Moisture in coal and significance of accurate determination of oxygen. [19 refs]

Fundamentally one might expect to distinguish four types of moisture in coal: (1) surface moisture (adsorbed moisture), (2) inherent moisture (equilibrium moisture), (3) decomposition moisture (organic moisture), and (4) moisture due to mineral matter present in coals (water of hydration). Experimentally, however, these moisture categories cannot readily be distinguished. In practice the coal analyst determines moisture in procedures amenable to the different stages of coal handling and utilization. Four categories of moisture are distinguished in the analytical process called the Proximate Analysis of Coal, which also includes the determination of Coal Ash, the estimation of the Mineral Matter based on ash, the determination of the Volatile Matter and that of the Fixed Carbon. The four classes of moisture customarily determined in coal can be essentially grouped by steps: (1) the As-Received Moisture, which is also called the total moisture (the adsorbed surface plus the absorbed inherent capillary moisture); (2) the Air-Dried Moisture, which is that moisture left after air drying; (3) the Air-Dry Moisture, which is lost by drying in air an as is coal sample under conditions close to ambient; and (4) the Equilibrium Moisture. Descriptions of the methods used are presented.