Dielectric losses and dielectric constants at radio frequencies for nitrobenzene, water and xylene. The method of resistance variation was used to measure the phase difference psi and dielectric constant K for frequencies between 2 x 105 and 14 x 105 cycles/sec. Special cells were required. (1) Variation with frequency. The results agree approximately with the equations: For carefully dried nitrobenzene at 30°C, psi = .028° + 6.03 x 104/f; for distilled water at 23.5°, psi = 0.8° + 2.09 x 106/ f. These indicate that in addition to the true dielectric loss there is a leakage through the liquid proportional to 1/f. For xylene, psi was too small to measure, less than .01° at 3 x 10 5 cycles. K was found to be practically independent of the frequency, being 2.24 for xylene and of the order of 100 for water. (2) Variation with temperature, for nitrobenzene. K decreased from 42 at 20° to 24 at 14.2°, while psi increased in the same range in the ratio of 7 to 1. These values were obtained, however, for a sample of nitrobenzene for which psi was 12 times as great as for a carefully dried sample.