Evidence has been found that solid solution of 10 mol% lead titanate in lead magnesium niobate bears strong resemblance to spin and dipolar glasses. The frequency dispersion of the temperature of the permittivity maximum, Tm, has been analyzed using the Vogel-Fulcher relationship. The difference between the solid solution and glass was discussed. Based on this analysis, a new ralationship:ω = ω0exp {- (T0/Tm)p},was introduced which is more suitable and effective for relaxor ferroelectrics to analyze the frequency dispersion of the temperature of the permittivity maximum than Vogel-Fulcher relationship. The dielectric relation of the solid solution was measured The results were analyzed using the new relationship, and activation energy of 0.037 eV was obtaived.