ON THE SECONDARY, GREEN.
Green, which occupies the middle station in the natural scale of colours
and in relation to light and shade, is the second of the secondary
colours. It is composed of the extreme primaries, _yellow_ and _blue_,
and is most perfect in hue when constituted in the proportions of three
of yellow to eight of blue of equal intensities; because such a green
will exactly neutralize and contrast a perfect red in the ratio of
eleven to five, either of space or power. Of all compound colours, green
is the most effective, distinct, and striking, causing surprise and
delight when first produced by a mixture of blue and yellow, so
dissimilar to its constituents does it appear to the untutored eye.
Compounded with orange, green converts it into the one extreme tertiary
_citrine_; while mixed with purple, it becomes the other extreme
tertiary _olive_: hence its relations and accordances are more general,
and its contrasts more agreeable with all colours, than those of any
other individual colour. Accordingly it has been adopted very wisely in
nature as the common garb of the vegetal creation. It is, indeed, in
every respect a central or medial colour, being the contrast,
compensatory in the proportion of eleven to five, of the middle primary
_red_, on the one hand, and of the middle tertiary _russet_, on the
other; while, unlike the other secondaries, all its hues, whether
tending to blue or yellow, are of the same denomination.
These attributes of green, which render it so universally effective in
contrasting colours, cause it also to become the least useful in
compounding them, and the most apt to defile other colours in mixture.
Nevertheless it forms valuable semi-neutrals of the olive class with
_black_, for of such subdued tones are those greens by which the more
vivid tints of nature are opposed. Accordingly, the various greens of
foliage are always more or less semi-neutral in hue. As green is the
most general colour of vegetal nature and principal in foliage; so red,
its harmonizing colour, with compounds of red, is most general and
principal in flowers. Purple flowers are commonly contrasted with
centres or variegations of bright yellow, as blue flowers are with like
relievings of orange; and there is a prevailing hue, or character, in
the green colour of the foliage of almost every plant, by which it is
harmonized with the colours of its flowers.
The chief discord of green is blue; and when they approximate or
accompany each other, they require to be resolved by the opposition of
warm colours. It is in this way that the warmth of distance and the
horizon reconciles the azure of the sky with the greenness of a
landscape. Its less powerful discord is yellow, which needs to be
similarly resolved by a purple-red, or its principles. In tone, green is
cool or warm, sedate or gay, either as it inclines to blue or to yellow;
yet in its general effects it is cool, calm, temperate, and refreshing.
Having little power in reflecting light, it is a retiring colour, and
readily subdued by distance: for the same reason, it excites the retina
less than most colours, and is cool and grateful to the eye. As a colour
individually, green is eminently beautiful and agreeable, but it is more
particularly so when contrasted by its compensating colour, red, as it
often is in nature, even in the green leaves and young shoots of plants
and trees. "The autumn only is called the painter's season," remarks
Constable, "from the great richness of the colours of the dead and
decaying foliage, and the peculiar tone and beauty of the skies; but the
spring has, perhaps, more than an equal claim to his notice and
admiration, and from causes not wholly dissimilar,--the great variety of
tints and colours of the living foliage, accompanied by their flowers
and blossoms. The beautiful and tender hues of the young leaves and
buds are rendered more lovely by being contrasted, as they now are, with
the sober russet browns of the stems from which they shoot, and which
still show the drear remains of the season that is past."
The number of pigments of any colour is in general proportioned to its
importance; hence the variety of greens is very great, though the
classes of those in common use are not very numerous. Of the three
secondaries, green is the colour most often met with, and, consequently,
the most often compounded: for this last reason, perhaps, the palette is
somewhat deficient in really good original greens--more deficient than
there is any necessity for.
CHROME OXIDES.
