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SL- and AT-cut quartz crystal resonators which are commonly used in frequency control devices were examined in the scanning electron microscope. The quartz slices were resonated at frequencies ranging from 455 kHz to 15 MHz. Variations in surface charges which were produced during resonance strongly affected secondary electron emission. Therefore, micrographs could be obtained which were characteristic of the various modes of motion of the resonators. From displacements of topographical features during resonance approximate values for the amplitudes of face and thickness shear were obtained.

1,4‐Dioxan, Tetrahydrofuran and Dimethoxyethan were dried over potassium and subsequently degassed, under high vacuum conditions. The u. v. spectra and the electric conductivities of the high purity ethers were measured. The solvents could be stored under high vacuum conditions for an unlimited period of time, without any changes of their physico‐chemical properties. Treatment with potassium under high vacuum conditions caused a partial cleavage of the high purity ethers resulting in increased electric conductance and absorption of light.