The fact that cyclo-octatetraene—in contrast to benzene—shows a markedly unsaturated character has generally been used as an argument in favour of the assumption that the molecule contains alternate double and single bonds. The resonance energy, which is not much smaller per CH-group than that of benzene, makes the correctness of this assumption seem rather doubtful. On the other hand, a preliminary Raman analysis leads E. R. Lippincott and R. C. Lord, jun.1, to believe that the spectrum can best be interpreted on the basis of a puckered eight-membered ring with alternate single and double bonds.