Letter from Thomas Gold to Dr Wolfgang Seiler, Max-Planck-Institut fur Chemie, Chemie der Atmosphare und Physikalische Chemie der Isotope, Saarstrasse 23,D-6500 Mainz, West Germany Thanks him for his letter. Is enclosing some of the papers on the subject of the deep Earth gas. There is a great deal of evidence also in the Soviet and in the Japanese literature, and Gold will send him some reference to this. Discusses the present status of the CH4 change form 1.4 ppm to 1.8 ppm. 19 September 1979