By numerous methods both wet and dry, oxides of chromium are obtainable
pale and deep, bright and subdued, warm and cool, opaque and
transparent: sometimes hydrated, in which case they cannot be employed
in enamelling; and sometimes anhydrous, when they are admissible
therein. But whatever their properties may be, chemical, physical, or
artistic, they are all strictly stable. Neither giving nor receiving
injury by admixture, equally unaffected by foul gas and exposure to
light, air, or damp, these oxides are perfectly unexceptionable in every
respect. For the most part they are eligible in water and oil, drying
well in the latter vehicle, and requiring in the former much gum. They
have long been known as affording pure, natural, and durable tints; but,
until within the last few years, have been rather fine than brilliant
greens. Lately, however, processes have been devised, yielding them
almost as bright, rich, and transparent, as the carmine of cochineal
itself.
175. OXIDE OF CHROMIUM,
_Opaque Oxide of Chromium_, _Green Oxide of Chromium_, _Chrome Oxide_,
_True Chrome Green_, _Native Green_, _&c._, is found native in an impure
state as Chrome Ochre, but is always artificially prepared for artistic
use. Obtained anhydrous by dry modes, this is the only chrome oxide
available in enamelling, and is the one seen on superior porcelain. It
is a cold, sober sage green, deep-toned, opaque, and, although dull,
agreeable to the eye. Its tints with white are peculiarly delicate and
pleasing, possessing a silvery luminous quality, and giving the effect
of atmosphere. Being very dense and powerful, it must be employed with
care to avoid heaviness, and is preferably diluted with a large quantity
of white, or compounded with transparent yellow. In the hands of a
master, this gray-green furnishes lustrous hues with brown pink, Italian
pink, and Indian yellow; three beautiful but fugitive pigments, of
which the two last may be replaced by aureolin. Of this Mr. Penley
observes, "as adapted for the colouring of foliage and herbage, it is
impossible to say too much in its praise. It imparts the vividness and
freshness of nature to every colour with which it is combined;" and he
brackets oxide of chromium with aureolin as a compound hue "extremely
useful." In flat tints, the oxide sometimes does not wash well in water.
176. TRANSPARENT OXIDE OF CHROMIUM
being deficient in body, is only eligible in oil. A very pale
greyish-white green in powder, it gives an agreeable yellowish green of
some depth in oil, moderately bright, but not very pure or clear.
We are acquainted with another transparent chrome oxide of far greater
beauty, brightness, purity, and clearness than the above. Of a bluish
green hue, a difficulty in getting it to mix with oil renders it at
present unavailable.
177. VERONESE GREEN,
or _French Veronese Green_, is a comparatively recent introduction,
similar in colour and general properties to the following; beside which,
however, it appears dull, muddy, and impure. It is often adulterated
with arsenic to an enormous extent, which interferes with its
transparency, mars its beauty, and renders it of course rankly
poisonous.
178. VIRIDIAN
is a still later addition to the palette, and the only permanent green
which can be described as gorgeous, being not unlike the richest velvet.
Pure and clear as the emerald, it may be called the Prussian Blue of
Greens, of such richness, depth, and transparency is it. In hue of a
bluish-green, its deepest shades verge on black, while its light tints
are marked by transparent clearness unsurpassed. No compound of blue and
yellow will afford a green at once so beautiful and stable, so gifted
with the quality of light, and therefore so suited for aerial and liquid
effects. Used with aureolin, it gives foliage greens sparkling with
sunshine; and, fitly compounded, will be found invaluable for the glassy
liquidity of seas, in painting which it becomes incumbent to employ
pigments more or less transparent. "The general failing in the
representation of the sea is, that instead of appearing liquid and thin,
it is made to bear the semblance of opacity and solidity. In order to
convey the idea of transparency, some object is often placed floating on
the wave, so as to give reflection; and it is strange that we find our
greatest men having recourse to this stratagem. To say it is not true in
all cases, is saying too much; but this we do assert, that as a general
principle it is quite false, and we prove it in this way: water has its
motion, more or less, from the power of the wind; it is acted upon in
the mass, and thus divided into separate waves, and these individually
have their surface ruffled, which renders them incapable of receiving
reflection. The exception to this will be, where the heaving of the sea
is the result of some gone-by storm, when the wind is hushed, and the
surface becomes bright and glassy. In this state, reflections are
distinctly seen. Another exception will be in the hollow portion of the
waves, as they curl over, and dash upon the shore."
