Abstract
The velocity of the α-β transition was measured in two cases, i.e., when α-crystals stayed in the saturated aqueous solution, and when they were left to stand in an air-bath at various temperatures ranging from 20° to 100°C. And it was deduced from the results of the measurement that this transition is due to the recrystallization of α-crystals into the β-form on the inner surfaces of the crystal and in the bulk of the solution, and the transition on the inner surfaces will be dominant, especially at the initial stage of the transition.