Mechanical pencil Mechanical pencil A mechanical pencil (US English) or propelling pencil (UK English), also clutch pencil, is a pencil with a replaceable and mechanically extendable solid pigment core called a "lead" . The lead, often made of graphite, is not bonded to the outer casing, and can be mechanically extended as its point is worn away. Other names include microtip pencil, automatic pencil, drafting pencil, technical pencil, click pencil, pump pen, pump pencil, leadholder, pen pencil (Indian English), and lead pencil (Bangladeshi and American English). Mechanical pencils are used to provide lines of constant width without sharpening in technical drawing and
Lead conducted on how to remove lead from biosystems by biological means: Fish bones are being researched for their ability to bioremediate lead in contaminated soil. The fungus "Aspergillus versicolor" is effective at removing lead ions. Several bacteria have been researched for their ability to remove lead from the environment, including the sulfate-reducing bacteria "Desulfovibrio" and "Desulfotomaculum", both of which are highly effective in aqueous solutions. Lead Lead is a chemical element with symbol Pb (from the Latin "plumbum") and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and