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Lake &c And Are Obtained From The Coccus Cacti An Insect Found On








a species of cactus, from the juice of which it extracts its
nourishment. This coccus is a native of Mexico, where two kinds are
recognised, under names which signify wild cochineal and fine cochineal.
The latter may be considered a cultivated product, its food and wants
being carefully attended to, while the former is left in a natural
state, and is less valuable. Wild cochineal is distinguished by having a
woolly downy coat, which is not the case with the fine cochineal. The
females, of which there are from one hundred and fifty to two hundred
for each male, are marked by the absence of wings, and constitute the
commercial article. They are generally killed by immersion in boiling
water, which causes them to swell to twice their natural size, and are
then dried and packed for market. The insects shrivel in drying, and
assume the form of irregular grains, fluted and concave. The best sorts
have a silvery-grey colour, with a purplish reflection, and seem to be
dusted with a white powder. This appearance is often given by means of
heavy spar, carbonate of lead, Venice talc, &c. A good lens, however,
will mostly expose the fraud; or it may be detected by macerating the
insect in water, and allowing the loosened pulverised particles to
settle.

Cochineal is a very rich colouring substance, yielding about half its
weight of real colouring matter, which may be easily extracted by
boiling in water. Dr. Warren De La Rue, who examined the living animal,
states that on piercing the side of the insect a purplish-red fluid
exuded, containing the colouring matter in minute granules. This
colouring matter he succeeded in obtaining pure, in the form of a
purple-brown friable mass, pulverizable to a fine red powder,
transparent when viewed by the microscope, and soluble both in water and
alcohol in all proportions. At temperatures above 136 deg. it decomposed,
and by alkalies its colour was turned to purple. These facts account for
the care required in drying cochineal lakes, and for their liability to
change of hue when in contact with alkaline substances, as in mural
decoration.

The lakes of cochineal may be known from those of the dye-woods by their
solubility in ammonia, a liquid which purples but does not dissolve the
colours produced from the latter.

TTITLE CARMINE.

A name once given only to the fine feculences of kermes and cochineal
tinctures, now denotes generally any pigment which resembles them in
beauty, richness of hue, and powdery texture. We have, therefore, blue
and other coloured carmines, though the term is usually confined to the
crimson and scarlet lakes of cochineal. As at present commonly
understood, carmine is that preparation of cochineal which contains the
most colouring matter and the least aluminous base. Hence it is the
richest, deepest, most intense, and most permanent. Although not to be
classed as durable, yet by reason of its extreme depth, carmine is more
stable than the weaker crimson, scarlet, and purple lakes. When
well-made, pure, and employed alone and in body, it has been known to
retain its colour for years, especially if protected by oil or varnish.
In tint with white lead, however, it has no stability; and though little
affected by impure air, in glazing it is soon discoloured and destroyed
by the action of light. Of great power in its full touches, it possesses
considerable clearness in the pale washes, and works admirably. In
landscape, carmine is seldom used, the colour being chiefly valued in
flower painting and illumination.

It has been erroneously stated that the finest carmines cannot be made
in England, owing to a want of clearness in the atmosphere and a
scarcity of sunshine. For many years, however, they have been produced
in this country, not only finer than any foreign preparations, but
equally good in winter as in summer.

Carmine is sometimes sophisticated with starch, vermilion, and with
alumina not formed in the process of manufacture. Occasionally also, a
portion of the animal matter of the cochineal from which it has been
obtained is left mixed with it. These accidental or intentional
impurities may mostly be detected by heating the carmine with liquid
ammonia, which entirely dissolves the colouring matter and leaves the
impurities in an insoluble state.

TTITLE CRIMSON LAKE

Is a cochineal pigment containing more aluminous base than carmine, and
is consequently weaker in colour and less stable. Deficient in much of
the depth and brilliancy which belong to the latter, it is more commonly
employed and more generally useful. This lake is of service in mixing
tints, to impart richness, in flower painting and illumination, and is,
like all cochineal colours, of greater utility in water than in oil.
With cobalt and gamboge it yields an excellent gray, and with cobalt
alone a fine purple for heather. Distant hills may be strengthened with
a tint of French blue and lake, and Vandyke brown with the crimson will
be found admirable for a rich coloured foreground. Many other beautiful
tints, unexceptionable in an artistic sense, are afforded by crimson
lake on admixture. It should be remembered, however, that not one of
them is permanent as far as the lake is concerned. All cochineal
pigments are more or less affected by strong light, which weakens their
tints, and in time deprives them of colour; and it is not by being
compounded that a fugitive colour is rendered durable.

TTITLE SCARLET LAKE

Is prepared in the form of drops from cochineal, and is of a fine
transparent red colour and excellent body, though, like other lakes, it
dries slowly. Discoloured and destroyed by strong light both in water
and oil, and not permanent in tint with white lead or in combination
with other pigments, it possesses the common attributes of cochineal
lakes. Yet when well prepared, used in sufficient body, and not unduly
exposed, it has been found to last a lengthened period; but it ought
never to be employed in glazing, nor at all in works that aim at high
reputation and stability. It is in general tinted with vermilion, which
has probably been mixed with lakes at all times to give their scarlet
hue and add to their weight; for upon examining with a powerful lens
some fine pictures of ancient masters, in which lake had been used in
glazing, particles of vermilion were apparent, from which lake had
evidently flown. Unfortunately, these lakes are injured by vermilion as
they are by lead, so that glazings of cochineal over vermilion or lead
are particularly apt to vanish. This effect is very remarkable in
several pictures of Cuyp, where he has introduced a figure in red from
which the shadows have disappeared, owing to their having been formed
with lake over vermilion. The scarlet hue of this lake should properly
be imparted to it during the process of manufacture, and not by
subsequent mechanical admixture.

TTITLE PURPLE LAKE

Is a species of crimson lake with a purple cast, transparent and
deep-toned, and useful in shadows: in other respects resembling that
pigment. Red being its predominant colour, we have preferred classing
this so-called purple among the reds, in spite of its name. On the whole
it is more durable than crimson lake.

TTITLE FLORENTINE LAKE

Differs from scarlet lake only in the mode of preparation. Formerly the
lake so called was extracted from the shreds of scarlet cloth. The same





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