The Secret Science of Covert Inks
Port Townsend: Loompanics Unlimited, 1987. Edition Not Stated. Presume first edition. Paperback. 8vo., 128pp. Sample Recipe: 'Chinese Red Secret Ink'. Used by agents of the Chinese Ministry of Public Security, this ink is made by mixing one part each of phenolphthalein, glycerin, alcohol, and carbon tetrachloride. When dry, it is..... More