As viridian, like the sea, is naturally "liquid and thin, bright and
glassy," the extract we have quoted from Mr. Penley, points to this
green as a pigment peculiarly adapted for marine painting; in which, it
may be added, its perfect permanence and transparency will be
appreciated in glazing. Its fitness for foliage has been remarked; but
in draperies the colour will prove equally useful, and in illumination
will be found unrivalled. In the last branch of art, indeed, viridian
stands alone, not only through its soft rich brilliancy, but by the
glowing contrast it presents with other colours: employed as a ground,
it throws up the reds, &c., opposed to it, in a marvellous manner. Like
the three preceding oxides of chromium, viridian neither injures nor is
injured by other pigments; is unaffected by light, damp, or impure air;
and is admissible in fresco. In enamelling it cannot be used; the
colour, depending on the water of hydration, being destroyed by a strong
heat.
COPPER GREENS
are commercially known as _Emerald Green_, _Malachite Green_, _Scheele's
Green_, _Schweinfurt Green_, _Verdigris_, _Green Bice_, _Green
Verditer_, _Brunswick Green_, _Vienna Green_, _Hungary Green_, _Green
Lake_, _Mineral Green_, _Patent Green_, _Mountain Green_, _Marine
Green_, _Saxon Green_, _French Green_, _African Green_, _Persian Green_,
_Swedish Green_, _Olympian Green_, _Imperial Green_, _Mitis Green_,
_Pickle Green_, &c.
The general characteristics of these greens are brightness of colour,
well suited to the purposes of house-painting, but seldom adapted to the
modesty of nature in fine art; considerable permanence, except when
exposed to the action of damp and impure air, which ultimately blacken
most of them; and good body. They have a tendency to darken by time, dry
well as a rule in oil, and are all more or less poisonous, even those
not containing arsenic.
179. EMERALD GREEN,
_Schweinfurt Green_, _Vienna Green_, _Imperial Green_, _Brunswick
Green_, _Mitis Green_, &c., is a cupric aceto-arsenite, prepared on the
large scale by mixing arsenious acid with acetate of copper and water.
It differs from Scheele's Green, or cupric arsenite, in being lighter,
more vivid, and more opaque. Powerfully reflective of light, it is
perhaps the most durable pigment of its class, not sensibly affected by
damp nor by that amount of impure air to which pictures are usually
subject: indeed it may be ranked as permanent both in itself and when in
tint with white. It works better in water than in oil, in which latter
vehicle it dries with difficulty. Bearing the same relation to greens
generally as Pure Scarlet bears to reds, its vivid hue is almost beyond
the scale of other bright pigments, and immediately attracts the eye to
any part of a painting in which it may be employed. Too violent in
colour to be of much service, it has the effect, when properly placed,
of toning down at once, by force of contrast, all the other greens in a
picture. If discreetly used, it is occasionally of value in the drapery
of a foreground figure, where a bright green may be demanded; or in a
touch on a gaily painted boat or barge. When required, no mixture will
serve as a substitute. Compounded with aureolin, it becomes softened and
semi-transparent, yielding spring tints of extreme brilliancy and
beauty.
180. SCHEELE'S GREEN,
or _Swedish Green_, resembles the preceding variety in being a compound
of copper and arsenic, and therefore rankly poisonous; but differs from
it in containing no acetic acid, in possessing less opacity, and in
having a darker shade. It is a cupric arsenite, with the common
attributes of emerald green, under which name it is sometimes sold. Of
similar stability, it must not be employed with the true Naples yellow
or antimoniate of lead, by which it is soon destroyed.
Upon the lavish use of this dangerous pigment in colouring toys,
dresses, paper-hangings, artificial leaves, and even cheap
confectionery, it is not our province to enlarge: the constant-recurring
diseases and deaths, which, directly or indirectly, result from the
employment of arsenical pigments, are such every-day facts that they are
merely deplored and forgotten. With arsenic on our heads, our clothes,
our papers, our sweets, our children's playthings, we are so accustomed
to live--and die--in a world of poison, that familiarity with it has
bred contempt. Into the fatal popularity, therefore, of arsenical
colours for decorative purposes, we shall not further enter; but it
behoves us to deprecate their presence, and the presence of all
poisonous pigments, in colour-boxes for the young. It is one of the
pleasures of childhood to suck anything attractive that comes in its
way, openly if allowed, furtively otherwise: and as in early life we
have a preference for brilliancy, so vivid a pigment as Scheele's green
is an object of special attention. Artistically, it matters little
whether a pigment is noxious or not, but we hold that poison should not
be put into the hands of the young; and indeed are of opinion that a box
of colours is about the worst present a child can receive.
