The nature of the liquid state of matter is the subject of less definite conceptions than that of either the solid or the gaseous state. A clear concept obtains for the state of a gas on the basis of the molecular kinetic theory, in terms of a system of particles in random translatory movement. An equally clear general conception exists for the crystalline solid state, on the basis of the space lattice theory, in terms of atom‐groups arranged in regular periodic ordering. Such atoms or atom‐groups have no free translatory motion relative to the ensemble, but their thermal energy is due to vibrations about the centers of position which constitute the particular space group.