Yallourn brown coal and its calcium form have been pyrolyzed in three different gas mixtures: 23% methane in argon, 50% hydrogen in argon, and 9. 4% toluene in argon, at heating rates of 10**7 K s** minus **1 and residence times of approx. 2 ms. The products have been compared with those obtained in the argon. The highly reactive molecule, ketene, was detected in the pyrolysate gases from both the 'raw' and calcium-form coals when pyrolyzed in the above mixtures. Ketene was not detected in the pyrolysate gases, however, when the coals were pyrolyzed in argon alone. When pyrolyzed in 23% methane/argon the maximum yield of carbon monoxide from the 'raw' coal was found to be much lower than when pyrolyzed in pure argon.
