimilation with distance. There is an ancient doctrine that the azure of the sky is a compound of light and darkness, and some have argued hence that blue is not a primary colour, but a mixture of black and white; but pure or neutral black and white compound in infinite shades, all of which are neutral also, or grey. It is true that a mixture of black and white is of a cool hue, because black is not a primary colour, but a compound of the three primary colours in which blue predominates, a predominance which is rendered more sensible when black is diluted with white. As to the colour of the sky, in which light and shade are combined, that is likewise neutral, and never blue except by contrast; thus, the more the light of the sun partakes of a golden or orange hue, and the more parched and burnt the earth is, the bluer appears the sky, as in Italy and all hot countries. In England, where the sun is cooler, and a perpetual verdure reigns, infusing blue latently into the landscape, the sky is warmer and nearer to neutrality, partaking of a diversity of greys, which beautifully melodize with blue as their key, and harmonize with the light and landscape. Therefore the colour of the sky is always a contrast to the direct and reflected light of the scene: if this light were of a rose colour, the neutral of the sky would be converted into green, or if purple, the sky would become yellow. Similarly would it be in all cases, according to the laws of chromatic equivalence and contrast, as may be often seen in the openings of coloured clouds at the rising and setting of the sun.

In art, blue is apt to be discordant in juxtaposition with green, and less so with purple, both which are cool colours; consequently blue requires its contrast, orange, in equal proportion whether of surface or intensity, to compensate or resolve its dissonances and correct its coldness. In nature, however, blue is not discordant with either green or purple, nor are any two colours (as we have said before) ever found so. On the palette of nature each colour is an example of colouring: no colour is too absolute or defined, no perfectly pure blue appears beside a perfectly pure green. A blue flower nestled in its green leaves does not offend the nicest eye, but the blue and green are not blue and green alone. There is, perhaps, but a single gleam of pure colour in each: the rest is composed of such varied hues and tints and shades, so broken and blended and beautifully harmonized, that no jarring discord is possible. Hue melts into hue, tint into tint, shade into shade; and thus does the simplest weed teach a lesson in colouring the proudest painter may stoop to learn.

We have spoken of blue, which is termed a cold colour, as retiring; and of yellow and red, which are called warm colours, as advancing. By this we must not be understood to mean that blue, as blue, expresses distance; or that yellow and red, as yellow and red, express nearness. Colours are advancing or retiring in their quality—as depth, delicacy, &c., not in their hue. A blue object set side-by-side a yellow one will not look an inch farther off, but a red or orange cloud, in the upper sky, will always seem to be beyond a blue cloud close to us, as it is in reality. We grant that in certain objects, blue is a sign of distance, but that is not because blue, as a mere colour, is retiring; but because the mist in the air is blue, and therefore any warm colour which has not strength of light enough to pierce the mist is lost or subdued in its blue. Blue in itself, however, is no more, on this account, retiring, than brown is retiring, because when stones are seen through brown water, the deeper they lie, the browner they appear. Neither blue nor yellow nor red possesses, as such, the smallest power of expressing either nearness or distance; they merely express themselves under the peculiar circumstances which render them at the moment, or in that place, signs of nearness or distance. Thus, purple in a violet is a sign of nearness, because the closer it is looked at the more purple is seen; but purple in a mountain is a sign of distance, because a mountain close at hand is not purple, but green or grey. It may, indeed, be generally assumed that a tender or pale colour will more or less denote distance, and a powerful or dark colour nearness; but even this is not always so. Heathery hills will usually give a pale and tender purple near, and an intense or dark purple far away: the rose colour of sunset on snow is pale on the snow at one's feet, but deep and full on the snow in the distance; and the green of a Swiss lake is pale in the clear waves on the beach, but intense as an emerald in the sunstreak, six miles from shore. And in any case, when the foreground is in strong light, with much water about it or white surface, casting intense reflections, all its colours may be perfectly delicate, pale, and faint; while the distance, when it is in shadow, may relieve the whole foreground with deepest shades of purple, blue green, or ultramarine blue.

There is one law, however, about distance, which has some claims to be considered constant, namely, that dulness and heaviness of colour are more or less indicative of nearness. All distant colour is pure colour: it may not be bright, but it is clear and lovely, not opaque nor soiled; for the air and light coming between us and any earthy or imperfect colour, purify or harmonize it; hence a bad colourist is peculiarly incapable of expressing distance. It is not of course meant that bad colours are to be used in the foreground by way of making it come forward; but only that a failure in colour there will not put it out of its place. A failure in colour in the distance will at once do away with its remoteness; a dull-coloured foreground will still be a foreground, though coloured badly; but an ill-painted distance will not be merely a dull distance, it will be no distance at all.

