Purple Ink
Grind, or dissolve some lake in water; otherwise express the juice from the deepest coloured beats; to either of these, add a little blue and gum water. To write in various Colours, with the same Pen, Ink and Paper. Take a sheet of white paper, and wet some parts of it with a solution of sub-carbonate of potass' wet some other parts of it with the same but more diluted; some other parts with diluted muriatic acid; and other parts with a solution of sulphate of iron; dry the paper and it will be white as ever. Then take the juice of blue violets, or tincture of red cabbage, (water that has been poured while hot, upon red cabbage in thin slices,) and with it write on the paper. The ink is of itself, a faint purple; where the paper was wet with acid, it will instantly become red; on the diluted alkali, it will become green; on the stronger alkaline solution, it will take a yellow; and on the sulphate of iron, it will become deep purple or brown. Thus you will have several colours in the same line of writing.