Results of the gas quality analysis program for Project Rulison are presented and compared with previous experience. In general, the Rulison results complement those reported for Project Gasbuggy. Anomalous behavior of CO2 and H2 was seen in both experiments and is assumed to be due to ebullition of these gases from chimney water. Also, a CO2 source free of 14C and 85Kr was identified in the Rulison experiment, suggesting late-time liberation of this gas from carbonate minerals. Dilution effects, resulting from gas production plus formation gas influx, appear to control the concentrations of other chimney gas components. Water leakage into the Gasbuggy chimney strongly affected the chemical distribution of tritium in that experiment. No such dilution is suspected at Rulison, and the tritium exchange between hydrogen gas and water appears to have maintained equilibrium throughout the production testing period. Tritium apparently was not exchanged between the hydrocarbon gases and hydrogen or water in either nuclear chimney except at very early times, although an unexplained decrease in the CH3T/85Kr ratio was observed during production testing of Project Gasbuggy.