This seeming digression is not out of place, as it will enable the artist better to understand that it is in their quality, not in their hue, that colours are advancing or retiring; and that he must rely on the depth, delicacy, &c., of his pigments, and not simply on their colours, to produce effects of distance.

Of all colours, except black, blue contrasts white most powerfully. In all harmonious combinations of colours, whether of mixture or neighbourhood, blue is the natural, prime, or predominating power. Accordingly, blue is universally agreeable to the eye in due relation to the composition, and may more frequently be repeated therein, pure or unbroken, than either of the other primaries; whence the employment of ultramarine by some masters throughout the colouring of a picture.

Blue pigments, like blue flowers, are more rare than those of the other primary colours. In permanent blues the palette is very deficient, the list being exhausted when the native and artificial ultramarines and the cobalts have been mentioned. That there is room for new blues, durable and distinct, cannot therefore be denied. A good addition has been made of late years in the German Colin, known here as Cerulian Blue and Coeruleum. What is chiefly wanted, however, is a colour combining the wonderful depth, richness, and transparency of Prussian blue with the strict stability of ultramarine. A permanent Prussian blue would be the most valued gift the palette could receive.

COBALT BLUES

comprise Cerulian Blue or Coeruleum, Cobalt Blue, Smalt, Royal Blue, Dumont's Blue, Saxon Blue, Thnard's Blue, Leithner's Blue, Hungary Blue, Dutch Ultramarine, Zaffre or Enamel Blue, Vienna Blue, Paris Blue, Azure, &c., and are obtained by the action of heat on mixtures of earthy or metallic bases with cobalt. They are divisible into three classes—the stannic cerulian blue, the aluminous cobalt blues, and the siliceous smalts. Of these, the first possesses the least depth; the second hold a middle position; while the third are marked by exceeding richness. Although not to be ranked with ultramarine, the stannic and aluminous blues may be described as durable, or at least as durable rather than semi-stable. There are, as we have before observed, different degrees of permanence, and the blues in question are not readily affected. With regard to smalts, they are, as artist's pigments, inferior in stability to other blues of cobalt.

123. CERULIAN BLUE,

or Coeruleum. Under the name Colin there has of late years been imported from Germany the cobalt blue with a tin base to which reference has just been made. This comparatively new pigment—which likewise contains or is mixed with gypsum, silica, and sometimes magnesia—has the distinctive property of appearing a pure blue by artificial light, tending neither to green on the one hand nor to purple on the other. This advantage, added to its permanence, has conferred a popularity upon coeruleum which its mere colour would scarcely have gained for it. A light and pleasing blue, with a greenish-grey cast by day, it possesses little depth or richness, and is far excelled in beauty by a good aluminous cobalt. A certain chalkiness, moreover, somewhat detracts from its transparency, and militates against its use in water. It is in oil, and as a night colour, that coeruleum becomes of service, as our present system of lighting picture galleries by gas affects the purity of blues generally. If those galleries were illuminated by means of the electric light, we have it on the authority of Chevreul that all colours and shades would show as well as by day: the same purpose would be answered by the magnesium light. Some artificial lights are the ruin of colours; in the soda flame (alcohol and salt) for instance, yellow chromate of lead appears white, while red ochre and aniline blue appear black.

Like other blues of cobalt, coeruleum assumes a greenish obscurity in time, but like them it resists for a lengthened period both the action of light and impure air, although chemically it is more open to the influence of the latter, owing to its tin base. In admixture it may safely be employed, as well as in fresco or enamel. For stage skies, &c., in high-art scenery, the blue is admirably adapted. Now that there are so many scene-painters who are artists—and so many artists who are scene-painters—in bringing Nature to the foot-lights the effect of gas on colours is of importance.

