This report covers the experimental findings of a one year project to investigate the interaction between the guest (aliphatic) and host (aromatic) components of coal. A short overview of the current status of coal chemistry and coal formation is given. The thermal behavior of ..cap alpha..-hydroxycarboxylic acids is studied and polymers prepared from them. Coals are solvent extracted and the extraction behavior discussed. Pyrolytic events of coals are quantified and evaluated with regard to the gasification of coal. Results show that only small fractions of coal are extracted by nonreactive solvents below 100/sup 0/C, whereas reactive solvents, such as amines, extract significant amounts by dismembering the host. Other results show that the pyrolysis of coal is characterized by five thermal events which are quantified and related to chemical events and energies of reaction. The aliphatic material in bituminous coals is demonstrated to be separate from the aromatic component up to the micrometer size and evidence for the introduction of the aliphatic component by plants via triglycerides along with the bulk of the coal is presented. 82 refs., 60 figs., 11 tabs.