The exchange of CH4 in tritium has been measured at concentrations of 1.45 and3.00 mol% to display the time evolution of CT4. It is observed that the total methane concentration decreases with time, and no masses >24 amu are observed using mass spectroscopy. After 18 months, only 0.2% CT4 gas remained in the 3.00% CH4 experiment. These observations indicate that carbon is being removed from the gas phase. A model based on ion/molecule interactions is presented to explain the formation of CT4 and free carbon.