12 February 1965
Vol 147, Issue 3659

About The Cover

Electron micrograph of screw dislocations in graphite. Dislocations are lattice defects resulting from an abnormal spiral arrangement of the planes of the atomic layer. While many such defects apear in arificial graphite, they are rarely present in natural graphite. They have been made visible under electron microscopy by a chemical etch in carbon dioxide and by a susequent ``decoration'' with gold; the gold accumulated at the steps of the monatomic surface (about X 93). See page 733. [Argonne National Laboratory]