The painters, who lived at the time when the arts were restored in Italy, used this pigment; and the bright greens seen in some old pictures are made by glazings of verdigris. It is often largely adulterated with chalk and sulphate of copper.
183. MIXED GREEN
Green, being a compound of blue and yellow, may be got by combining those colours in the several ways of working—by mixing, glazing, hatching, or otherwise blending them in the proportions of the various hues required. To obtain a pure green, which consists of blue and yellow only, a blue should be chosen tinged with yellow rather than with red, and a yellow tinged with blue. If either a blue or a yellow were taken, tinged with red, this latter colour would go to produce some grey in the compound, which would tarnish the green. The fine nature-like greens, which have lasted so well in some of the pictures of the Italian schools, appear to have been compounded of ultramarine, or ultramarine ashes and yellow. Whatever pigments are employed on a painting in the warm yellow hues of the foreground, and blue colouring of the distance and sky, are advantageous for forming the greens in landscape, &c., because they harmonize better both in colouring and chemically, and impart homogeneity to the whole: a principle conducive to a fine tone and durability of effect, and applicable to all mixed tints. In compounding colours, it is desirable not only that they should agree chemically, but that they should have, as far as possible, the same degree of durability. In these respects, aureolin and ultramarine, gamboge and Prussian blue, Indian yellow and indigo, are all judicious mixtures, although not all to be recommended.
| PERMANENT YELLOWS. | PERMANENT BLUES. |
|---|---|
| Aureolin. | Cerulian Blue. |
| Cadmium Yellow, pale. | Cobalt Blue. |
| Cadmium Yellow, deep. | Genuine Ultramarine. |
| Lemon Yellow. | Brilliant Ultramarine. |
| Mars Yellow. | French Ultramarine. |
| Naples Yellow, modern. | New Blue. |
| Ochres. | Permanent Blue. |
| Orient Yellow. | |
| Raw Sienna. |
The foregoing yellows and blues are in no wise inimical to each other, and yield the best mixed greens, chemically considered, the palette can afford. In an artistic sense, we confess, the result is not so satisfactory: the list of blues, it must be admitted, being somewhat scant. Among the latter there is no pigment with the wonderful depth, richness, and transparency of Prussian blue, and none consequently which will furnish with yellow a green of similar quality. That the artist, therefore, will dispense with Prussian blue, it would be too much to expect. There is, however, less necessity for it since the introduction of viridian, a green resembling that which is produced by admixture of Prussian blue and yellow, and which may be varied in hue by being compounded with aureolin or ultramarine. Our object in this work is to give precedence to the chemical rather than the artistic properties of pigments, to separate the strictly stable from the semi-stable, and the semi-stable from the fugitive. A colour or a mixture may be chemically bad but artistically good, and vice versâ; but the chemist looks upon no pigment or compound with favour unless it be perfectly permanent, and ignores its mere beauty when void of durability. Hence, all artistic considerations are set aside in our lists of permanent pigments: if it be possible to use them alone, so much the better for the permanence of painting; if not, so much the worse will it be, according to the degree of fugacity of the colours employed.
184. BRONZE,
and the three succeeding varieties, are greens resembling each other in being semi-stable, and more or less transparent. Bronze is a species of Prussian green, of a dull blue-black hue. In its deep washes it appears a greenish-black with a coppery cast. It is used in ornamental work, and sometimes as a background tint for flower pieces.
185. CHROME GREENS,
commonly so called, are compounds of chromate of lead and Prussian blue, a mixture which is also known as Brunswick Green. Fine bright greens, they are suited to the ordinary purposes of mechanic painting, but are quite unfit for the artist's craft, chrome yellow reacting upon and ultimately destroying Prussian blue when mixed therewith. For the latter, cheap cobalts and ultramarines are preferably substituted, although they do not yield greens of like power and intensity.
Under the names of English Green, Green Cinnabar, &c., 'new' green pigments have been from time to time introduced, which have turned out mixtures of Prussian blue and chromate of lead; not made, however, by compounding the two, but directly by processes similar to the following:—A mixed solution of the acetates of lead and iron is added to a mixed solution of the yellow prussiate and chromate of potash, the necessary acetate of iron being obtained by precipitating a solution of acetate of lead by sulphate of iron, and filtering the supernatant liquid. Or; to a solution of Prussian blue in oxalic acid, first chromate of potash is added, and then acetate of lead.