181. MALACHITE GREEN,
or _Mountain Green_, is met with in Cumberland, and is also found in the
mountains of Kernhausen, whence it is sometimes called _Hungary Green_.
It is prepared from malachite, a beautiful copper ore employed by
jewellers, and is a hydrated dicarbonate of copper, combined with a
white earth, and often striated with veins of mountain blue, to which it
bears the same relation that green verditer bears to blue verditer. The
colour, which may be extracted from the stone by the process followed
for native ultramarine, varies from emerald-green to grass-green, and
inclines to grey. It has been held in great esteem by some, and
considered strictly stable, on the assumption, probably, that a pigment
obtained from a stone like ultramarine, and by the same method, could
not be otherwise than permanent. That it is so, with respect to light
and air, there is no denying; but the green, when separated from the ore
and purified for artistic use, is merely a carbonate of copper, and
therefore subject to the influence of damp and impure air, in common
with other non-arsenical copper colours. As a pigment, native malachite
green has the same composition, or very nearly the same, as that which
can be artificially produced, and answers to the same tests. Water-rubs
of the two varieties which we exposed to an atmosphere of sulphuretted
hydrogen became equally blackened by the gas. Practically, there is
little or no difference between them: both preserve their colour if kept
from damp and foul air, both are injured by those agents, and both are
liable to darken in time, especially when secluded from light. The
artificial, however, can be obtained of a much finer colour than the
natural, which it may be made to resemble by admixture with mineral
gray. On the whole, they can scarcely be recommended for the palette,
and are certainly inferior in durability to Scheele's and Schweinfurt
greens. In fresco painting they have been pronounced admissible; but,
apart from the question of damp, we should deem the conjunction of lime
with carbonate of copper not favourable to permanence. By the action of
alkalies, even the native green malachite may be converted into blue;
and it becomes a question whether the dingy greenish-blue on some
ancient monuments was not originally malachite green.
182. VERDIGRIS,
or _Viride Æris_, is of two kinds, common or impure, and crystallized or
_Distilled Verdigris_, or, more properly, refined verdigris. The best is
made at Montpellier in France, and is a sub-acetate of copper of a
bright green colour inclining to blue. The least durable of the copper
greens, it soon fades as a water-colour by the action of light, &c., and
becomes first white and ultimately black by damp and foul gas. In oil,
verdigris is permanent with respect to light and air, but moisture and
an impure atmosphere change its colour, and cause it to effloresce or
rise to the surface through the oil. It dries rapidly, and is
exceptionally useful with other greens or very dark colours. In varnish
it stands better; but cannot be considered safe or eligible, either
alone or compounded. Vinegar dissolves it, forming a solution used for
tinting maps, and formerly much employed for colouring pickles, &c.
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.
By the last process, superior and more permanent chrome greens may be
produced, free from lead, by using chloride of barium or nitrate of
bismuth in place of the acetate of lead. Chromate of baryta, or chromate
of bismuth is then formed, neither of which acts on the Prussian blue.
It should be added that where the latter pigment is present, no green
will serve for painting walls containing lime, as its action alters the
tint of the Prussian blue.
186. HOOKER'S GREEN
is a compound of Prussian blue and gamboge, two pigments possessing a
like degree of stability, and perfectly innocuous to each other. It is a
mixture more durable and more transparent than chrome greens made with
chromate of lead. There are two varieties in common use--No. 1, a light
grass green, in which the yellow predominates; and No. 2, a deeper and
more powerful green, with a larger amount of blue.
