The thermal decomposition of oxalates of ammonium and potassium was studied by simultaneous TGA, DTA, and EGA (effluent gas analysis). Of the simple oxalates, the potassium compound is more stable than the lithium compound, as has been observed for the corresponding carbonates and sulfates.Ammonium oxalate is much less stable than either of the alkali metal oxalates. Potassium titanyl oxalate is less stable than potassium oxalate, and ammonium titanyl oxalate is more stable than ammonium oxalate.Ia I

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289tivation energy must involve the dependence of the internal state of the glass on cooling rate.The high-temperature curvature of the permeability plots may also be related to the internal state of the glass. At the higher temperatures (about 35OoC), where curvature begins to appear, the ions of the glass network may gain the mobility necessary to allow the structure to relax or to alter the structural configuration. This alteration, which may be a slight change in bond angles or density, could then affect the permeation rate. Thus, the high-temperature curvature and the dependence of permeation behavior on cooling rate are phenomena related to the internal state of the glass.