The theory of elasticity in two-dimensional systems is discussed and applied to several specific cases of interest. In particular the elastic behavior of solid Langmuir−Blodgett films is reviewed and the appropriate elastic moduli are derived in terms of the Lamé coefficients under several commonly encountered boundary conditions. These results are particularly useful in the interpretation of Langmuir−Blodgett film data.

The magnetic properties of the RRh4B4 (R represents rare-earth metal) compounds are discussed in terms of a combined crystalline-electric-field and molecular-field approach. Magnetization data taken on single-crystal ErRh4B4 in five orientations are used to obtain the crystal-field and molecular-field coefficients, resulting in a complete analysis for the paramagnetic properties of this compound. The crystal-field parameters are additionally used to discuss all previously published magnetic data for polycrystalhne RRh4B4 compounds. For these highly anisotropic materials, the effect of preferential crystallite orientation on the observed data is pointed out. Consideration of the variation of the magnetic transition temperature T between different constituent rare earths has verified a previous conclusion that the crystal field has a pronounced effect on T, but this alone does not fully explain the observations.

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The determination of viscosity from the attenuation of capillary waves was first suggested by Stokes more than a century ago. At the time, it was not practical to measure the attenuation of surface waves with the requisite precision to render the method useful. We describe a noncontact method for measuring the wavelength and amplitude of single-frequency capillary waves to obtain reliable values of the surface tension and viscosity. The attenuation data for several glycerin-water mixtures are used to obtain the viscosity as a function of glycerin concentration. For a wide range of viscosity, the method yields results that are in good agreement with the most reliable published data.

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