_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.