Put some green in wine, and rub it well with your finger; when it has settled, take the liquid part and put it in moderate sunlight, or elsewhere, to thicken. When it is fit for writing, put it in a vessel made of glass or wax, and you will be able to keep it in good condition for a long time. If it is too dark, add a little saffron and the powder of calcified bones. If you wish to illuminate more easily, take some yolk of egg, and mix the green wine with it, and grind the green pigment with this mixture upon the stone, and temper it with the same; and thus it will be good.