The program of work on the perturbation of spectral frequencies by solid matrices in the vacuum ultraviolet is a kind of an extension of the observations of pressure effects on spectral lines under various high pressures of foreign gas as outlined by Vodar B. Vodar, Proc. Roy. Soc. A255, 44 1950. In this difficult region, this study was made of the absorption spectra of atoms in the ultraviolet commencing with the relatively simple mercury whose resonance lines lie at 2537 A and 1850 A and then to the more difficult cases of xenon with its lines at 1469 A and 1296 A and finally to krypton with its lines at 1236 A and 1165 A. This study of the complete spectra of xenon and of krypton both in the pure state and in rare gas matrices using the direct absorption spectrum technique is believed to be the first of its kind. Results in general agree with those of G. Baldini obtained in a different way. Results with xenon in krypton and krypton in argon and the preliminary results with krypton in neon are quite new as they have not yet been repeated by others.