GELIFICATION OF WOOD DURING COALIFICATION.

Coalified wood was examined by SEM and CPMAS**1**3C NMR to delineate chemical and physical alterations responsible for gelification. Early coalification selectively degrades cellulosic components, preserving lignin-like components that are eventually transformed to coal. Cellular morphology persists until the chemical composition becomes uniform, at which point the cells coalesce under compaction and gelify.