It is shown experimentally that the relative motion of the superfluid and normal components of He II in a second-sound wave is accompanied by the appearance of electric induction. The process is reversible. It is shown that the amplitude ratio of the temperature and induction potential oscillations is a temperature-independent constant equal to 2.3×104 K/V.

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High-precision pressure measurements in solid 4 He, grown by the capillary blocking technique, have been made in temperatures range from 50 to 500 mK. The temperature dependence of pressure indicates that aside from the usual phonon contribution ϳT 4 , there is an additional contribution ϳT 2 , the latter becoming dominant at temperatures T Ͻ 300 mK, where an abnormal behavior attributed to supersolidity has been observed. The data suggest the appearance of a glassy phase ͑that might be responsible for the anomalous behaviors observed previously͒. A dramatic pressure decrease has been observed under annealing of the samples. The glassy contribution to the pressure can be eliminated in well-annealed crystals.