Work done during the third quarter of this contract is presented. Several new subroutines were developed for calculating quantities such as the mass sources due to gas phase and heterogeneous reactions, the transport properties and thermodynamic properties of gaseous mixtures, and heat transfer through the reactor walls. Also, several subroutines in the Baum-Levine program have been modified for use in the pulsating coal gasification program. Several of the newly developed and modified subroutines have also been checked out for their proper operation. This testing will continue into the fourth quarter at the completion of which parametric studies will begin. Considerable progress has also been accomplished during this quarter in the development of the boundary routines. This work involves: (1) the development of the characteristic equations; (2) the determination of the gasifier boundary conditions; and (3) the development of the boundary routines for solving the characteristic equations subject to the specified boundary conditions. The first part of this development has been completed. The second part of the problem has turned out to be more difficult than anticipated and work is currently underway to resolve it. It is expected that this problem will be resolved and the boundary routines developed within the fourth quarter of the research program. 10 refs., 3 figs.