  We present evidence that solar structure changes with changes in solar
activity. We find that the adiabatic index, Gamma_1, changes near the second
helium ionization, i.e., at a depth of about 0.98 R_sun. We believe that this
change is a result of the change in the effective equation of state caused by
magnetic fields. Inversions should be able to detect the changes in Gamma_1 if
mode sets with reliable and precise high-degree modes are available.
