α-METHYLSTYRENE has been polymerized at 25° C., using stannic chloride as catalyst, both in solution and in undiluted monomer, giving polymers of molecular weight up to approximately 11,000. Staudinger1, using this catalyst, obtained only a very low degree of polymerization (up to octamer), presumably due to the high temperatures reached in his experiments. The molecular weight of the polymer can be increased three-fold by polymerizing at 0° C., in agreement with the aluminium chloride-catalysed reaction2.