Pencil thereby pushing a new tip to the top. Invented by Harold Grossman for Empire Pencil Company in 1967 and subsequently improved upon by Arthur D. Little for Empire from 1969 through the early 1970s; the plastic pencil was commercialised by Empire as the "EPCON" Pencil. These pencils were co-extruded, extruding a plasticised graphite mix within a wood-composite core. Residual graphite from a pencil stick is not poisonous, and graphite is harmless if consumed. Although lead has not been used for writing since antiquity, lead poisoning from pencils was not uncommon. Until the middle of the 20th century the paint used
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