Sometimes on TV I see medieval westerners sprinkle some kind of powder on their quills after they finish writing with them, what's the point?

The quill leaked ink and stained the business contract, costing Waltman a big deal. This incident made him very stimulated, determined to reform. The quill pen could not store ink, he added a leather pouch to store ink. Goose quill pen out of a leak, he designed for the pen with a capillary tongue and a small crack in the nib of the pen, the ink along the cracks slowly flow down. Heavy press the nib, the cracks expand, the ink more down, gently point the nib, the cracks close, the ink becomes talk. From then on, fountain pens and pencils together, replacing the quills long used by Europeans.

The earliest ink was a watery solution of dye. This kind of ink to write words, water-soaked ooze, easy to fade, can not be preserved for a long time. Later, chemists found that the plants contain tannic acid and iron ions generated by the black substance of iron tannate can be firmly adhered to the paper, cloth and other fibers, the formation of handwriting, but also never fade it. How nice to use it as ink. However, ferric saddle acid is a fine powder, in the water does not dissolve, will clog the nib of the cracks and capillaries, can not be used at all. On the other hand, ferrous sulfate can be dissolved in acidic aqueous solution, slowly oxidized when exposed to air, and automatically transformed into black ferrous sulfate. By dissolving ferrous sulphate and kneaded acid in water, doesn't it become ink? But this ink has almost no color and looks similar to water. So you have to mix some blue dye to make it work.