187. PRUSSIAN GREEN,
like the preceding, is composed of Prussian blue and gamboge; but
contains a very great excess of the former, and is therefore a
bluish-green of the utmost depth and transparency, verging on black in
its deep washes. Yellow ochre may be employed instead of gamboge, but is
not so eligible.
A true Prussian green, which has been recommended as a pigment, can be
produced as a simple original colour, with a base wholly of iron. It is
got by partially decomposing the yellow oxalate of protoxide of iron
with red prussiate of potash. We have made this green and given it a
fair trial, but our verdict is decidedly against it. In colour it is
far from being equal to a good compound of Prussian blue and gamboge,
and it assumes a dirty buff-yellow on exposure to light and air, the
film of blue on the oxalate more or less disappearing.
Another Prussian green, with a base of cobalt, is obtained by
precipitating the nitrate of that metal with yellow prussiate of potash.
According to the mode adopted, and the degree of heat, either a light or
dark green results; but this also is inferior in colour, and presents no
advantage as to permanence.
188. SAP GREEN,
_Verde Vessie_, or _Iris Green_, is a vegetal pigment prepared from the
juice of the berries of the buckthorn, the green leaves of the woad, the
blue flowers of the iris, &c. It is usually preserved in bladders, and
is thence sometimes called _Bladder Green_. When good, it is of a dark
colour and glossy fracture, extremely transparent, and a fine natural
yellowish green. This gummy juice, inspissated and formed into a cake,
is occasionally employed in flower painting. It is, however, a very
imperfect pigment, disposed to attract the moisture of the atmosphere,
and to mildew; while, having little durability in water and less in oil,
it is not eligible in the one and is totally useless in the other.
Similar pigments, obtained from coffee-berries, and named Venetian and
Emerald Greens, are of a colder colour, equally defective and fugitive,
and now obsolete.
189. TERRE VERTE,
or _Green Earth_, is a sober bluish green with a grey cast. It is a
species of ochre, containing silica, oxide of iron, magnesia, potash,
and water. Not bright and of little power, it is a very durable pigment,
being unaffected by strong light or impure air, and combining with other
colours without injury. It has not much body, is semi-transparent, and
dries well in oil. Veins of brownish or reddish ochre are often found
mixed with terre verte, to the detriment of its colour; and there are
varieties of this pigment with copper for their colouring matter, which,
although generally brighter, are inferior in other respects, and not
true terre vertes. Verona Green and Verdetto or Holy Green, are
ferruginous native pigments of a warmer hue. These are met with in the
Mendip Hills, France, Italy, and the island of Cyprus, and have been
used as pigments from the earliest times. Rubens has availed himself
much of terre verte, not in his landscapes merely, but likewise in the
carnation tints in his figures of a dead Christ. It is evident that much
of the glazing is done with this colour: it is, in fact, most useful in
glazing; because, having only a thin substance, it can be rendered pale
by a small portion of white; although in the end it becomes darker by a
concentration of its molecules. Mérimée states that in the greater part
of Alexander Veronese's works--in his Death of Cleopatra, in the Louvre,
for instance--there are some demi-tints which are too green, and which
it is certain were not so originally. Terre verte, therefore, must be
employed with caution; and it would be well to ascertain beforehand
whether a mineral colour will in time become darker than when first laid
on the picture, by putting a drop of oil on the powder in its natural
state. If the tone this gives to it be more intense than that which it
acquires by being ground up, it may fairly be assumed that it will
attain to the same degree of strength whenever, having completely dried,
its molecules shall have re-united as closely as it is possible. Umber
and terra di Sienna are of this class.
In combination with Indian red and Naples yellow, terre verte forms a
series of mild russet greens, of much use in middle distance.
* * * * *
190. _Chrome Arseniate_
is an agreeable apple-green colour, prepared from arseniate of potash
and salts of chromic oxide. It is durable, but possesses no advantages
over the chrome oxides, and is of course poisonous.
