Liquid Crystals—Soap Solutions and X-rays

Abstract

AMONGST the earliest examples of Lehmann's liquid crystals were the transparent double cones of ammonium oleate. MacLennan's work has shown that this transparent anisotropic state is common in soap solutions. The accompanying photograph (Fig. i), taken by Mr. W. J. Elford in this laboratory at the suggestion of my colleague Mr. Piper and myself, shows the very striking appearance presented by these transparent solutions when examined in slightly convergent light between crossed Nicols. The transparent conic anisotropic liquid shown occurs in 2.5 weight normal potassium laurate at 45° C, magnification 200 diameters, and it exhibits very clearly the characteristic fan-like structure composed of focal lines.