Show for secret writing most invisible inks are made with paste drier as a base and one of the mineral salts us a coloring medium heat la Is used to develop tho the printing and moisture to make it disappear of the chemicals possessing this property are cobalt chloride barium sulphate barium barquin nitrate copper chloride white dilute sulphuric acid potassium sa s1 um nitrate and equal parts of alum and garlic juice another form of invisible ink Is made from a mixture of transparent tint base and paste drier it Is invisible when dry but shows up bli clearly when rubbed with an ordinary lead pencil |