Letter from Thomas Gold to Dr L K Levsky, University Embankment 7/9, Leningrad State University, Institute of Earth Crust, Leningrad, 199164, USSR Encloses his recent paper on the outgassing of the Earth, and wonders whether Levsky has any observational material of relevance to this. Gold is of course aware of the generally known noble gas and isotopic information, and also of some information based on noble gases that indicate a regionally different mantle composition. He will certainly be very interested in Levsky's comments. 1 February 1979