possible if the field energy is transferred only to a frRctlon of plasma particles~for instance to paltlcles matching some resonance condition similar to the static-corkscrew conditions; complications are introduced by field self-consistency and time dependence at the focus.Measurement of the tilt angle of the smectic C phase of terephthal-bis-(4-n-butylaniline) has been made using conoscopic observation and circularly polarized light. The new phenomenon of a smectic C phase with a temperature-dependent tilt angle is reported.Terephthal-his-(4-n-butylanaline) has nematic, smectic A, smectic C, and smectic J3 liquid-crystalline phases. The tilt angle of smectic C changes from 0 at the smectic-

Convergent light observations have been made on three liquid crystalline substances with nematic and smectic phases. The nematic phase was observed to be uniaxial as expected, but smectic C was found to be biaxial. The optic axial angle 2V for smectic C was found to be on the order of 20° for all three compounds. Also, the tilt angle for smectic C is nearly 45° for all three liquid-crystal systems. Anisotropy of the degrees of order is suggested as a partial explanation for the biaxial character of smectic C.We have studied three compounds which exhibit a nematic phase and a single smectic phase of the type classified by Sackmann and Demus 1 as type C. The smectic phases classified by Sackmann and Demus correspond to different molecular arrangements and are separated from each other by first-order phase transitions.The nematic phase has a long-range order such that the long axes of the molecules are nearly parallel and the parallelism of the long axis generally varies continuously throughout the bulk of the liquid. Assuming a random arrangement of the center of mass and free rotation about the long molecular axis, nematic liquids would be uniaxial. All observations do show the nematic phase to be uniaxial. Smectic A is a system in which the molecules are arranged in layers with the long molecular axis perpendicular to the layer. 2 If the centers of mass within the layers are random and free rotation is assumed, then smectic A would be uniaxial. Experimentally, all smectic -A phases have been shown, in general, to be uniaxial. Smectic C is generally considered to have a structure such that the molecules are arranged in layers but with the long molecular axis tilted with respect to the layer normal. 2 In general, it has been assumed that all smectic phases including smectic C would show uniaxial character and, in fact, Friedel 3 argued that all smectic phases would be uniaxial.

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The effects of ultrasound on the optical properties of an aligned layer of nematic liquid crystal are described. It was observed that the birefringence of a normally oriented nematic liquid crystal was a function of the acoustic energy, and that with sufficient incident acoustic energy, a scattering phenomenon similar to dynamic scattering occurred.

The synthesis and mesomorphic behavior of 3,5-bis-(p-n-alkoxyphenyl)isoxazole (series I) and 3,5-bis-(p-n-alkoxypheny1)pyrazole (series 11) are reported for the number of carbon atoms ( n ) in the alkoxy chains varying from three to eight. Series I shows an enantiotropic nematic phase for all n and an enantiotropic smectic phase for n 2 6. Series I1 shows one smectic phase SI for all n and an additional smectic phase SII for n 3 6. From optical and X-ray data, the smectic phase of series I is identified as smectic C and in series I1 the SI phase is classified as smectic A and SII as a smectic C with a temperature dependent tilt angle. The 1-methyl substituted pyrazole was prepared and did not show mesophases.

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Small angle x-ray scattering data have been obtained for concentrated suspensions of southern bean mosaic virus containing approximately 20, 10, and 5 gm virus per 100 ml of suspension. In addition, the scattering from independent virus particles was determined from the scattering curves for dilute suspensions. The Zernike-Prins equation was used to compute the pair correlation functions for the concentrated suspensions. The pair correlation functions indicated relatively weak interparticle forces. The effective distance of closest approach of two particles was appreciably greater than the particle diameter, which was approximatley 285 Å. The interaction potential energy for a pair of molecules was estimated by three different approximate theories.