Prussian blue (ferric ferrocyanide) provides the coloring pigment for this
ink. Dissolve 1 gram of ferric ammonium sulfate in 10 cc. of water. Dissolve 2 grams of potassium or sodium ferrocyanide in 15 cc. of water. Mix the
two solutions, filter and thoroughly wash the precipitate. Then add just enough oxalic acid solution to dissolve the precipitate forming a syrupy
liquid. Finally, thin with water and your ink is ready for writing. |