The presence of isopropyl groups in amber in larger amounts is regarded as the crucial point of the problem. The deformation bands of an isopropyl group are now identified in amber as well as in its derivatives. Terpenes with isopropyl groups are found in amber oil as well as in pyrolysates of amber. Dehydrogenation of reduced amber samples yield homoretene and mass spectra show the masses of dimeric abietic acid as well as of propylene. The differences between succinin and copal-polymerisates are listed. Mass spectra show the Baltic amber to be essentially the same as the earlier ambers of the Landenien and Montien. Since Baltic amber normally is found on secondary, tertiary or even farther deposits, while the other ambers mentioned are in their primary deposit, amber is claimed to have originated in the Cretaceous. See also <i>AATA</i> <b>23-2786</b> (following abstract). -- AATA