4-Hydroxy-3-methoxy benzaldehyde (vanillin) precipitates titanium quantitatively between pH 3·5 and 6·5. The precipitate on ignition gives TiO 2 which can be weighed. Titanium can be readily separated and estimated gravimetrically in the presence of chromium (III), cobalt (II), copper (II), iron (III), manganese (II), molybdenum (VI), nickel (II), tungsten (VI), uranium (VI), vanadium (V), zinc (II), zirconium (IV), and trivalent rareearths.