Annealing Of Glass

The rate of removal of mechanical strain should follow maxwells first order law but for glasses it has been found that the rate is proportional to the square of the birefringence. The authors explain this in terms of the structural picture of glass. During annealing the stress optical constant of the glass as well as its viscosity undergoes a continuous change. Birefringence is not a correct measure of the stress and the adams-williamson findings are only apparently in contradiction to the classical derivation of maxwell.