1. Cf. Djerassi, C., Chem. Rev., 43, 271 (1948).
2. Hebbelynck, M., and Martin, R. H., Bull. Soc. Chim. Belg., 59, 193 (1950).
3. Cf. Noyes, jun., W. A., and Leighton, Ph. A., “The Photochemistry of Gases”, 84 (A.C.S. Monograph 86, N.Y., 1941).
4. Cf., for example, the recent results of Ritchie, M., and Winning, W. I. H., J. Chem. Soc., 3579 (1950).
5. Cf. the experiments on prepyrolysis of acetaldehyde ( Niclause, M., Goldfinger, P., and Letort, M., C.R. Acad. Sci., Paris, 229, 437 (1949), based on the same idea.