Sap green (Sea Green, Bladder Green, Berry Green, Leaf Green, Chemical Green), sap colour made from the juice of not quite ripe buckthorn berries (s. Rhamnus) with the addition of alum. Sap green is hard, dense, heavy dark in colour and sweet in taste. It is used to dye leather, paper, wallpaper, for painting and illumination, varnishing, and to prepare green ink etc.
Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909