THE PROTEAN ELEMENT CARBON IN NEW GUISES

Whether anything made of only the atoms of a single element can decently be classed as a polymer is a question fit for pedants. But new forms of this most remarkable of elements, discovered in the past two decades or so, have opened new vistas to the eager gaze of chemists and physicists. They are, moreover, finding practical applications of a kind which would have seemed closer to science fiction than science only a few years ago. So all this excitement can scarcely be disregarded here. 

Until late in the past century only two ordered forms of carbon were known to science. There was diamond, with its perfect crystal structure, and there was graphite, also crystalline, but black and flaky and not at all transparent. Besides those there 

These sheets are semiconductors— they are intermediate in their electrical character between conductors and insulators. Transistors are made of such materials, and applications of this sort for graphenes are anticipated. But graphene sheets are, as we shall see later, semiconductors of a kind not previously encountered, with properties that may one day change the face of electronics. 

The helical form may be left- or right-handed Gust like an a-helix in a protein (p. 35), but of course unlike protein or nucleic acid helices, it is not made of asymmetric units, so has no preference for one handedness over the other). This form is called chiral from 

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