Abstract

Abstract Examination of the paraffin n-hectane in the electron microscope has given evidence of two different growth mechanisms for crystals of this compound. The one corresponds to the spiral growth mechanism already observed for n-hexatriacontane (Dawson & Vand 1951), and the orthorhombic lozenge-shaped crystals of n-hectane show the typical spiral growth steps already described. The other growth mechanism gives rise to lath-shaped crystals and operates when growth takes place by the slow evaporation of a cold solution of n-hectane in xylene. The laths are invariably twinned across the diagonal of the orthorhombic cell, and growth in one direction is greatly accelerated by the occurrence of an indestructible step at the twin boundary.