The formation of a number of clathrate hydrates, similar in structure to the wellknown tetrahydrofuran hydrate, has recently been shown by a study of their dielectric properties (I). The existence of a similar hydrate of 1,3-dioxolane is shown by the dielectric behavior described here. Values of the static dielectric constant of liquid dioxolane and its dipole moment in cyclohexane solution are also reported.1,3-Dioxolane was refluxed and distilled over calcium hydride. Solid and liquid samples were measured in cell 1, as previously described (I), and solutions in a Balsbaugh 3-terminal cell of 35 p F capacitance. Dipole Moment of DioxolaneFor seven solutions of dioxolane in cyclohexane a t 20" in the concentration range between 0.002 and 0.013 weight fraction, the method of Guggenheim (2) gave a dipole moment of 1.50 rt 0.02 D.Values of 1.47 (3) and 1.34 (4) D, both for benzene solutions a t 25", have previously been reported.T o test the suggestion (4) that erroneously high dipole moments may arise from the presence of water, a second series of measurements, this time a t 25", was made a t 11 concentrations between 0.0009 and 0.0097 weight fraction of dioxolane. For this series, dioxolane and cyclohexane were 'Issued as N.R.C. No. 9330. ZNow at the Canadian General Electric Co., Toronto, Ontario.aSummer student, 1966.stored over calcium hydride and solutions were prepared in a dry box. T h e resulting dipole moment was 1.467 rt 0.012 D. Indirect confirmation that the proper dipole moment is "high" is proved by the Onsager dipole moment of the liquid and the limiting high-frequency dielectric constant of the hydrate (see below). Dielectric Constant of DioxolaneValues of the static dielectric constant of liquid dioxolane a t 10 kc s-' and a t 19 temperatures between +25 and -103" are given by €0 = -1.644 + 2571/T to an average deviation of less than 0.2y0. . A t +20°, €0 = 7.13, n~ = 1.4000 k 0.0002, and the density = 1.0600 g cm-3 (4). Use of these values in the Onsager equation yields a dipole moment of 1.59 D. Dioxolane HydrateT h e dielectric behavior outlined below shows the formation by dioxolane of a typical clathrate hydrate which was found to melt congruently a t -3".Dielectric constants and losses were measured a t frequencies between 0.050 and 500 kc s-I over a range of temperatures for three samples of composition between 16.4 and 17.0 water molecules per molecule of dioxolane (D) . Representative complex dielectric constant loci of the D .17H20 sample are shown in Fig. 1. T h e other samples exhibited similar loci a t the higher temperatures, but a t lower temperatures

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The thermal diffusivity of a biaxial weave alumina-fiberreinforced chemical-vapor-deposited (CVD) Sic composite heated to 1500°C, which is above the manufacturing temperature, was found to exhibit an increase for heat flow parallel to the fiber plane, whereas a decrease was observed perpendicular to the fiber plane. The increase parallel to the fiber plane was thought to be due to the annealing of the fibers and matrix. The decrease perpendicular to the fiber plane was found to be the result of interfacial debonding and matrix cracking within the plane of the fibers. [