Copying pencil 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 pencils were introduced in the 1870s and were originally marketed for copying documents, especially for making permanent copies of a permanent original. This was achieved by creating a hand-written document using a copying pencil, laying a moist tissue paper over the document and pressing down with a mechanical press. The water-soluble dye in the writing would be transferred
Lead(II) thiocyanate has not been confirmed by other sources than the author of this article, experiments show that even if there is no precipitation of lead(II) thiocyanate in the solution, crystals of the salt may form. Lead(II) thiocyanate can be formed from the acidification of Lead Nitrate Pb(NO) with nitric acid (HNO) in the presence of Thiocyanic acid (HSCN) Lead(II) thiocyanate may be made by reacting lead(II) acetate (Pb(CHCOO)) solved in water with either potassium thiocyanate (KSCN) or ammonium thiocyanate (NHSCN), thus causing a white precipitation of solid lead(II) thiocyanate. Ion reaction: When exposed to UV or visible light lead thiocyanate will