124. COBALT BLUE,

to which the various appellations have been given of Thnard's Blue, Vienna Blue, Paris Blue, Azure, Cobalt-Ultramarine, &c., is the name now exclusively confined to that preparation of cobalt which has a base of alumina. It may, therefore, be not improperly called a blue lake, the colour of which is brought up by fire, in the manner of enamel blues. The discovery of this important pigment was made in 1802 by M. Thnard, who obtained it by calcining a well-combined mixture of alumina and crystals of cobalt. There may be employed with the aluminous base, either the arseniate, the borate, or the phosphate of cobalt; but the latter in preference, as it produces the purest colour. The arseniate has always a violet tinge, more visible by gas-light than by day; while, on account of the arsenic, the blue is more apt to be greened by impure air, by reason of the formation of yellow sulphide of arsenic. The purity of the colour, however, does not altogether depend on the compound of cobalt used; in a great measure—as with other pigments—it rests on the purity of the materials. To obtain a perfect blue, neither inclining to purple nor green, the cobalt and alumina should be freed from iron, and the former, as much as possible, from nickel also. With the absence of these and proper skill, a true and brilliant blue may be produced, almost rivalling the finest ultramarine. Apart, too, from its increased beauty, a cobalt blue containing no iron or nickel is of greater permanence than the ordinary products, being less liable to that greenness and obscurity which time confers.

Though not possessing the body, transparency, and depth of ultramarine, nor its natural and modest hue, commercial cobalt blue works better in water than that pigment in general does; and is hence an acquisition to those who have not the management of the latter. Resisting the action of strong light and acids, its beauty declines by time, while impure air greens and ultimately blackens it. Nevertheless, these changes are not readily effected, especially in well made samples full of colour, and sometimes the green tone is mechanically imparted. What wheat is to a loaf, colour is to a pigment—it has to be ground and made up for use; in the one vehicle to be mixed with gums, in the other with oils. It often happens that colours have an antipathy to the latter, and refuse to compound kindly therewith. Occasionally this repugnance manifests itself in a few days, occasionally not for months. We know of a green which flatly declines to have anything to do with oils, sinking and separating therefrom in the course of a week, and leaving the clear oil on the top. Repeatedly have colours to be coaxed to behave themselves as pigments, coaxed not to 'run,' to work well, to dry well, &c.; and in the humouring of their likes and dislikes the skill and patience of the artist-colourman are sometimes severely taxed. Given a colour, it might puzzle most chemists to convert it into a pigment; luckily Commerce lends her aid. Lasting success, it is true, does not always follow, and oils will rise to the surface now and then, giving green hues to blues, orange hues to reds, and buff hues to yellows. Hence changes of colour have been imputed before now to chemical alteration, when in reality the results have been physical, caused by the subsidence of the pigments, and the floating of the vehicles employed.

Cobalt blue dries well in oil, does not injure or suffer injury from pigments in general, and may be used with a proper flux in enamel, as well as in fresco. It affords clear bright tints in skies and distances, but is apt to cause opacity if brought too near the foreground, and to assume a violet tinge by artificial light. With madder brown it yields a range of fine pearly neutrals; and with light red, in any proportion, gives beautiful cloud tints. In combination with aureolin and sepia, or rose madder, cobalt furnishes most agreeable and delicate tints for distant trees, when under the influence of a soft light, or hazy state of the atmosphere. In water-colour painting, cobalt is tolerably firm on paper, and consequently answers better for some purposes than French blue. In middle distances, if the cobalt possess a tendency to chalkiness, the addition of a little indigo is a good corrective, especially where the blue tone is required to be sombre and dark: it should, however, be observed that the change is but temporary, indigo being a fugitive pigment. In marine painting in water-colours, cobalt is most useful for the remotest parts of seas and headlands. When dry, it can be changed by going over it with a slight wash of vermilion or light red, whereby a prismatic character is realized. Any strength of tone can be obtained by repeating the washes, and should the colour be too powerful, it may be reduced by pouncing it with a soft wet sponge; or if too cold and blue, by a thin wash of burnt Sienna, merely the water stained.

The blues of cobalt, on whatever base they may be prepared, are distinguished from native and artificial ultramarines by not being decolorised by acids.

125. SMALT,

Invented about the year 1540, in Saxony, is a vitreous compound of cobalt and silica, in fact a blue glass. Since the fifteenth century, cobalt has been used in different parts of Europe to tinge glass; and so intense is the colouring power of its oxide, that pure white glass is rendered sensibly blue by the addition of one thousandth part, while one twenty-thousandth part communicates a perceptible azure tint. In common with cobalt blue, the name Azure has sometimes been given to it. Varying exceedingly in quality and colour, the rougher kinds have been employed by the laundress, and in the making of porcelain, pottery, stained glass, encaustic tiles, &c.; as well as to cover the yellow tinge of paper. For this last purpose, however, smalt is not perfectly adapted, the colour being difficult to lay on uniformly, and the paper when written on blunting the nibs of pens. Hence it has been superseded to a great extent by artificial ultramarine, the presence of which may be detected by the yellow spot which a drop of acid leaves on the paper.

