Duprat registered a Patent for his "Improved Hair Dye" in 1863 (Patent #40,918). The primary ingredients were pomade or fat (50%), silver nitrate (3%), gallic acid (1%), and perfume. The silver nitrate and gallic acid were first dissolved in water or a suitable liquid, then they are stirred into the pomade separately, so the silver nitrate isn't decomposed by the gallic acid. The mixture was then mixed up and the dye was ready. Duprat claimed that this preparation would change hair back to its original color, keep the hair smooth and pliable, and is not injurious to the skin.