Copying pencil the wound. Such risks are not associated with ordinary graphite pencils. While these symptoms may appear after a couple of days they often develop only after weeks have passed since the injury was sustained. Surgery is required to remove the dye and the infected tissue and "the necrotizing action may be so severe and extensive amputation is necessary". Copying pencil A copying pencil, also indelible pencil or chemical pencil, is pencil whose lead contains a dye. The lead is fabricated by adding a dry water-soluble permanent dye to powdered graphite—used in standard graphite pencils—before binding the mixture with clay. Copying
White lead for bearings and in machine shops. What is commonly known today as the "Dutch method" for the preparation of white lead was described as early as Theophrastus of Eresos (ca. 300 BC), in his brief work on rocks or minerals, "On Stones" or "History of Stones." His directions for the process were repeated throughout history by many authors of chemical and alchemical literature. The uses of cerussa were described as an external medication and pigment. Clifford Dyer Holley quotes from Theophrastus' "History of Stones" as follows, in his book "The Lead and Zinc Pigments". Lead is placed in earthen vessels