A coarse gritty texture is peculiar to smalt, whether it be the Powder Blue of the washtub and Blue Sand of the pottery, or the Dumont's and Royal Blue of the artist and high-class manufacturer. But the strict stability which is a feature in smalt when used for painting on glass and enamel does not follow it to the studio: both in water and oil its beauty soon decays, as is often the case with other vitrified pigments; nor is it in other respects eligible, being, notwithstanding its richness and depth, very inferior to the cobalts preceding. It may seem a paradox that the same colour should be at once so durable and so fugitive, but we may briefly explain it by saying when vitreous pigments are reduced to that extreme state of division which the palette requires, they lose the properties they possess in a less finely divided state. The best smalt in lumps appears black, yields a blue powder on grinding, becomes paler on further grinding, and may be almost decolourised by continued and excessive grinding. Smalt, it has been stated, is merely a blue glass; and when a piece of blue glass, or a blue crystal of sulphate of copper, is reduced to the fineness of flour, the blue is lost. In vitrified and crystallised compounds, colour depends on cohesion: sufficiently separate the particles, and the colour more or less disappears. Not only, moreover, does grinding effect an optical change in vitreous pigments, but it imposes further alteration. That colour which was safe when locked up in a mass, crushed to minute atoms is no longer so: imbedded in glass or enamel it will endure for ages, but ground to impalpable powder becomes as liable to influence as though it had never been subjected to heat at all. To sum up, vitreous pigments are durable in a coarse or compact form, but are not more stable than others when reduced to extreme division. As far as regards artists' colours, therefore, vitrification does not impart permanence.

The grittiness to which we have referred is one of the defects of smalt, which cannot, consistently with preserving its colour be entirely freed from that drawback—an objection which pertains to vitreous pigments in general. Hence it does not wash well, and in mural decoration is sometimes applied to work by strewing the dry powdered colour upon a flat ground of white or blue oil paint immediately after the latter is laid on, whilst it yet remains wet. Of little body, it is a vivid and gorgeous blue; bright, deep, and transparent, bordering on the violet hue. It is chiefly employed in illumination and flower painting. The inferior kinds of smalt are occasionally adulterated with chalk.

126. CYANINE.

Beckmann is fully convinced that the cyanus of Theophrastus and the coeruleum of Pliny were a blue copper earth. However that may be, in these days both names signify cobalt compounds, coeruleum being a stannate of cobalt, and cyanine a mixture of cobalt and Prussian blue. Unlike the former, cyanine, being composed of two old colours, can lay no claim to originality. In the fourth chapter it was observed, "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." Whether these remarks are applicable to cyanine or not is a question for artists to decide: in our opinion, with so many semi-stable original pigments, the introduction of semi-stable compounds is to be deprecated. Cyanine is a rich, deep, transparent blue, but its richness and depth, as well as to a great extent its transparency, depend upon Prussian blue, which is not strictly stable. Hence the peculiar properties of cyanine remain unchanged only so long as the Prussian blue itself, the pigment losing its colour by degrees on exposure to air and light, and gradually assuming the tint of the paler but more permanent cobalt. A mixture, be it remembered, necessarily partakes of the qualities of its constituents, and if one of these be fugitive, the compound cannot preserve its original hue.

Within the last few years, a compound similar to cyanine has appeared, under the name of Leitch's Blue.

127. INDIGO,

or Indian Blue, was known to the ancients under the name of Indicum, whence its present appellation. In modern Europe, it first came into extensive use in Italy; but about the middle of the sixteenth century, the Dutch began to import and employ it in considerable quantity. Present in the woad plant, which is a native of Great Britain, indigo is chiefly derived from a genus of leguminous plants called Indigofera, found in India, Africa, and America. The colouring matter of these is wholly in the cellular tissue of the leaves, as a secretion or juice; not, however, in the blue state in which one is accustomed to see indigo, but as a colourless substance, which continues white only so long as the tissue of the leaf remains perfect: when this is by any means destroyed, oxygen is absorbed from the atmosphere, and the principle becomes blue. The best indigo is so light as to swim upon water, but the commercial article seldom contains more than 50 per cent. of blue colouring matter or true indigo, the remainder consisting of either accidental or intentional impurities.

In painting, indigo is not nearly so bright as Prussian blue, but it is extremely powerful and transparent, and may be described as a Prussian blue in mourning. Of great body, it glazes and works well both in water and oil. Its relative permanence as a dye has obtained it a false character of extreme durability as a pigment, a quality in which it is nevertheless very inferior even to Prussian blue. By impure air it is injured, and in glazing some specimens are firmer than others, but not durable; while in tint with white lead they are all fugitive. Employed in considerable body in shadow, it is more permanent, but in all respects Prussian blue is superior.