191. _Cobalt Green_,
Rinman's Green, Vert de Zinc or Zinc Green. True cobalt green is made by
igniting a very large quantity of carbonate of zinc with a very small
quantity of carbonate of cobalt. To give a green tint to an enormous
proportion of the former, an inappreciable amount of the latter will
suffice. Some samples which were analysed, consisted almost entirely of
zinc, there being only two or three per cent. of cobalt present. This
green presents an example of a pigment being chemically good and
artistically bad, or at least indifferent. It is a moderately bright
green, apt to vary in hue according to the mode of manufacture,
permanent both alone and compounded, but so sadly deficient in body and
power, as to have become almost obsolete. With other physical defects,
and a colour inferior to the chrome oxides, cobalt green has never been
a favourite with artists, though justly eulogised by chemists.
192. _Copper Borate_
is obtained by precipitating sulphate of copper with borax, washing the
residue with cold water, and, after drying, igniting it, fusion being
carefully avoided. In this manner, a pretty yellowish green is produced,
which upon longer ignition assumes a dark green shade: the mass is
levigated for use. The compound has the objection of being glassy, and
possessing little body, but is preferable to verdigris as to permanence.
193. _Copper Chrome_
may be prepared by several methods, but the colour is in no case so fine
as Scheele's or Schweinfurt green, nor is it as stable.
194. _Copper Stannate_,
or Tin-Copper Green, equals in colour any of the copper greens free from
arsenic. The cheapest way of making it is to heat 59 parts of tin in a
Hessian crucible with 100 parts nitrate of soda, and dissolve the mass
when cold in a caustic alkali. To the clear solution, diluted with
water, a cold solution of sulphate of copper is added: a reddish-yellow
precipitate falls, which on being washed and dried, becomes a beautiful
green. On the palette it would be superfluous, but for common purposes
might be found of service.
195. _Elsner's Green_
is also a combination of tin and copper. It is made by adding to a
solution of sulphate of copper a decoction of fustic, previously
clarified by a solution of gelatine. To this mixture are added ten or
eleven per cent. of protochloride of tin, and lastly an excess of
caustic potash or soda. The precipitate is then washed and dried,
whereupon it takes a green colour tinged with blue, but without the
brightness or durability of the preceding stannate.
196. _Green Bice_,
or Green Verditer, is the same in substance as blue verditer, which is
converted into green verditer by boiling. This pigment is one of the
least eligible of copper greens.
197. _Green Ochre._
By partially decomposing yellow ochre with prussiate of potash, we have
produced a fine dark blue-green, resembling Prussian green, of great
depth and transparency. There are, however, difficulties in the process;
and the results do not warrant us in pronouncing this green superior or
equal to a mixture of the ochre and Prussian blue.
198. _Green Ultramarine_
is French or artificial ultramarine before the final roasting. It is a
somewhat bright bluish-green, becoming a dull greenish-blue on continued
exposure. Chemically, it is not a bad colour; but artists generally have
decided against it.
199. _Manganese Green_,
or Cassel Green. By several methods, manganate of baryta may be obtained
either as an emerald-green, a bluish-green, or a pale green. The
manganates, however, are decomposed by contact with organic matter; and
hence the green would be liable to suffer from the vehicles employed, as
well as by being compounded with animal or vegetal pigments.
200. _Mineral Green_
is the commercial name of _Green Lakes_, prepared from sulphate of
copper. These vary in hue and shade, have all the properties of the
common non-arsenical copper-greens, and, not being subject to change of
colour by oxygen and light, stand the weather well, and are excellent
for the use of the house-painter, &c. Having a tendency to darken and
blacken by time and foul air, they are not eligible in the nicer works
of fine art.
Another Mineral Green adopted in Germany as a substitute for the
poisonous Schweinfurt green, is composed of chromate of lead, carbonate
of copper, oxide of iron, and chalk. Valueless for the palette, it has
not the beauty of Schweinfurt green, but is recommended as being free
from arsenic. It is not, however, altogether harmless, and should not
be used in confectionery or the like.
201. _Molybdenum Green._
A clear malachite green colour, when dried, is produced from molybdate
of soda and potash-chrome-alum, or from the molybdate and alum with
ammonia. Being more expensive than the chrome oxides and not better, its
introduction, for use by artists, would be attended with no advantage.
