A method of classifying coals by determining the ratio that exists between the carbon and hydrogen present in them. Thus, if a given coal contains 80% carbon and 5% hydrogen, the C/H ratio would be 80:5, or 16. Bituminous coals have a C/H ratio between 14 and 17, and most anthracites have a ratio between 24 and 29. Abbreviation: C/H ratio.