During the fourth quarter work continued on modifying the reactor. Scatter in the analysis of gas tar, and soot was improved by collecting the products without separating during the run and separating and sampling from the collected mixture. Data for a Kentucky No. 9 Bituminous were collected using the modified system at a furnace temperature of 1100/sup 0/C. The general behavior of the various species is similar to the data on the Beulah Lignite except that the quantities of species vary. Work continued on elucidating the mechanisms of particle swelling. Selected samples for a Pittsburgh Seam coal which exhibits both swelling and non-swelling, depending on heating conditions, were examined by electron microscopy. The micrographs show the sequence followed in swelling and where departures occur for the non-swelling case. The governing equations for bubble growth and rupture are discussed and the physical parameters for coal are considered. The bubble growth and rupture equations will be integrated into the pyrolysis theory. Work continued on applying AFR's pyrolysis model to other entrained flow reactors. The simulations are compared to data from the Penn State entrained flow reactor. 14 refs., 25 figs. 11 tabs.