PIGMENTS ' in
solution. It has been suggested by Laurie (The Pigments and Mediums of the Old
Masters^ pp. 35-38) that the transparent green colors of early illuminated manu-
scripts and of the *oiP paintings of the early Flemish masters were of this nature.
(For more complete discussion, see Verdigris.) Paint films colored with copper
resinate appear green-stained and do not owe their color to discrete green par-
ticles of any crystalline copper mineral or salt.
Coral (see Chalk).
Cremnitz White (see White Lead).
Diatomaceous Earth (infusorial earth, diatomite, celite) is a hydrous or
opalescent form of silica which is composed of the skeletal remains of very minute
aquatic organisms known as diatoms or radiolaria (see Ladoo, pp. 190-197).
Under the microscope, with fairly high magnification, many varieties of the tiny
diatom fossils can be seen. Deposits of this earth are found all over the world.
The largest and most extensively worked are in California, but they occur, also,
in Germany and in other parts of Europe. It is a light colored, light weight, finely
granular, and porous aggregate, insoluble in acids but soluble in alkalis. Diatoma-
ceous earth is widely used as a filter medium and as a bleaching agent for oils,
fats, and waxes; also as an inert and as an anti-settling agent in paints. Since it
adsorbs dyes, it serves as a base for certain lake colors.
Diatomite (see Diatomaceous Earth).
Dragon's Blood is a dark red, resinous exudation from the fruit of the rattan
palm, Calamus draco., which is indigenous to eastern Asia. The resin which is
collected from wounds in the bark, as well as from the fruit, is heated and molded
into short sticks which are sent to the market wrapped in palm leaves. The resin
is odorless. It is soluble in alcohol and other organic solvents, giving a red solu-
tion. Although dragon's blood has been used in the arts as a stain for coloring
varnishes, principally varnishes to be used over gold and other metals, it seldom
has been used directly as an artist's color. It is fugitive unless locked in a resin
film. Little is known about it in painting, but probably it has been used to a
slight extent in all periods up to the present. It was known very early in the
Near East, having been called 'cinnabaris* by Pliny (see Bailey, I, 121), who
admits confusion with the Greek word, 'cinnabar,* which meant minium or
mercuric sulphide. It is he who established the myth that it was a product of the
mingling of the blood of those traditional enemies, the dragon and the elephant,
in a furious death struggle. Cennino Cennini mentions its use in illuminations
but he discredits it (Thompson, The Craftsman's Handbook^ p. 2,6). Dragon's
blood is no longer listed by artists' colormen.
Dutch Pink (see Pink).
Dye is a coloring matter which is used in solution as a stain. It is different
from a pigment which is used suspended in a medium for painting (see Hackh).
Most of the dyes are complex, organic, chemical compounds and may be derived
from natural sources (like madder), but the great bulk is now made synthetically