Letter from Thomas Gold to Professor Mike MacElroy, Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts Encloses the addition to his paper on outgassing of the Earth, showing up the reation to atmospheric oxygen. Tthe figures can be pushed around a little, but cannot make ends meet with the carbon all supplied as CO2. States it is curious that this has not been discussed before. The other point is that the atmospheric oxygen is likely to have varied a great deal as tectonic processes varied. 28 April 1978