Function W(r) for solar envelope models with heavy‐element abundance ﹩Z=0.0181﹩ constructed with CEFF equation of state but for different heavy‐element mixtures, as marked in the figure. These mixtures include cases where the relative abundance of C, N, or O are increased by a factor of 2 over the GS value. All these models have the convection zone base at ﹩r_{b}=0.7133﹩ R_⊙, and have a hydrogen abundance ﹩X=0.739﹩.