Pale Chrome And Deep Chrome Are Chromates Of Lead In Which The

: ON THE PRIMARY, YELLOW.

latter metal more or less exists, according to the paleness or depth of

the colour. Of modern introduction, they are distinguished for their

brilliancy, their opacity and body, and their going cordially into tint

with white, both in water and oil. Owing, however, to a harshness and

hardness of tone for which they are peculiar, a coarse and disagreeable

effect is apt to be produced by their use. In general, they do not

ccord with the modest hues of nature, nor harmonize well with the

softer beauty of other colours. Rivalling the cadmiums in brightness,

they are wanting in the mellow richness which belongs to the deeper

varieties of those pigments, as well as in their permanency. Although

they resist the sun's rays for a lengthened period, after some time they

lose their original hue, whether employed alone or in tint, and may even

become black in impure air. Upon several pigments they produce serious

changes, ultimately destroying Prussian and Antwerp blues, when

compounded therewith in the composition of greens, &c. Ranging from

lemon to deep yellow, in oil, provided the atmosphere be good, the

chromes may be found comparatively durable; but, on the whole, the

artist cannot trust to them his reputation as a colourist.



The chromates are often mixed with sulphate of lead, as well as with the

sulphates of baryta and lime. The presence of the first is especially

objectionable, as increasing the tendency of the yellows to be blackened

by foul gas. The sulphates of baryta and lime, however, are sometimes

formed in the process of preparation, in which case they are rather an

advantage than otherwise; inasmuch as they not only lend a softness to

the colour, but decrease the proportion of leaden base, and consequently

the tendency referred to. We may remark, indeed, with respect to

pigments, that it is difficult in many instances to say where

manufacture ends and adulteration begins. A substance may be present

which, although not absolutely essential to the colour itself, has been

legitimately employed to impart a desired quality, or a certain tint.



TTITLE COLOGNE YELLOW



Is a cheap inferior chrome yellow, unfit for artistic purposes, and

consists of twenty-five parts of chromate of lead, fifteen of sulphate

of lead, and sixty of sulphate of lime.



TTITLE JAUNE MINERALE



Is prepared in Paris, and differs in no essential particular from

ordinary chromate of lead, except in the paleness of its colour. The

chrome yellows have also obtained other names from places or persons,

whence they have been brought or by whom they have been made. Another

lead yellow, not a chromate, has likewise been called jaune minerale.



TTITLE CITRON YELLOW



Is chromate of zinc, a bright pale lemon-like yellow, slightly soluble

in water. It is not affected by foul gas, but does not preserve its

colour on exposure to light and air, or even when kept in a book. In

contact with organic substances it is apt to turn green. Compounded,

especially for foliage tints, this yellow is eligible; but if purity of

hue be desired, it should certainly not be employed alone. In this

chromate, as in many others, the affinity of the chromic acid to the

base is small; the former is liable to separate from the latter, and, by

deoxidation, to become converted into green oxide of chromium.



TTITLE GALLSTONE



Is a deep-toned gorgeous yellow, affording richer tints than most other

yellows, but it cannot be depended on for permanency, and therefore is

seldom employed. Its colour is soon changed and destroyed by strong

light, though not subject to alteration by impure air. In oil it is

ineligible. A true gallstone is an animal calculus formed in the

gall-bladder, chiefly of oxen; but the pigment sold under that name is

often replaced by a substitute, resembling the original in colour, but

of greater stability.



TTITLE GAMBOGE,