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Paper chromatography is a technique in which a substance is separated out into its constituent parts as it dissolves in a solvent and spreads along the paper. Different pigments in the inks are carried a different distance by the solvent, as they travel at different rates. Seven inks were used here, from top to bottom: light green, dark green, dark brown, black, orange, light brown and red. The chromatography reveals that there are five separate pigments used to make up the different colours in this range of inks. The black ink contains them all, and the others contain a combination of some of them. The solvent was 1% salt solution in water. The run time was three hours