The nature of the liquid state

Abstract

In his recent lecture to the chemical society on "The Significance of Crystal Structure," Sir William Bragg has described and discussed the extremely important results obtained in his laboratory by the X-ray analysis of various carbon compounds, notably those belonging to the aromatic series. The special feature brought to light by the investigations is that the ultimate unit of crystal structure or elementary parallelepiped is not the chemical molecule, but, generally speaking, is a complex formed by the union of two, three, or four molecules. Further, the symmetry of the crystal tends to increase with the number of molecules in the unit, and also with the symmetry of the molecule itself. In fact, there are simple quantitative rules, first stated by Shearer, connecting these quantities.