. . . . . . . "Among suitable hydrolysis catalysts are ones that comprise a material selected from the group consisting of phosphoric acid and acid phosphates, alkali metal hydroxides and carbonates, such as sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, alkali metal silicates, alkaline earth metal hydroxides and oxides, aluminum hydroxide and oxides, and mixtures of two or more of" . . . .