Sap Green, Or Verde Vessie, 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, etc. 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 of a fine natural green colour. Though much employed as a water-colour without gum, which it contains naturally, it is a very imperfect pigment, disposed to attract the moisture of the atmosphere, and to mildew; and, having little durability in water-colour painting, and less in oil, it is not eligible in the one, and is totally useless in the other.

Similar pigments, prepared from coffee-berries, and called Venetian and Emerald greens, are of a colder colour, very fugitive, and equally defective as pigments.

IX. Invisible Green

See Olive Pig-merits.