In 15 Substances of general formula transition temperatures, transition enthalpies and entropies, densities and phase transition volumina, order parameters of a dissolved dye and optical refractive indices were measured. Additional miscibility and X-ray investigations were performed. The results are discussed on the basis of molecular statistical theories of the nematic state and point to a conformation of the long lateral chains which is nearly parallel to the molecular long axes. The results further show the dominating importance of the steric repulsive forces in stabilizing the nematic state.
