Ash, as determined by this test method, is the residue
remaining after burning the coal and coke. Ash obtained differs
in composition from the inorganic constituents present in the
original coal. Incineration causes an expulsion of all water, the
loss of carbon dioxide from carbonates, the conversion of iron
pyrites into ferric oxide, and other chemical reactions. Ash, as determined by this test method, will differ in amount from ash
produced in furnace operations and other firing systems because
incineration conditions influence the chemistry and
amount of the ash. References for correcting ash results
determined by this test method to a mineral-matter-free basis
are listed in Classification D388,