A New Structure of Carbon

ATTENTION has been directed by Taylor and Laidler¹ to the appearance of `extra' lines on X-ray photographs of graphite. These lines are given by several quite unrelated specimens and they do not seem to be connected with impurities. Finch and Wilman² and Taylor and Laidler¹ tried to interpret them as secondary diffraction phenomena of the graphite structure, but without producing any convincing evidence for their theories³. We find, however, that the lines may be explained by the presence of about 10 per cent of another structure that is closely related to graphite, and this therefore implies that carbon can exist in three different crystalline forms.