Cooking For Engineers

[Michael Chu]

Go to What is pencil lead?

Article Digest:
Pencil lead is a combination of graphite (a form of pure carbon) and clay. Why is it called pencil lead if there's no lead in it? Before the 16th century, when graphite was first used in writing implements, people used lead to leave gray markings on paper or papyrus. When graphite began to be used, it was still referred to as lead because it was initially believed that graphite was a type of lead powder that they referred to as "black lead". It wasn't until the late 1780's that black lead was renamed graphite (from the Greek graphein meaning "to write").