Despite this want of stability, indigo is a favourite colour with many artists, who sacrifice by its use future permanence to present effect. It is so serviceable a pigment for so many purposes, especially in admixture, that its sin of fugacity is overlooked. Hence we find indigo constantly mentioned in works on painting, their authors forgetting or not caring to remember that wholesome axiom, a fugitive colour is not rendered durable by being compounded. Artistically, it is adapted for moonlights, and when mixed with a little lamp black, is well suited for night clouds, distant cliffs, &c. With a little raw umber and madder it is used for water in night effects. With the addition of a little madder it forms a good gray; and with madder and burnt Sienna is useful for dark rocks, this combination, with raw Sienna, being also eligible for boats. For these and other mixed tints, however, Prussian blue saddened by black with a suspicion of green in it, is equally fitted, and is more permanent. Indeed, it would be perhaps justifiable to introduce such a compound, under the name say, of Factitious Indigo.

Indigo in dust, or in small bits, is often adulterated with sand, pulverized slate, and other earthy substances. That indigo is best which is lightest, brightest, most copper-coloured, most fine-grained, and inodorous.

128. INTENSE BLUE

is indigo refined by solution and precipitation. By this process, indigo becomes more durable, and, being separated from impurities, is rendered much more powerful, transparent, and deep. It washes and works admirably in water; in other respects it possesses the common properties of indigo. It is apt, however, to penetrate the paper on which it is employed, if not well freed by washing from the acid and saline matter used in its preparation. This is not always easily effected, and we cannot help thinking that in the manufacture of intense blue a dry method would be preferable. Indigo may, by cautious management, be volatilized, and therefore be most thoroughly purified without the aid of acids and alkalies. The best mode of subliming this substance is to mix one part of indigo with two parts of plaster of Paris, make the whole into a paste with water, spread it upon an iron plate, and, when quite dry, heat it by a spirit lamp. The volatilization of the indigo is aided by the vapour of water disengaged from the gypsum, and the surface of the mass becomes covered with beautiful crystals of pure indigo, which may be readily removed by a thin spatula. At a higher temperature, charring and decomposition take place.

129. PRUSSIAN BLUE,

otherwise called Berlin Blue, Paris Blue, Prussiate of Iron, Ferrocyanide of Iron, &c., was accidentally discovered in 1710 by Diesbach, a colour-maker at Berlin. It is a compound of iron and cyanogen, of varying composition, formed by adding yellow prussiate of potash to a persalt of iron, or by oxidizing the precipitate obtained from the prussiate and a protosalt. The finest blue is furnished by sesquinitrate of iron, but the salt almost exclusively employed is the protosulphate, the freedom of which from copper is essential to the colour of the blue. As is the case with other pigments, Prussian blue differs considerably in colour, in depth, and in permanence, according to the purity of the materials, the mode of manufacture, and the absence of adulterants. Like smalt, it is known in the washtub as well as in the studio; and in the cheaper varieties, alumina, starch, chalk, oxide of iron, &c., are often largely present. A good unsophisticated sample in the dry state is intense blue, almost black, hard and brittle, much resembling in appearance the best indigo, and having a similar copper-red fracture. It does not effervesce with acids, as when adulterated with chalk; nor become pasty with boiling water, as when sophisticated with starch. Further, it feels light in the hand, adheres to the tongue, is inodorous, tasteless, not poisonous, and is insoluble in water. Forming a bulky mass while moist, Prussian blue shrinks to a comparatively small compass when well washed and dried by gentle heat; and, when once dried, being difficult to reduce again to the state of extreme division which it possessed while wet, it is frequently sold and used in paste for common purposes. We have said that a good sample of Prussian blue is insoluble in water, and for artistic use it should certainly be so, as otherwise it has a tendency to stain the fabric on which it is employed, a defect formerly very prevalent. All Prussian blues, however, are not insoluble, and these are not only liable to the drawback named, but are less to be depended on for permanence. Improper proportions, for instance, of sesquichloride of iron and potash-ferrocyanide will yield a blue which, when washed even with cold water, continually imparts to it a yellow or green colour, through the partial solution of the prussiate. All commercial Prussian blue, and indeed that which is prepared by careful chemical processes, give up the ferrocyanide to boiling water, thereby colouring it greenish yellow; but a sample which parts with its prussiate to cold water is quite unfitted for the palette, for which the most perfect specimen is none too stable.