[Fr. encre.] A liquor or substance used for writing or printing. Writing ink is made of gall-nuts, sulphate of iron, gum, and water. Copying ink has more gum than writing ink; while blue ink is made of Prussian blue, oxalic acid, and water; and red ink is got from Brazil wood, but now generally from potassium eosin. Black printing ink is much thicker than writing ink, and is usually made of lamp black or ivory black mixed with burnt linseed oil.