There is likewise obtainable a copper molybdate, by adding neutral
molybdate of soda in excess to sulphate of copper. The precipitate is a
very pale green colour, flocculent at first, but crystalline after
washing. Like the chrome molybdate it would be superfluous as a pigment.
202. _Quinine Green_
is rather adapted for a dye than an artist-colour. It is furnished by
acting on quinine with hypochlorite of lime, hydrochloric acid, and
ammonia, successively. Thus prepared, the green resembles a resin,
insoluble in water, but soluble in alcohol, and turned blue by acetic
acid. Its alcoholic solution dyes silk green, and also woollen and
cotton when mordanted with albumen.
203. _Roman Green_,
brought from Rome some years back by a President of the Royal Academy,
appeared to be a mixture of Prussian blue and Dutch or Italian pink. It
was a fugitive compound, which became blue in fading.
204. _Silicate of Baryta._
One part of silica heated to whiteness with three parts of baryta,
yields a pale green solid mass, permanent, but deficient in colour when
ground. It might be employed in enamelling.
205. _Titanium Green_
has been proposed as a substitute for the green arsenical pigments in
common use; but, apart from its expense, the colour is very inferior to
Scheele's green, &c. Titanium green is a ferrocyanide of that metal,
produced by adding yellow prussiate of potash to a solution of titanic
acid in dilute hydrochloric acid, and heating the mixture to ebullition
rapidly. The dark green precipitate is washed with water acidulated with
hydrochloric acid, and dried with great care, since it decomposes at
temperatures above 100°.
206. _Uranium Green_
is an oxide of a deep dull green colour, inclining to olive, and nearly
black when in lumps. A durable but unattractive preparation, equalled in
permanence and far surpassed in beauty by many cheaper compounds.
207. _Vanadium Green_
falls when ferrocyanide of potassium is added to vanadic acid dissolved
in a strong acid. It is a beautiful green precipitate, but at present
simply a curiosity, owing to the rarity of the metal vanadium.
* * * * *
Adopting our usual custom of separating the wheat from the chaff, we
point to the opaque and transparent oxides of chromium, Veronese green,
viridian, emerald green, Scheele's green, and terre verte, as more or
less worthy of being dubbed durable.
As semi-stable, malachite green, bronze, Hooker's green, and Prussian
green, must be classed.
Verdigris, chrome greens, and sap green, should be branded as fugitive:
the chrome greens, because they are always commercially composed of
chromate of lead and Prussian blue, two compounds which are semi-stable
in themselves, but become fugacious when compounded.
A reference to the numbered italicised greens will show that there are
many not known to the palette, which are nevertheless very greatly
superior, as regards permanence, to some that disgrace it. Why these
latter are suffered to hold their position is a mystery not easily
explained: it is hard to reconcile the deplored degeneracy of modern
pigments with the popularity of semi-stable and fugitive colours.
Pictures do not stand, is the common cry; therefore, says the public,
there are no good pigments now-a-days. To which we answer, newly built
houses are constantly falling down; therefore there are no good bricks
in these times. Of a truth, one conclusion is as reasonable as the
other: in either case, if rotten materials be used, the result cannot be
lasting; but in neither case does it follow, because such materials are
employed, that there are no better obtainable. A well-built house
implies a conscientious builder, and a well-painted picture implies a
conscientious artist. It is because, we fear, that there are so few
conscientious artists, that there are so few permanent paintings; not,
certainly, because there are no good pigments. In this last belief,
however, the public is encouraged by certain painters, who seek thereby
to excuse their own shortcomings, forgetting that it is a bad workman
who finds fault with his tools. It has been well observed that when
artists speak regrettingly of lost 'systems,' or pigments enjoyed by the
mediævalists and unattainable now, it would be far better were they to
make the best use of existing materials, and study their further
development. There is no need for this cant cry of fugacity, which casts
such a blight on modern art. Durable pigments are not yet obsolete, they
have only to be employed and employed properly to furnish paintings
equal in permanence to those of the old masters. "Titian," says Haydon,
"got his colours from the colour shops on the Rialto, as we get ours
from Brown's; and if Apelles or Titian were living now, they would paint
just as good works with our brushes and colours as with their own."