05-08U

The present work contains results of experimental investigation of external factors, such as dessicating/wetting, thermal annealing, uniaxial pressures, hydrostatic pressure on dielectric permittivity of Rochelle salt crystals. The obtained results are compared with available literature data. A conclusion is made that the dispersion of experimental data can be attributed to internal polar point defects in crystals and to influence of storage conditions. The field and stress dependences of permittivity are analyzed within the phenomenological Landau approach.