II. The internal fiction peak observed near room temp. in tank plate glass at a period of the order of seconds and previously attributed to Na+ion diffusion is further discussed. The temp. of max. internal friction is shown to vary with the frequency of vibration with an activation energy of about 16 k.cal/mol. for air chilled glass. (8 figs) III. Heat treatment or annealing decreases the internal friction peak commonly attributed to Na+ diffusion in tank plate glass, a typical soda lime silica glass. The peak if shifted to higher temps. as constant frequency of vibration or to lower frequencies at constant temp. The activation energy for the shift is greater in the annealed glass and agrees with the activation energy for the electrical conductivity and alkali durability of annealed glass. Heat treatment also decreases the internal friction caused by elastico viscous effects. (5 figs., 1 table.) IV. The residual change and anomalous absorption current reported for certain glasses can be explained by making reference to internal friction peaks caused by the stress diffusion of Na+ or K+ions. When an electrical potential gradient or "electrical stress" is applied to any of these glasses, the "induced electrical strain" is associated with the time consuming formation of a new equilibrium distribution of Na+.(2 figs)
