Abstract
In order to find out new ways of chemical utilization of coal, it is important to investigate thoroughly its essence. Many studies have so far been done on the structure of coal, however, there still remain many unsolved questions such as the size of structural unit, its chemical structure, and the construction of coal molecule from the unit.
The author made clear the chemical structure of regenerated humic acid obtained from the nitric oxidation of coal. He then showed with the model that humic acid, whose primary structural unit is considered C25H24O1.2, is made by means of the ether-linkage of the unit. Its molecular weight is about several thousands. He also made clear that the coal molecule has heterogeneous stucture consisting of two different struc-tural parts: the aromatic part forming skeleton of humic acid, and the hydro-aromatic part which combines its stuctural unit.
