AQUESTION OF DIMENSION

摘要

Natural carbon comes in many guises. Two of the most familiar - soot and charcoal - are amorphous collections of carbon atoms and share a characteristic most associated with carbon: they are black. That opacity is also a feature of graphite, one of the two common, pure, crystalline forms of carbon. Graphite, which forms at everyday temperatures and pressures, is a good conductor and supremely soft, well known as the principal component of pencil lead.