1. See Part 1 of the collected papers of W. H. Carothers, in Vol. 1 of "High Polymers" (Interscience Publishers, Inc., New York, 1940).
2. For a more detailed discussion of this question see Whinfield, Chem. and Ind., 62, 354 (1943).
3. J. Amer. Chem. Soc., 31, 1919 (1909).